NAPAC2016 - List of Keywords (ion)

Paper	Title	Other Keywords	Page
MOA2IO02	The BNL EBPM Electronics, High Performance for Next Generation Storage Rings	storage-ring, feedback, operation, experiment	1
	K. Vetter ORNL, Oak Ridge, Tennessee, USA W.X. Cheng, J. Mead, B. Podobedov, Y. Tian BNL, Upton, Long Island, New York, USA
	Funding: DOE contract DE-AC02-98CH10886 A custom state-of-the-art RF BPM (EBPM) has been developed and commissioned at the Brookhaven National Laboratory (BNL) National Synchrotron Light Source II (NSLS-II). A collaboration between Lawrence Berkeley National Laboratory (LBNL) Advanced Light Source (ALS) and BNL has proven to be a key element in the success of the NSLS-II EBPM. High stability coherent signal processing has allowed for demonstrated 200nm RMS spatial resolution and true turn-by-turn position measurement capability. Sub-micron 24 hr. stability has been demonstrated at NSLS-II by use of 0.01C RMS thermal regulation of the electronics racks without the need of active pilot tone correction.
	Slides MOA2IO02 [4.334 MB]
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MOA2CO03	Measurement of Tune Shift with Amplitude from BPM Data with a Single Kicker Pulse	kicker, feedback, lattice, experiment	6
	Y. Hidaka, W.X. Cheng, B. Podobedov BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886. Measurements of amplitude-dependent tune shift are critical for understanding of nonlinear single particle dynamics in storage rings. The conventional method involves scanning of the kicker amplitude while having a short bunch train at the top of the kicker pulse. In this paper we present a novel, alternative technique that uses a long continuous bunch train, or a sequence of bunch trains, that are spread along the ring, such that different bunches experience different kick amplitudes with a single shot of a kicker pulse. With these beams, a curve of tune shift with amplitude can be extracted from the recently added new NSLS-II BPM feature called gated turn-by-turn (TbT) BPM data that can resolve bunches within a turn, either alone or together with a bunch-by-bunch BPM data. This technique is immune to pulse-to-pulse jitters and long-term machine drift.
	Slides MOA2CO03 [1.961 MB]
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MOA2CO04	MICE Operation and Demonstration of Muon Ionization Cooling	emittance, simulation, optics, cavity	10
	A. Liu Fermilab, Batavia, Illinois, USA
	Funding: DOE, NSF, STFC, INFN, CHEPP and more The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling, the only technique that, given the short muon lifetime, can reduce the phase-space volume occupied by a muon beam quickly enough. MICE will demonstrate cooling in two steps. In the first one, Step IV, MICE will study the multiple Coulomb scattering in liquid hydrogen (LH₂) and lithium hydride (LiH). A focus coil module will provide focusing on the absorber. The transverse emittance will be measured upstream and downstream of the absorber in two spectrometer solenoids (SS). Magnetic fields generated by two match coils in the SSs allow the beam to be matched into flat-field regions in which the tracking detectors are installed. This paper will present preliminary results and present plans for data taking of MICE Step IV, together with the design of the MICE Cooling Demonstration Step (Step DEMO), which requires addition of RF systems in the current setup.
	Slides MOA2CO04 [10.025 MB]
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MOB2CO03	Collider in the Sea: Vision for a 500 TeV World Laboratory	collider, luminosity, hadron, dipole	13
	P.M. McIntyre, S.P. Bannert, J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov Texas A&M University, College Station, USA S. Assadi HiTek ESE LLC, Madison, USA D. Chavez DCI-UG, León, Mexico N. Pogue LLNL, Livermore, California, USA
	A design is presented for a hadron collider in which the magnetic storage ring is configured as a circular pipeline, supported in neutral buoyancy in the sea at a depth of ~100 m. Each collider detector is housed in a bathysphere the size of the CMS hall at LHC, also neutral-buoyant. Each half-cell of the collider lattice is ~300 m long, housed in a single pipe that contains one dipole, one quadrupole, a correction package, and all umbilical connections. A choice of ~4 T dipole field, 2000 km circumference provides a collision energy of 700 TeV. Beam dynamics is dominated by synchrotron radiation damping, which sustains luminosity for >10 hours. Issues of radiation shielding and abort can be accommodated inexpensively. There are at least ten sites world-wide where the collider could be located, all near major urban centers. The paper summarizes several key issues; how to connect and disconnect half-cell segments of the pipeline at-depth using remote submersibles; how to maintain the lattice in the required alignment; provisions for the injector sequence.
	Slides MOB2CO03 [3.440 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOB2CO03
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MOB2CO04	Multiphysics Analysis of Crab Cavities for High Luminosity LHC Upgrade	cavity, luminosity, simulation, electromagnetic-fields	17
	O. Kononenko, Z. Li SLAC, Menlo Park, California, USA R. Calaga, C. Zanoni CERN, Geneva, Switzerland
	Funding: The work is supported by U.S. Department of Energy under Contract No. DE-AC02-76SF00515. Development of the superconducting RF crab cavities is one of the major activities under the high luminosity LHC upgrade project that aims to increase the machine discovery potential. The crab cavities will be used for maximizing and leveling the LHC luminosity hence having tight tolerances for the operating voltage and phase. RF field stability in its turn is sensitive to Lorentz force and external loads, so an accurate modelling of these effects is very important. Using the massively parallel ACE3P simulation suite developed at SLAC, we perform a corresponding multiphysics analysis of the electro-mechanical interactions for the RFD crab cavity design in order to ensure the operational reliability of the LHC crabbing system.
	Slides MOB2CO04 [5.725 MB]
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MOA3IO01	High Energy Coulomb Scattered Electrons Detected in Air Used as the Main Beam Overlap Diagnostics for Tuning the RHIC Electron Lenses	electron, proton, alignment, detector	20
	P. Thieberger, Z. Altinbas, C. Carlson, C. Chasman, M.R. Costanzo, C. Degen, K.A. Drees, W. Fischer, D.M. Gassner, X. Gu, K. Hamdi, J. Hock, Y. Luo, A. Marusic, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin BNL, Upton, Long Island, New York, USA S.M. White ESRF, Grenoble, France
	Funding: Work supported by Brookhaven Science Associates under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy A new type of electron-ion beam overlap monitor has been developed for the RHIC electron lenses. Low energy electrons acquire high energies in small impact parameter Coulomb scattering collisions with relativistic ions. Such electrons can traverse thin vacuum windows and be conveniently detected in air. Counting rates are maximized to optimize beam overlap. Operational experience with the electron backscattering detectors during the 2015 p-p RHIC run will be presented. Other possible real-time non-invasive beam-diagnostic applications of high energy Coulomb-scattered electrons will be briefly discussed. Most of this material appears in an article by the same authors entitled "High energy Coulomb-scattered electrons for relativistic particle beam diagnostics", Phys. Rev. Accel. Beams 19, 041002 (2016)
	Slides MOA3IO01 [2.164 MB]
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MOA3CO03	Bunch Shape Monitor Measurements at the LANSCE Linac	linac, electron, target, detector	25
	I.N.D. Draganic, D. Baros, C.M. Fortgang, R.W. Garnett, R.C. McCrady, J.F. O'Hara, L. Rybarcyk, C.E. Taylor, H.A. Watkins LANL, Los Alamos, New Mexico, USA A. Feschenko, V. Gaidash, Yu.V. Kiselev RAS/INR, Moscow, Russia
	Two Bunch Shape Monitors (BSM) [1] have been developed, fabricated and assembled for the first direct longitudinal beam measurements at the Los Alamos Neutron Science Center (LANSCE) linear accelerator (linac). The BSM detectors use different radio frequencies for the deflecting field: first harmonic (201.25 MHz) and second harmonic (402.5 MHz) of fundamental accelerator radio frequency. The first BSM is designed to record the proton beam longitudinal phase distribution after the new RFQ accelerator at a beam energy of 750 keV with phase resolution of 1.0 degree and covering phase range of 180 degree at 201.25 MHz. The second BSM is installed between DTL tanks 3 and 4 of the LANSCE linac in order to scan both H⁺ and H⁻ beams at a beam energy of 73 MeV with a phase resolution up to 0.5 degree in the phase range of 90 degree at 201.25 MHz. Preliminary results of bunch shape measurements for both beams under different beam gates (pulse length of 150 us, 1 Hz repetition rate, etc.) will be presented and compared high performance simulation results (HPSIM) [2]. [1] A. Feschenko, Proc. of RUPAC2012, FRXOR01, Saint Petersburg, Russia, pp. 181 - 185. [2] X. Pang, L. Rybarcyk, and S. Baily, Proc. of HB2014, MOPAB30, East Lansing, MI, USA, pp. 99-102.
	Slides MOA3CO03 [4.942 MB]
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MOA3CO04	Operational Experience with Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators	undulator, operation, site, kicker	28
	J.C. Dooling, K.C. Harkay, V. Sajaev, H. Shang ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-m-long SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps* by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS. K. Harkay et al., these proceedings
	Slides MOA3CO04 [1.188 MB]
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MOB3IO01	Commissioning of the Phase-I SuperKEKB B-Factory and Update on the Overall Status	electron, vacuum, emittance, coupling	32
	Y. Ohnishi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, Y. Funakoshi, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong KEK, Ibaraki, Japan M.E. Biagini, M. Boscolo, S. Guiducci INFN/LNF, Frascati (Roma), Italy D. El Khechen LAL, Orsay, France
	The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented.
	Slides MOB3IO01 [10.375 MB]
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MOB3IO02	LHC Operation at 6.5 TeV: Status and Beam Physics Issues	luminosity, operation, MMI, radiation	37
	G. Papotti, M. Albert, R. Alemany-Fernandez, E. Bravin, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, G. Iadarola, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, T. Persson, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J. Wenninger CERN, Geneva, Switzerland
	LHC operation restarted in 2015 after the first Long Shutdown, planning for a 4-year long run until the end of 2018 (called Run 2). The beam energy was fixed at 6.5 TeV. The year 2015 was dedicated to establishing operation at the high energy and with 25 ns beams, in order to prepare production for the following three years. The year 2016 was the first one dedicated to production, and it turned out to be a record-breaking year, in which the goals in both peak and integrated luminosities with proton-proton beams were achieved and surpassed. This paper revisits 2015 and 2016, shortly highlighting the main facts in the timelines, recalling the parameters that characterized luminosity production, and sketching the main limitations and the main highlights of results for selected topics, including a particular focus on the beam physics issues.
	Slides MOB3IO02 [15.183 MB]
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MOB3CO03	RHIC Au-Au Operation at 100 GeV in Run16	operation, cavity, luminosity, electron	42
	X. Gu, J.G. Alessi, E.N. Beebe, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, J.P. Jamilkowski, J.S. Laster, V. Litvinenko, C. Liu, Y. Luo, M. Mapes, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, I. Pinayev, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, Q. Wu, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang BNL, Upton, Long Island, New York, USA
	In order to achieve higher instantaneous and integrated luminosities, the average Au bunch intensity in RHIC has been increased by 30% compared to the preceding Au run. This increase was accomplished by merging bunches in the RHIC injector AGS. Luminosity leveling for one of the two interaction points (IP) with collisions was realized by continuous control of the vertical beam separation. Parallel to RHIC physics operation, the electron beam commissioning of a novel cooling technique with potential application in eRHIC, Coherent electron Cooling as a proof of principle (CeCPoP), was carried out. In addition, a 56 MHz superconducting RF cavity was commissioned and made operational. In this paper we will focus on the RHIC performance during the 2016 Au-Au run.
	Slides MOB3CO03 [2.173 MB]
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MOB3CO04	High Luminosity 100 TeV Proton-Antiproton Collider	proton, collider, antiproton, quadrupole	45
	S.J. Oliveros, J.G. Acosta, L.M. Cremaldi, T.L. Hart, D.J. Summers UMiss, University, Mississippi, USA
	The energy scale for new physics is known to be in the multi-TeV range, signaling the potential need for a collider beyond the LHC. A 10³⁴ cm−2 s−1 luminosity 100 TeV proton-antiproton collider is explored. Prior engineering studies for 233 and 270 km circumference tunnels were done for Illinois dolomite and Texas chalk signaling manageable tunneling costs. At a ppbar the cross section for high mass states is of order 10x higher with antiproton collisions, where antiquarks are directly present rather than relying on gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets, because lower beam currents can produce the same rare event rates. In our design the increased momentum acceptance (11 ± 2.6 GeV/c) in a Fermilab-like antiproton source is used with septa to collect 12x more antiprotons in 12 channels. For stochastic cooling, 12 cooling systems would be used, each with one debuncher/momentum equalizer ring and two accumulator rings. One electron cooling ring would follow. Finally antiprotons would be recycled during runs without leaving the collider ring, by joining them to new bunches with synchrotron damping.
	Slides MOB3CO04 [1.304 MB]
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MOA4IO01	Performance of the Low Charge State Laser Ion Source in BNL	laser, target, plasma, ion-source	49
	M. Okamura, J.G. Alessi, E.N. Beebe, M.R. Costanzo, L. DeSanto, S. Ikeda, J.P. Jamilkowski, T. Kanesue, R.F. Lambiase, D. Lehn, C.J. Liaw, D.R. McCafferty, J. Morris, R.H. Olsen, A.I. Pikin, R. Schoepfer, A.N. Steszyn BNL, Upton, Long Island, New York, USA
	In March 2014, a Laser Ion Source (LIS) was commissioned which delivers high brightness low charge state heavy ions for the hadron accelerator complex in Brookhaven National Laboratory (BNL). Since then, the LIS has provided many heavy ion species successfully. The induced low charge state (mostly singly charged) beams are injected to the Electron Beam Ion Source (EBIS) where ions are then highly ionized to fit to the following accelerator's Q/M acceptance, like Au³²⁺. Last year, we upgraded the LIS to be able to provide two different beams into EBIS on a pulse-to- pulse basis. Now the LIS is simultaneously providing beams for both the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL). In the conference we present achieved performance and developed new techniques of the LIS.
	Slides MOA4IO01 [7.796 MB]
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MOA4IO02	Recent Progress in High Intensity Operation of the Fermilab Accelerator Complex	proton, booster, target, experiment	54
	M.E. Convery Fermilab, Batavia, Illinois, USA
	We report on the status of the Fermilab accelerator complex. Beam delivery to the neutrino experiments surpassed our goals for the past year. The Proton Improvement Plan is well underway with successful 15 Hz beam operation. Beam power of 700 kW to the NOvA experiment was demonstrated and will be routine in the next year. We are also preparing the Muon Campus to commission beam to the g-2 experiment.
	Slides MOA4IO02 [3.574 MB]
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MOA4CO03	Complete Beam Dynamics of the JLEIC Ion Collider Ring Including Imperfections, Corrections, and Detector Solenoid Effects	dynamic-aperture, multipole, solenoid, detector	57
	G.H. Wei, F. Lin, V.S. Morozov, F.C. Pilat, Y. Zhang JLab, Newport News, Virginia, USA Y.M. Nosochkov SLAC, Menlo Park, California, USA M.-H. Wang Self Employment, Private address, USA
	Funding: This paper has been authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported also by the U.S. DOE Contract DE-AC02-76SF00515. The JLEIC is proposed as a next-generation facility for the study of strong interaction (QCD). Achieving its goal luminosity of up to 1034 cm^-2s⁻¹ requires good dynamical properties and a large dynamic aperture (DA) of ~ ±10 σ of the beam size. The limit on the DA comes primarily from non-linear dynamics, element misalignments, magnet multipole components, and detector solenoid effect. This paper presents a complete simulation including all of these effects. We first describe an orbit correction scheme and determine tolerances on element misalignments. And beta beat, betatron tunes, coupling, and linear chromaticity perturbations also be corrected. We next specify the requirements on the multipole components of the interaction region magnets, which dominate the DA in the collision mode. Finally, we take special care of the detector solenoid effects. Some of the complications are an asymmetric design necessary for a full acceptance detector with a crossing angle of 50 mrad. Thus, in addition to coupling, the solenoid causes closed orbit excursion and excites dispersion. It also breaks the figure-8 spin symmetry. We present a scheme with correction of all of these effects.
	Slides MOA4CO03 [1.502 MB]
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MOA4CO04	Compact Carbon Ion Linac	linac, DTL, rfq, accelerating-gradient	61
	P.N. Ostroumov, A. Goel, B. Mustapha, A. Nassiri, A.S. Plastun ANL, Argonne, USA L. Faillace, S.V. Kutsaev, E.A. Savin RadiaBeam, Marina del Rey, California, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under Accelerator Stewardship Grant, Proposal No. 0000219678. Argonne National Laboratory is developing an Advanced Compact Carbon Ion Linac (ACCIL) in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver up to 10⁹ carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. To optimize the linac design in this energy range both backward traveling wave and coupled cell standing wave S-band structures were analyzed. To achieve the required accelerating gradients our design uses accelerating structures excited with short RF pulses (~500 ns flattop). The front-end accelerating structures such as the RFQ, DTL and Coupled Cell DTL are designed to operate at lower frequencies to maintain high shunt impedance. In parallel with our design effort ANL's RF test facility has been upgraded and used for the testing of an S-band high-gradient structure designed and built by Radiabeam for high pulsed RF power operation. The 5-cell S-band structure demonstrated 52 MV/m acceleration field at 2 μs 30 Hz RF pulses. A detailed physics design, including a comparison of different accelerating structures and end-to-end beam dynamics simulations of the ACCIL will be presented.
	Slides MOA4CO04 [3.531 MB]
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MOB4IO02	ERL-Ring and Ring-Ring Designs for the eRHIC Electron-Ion Collider	electron, luminosity, proton, linac	64
	V. Ptitsyn BNL, Upton, Long Island, New York, USA
	An overview of the eRHIC project.
	Slides MOB4IO02 [6.001 MB]
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MOB4CO03	Design of Muon Collider Lattices	collider, sextupole, quadrupole, factory	69
	Y.I. Alexahin Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE A Muon Collider promises unique opportunities both as an energy frontier machine and as a factory for detailed study of the Higgs boson and other particles. However, in order to achieve a competitive level of luminosity a number of demanding requirements to the collider optics should be satisfied arising from short muon lifetime and relatively large values of the transverse emittance and momentum spread in muon beams that can realistically be obtained with ionization cooling. Basic solutions which make possible to achieve these goals with Nb3Sn magnet parameters are presented.
	Slides MOB4CO03 [0.794 MB]
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MOB4CO04	Design of the Room-Temperature Front-End for a Multi-Ion Linac Injector	rfq, linac, light-ion, heavy-ion	73
	A.S. Plastun, Z.A. Conway, B. Mustapha, P.N. Ostroumov ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S.DOE, Office of Science, Office of Nuclear Physics, contract DE-AC02-06CH11357. This research used resources of ANL's ATLAS, which is a DOE Office of Science User Facility. A pulsed multi ion injector linac is being developed by ANL for Jefferson Laboratory's Electron Ion Collider (JLEIC). The linac is designed to deliver both polarized and non polarized ion beams to the booster synchrotron at energies ranging from 135 MeV for hydrogen to 43 MeV/u for lead ions. The linac is composed of a 5 MeV/u room temperature section and a superconducting section with variable velocity profile for different ion species. This paper presents the results of the RF design of the main components and the beam dynamics simulations of the linac front-end with the goal of achieving design specifications cost-effectively.
	Slides MOB4CO04 [2.545 MB]
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MOPOB05	Tokamak Accelerator	plasma, vacuum, ECR, experiment	76
	G. Li ASIPP, Hefei, People's Republic of China
	Tokamak accelerator within plasma is analyzed to be implemented in existing machines for speeding the development of fusion energy with seeding fast particles from high current accelerators - the so-called two-component reactor approach [J. M. Dawson, H. P. Furth, and F. H. Tenney, Phys. Rev. Lett. 26, 1156 (1971)]. All plasma particles are heated at the same time by inductively-coupled power transfer (IPT) within an energy confinement time. This could facilitate the attainment of ignition in tokamak by forming high-gain high-field (HGHF) fusion plasma suggested in [Li. G., Sci. Rep.5, 15790 (2015)]. HGHF mechanism is validated by the flux-conserving process existed in discharges of tokamak plasma at normal operation with long pulses or at compression process within an energy confinement time. Differences between HGHF plasma and former unity-beta plasma are discussed. Tokamak as an accelerator could scale down the design capacity of fusion power plant by simply inserting in-vacuum vertical field coils (IVC) within its vacuum vessel, such as China Fusion Engineering Test Reactor (CFETR).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB05
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MOPOB06	MAX IV and Solaris Linac Magnets Production Series Measurement Results	linac, gun, storage-ring, septum	79
	M.A.G. Johansson MAX IV Laboratory, Lund University, Lund, Sweden R. Nietubyć NCBJ, Świerk/Otwock, Poland
	The linacs of the MAX IV and Solaris synchrotron radiation light sources, currently in operation in Lund, Sweden, and Kraków, Poland, use various conventional magnet designs. The production series of totally more than 100 magnets of more than 10 types or variants, which were all outsourced to industry, with combined orders for the types that are common to both MAX IV and Solaris, were completed in 2013 with mechanical and magnetic QA conforming to specifications. This article presents an overview of the different magnet types installed in these machines, and mechanical and magnetic measurement results of the full production series.
	Poster MOPOB06 [2.535 MB]
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MOPOB07	Off-Orbit Ray Tracing Analysis for the APS-Upgrade Storage Ring Vacuum System	vacuum, photon, storage-ring, site	82
	J.A. Carter, K.C. Harkay, B.K. Stillwell ANL, Argonne, Illinois, USA
	Funding: Argonne National Laboratory's work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357. A MatLab program has been created to investigate off-orbit ray tracing possibilities for the APS-Upgrade stor-age ring vacuum system design. The goals for the pro-gram include calculating worst case thermal loading conditions and finding minimum shielding heights for photon absorbers. The program computes the deviation possibilities of synchrotron radiation rays emitted along bending magnet paths using discretized local phase space ellipses. The sizes of the ellipses are computed based on multi-bend achromat (MBA) lattice parameters and the limiting aperture size within the future storage ring vacuum system. For absorber height calculations, rays are projected from each point in the discretized ellipse to the locations of downstream absorbers. The absorber heights are mini-mized while protecting downstream components from all possible rays. For heat loads, rays are projected until they hit a vacuum chamber wall. The area and linear power densities are calculated based on a ray's distance trav-elled and striking incidence angle. A set of worse case local heat loads is collected revealing a maximum condi-tion that each vacuum component must be designed to withstand.
	Poster MOPOB07 [12.749 MB]
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MOPOB08	Streak Camera Measurements of the APS PC Gun Drive Laser	laser, factory, gun, optics	85
	J.C. Dooling ANL, Argonne, Illinois, USA A.H. Lumpkin Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic (SH, 527 nm) and fourth harmonic (FH. 263 nm) wavelengths. The drive laser is a Nd:Glass-based CPA with the IR wavelength (1053 nm) twice doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay employs an etalon with known spacing between reflecting surfaces; this etalon is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB08
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MOPOB10	Design of the HGVPU Undulator Vacuum Chamber for LCLS-II	vacuum, alignment, undulator, operation	89
	J.E. Lerch, J.A. Carter, P.K. Den Hartog, G.E. Wiemerslage ANL, Argonne, Illinois, USA
	A vacuum chamber has been designed and prototyped for the new Horizontal Gap Vertically Polarization Undulator (HGVPU) as part of the LCLS-II upgrade project. Numerous functional requirements for the HGVPU assembly constrained the vacuum chamber design. These constraints included spatial restrictions to achieve small magnet gaps, narrow temperature and alignment specifications, and minimization of wall erosion and pressure drop within the cooling channels. This led to the design of a 3.5-meter length, thin walled, extruded aluminium chamber with interior water cooling. FEA stress analysis was performed to ensure the chamber will not fail under vacuum and water pressure. A cooling scheme was optimized to ensure water flow is sufficient to maintain temperature without the risk of erosion and to minimize pres-sure drop across the chamber.
	Poster MOPOB10 [60.628 MB]
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MOPOB11	Research and Development on the Storage Ring Vacuum System for the APS Upgrade Project	photon, vacuum, storage-ring, impedance	92
	B.K. Stillwell, B. Brajuskovic, J.A. Carter, H. Cease, R.M. Lill, G. Navrotski, J. R. Noonan, K.J. Suthar, D.R. Walters, G.E. Wiemerslage, J. Zientek ANL, Argonne, Illinois, USA M.P. Sangroula IIT, Chicago, Illinois, USA
	Funding: UChicago Argonne, LLC, operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. A number of research and development activities are underway at Argonne National Laboratory to build confidence in the designs for the storage ring vacuum system required for the Advanced Photon Source Upgrade project (APS-U) [1]. The predominant technical risks are: excessive residual gas pressures during operation, insufficient beam position monitor stability, excessive beam impedance, excessive heating by induced electrical surface currents, and insufficient operational reliability. Present efforts to mitigate these risks include: building and evaluating mock-up assemblies, performing mechanical testing of chamber weld joints, developing computational tools, investigating design alternatives, and performing electrical bench measurements. Status of these activities and some of what has been learned to date will be shared. *B. Stillwell et al., Conceptual Design of a Storage Ring Vacuum System Compatible with Implementation of a Seven Bend Achromat Lattice at the APS, in Proc. IPAC'14, Dresden, Germany, 2409-2411.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB11
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MOPOB12	A High Bandwidth Bipolar Power Supply for the Fast Correctors in the APS Upgrade	power-supply, controls, ISOL, interface	96
	J. Wang, G.S. Sprau ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The APS Upgrade of a multi-bend achromat (MBA) storage ring requires a fast bipolar power supply for the fast correction magnets. The key performance requirement of the power supply includes a small-signal bandwidth of 10 kHz for the output current. This requirement presents a challenge to the design because of the high inductance of the magnet load and a limited input DC voltage. A prototype DC/DC power supply utilizing a MOSFET H-bridge circuit with a 500 kHz PWM has been developed and tested successfully. The prototype achieved a 10-kHz bandwidth with less than 3-dB attenuation for a signal 0.5% of the maximum operating current of 15 amperes. This paper presents the design of the power circuit, the PWM method, the control loop, and the test results.
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MOPOB13	Post Irradiation Examination Results of the NT-02 Graphite Fins Numi Target	target, radiation, proton, operation	99
	K. Ammigan, P. Hurh, V.I. Sidorov, R.M. Zwaska Fermilab, Batavia, Illinois, USA D. Asner, A.M. Casella, D.J. Edwards, A.L. Schemer-Kohrn, D.J. Senor PNNL, Richland, Washington, USA
	Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The NT-02 neutrino target in the NuMI beamline at Fermilab is a 95 cm long target made up of segmented graphite fins. It is the longest running NuMI target, which operated with a 120 GeV proton beam with maximum power of 340 kW, and saw an integrated total proton on target of 6.1 x 1020. Over the last half of its life, gradual degradation of neutrino yield was observed until the target was replaced. The probable causes for the target performance degradation are attributed to radiation damage, possibly including cracking caused by reduction in thermal shock resistance, as well as potential localized oxidation in the heated region of the target. Understanding the long-term structural response of target materials exposed to proton irradiation is critical as future proton accelerator sources are becoming increasingly more powerful. As a result, an autopsy of the target was carried out to facilitate post-irradiation examination of selected graphite fins. Advanced microstructural imaging and surface elemental analysis techniques were used to characterize the condition of the fins in an effort to identify degradation mechanisms, and the relevant findings are presented in this paper.
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MOPOB14	Experimental Results of Beryllium Exposed to Intense High Energy Proton Beam Pulses	experiment, proton, target, radiation	102
	K. Ammigan, B.D. Hartsell, P. Hurh, R.M. Zwaska Fermilab, Batavia, Illinois, USA A.R. Atherton STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom M.E.J. Butcher, M. Calviani, M. Guinchard, R. Losito CERN, Geneva, Switzerland O. Caretta, T.R. Davenne, C.J. Densham, M.D. Fitton, P. Loveridge, J. O'Dell STFC/RAL, Chilton, Didcot, Oxon, United Kingdom V.I. Kuksenko, S.G. Roberts University of Oxford, Oxford, United Kingdom S.G. Roberts CCFE, Abingdon, Oxon, United Kingdom
	Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Beryllium is extensively used in various accelerator beam lines and target facilities as material for beam windows, and to a lesser extent, as secondary particle production targets. With increasing beam intensities of future accelerator facilities, it is critical to understand the response of beryllium under extreme conditions to reliably operate these components as well as avoid compromising particle production efficiency by limiting beam parameters. As a result, an exploratory experiment at CERN's HiRadMat facility was carried out to take advantage of the test facility's tunable high intensity proton beam to probe and investigate the damage mechanisms of several beryllium grades. The test matrix consisted of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. This paper outlines the experimental measurements, as well as findings from Post-Irradiation-Examination (PIE) work where different imaging techniques were used to analyze and compare surface evolution and microstructural response of the test matrix specimens.
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MOPOB16	Higher Order Modes Analysis of Fermilab's Recycler Cavity	impedance, cavity, dipole, HOM	106
	M.H. Awida, J.E. Dey, T.N. Khabiboulline, V.A. Lebedev, R.L. Madrak Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE Two recycler cavities are being employed in Fermilab's Recycler Ring for the purpose of slip stacking proton bunches, where 6 batches of 8 GeV protons coming from the Booster are stacked on top of 6 circulating batches. Slip stacking requires two RF cavities operating at 52.809 and 51.545 MHz. In this paper, we report on the analysis of higher order modes in the Recycler cavity, presenting the values for R/Q and shunt impedances. Knowing the frequencies and properties of higher order modes is particularly critical for beam physics and avoidance of beam instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB16
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MOPOB17	Resonant Frequency Control for the PIP-II Injector Test RFQ: Control Framework and Initial Results	controls, rfq, framework, operation	109
	A.L. Edelen, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA D.L. Bowring, B.E. Chase, J.P. Edelen, D.J. Nicklaus, J. Steimel Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359. For the PIP-II Injector Test (PI-Test) at Fermilab, a four-vane radio frequency quadrupole (RFQ) is designed to accelerate a 30-keV, 1-mA to 10-mA H' beam to 2.1 MeV under both pulsed and continuous wave (CW) RF operation. The available headroom of the RF amplifiers limit the maximum allowable detuning to 3 kHz, and the detuning is controlled entirely via thermal regulation. Fine control over the detuning, minimal manual intervention, and fast trip recovery is desired. In addition, having active control over both the walls and vanes provides a wider tuning range. For this, we intend to use model predictive control (MPC). To facilitate these objectives, we developed a dedicated control framework that handles higher-level system decisions as well as executes control calculations. It is written in Python in a modular fashion for easy adjustments, readability, and portability. Here we describe the framework and present the first control results for the PI-Test RFQ under pulsed and CW operation.
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MOPOB20	Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators	cavity, induction, accelerating-gradient, ECR	113
	M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko Fermilab, Batavia, Illinois, USA M. Martinello Illinois Institute of Technology, Chicago, Illlinois, USA J. Zasadzinski IIT, Chicago, Illinois, USA
	The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.
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MOPOB23	The Radiation Damage In Accelerator Target Environments (RaDIATE) Collaboration R&D Program - Status and Future Activities	radiation, target, proton, experiment	117
	P. Hurh Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The RaDIATE collaboration (Radiation Damage In Accelerator Target Environments), founded in 2012, has grown to over 50 participants and 11 institutions globally. The primary objective is to harness existing expertise in nuclear materials and accelerator targets to generate new and useful materials data for application within the accelerator and fission/fusion communities. Current activities include post-irradiation examination of materials taken from existing beamlines (such as the NuMI primary beam window from Fermilab) as well as new irradiations of candidate target materials at low energy and high energy beam facilities. In addition, the program includes thermal shock experiments utilizing high intensity proton beam pulses available at the HiRadMat facility at CERN. Status of current RaDIATE activities as well as future plans will be discussed, including special focus on the upcoming RaDIATE irradiation at the Brookhaven Linac Isotope Producer facility (BLIP) in which multiple materials of interest (e.g. beryllium, graphite, silicon, titanium, iridium) will simultaneously be exposed to 120 - 181 MeV proton beam to relevant radiation damage levels.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB23
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MOPOB24	Design of Main Coupler for 650 MHz SC Cavities of PIP-II Project	cavity, vacuum, cryomodule, proton	121
	O.V. Pronitchev, S. Kazakov Fermilab, Batavia, Illinois, USA
	Proton Improvement Plan-II at Fermilab has designed an 800MeV superconducting pulsed linac which is also capable of running in CW mode. The high energy section from 185MeV to 800MeV will be using cryomodules with two types of 650MHz elliptical cavities. Both types of cryomodules will include six 5-cell elliptical cavities. Each cavity will have one coupler. Updated design of the 650 MHz main coupler is reported.
	Poster MOPOB24 [1.016 MB]
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MOPOB25	The Use of KF Style Flanges in Low Particlulate Applications	vacuum, diagnostics, hardware, cavity	124
	K.R. Kendziora, J.J. Angelo, C.M. Baffes, D. Franck, R.J. Kellett Fermilab, Batavia, Illinois, USA
	Funding: Fermilab, Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy As SCRF particle accelerator technology advances the need for 'low particulate' and 'particle free' vacuum systems becomes greater and greater. In the course of the operation of these systems, there comes a time when vari-ous instruments have to be temporarily attached for diag-nostic purposes: RGAs, leak detectors, and additional pumps. In an effort to make the additions of these instru-ments easier and more time effective, we propose to use KF style flanges for these types of temporary diagnostic connections. This document will describe the tests used to compare the particles generated using the assembly of the, widely accepted for 'particle free' use, conflat flange to the proposed KF style flange, and demonstrate that KF flanges produce less particles.
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MOPOB27	Superconducting Coil Winding Machine Control System	controls, FPGA, operation, software	127
	J.M. Nogiec, S. Kotelnikov, A. Makulski, K. Trombly-Freytag, D.G.C. Walbridge Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract no. DE-AC02-07CH11359. The Spirex magnet coil winder has been equipped with an automation system, which allows operation from both a computer and a remote control unit. This machine is about 6m long with a bridge that moves along a track and supports a rotating boom holding a spool of cable and providing cable tension. The machine control system is distributed between three layers: PC, RTOS, and FPGA providing respectively HMI, operational logic and controls. The PC stores the history of operation, shows the machine positions, status, and their history. Keeping cable tension constant is non-trivial in situations where the length of the cable changes with varying speeds. This has been addressed by a PID controller with feed forward augmentation and low-pass filters. Another challenging problem, synchronizing multiple servo motors, has been solved by designing an innovative decentralized algorithm. Extra attention was given to the safety aspects; a fail-safe, redundant safety system with interlocks has been developed, including protection for the operator and the superconducting cable against such situations as accidental over tension, or fast movement of the cable due to operational errors.
	Poster MOPOB27 [1.952 MB]
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MOPOB28	Progress on the Design of a Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster	cavity, booster, simulation, injection	130
	R.L. Madrak, J.E. Dey, K.L. Duel, J. Kuharik, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine Fermilab, Batavia, Illinois, USA
	A perpendicular biased 2nd harmonic cavity is being designed and built for the Fermilab Booster. Its purpose is to flatten the bucket at injection and thus change the longitudinal beam distribution to decrease space charge effects. It can also help with transition crossing. The cavity frequency range is 76 - 10⁶ MHz. It is modeled using CST microwave studio and COMSOL. The power amplifier will use the same tetrode as is used for the fundamental mode cavities in the Fermilab Booster (Y567B). We discuss recent progress on the cavity design, plans for testing the tuner's garnet material, and tests of the power source.
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MOPOB29	Measurements of the Properties of Garnet Material for Tuning a 2nd Harmonic Cavity for the Fermilab Booster	cavity, solenoid, resonance, ISOL	134
	R.L. Madrak, W. Pellico, G.V. Romanov, C.-Y. Tan, I. Terechkine Fermilab, Batavia, Illinois, USA
	A perpendicular biased 2nd harmonic cavity is being designed and built for the Fermilab Booster, to help with injection and transition. The frequency range is 76 - 10⁶ MHz. The garnet material chosen for the tuner is AL800. To reliably model the cavity, its static permeability and loss tangent must be well known. We present our measurements of these properties.
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MOPOB30	Development and Comparison of Mechanical Structures for FNAL 15 T Nb3Sn Dipole Demonstrator	dipole, operation, collider, controls	137
	A.V. Zlobin, I. Novitski Fermilab, Batavia, Illinois, USA
	Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy Main design challenges for 15 T accelerator magnets are large Lorentz forces at this field level. The large Lorentz forces generate high stresses in the coil and mechanical structure and, thus, need stress control to maintain them at the acceptable level for brittle Nb3Sn coils and other elements of magnet mechanical structure. To provide these conditions and achieve the design field in the FNAL 15 T dipole demonstrator, several mechanical structures have been developed and analysed. The possibilities and limitations of these designs are discussed in this paper.
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MOPOB32	Design and Test of the Prototype Tuner for 3.9 GHz SRF Cavity for LCLS II Project	cavity, SRF, cryomodule, FEL	140
	Y.M. Pischalnikov, E. Borissov, J.C. Yun Fermilab, Batavia, Illinois, USA
	Fermilab is responsible for the design of the 3.9GHz cryomodule for the LCLS-II that will operate in continuous wave (CW) mode. Bandwidth of the SRF cavities will be in the range of the 180Hz. In our tuner design, we adopted as the slow tuner-mechanism slim blade tuner originated by INFN for the European XFEL 3.9GHz. At the same time bandwidth of the SRF cavities for LCLS II will be in the range of the 180Hz and fine/fast tuning of the cavity frequency required. We added to the design fast/fine tuner made with 2 encapsulated piezos. First prototype tuner has been built and went through testing at warm conditions. Details of the design and summary of the tests will be presented in this paper.
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MOPOB33	LCLS-II Tuner Assembly for the Prototype Cryomodule at FNAL	cavity, cryomodule, SRF, operation	143
	Y.M. Pischalnikov, E. Borissov, T.N. Khabiboulline, J.C. Yun Fermilab, Batavia, Illinois, USA
	The tuner design for LCLS-II has been thoroughly verified and fabricated for used in the LCLS-II prototype modules. This paper will present the lessons learned during the installation of these tuners for the prototype modules at FNAL, including installation procedures, best practices, and challenges encountered.
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MOPOB35	Design of the LBNF Beamline Target Station	target, shielding, radiation, focusing	146
	S. Tariq, K. Ammigan, K. Anderson, S.A. Buccellato, C.F. Crowley, B.D. Hartsell, P. Hurh, J. Hylen, P.H. Kasper, G.E. Krafczyk, A. Lee, B.G. Lundberg, A. Marchionni, N.V. Mokhov, C.D. Moore, V. Papadimitriou, D. Pushka, I.L. Rakhno, S.D. Reitzner, V.I. Sidorov, A.M. Stefanik, I.S. Tropin, K. Vaziri, K.E. Williams, R.M. Zwaska Fermilab, Batavia, Illinois, USA C.J. Densham STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The Long Baseline Neutrino Facility (LBNF) project will build a beamline located at Fermilab to create and aim an intense neutrino beam of appropriate energy range toward the DUNE detectors at the SURF facility in Lead, South Dakota. Neutrino production starts in the Target Station, which consists of a solid target, magnetic focusing horns, and the associated sub-systems and shielding infrastructure. Protons hit the target producing mesons which are then focused by the horns into a helium-filled decay pipe where they decay into muons and neutrinos. The target and horns are encased in actively cooled steel and concrete shielding in a chamber called the target chase. The reference design chase is filled with air, but nitrogen and helium are being evaluated as alternatives. A replaceable beam window separates the decay pipe from the target chase. The facility is designed for initial operation at 1.2 MW, with the ability to upgrade to 2.4 MW, and is taking advantage of the experience gained by operating Fermilab's NuMI facility. We discuss here the design status, associated challenges, and ongoing R&D and physics-driven component optimization of the Target Station.
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MOPOB36	Design of the High Beta 650 MHz Cryomodule - PIP II	cavity, cryomodule, vacuum, cryogenics	149
	V. Roger, T.H. Nicol, Y.O. Orlov Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy In this paper the design of the high beta 650 MHz cryomodule will be presented. This cryomodule is composed of six 5-cell 650 MHz elliptical cavities, designed for β=0.92. These cryomodules are the last elements of the Super Conducting (SC) linac architecture which is the main component of the Proton Improvement Plan-II (PIP-II) at Fermilab. This paper summarizes the design choices which have been done. Mechanical, thermal and cryogenic analyses have been performed to ensure the proper operation. First the concept of having a strong-back at room temperature has been validated. Then the heat loads have been estimated and all the components have been integrated inside the cryomodule by designing the supports, the beam line, the thermal shield and the cryogenic lines. All these elements and the calculations leading to the design of this cryomodule will be described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB36
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MOPOB39	A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch	linac, electron, ECR, operation	152
	G.W. Saewert, D. Frolov, H. Pfeffer Fermilab, Batavia, Illinois, USA
	Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB39
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MOPOB40	Quench Training Analysis of Nb3Sn Accelerator Magnets	dipole, quadrupole, operation, magnet-design	155
	S. Stoynev, K.H. Riemer, A.V. Zlobin Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Nb3Sn accelerator magnet technology has made significant progress during the past decades. Thanks to that 11-12 T Nb3Sn dipoles and quadrupoles are planned to be used in accelerators such as LHC in near future for the luminosity upgrade and in longer term for the LHC energy upgrade or a future Very High Energy pp Collider. However, all the state of the art Nb3Sn accelerator magnets show quite long training. This specific feature significantly raises the required design margin or limit the nominal operation field of Nb3Sn accelerator magnets and, thus, increases their cost. To resolve this problem Fermilab has launched a study aiming to analyze the relatively large amount of Nb3Sn magnet training data accumulated at Fermilab magnet test facility. The ultimate goal is to correlate magnet design and manufacturing features and magnet material properties with training performance parameters which will eventually allow us to optimize both the magnet design, fabrication and the training processes. This paper describes the general strategy of the analysis and presents the first results based on partial data processing. Conclusions and further steps are also outlined and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB40
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MOPOB41	Field Quality Measurements in the FNAL Twin-Aperture 11 T Dipole for LHC Upgrades	dipole, quadrupole, magnet-design, ion-effects	158
	T. Strauss, G. Apollinari, E.Z. Barzi, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, S. Stoynev, D. Turrioni, G. Velev, A.V. Zlobin Fermilab, Batavia, Illinois, USA B. Auchmann, S. Izquierdo Bermudez, M. Karppinen, L. Rossi, F. Savary, D. Smekens CERN, Geneva, Switzerland
	Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404 FNAL and CERN magnet groups are developing a twin-aperture Nb3Sn 11 T dipole suitable for installation in the LHC to provide room for additional collimators in the dispersion suppressor (DS) areas. Two of these magnets with a collimator in between will replace one regular MB dipole. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been assembled and tested at FNAL in 2012-2014. The 1 m long collared coils were then assembled into the twin-aperture configuration and tested in 2015. The first magnet test was focused on the quench performance of twin-aperture magnet configuration including magnet training, ramp rate sensitivity and temperature dependence of magnet quench current. In the second test performed in July 2016 field quality in one of the two magnet apertures has been measured and compared with the data for the single-aperture models. These results are reported and discussed in this paper.
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MOPOB44	Thyratron Replacement	operation, klystron, network, linear-collider	162
	I. Roth, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: *Work supported by US Department of Energy under contract DE-SC0011292 Semiconductor thyristors have long been used as a replacement for thyratrons in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. It is, however, possible to assemble these devices in arrays to reach the required performance levels without sacrificing their inherent speed. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6μs, and 120 Hz.
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MOPOB46	Long Pulse Solid-State Pulsed Power Systems Built to ESS Specifications	klystron, operation, high-voltage, power-supply	165
	I. Roth, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA J. Domenge Sigma Phi Electronics, Wissembourg, France J.L. Lancelot Sigmaphi, Vannes, France
	Diversified Technologies, Inc. (DTI), in partnership with SigmaPhi Electronics (SPE) has built three long pulse solid-state klystron transmitters to meet spallation source requirements. Two of the three units are installed at CEA Saclay and the National Institute of Nuclear and Particle Physics (IN2P3), where they will be used as test stands for the European Spallation Source (ESS). The systems delivered to CEA and IN2P3 demonstrate that the ESS klystron modulator specifications (115 kV, 25 A per klystron, 3.5 ms, 14 Hz) have been achieved in a reliable, manufacturable, and cost-effective design. There are only minor modifications required to support transition of this design to the full ESS Accelerator, with up to 100 klystrons. The systems will accommodate the recently-determined increase in average power (~660 kW), can offer flicker-free operation, are equally-capable of driving Klystrons or MBIOTs, and are designed for an expected MTBCF of over ten years, based on operational experience with similar systems.
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MOPOB47	Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade	impedance, cavity, HOM, coupling	167
	T.H. Luo, K.M. Baptiste, M. Betz, J.M. Byrd, S. De Santis, S. Kwiatkowski, S. Persichelli, Y. Yang LBNL, Berkeley, California, USA
	The ALS upgrade to a diffraction-limited light source (ALS-U) depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. In order to achieve lengthening in excess of fourfold necessary to this end, we are investigating the use of the same passive 1.5 GHz normal-conducting RF cavities currently used on the ALS. While the upgraded ring RF parameters and fill pattern make it easier as long as the beam-induced phase transient is concerned, the large lengthening factor and the strongly non-linear lattice require particular attention to the cavities contribution to the machine overall impedance budget. In this paper we present our estimates of the narrow-band impedance obtained by numerical simulation and bench measurements of the cavities' resonant modes.
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MOPOB49	Persistent Current Effects in RHIC Arc Dipole Magnets Operated at Low Currents	dipole, operation, ion-effects, detector	170
	X. Wang, S. Caspi, S.A. Gourlay, G.L. Sabbi LBNL, Berkeley, California, USA A.K. Ghosh, R.C. Gupta, A.K. Jain, P. Wanderer BNL, Upton, Long Island, New York, USA
	Funding: BNL work was supported by Brookhaven Science Associates, LLC under Contract# DESC0012704 with the U.S. DOE. LBNL work was supported by the U.S. DOE under Contract# DEAC02- 05CH11231. The Relativistic Heavy Ion Collider (RHIC) arc dipoles at Brookhaven National Laboratory are operated at low field for low energy Au-Au studies. Indications of strong nonlinear magnetic fields have been observed at these low currents due to the persistent current effects of superconducting NbTi filaments. We report the details of the measurement and calculation of the field errors due to persistent current effect. The persistent current induced field errors calculated with a model based on the strand magnetization data agree well with the measurements of a spare arc dipole magnet. The dependence of the persistent current effects on the park current is calculated based on the validated model.
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MOPOB51	High-Efficiency 500-W RF-Power Modules for UHF	operation, klystron, ISOL, proton	174
	F.H. Raab Green Mountain Radio Research, Boone, USA
	Funding: U.S. DoE DE-SC0002548, DE-SC0006200, and DE-SC0006237. GMRR IR&D. GMRR has developed solid-state RF-power modules that deliver up to 650 W at frequencies from 325 to 704 MHz. The nominal output of 500 W is delivered with an overall efficiency from 79% at 704 MHz to 83% percent at 325 MHz. In contrast to conventional solid-state power amplifiers, high efficiency is maintained over a wide range of output powers; e.g., 70 percent or better for outputs of 30 W or higher. Each 500-W module contains five 120-W RF power amplifiers (PAs) and a Gysel* splitter and combiner. The class-F** PAs employ GaN FETs and produce over 120 W with efficiencies from 82-86%. A class-S modulator maintains high efficiency over nearly the entire range of amplitudes. Supporting hardware includes a control computer, DSP, low-level RF amplifiers, and drivers. The 500-W modules are intended to be building blocks of a multi-kW RF power source. A system based these modules will consume 1/3 to 1/2 of the prime power required by a system based upon klystrons or conventional solid-state amplifiers and will have significantly lower cooling requirements. * U. H. Gysel, Int. Microwave Symp. Digest, May 12 - 14, 1975. ** F. H. Raab et al., IEEE Trans. Microwave Theory Tech., March 2002.
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MOPOB52	Dielectric Loaded High Pressure Gas Filled RF Cavities for Use in Muon Cooling Channels	cavity, solenoid, plasma, accelerating-gradient	177
	B.T. Freemire IIT, Chicago, Illinois, USA M. Backfish, D.L. Bowring, A. Moretti, D.W. Peterson, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, Illinois, USA R.P. Johnson Muons, Inc, Illinois, USA A.V. Kochemirovskiy University of Chicago, Chicago, Illinois, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. High brightness muon beams require significant six dimensional cooling. One cooling scheme, the Helical Cooling Channel, employs high pressure gas filled radio frequency cavities, which provide both the absorber needed for ionization cooling, and a means to mitigate RF breakdown. The cavities are placed along the beam's trajectory, and contained within the bores of superconducting solenoid magnets. Gas filled RF cavities have been shown to successfully operate within multi-Tesla external magnetic fields, and not be overcome with the loading resulting from beam-induced plasma. The remaining engineering hurdle is to find a way to fit 325 and 650 MHz single cell pillbox cavities within the bores of the magnets using modern technology. One method to accomplish this is to partially fill the cavities with a dielectric material. Alumina (Al2O3) is an ideal dielectric, and the experimental test program to determine its performance under high power in a gas filled cavity has concluded. The final results, and their implications for the design of a muon cooling channel based on gas filled RF cavities will be discussed.
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MOPOB53	Simulation of Ping-Pong Multipactor with Continuous Electron Seeding	simulation, electron, multipactoring, resonance	181
	M. Siddiqi, R.A. Kishek UMD, College Park, Maryland, USA
	Funding: National Science Foundation grant No. PHY1535519 Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics . In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented. R.A. Kishek, Physics of Plasmas 20, 056702 (2013).
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MOPOB54	Superferric Arc Dipoles for the Ion Ring and Booster of JLEIC	dipole, multipole, quadrupole, collider	184
	P.M. McIntyre, J. Breitschopf, T. Elliott, R. Garrison, J. Gerity, J.N. Kellams, A. Sattarov Texas A&M University, College Station, USA D. Chavez DCI-UG, León, Mexico
	Funding: This work was supported by a grant from the NP Division of the US Dept. of Energy. The JLEIC project requires 3 T superferric dipoles and quadrupoles for the half-cell arcs of its Ion Ring and Booster. A superferric design using NbTi cable-in-conduit conductor is being developed. A mockup winding has been completed, with the objectives to develop and evaluate the coil structure and the winding tooling and methods, and to measure errors in the position of each cable turn in the dipole body. The results of the mockup winding study are presented. The CIC design is now ready for construction and testing of a first model dipole.
	Poster MOPOB54 [1.147 MB]
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MOPOB55	Room Temperature Magnets in FRIB Driver Linac	linac, quadrupole, alignment, dipole	188
	Y. Yamazaki, N.K. Bultman, E.E. Burkhardt, F. Feyzi, K. Holland, A. Hussain, M. Ikegami, F. Marti, S.J. Miller, T. Russo, J. Wei, Q. Zhao FRIB, East Lansing, USA W.J. Yang, Q.G. Yao IMP/CAS, Lanzhou, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511. The FRIB Driver Linac* is to accelerate all the stable ions beyond 200 MeV/nucleon with a beam power of 400 kW. The linac is unique, being compactly folded twice. In this report, the room temperature magnets, amounting 147 in total, after Front End with a 0.5-MeV RFQ, are detailed, emphasizing the rotating coil field measurements and fiducialization. *E. Pozdeyev et al., "Status of FRIB" in this conference. T. Xu, "Superconducting Cryomodule Development and Production for the FRIB Linac" in this conference.
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MOPOB56	Frequency Domain Simulations of Rf Cavity Structures and Coupler Designs for Co-Linear X-Band Energy Booster (CXEB) with ACE3P	cavity, GUI, simulation, electron	191
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	Due to their higher intrinsic shunt impedance X-band accelerating structures offer significant gradients with relatively modest input powers, and this can lead to more compact light sources. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3-GHz, L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the frequency domain simulation results using the ACE3P Electromagnetic Suite's OMEGA3P and S3P for our proposed Co-linear X-band Energy Booster (CXEB) system that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structures while driven solely by the beam from the L-band system.
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MOPOB57	Wakefield Excitation in Power Extraction Cavity of Co-Linear X-Band Energy Booster in Time Domain With ACE3P	cavity, wakefield, impedance, extraction	195
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	We provide the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB). Here, using the time domain solver T3P of the ACE3P Suite we provide the single bunch and multiple bunch wakefield excitation mechanism for the power build up when using a symmetric Gaussian bunch distribution in our traveling wave (TW) X-band power extraction cavity (PEC). Finally, we determine the achievable X-band power at the end of the PEC structure.
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MOPOB58	Eddy Current Calculations for a 1.495 GHz Injection-Locked Magnetron	interaction-region, cavity, injection, klystron	198
	S.A. Kahn, A. Dudas, R.P. Johnson, M.L. Neubauer Muons, Inc, Illinois, USA H. Wang JLab, Newport News, Virginia, USA
	An injection-locked amplitude modulated magnetron is being developed as a reliable, efficient RF source that could replace klystrons used in particle accelerators. The magnetron amplitude is modulated using a trim magnetic coil to alter the magnetic field in conjunction with the anode voltage to suppress the emittance growth due to microphonics and changing beam loads. The rate for microphonic noise can have frequencies in the range 10-50 Hz. This is competitive to the inductive decay time of the trim coil. Eddy currents will be induced in the copper anode of the magnetron that will buck the field from the trim coil in the interaction region. This paper will describe the magnetic circuit of the proposed magnetron as well as the calculation and handling of the Eddy currents on the magnetic field.
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MOPOB59	Magnet Design for the Splitter/Combiner Regions of CBETA, the Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator	quadrupole, dipole, linac, magnet-design	201
	J.A. Crittenden, D.C. Burke, Y.L.P. Fuentes, C.E. Mayes, K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and New York State. The Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator (CBETA) will provide a 150-MeV electron beam using four acceleration and four deceleration passes through the Cornell Main Linac Cryomodule housing six 1.3-GHz superconducting RF cavities. The return path of this 76-m-circumference accelerator will be provided by 10⁶ fixed-field alternating-gradient (FFAG) cells which carry the four beams of 42, 78, 114 and 150-MeV. Here we describe magnet designs for the splitter and combiner regions which serve to match the on-axis linac beam to the off-axis beams in the FFAG cells, providing the path-length adjustment necessary to energy recovery for each of the four beams. The path lengths of the four beamlines in each of the splitter and combiner regions are designed to be adapted to 1-, 2-, 3-, and 4-pass staged operations. Design specifications and modeling for the 24 dipole and 32 quadrupole electromagnets in each region are presented. The CBETA project will serve as the first demonstration of multi-pass energy recovery using superconducting RF cavities with FFAG cell optics for the return loop.
	Poster MOPOB59 [8.982 MB]
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MOPOB60	Performance of the Cornell Main Linac Prototype Cryomodule for the CBETA Project	cavity, linac, HOM, cryomodule	204
	F. Furuta, N. Banerjee, J. Dobbins, R.G. Eichhorn, M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The main linac prototype cryomodule (MLC) is a key component for the Cornell-BNL ERL Test Accelerator (CBETA), which is a 4-turn FFAG ERL under construction at Cornell University. The MLC has been designed for high current and efficient continuous wave (CW) SRF cavity operation, and houses six high Q0 7-cell SRF cavities with individual beamline higher order-modes (HOMs) absorbers for strong HOM suppression in high beam current operation. Cavities have achieved specification values of 16.2MV/m with high Q0 of 2.0·10¹⁰ at 1.8K in CW operation after cooldown optimizations and RF processing. Damping of the HOMs has been measured in detail, indicating that the loaded quality-factors of all critical modes are low enough to avoid BBU in high current, multi-turn ERL operation. Microphonics measurements have been carried out as well, and vibration sources have been determined and eliminated. Here we report on these cryomodule performance studies.
	Poster MOPOB60 [3.321 MB]
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MOPOB61	Updates of Vertical Electropolishing Studies at Cornell with KEK and Marui Galvanizing Co. Ltd .	cathode, cavity, SRF, target	208
	F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, T. Saeki KEK, Ibaraki, Japan
	Cornell, KEK, and Marui Galvanizing Co. Ltd (MGI) have started new Vertical Electro-Polishing (VEP) R&D collaboration in 2014. MGI and KEK has developed their original VEP cathode named 'i-cathode Ninja'® which has four retractable wing-shape parts per cell for single-/9-cell cavities. One single cell cavity had processed with VEP using i-cathode Ninja at Cornell. Cornell also performed the vertical test on that cavity. We will present the details of process and RF test result at Cornell.
	Poster MOPOB61 [2.251 MB]
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MOPOB62	SRF Half Wave Resonator Activities at Cornell for the RAON Project	cavity, SRF, pick-up, heavy-ion	211
	M. Ge, F. Furuta, T. Gruber, S.W. Hartman, C. Henderson, M. Liepe, S. Lok, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J. Joo, J.-W. Kim, W.K. Kim, J. Lee, I. Shin IBS, Daejeon, Republic of Korea
	The RAON heavy-ion accelerator requires ninety-eight 162.5MHz Half-Wave-Resonators (HWR) with a geometrical β=0.12. Cornell University will test a prototype HWR as well as develop a frequency tuner for this cavity. In this paper we report on the progress in designing, fabricating, and commissioning of new HWR preparation and testing infrastructure at Cornell. The HWR infrastructure work includes new input and pick-up couplers, a modified vertical test insert with a 162.5MHz RF system, a new High-Pressure-Water-Rinsing (HPR) setup, and a modified chemical etching system.
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MOPOB63	Impact of Cooldown Procedure and Ambient Magnetic Field on the Quality Factor of State-of-the-Art Nb3Sn Single-Cell ILC Cavities	cavity, site, experiment, factory	215
	D.L. Hall, M. Ge, J.J. Kaufman, M. Liepe, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: DOE Single-cell Nb3Sn cavities coated at Cornell University have demonstrated quality factors of 10¹⁰ at 16 MV/m and 4.2 K in vertical tests, achieving the performance requirements of contemporary modern accelerator designs. In this paper, we present results demonstrating the impact of the cooldown procedure and ambient magnetic fields on the cavity's ability to achieve these quality factors and accelerating gradients. The impact of the magnetic fields from thermoelectric currents, generated by thermal gradients across the cavity during cooldown, are shown to be equivalent to the impact of magnetic fields trapped from ambient sources. Furthermore, the increase in the residual surface resistance due to trapped magnetic flux, from both ambient sources and thermoelectric currents, is found to be a function of the applied RF magnetic field amplitude. A hypothesis for this observation is given, and conclusions are drawn regarding the demands on the cooldown procedure and ambient magnetic fields necessary to achieve quality factors of 10¹⁰ at 4.2 K and 16 MV/m or higher.
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MOPOB65	Investigation of the Origin of the Anti-Q-Slope	cavity, ECR, experiment, SRF	218
	J.T. Maniscalco, M. Ge, D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The surface resistance of a superconductor, a property very relevant to SRF accelerators, has long been known to depend on the strength of the surface magnetic field. A recent discovery showed that, for certain surface treatments, microwave cavities can be shown to have an inverse field dependence, dubbed the ‘‘anti-Q-slope'', in which the surface resistance decreases over an increasing field. Here we present an investigation into what causes the anti-Q-slope in nitrogen-doped niobium cavities, drawing a direct connection between the electron mean free path of the SRF material and the magnitude of the anti-Q-slope. Further, we incorporate residual resistance due to flux trapping to calculate an optimal mean free path for a given trapped flux.
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MOPOB68	A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films	laser, niobium, controls, electron	221
	J. Musson, K. Macha, H.L. Phillips JLab, Newport News, Virginia, USA W. Cao, H. Elsayed-Ali ODU, Norfolk, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.
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MOPOB69	Wire Stretching Technique for Measuring RF Crabbing/Deflecting Cavity Electrical Center and a Demonstration Experiment on Its Accuracy	cavity, experiment, simulation, cryomodule	225
	H. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The fabrication accuracy of a superconducting RF crab cavity for the Large Hadron Collider High Luminosity Upgrade and the future Electron Ion Collider requires the cavity's electric center line relative to the crabbing plane within sub mm offset and sub degree in rotation. It is very hard for the cavity's niobium sheet formation, high temperature bake and chemistry processes and finally cooling down in cryomodule to satisfy such tight tolerance. A new wire stretching technique combining with the RF measurement in the deflecting modes has been demonstrated on the bench to detect less than 10um resolution on the RF signal when the wire is moving away from the ideal electric center line. The foundation of this technique and its difference from the use in other applications will be reviewed. Based on this principle, the possible implementations for detecting RF leakage to the higher older mode couplers, cavity string alignment and cryomodule assembly will be discussed.
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MOPOB71	Consideration on Determination of Coupling Factors of Waveguide Iris Couplers	cavity, DTL, coupling, simulation	229
	S.W. Lee, M.S. Champion, Y.W. Kang ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE. Waveguide iris couplers are frequently used to power accelerating cavities in low beta sections of ion accelerators. In ORNL Spallation Neutron Source (SNS), six drift tube linac (DTL) cavity structures have been operating. An iris input coupler with a tapered ridge waveguide and a waveguide ceramic disk window feeds each cavity. The original couplers and cavities have been in service for more than a decade. Since all DTL cavity structures are fully utilized for neutron production, none of the cavity structures is available as a test cavity or a spare. Maintaining spares of the iris couplers for operations and future system upgrade without using the full DTL structure, a test setup for precision tuning is needed. A smaller single-cell cavity may be used for pretuning of the coupling irises as the test cavity and high power RF conditioning of the iris couplers as the bridge waveguide. In this paper, study of using a single-cell cavity for the iris tuning and the conditioning is presented with 3D simulations. A single-cell test cavity has been built and used for low power bench measurement with the iris couplers to demonstrate the approach.
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MOPOB72	Update on CW 8 kW 1.5 GHz Klystron Replacement	klystron, operation, ISOL, controls	232
	A.V. Smirnov, S. Boucher RadiaBeam Systems, Santa Monica, California, USA R.B. Agustsson, D.I. Gavryushkin, J.J. Hartzell, K.J. Hoyt, A.Y. Murokh, T.J. Villabona RadiaBeam, Santa Monica, California, USA G.R. Branner, K.S. Yuk UC Davis, Davis, USA V. Khodos Sierra Nevada Corporation, Irvine, USA
	Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC0013136). JLAB upgrade program requires a ~8 kW, 1497 MHz amplifier operating at more than 55-60% efficiency, and 8 kW CW power to replace up to 340 klystrons. One of possibilities for the klystron replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. Design features and challenges related to amplifier modules and radial multi-way dividers/combiners are discussed including HFSS simulations and measurements.
	Poster MOPOB72 [1.199 MB]
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MOPOB76	Field Emission Dark Current Simulation for eRHIC ERL Cavities	cavity, electron, SRF, simulation	235
	C. Xu, I. Ben-Zvi, Y. Hao, V. Ptitsyn, K.S. Smith, B. P. Xiao, W. Xu BNL, Upton, Long Island, New York, USA
	The eRHIC project will be a electron and proton collider proposed in BNL. These high repetition rates will require Super-Conducting Radio-Frequency cavities with fundamental frequency of 650MHZ for high current applications. Each with a string of two of those cavities. The strong electromagnetic fields in the SRF cavities will extract electrons from the cavity walls and will accelerate those. Most dark current will be deposited locally, although some electrons may reach several neighbour cyromodules, thereby gaining substantial energy before they hit a collimator or other aperture. Simulation of these effects is therefore crucial for the design of the machine. Track3P code was used to simulate field-emission electrons from different SRF cavities setup to optimize the field emission dark current characterizes.
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MOPOB81	Deposition of Non-Evaporative Getters R&D Activity for HEPS-TF	vacuum, cathode, site, distributed	238
	P. He, D.Z. Guo, B. Liu, Y. Ma, Y.C. Yang, L. Zhang IHEP, Beijing, People's Republic of China
	Non Evaporable Getter(NEG) coating technology was widely used around the world's ultra-low emittance storage rings. It will provide the distributed pumping which is the obvious solution to solve the conductance limitation of narrow vacuum chamber at small magnet aperture. The HEPS-TF is the R&D project of HEPS (High Energy Photon Source), it will cover all of the key technology for HEPS accelerator system and beamlines. In order to meet the small aperture vacuum chamber distributed pumping requirement, the NEG coating R&D for HEPS vacuum chamber is under the way. Getter films deposited on the inner surface of the chamber would transform the vacuum chamber from an outgassing source into a pump. The coating test bench will be shown here and coating procedure will be presented.
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TUA1IO02	Status Report on the SPIRAL2 Facility at GANIL	rfq, linac, proton, experiment	240
	E. Petit GANIL, Caen, France
	The GANIL SPIRAL2 project is based on the construction of a superconducting ion CW LINAC with two experimental areas named S3 ('Super Separator Spectrometer') and NFS ('Neutron For Science'). This status will report the construction of the facility and the first beam commissioning results. The perspectives of the SPIRAL2 project, with the future construction of the low energy RIB experimental hall called DESIR and with the construction of a new injector with q/A>1/6 or 1/7, will also be presented.
	Slides TUA1IO02 [22.004 MB]
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TUA1IO03	Technological Challenges in the Path to 3.0 MW at the SNS Accelerator	operation, target, neutron, rfq	246
	K.W. Jones ORNL, Oak Ridge, Tennessee, USA
	This talk discusses the design and anticipated challenges associated with upgrading the SNS beam power from the original 1.4 MW baseline design to the upgrade goal of 3 MW.
	Slides TUA1IO03 [22.843 MB]
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TUA1CO04	Simulation of Beam Dynamics in a Strong Focusing Cyclotron	cyclotron, cavity, space-charge, focusing	251
	P.M. McIntyre, J. Gerity, A. Sattarov Texas A&M University, College Station, USA S. Assadi HiTek ESE LLC, Madison, USA K.E. Badgley Fermilab, Batavia, Illinois, USA N. Pogue LLNL, Livermore, California, USA
	Funding: This work is supported by the US Dept. of Energy Accelerator Stewardship Program. The strong-focusing cyclotron is an isochronous sector cyclotron in which slot-geometry superconducting half-cell cavities are used to provide sufficient energy gain per turn to fully separate orbits and superconducting quadrupoles are located in the aperture of each sector dipole to provide strong focusing and control betatron tune. The SFC offers the possibility to address the several effects that most limit beam current in a CW cyclotron: space charge, bunch-bunch interactions, resonance-crossing, and wake fields. Simulation of optical transport and beam dynamics entails several new challenges: the combined-function fields in the sectors must be properly treated in a strongly curving geometry, and the strong energy gain induces continuous mixing of horizontal betatron and synchrotron phase space. We present a systematic simulation of optical transport using modified versions of MAD-X and SYNERGIA. We report progress in introducing further elements that will set the stage for studying dynamics of high-current bunches.
	Slides TUA1CO04 [15.462 MB]
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TUA1CO05	Conceptual Design of a Ring for Pulse Structure Manipulation of Heavy Ion Beams at the MSU NSCL	rfq, extraction, acceleration, linac	255
	A.N. Pham, R. Ready, C.Y. Wong NSCL, East Lansing, Michigan, USA S.M. Lund FRIB, East Lansing, USA M.J. Syphers Northern Illinois University, DeKalb, Illinois, USA
	Funding: Research supported by Michigan State University, MSU NSCL, ReA Project, and NSF Award PHY-1415462. The Reaccelerator (ReA) Facility at the National Superconducting Cyclotron Laboratory (NSCL) located at Michigan State University (MSU) offers the low-energy nuclear science community unique capabilities to explore wider ranges of nuclear reactions and the structure of exotic nuclei. Future sensitive time-of-flight experiments on ReA will require the widening of pulse separation for improved temporal resolution in single bunch detection while minimizing loss of rare isotopes and cleaning of beam decay products that might pollute measurements. In this proceedings, we present a preliminary design of a heavy ion ring that will address the task of bunch compression, bunch separation enhancement, satellite bunches elimination, cleaning of decay products, beam loss mitigation, and improvement of beam transmission.
	Slides TUA1CO05 [4.991 MB]
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TUB1CO02	Operating Synchrotron Light Sources with a High Gain Free Electron Laser	FEL, undulator, electron, emittance	259
	S. Di Mitri, M. Cornacchia Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality. S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006
	Slides TUB1CO02 [2.353 MB]
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TUB1CO03	ALS-U: A Soft X-Ray Diffraction Limited Light Source	emittance, undulator, injection, impedance	263
	C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, S. Persichelli, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y.C. Yang LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source (ALS-U). The upgrade proposal will reuse much of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. We will report on the accelerator design progress as well as the details of the ongoing R+D program.
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TUA2IO01	AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN	plasma, proton, electron, wakefield	266
	A. Caldwell MPI-P, München, Germany
	It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.
	Slides TUA2IO01 [24.428 MB]
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TUA2CO03	A Novel Technique of Power Control in Magnetron Transmitters for Intense Accelerators	controls, cavity, operation, power-supply	271
	G.M. Kazakevich, R.P. Johnson, M.L. Neubauer Muons, Inc, Illinois, USA V.A. Lebedev, W. Schappert, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	A novel concept of a high-power magnetron transmitter allowing dynamic phase and power control at the frequency of locking signal is proposed. The transmitter compensating parasitic phase and amplitude modulations inherent in Superconducting RF (SRF) cavities within closed feedback loops is intended for powering of the intensity-frontier superconducting accelerators. The concept uses magnetrons driven by a sufficient resonant (injection-locking) signal and fed by the voltage which can be below the threshold of self-excitation. This provides an extended range of power control in a single magnetron at highest efficiency minimizing the cost of RF power unit and the operation cost. Proof-of-principle of the proposed concept demonstrated in pulsed and CW regimes with 2.45 GHz, 1kW magnetrons is discussed here. A conceptual scheme of the high-power transmitter allowing the dynamic wideband phase and mid-frequency power controls is presented and discussed.
	Slides TUA2CO03 [0.714 MB]
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TUA2CO04	Vacuum Breakdown at 110 GHz	experiment, cavity, vacuum, GUI	275
	S.C. Schaub MIT, Cambridge, Massachusetts, USA M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA

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MOA2IO02

The BNL EBPM Electronics, High Performance for Next Generation Storage Rings

storage-ring, feedback, operation, experiment

1

K. Vetter
ORNL, Oak Ridge, Tennessee, USA
W.X. Cheng, J. Mead, B. Podobedov, Y. Tian
BNL, Upton, Long Island, New York, USA

Funding: DOE contract DE-AC02-98CH10886
A custom state-of-the-art RF BPM (EBPM) has been developed and commissioned at the Brookhaven National Laboratory (BNL) National Synchrotron Light Source II (NSLS-II). A collaboration between Lawrence Berkeley National Laboratory (LBNL) Advanced Light Source (ALS) and BNL has proven to be a key element in the success of the NSLS-II EBPM. High stability coherent signal processing has allowed for demonstrated 200nm RMS spatial resolution and true turn-by-turn position measurement capability. Sub-micron 24 hr. stability has been demonstrated at NSLS-II by use of 0.01C RMS thermal regulation of the electronics racks without the need of active pilot tone correction.

Slides MOA2IO02 [4.334 MB]

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MOA2CO03

Measurement of Tune Shift with Amplitude from BPM Data with a Single Kicker Pulse

kicker, feedback, lattice, experiment

6

Y. Hidaka, W.X. Cheng, B. Podobedov
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886.
Measurements of amplitude-dependent tune shift are critical for understanding of nonlinear single particle dynamics in storage rings. The conventional method involves scanning of the kicker amplitude while having a short bunch train at the top of the kicker pulse. In this paper we present a novel, alternative technique that uses a long continuous bunch train, or a sequence of bunch trains, that are spread along the ring, such that different bunches experience different kick amplitudes with a single shot of a kicker pulse. With these beams, a curve of tune shift with amplitude can be extracted from the recently added new NSLS-II BPM feature called gated turn-by-turn (TbT) BPM data that can resolve bunches within a turn, either alone or together with a bunch-by-bunch BPM data. This technique is immune to pulse-to-pulse jitters and long-term machine drift.

Slides MOA2CO03 [1.961 MB]

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MOA2CO04

MICE Operation and Demonstration of Muon Ionization Cooling

emittance, simulation, optics, cavity

10

A. Liu
Fermilab, Batavia, Illinois, USA

Funding: DOE, NSF, STFC, INFN, CHEPP and more
The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling, the only technique that, given the short muon lifetime, can reduce the phase-space volume occupied by a muon beam quickly enough. MICE will demonstrate cooling in two steps. In the first one, Step IV, MICE will study the multiple Coulomb scattering in liquid hydrogen (LH₂) and lithium hydride (LiH). A focus coil module will provide focusing on the absorber. The transverse emittance will be measured upstream and downstream of the absorber in two spectrometer solenoids (SS). Magnetic fields generated by two match coils in the SSs allow the beam to be matched into flat-field regions in which the tracking detectors are installed. This paper will present preliminary results and present plans for data taking of MICE Step IV, together with the design of the MICE Cooling Demonstration Step (Step DEMO), which requires addition of RF systems in the current setup.

Slides MOA2CO04 [10.025 MB]

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MOB2CO03

Collider in the Sea: Vision for a 500 TeV World Laboratory

collider, luminosity, hadron, dipole

13

P.M. McIntyre, S.P. Bannert, J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov
Texas A&M University, College Station, USA
S. Assadi
HiTek ESE LLC, Madison, USA
D. Chavez
DCI-UG, León, Mexico
N. Pogue
LLNL, Livermore, California, USA

A design is presented for a hadron collider in which the magnetic storage ring is configured as a circular pipeline, supported in neutral buoyancy in the sea at a depth of ~100 m. Each collider detector is housed in a bathysphere the size of the CMS hall at LHC, also neutral-buoyant. Each half-cell of the collider lattice is ~300 m long, housed in a single pipe that contains one dipole, one quadrupole, a correction package, and all umbilical connections. A choice of ~4 T dipole field, 2000 km circumference provides a collision energy of 700 TeV. Beam dynamics is dominated by synchrotron radiation damping, which sustains luminosity for >10 hours. Issues of radiation shielding and abort can be accommodated inexpensively. There are at least ten sites world-wide where the collider could be located, all near major urban centers. The paper summarizes several key issues; how to connect and disconnect half-cell segments of the pipeline at-depth using remote submersibles; how to maintain the lattice in the required alignment; provisions for the injector sequence.

Slides MOB2CO03 [3.440 MB]

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MOB2CO04

Multiphysics Analysis of Crab Cavities for High Luminosity LHC Upgrade

cavity, luminosity, simulation, electromagnetic-fields

17

O. Kononenko, Z. Li
SLAC, Menlo Park, California, USA
R. Calaga, C. Zanoni
CERN, Geneva, Switzerland

Funding: The work is supported by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
Development of the superconducting RF crab cavities is one of the major activities under the high luminosity LHC upgrade project that aims to increase the machine discovery potential. The crab cavities will be used for maximizing and leveling the LHC luminosity hence having tight tolerances for the operating voltage and phase. RF field stability in its turn is sensitive to Lorentz force and external loads, so an accurate modelling of these effects is very important. Using the massively parallel ACE3P simulation suite developed at SLAC, we perform a corresponding multiphysics analysis of the electro-mechanical interactions for the RFD crab cavity design in order to ensure the operational reliability of the LHC crabbing system.

Slides MOB2CO04 [5.725 MB]

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MOA3IO01

High Energy Coulomb Scattered Electrons Detected in Air Used as the Main Beam Overlap Diagnostics for Tuning the RHIC Electron Lenses

electron, proton, alignment, detector

20

P. Thieberger, Z. Altinbas, C. Carlson, C. Chasman, M.R. Costanzo, C. Degen, K.A. Drees, W. Fischer, D.M. Gassner, X. Gu, K. Hamdi, J. Hock, Y. Luo, A. Marusic, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin
BNL, Upton, Long Island, New York, USA
S.M. White
ESRF, Grenoble, France

Funding: Work supported by Brookhaven Science Associates under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
A new type of electron-ion beam overlap monitor has been developed for the RHIC electron lenses. Low energy electrons acquire high energies in small impact parameter Coulomb scattering collisions with relativistic ions. Such electrons can traverse thin vacuum windows and be conveniently detected in air. Counting rates are maximized to optimize beam overlap. Operational experience with the electron backscattering detectors during the 2015 p-p RHIC run will be presented. Other possible real-time non-invasive beam-diagnostic applications of high energy Coulomb-scattered electrons will be briefly discussed.
Most of this material appears in an article by the same authors entitled "High energy Coulomb-scattered electrons for relativistic particle beam diagnostics", Phys. Rev. Accel. Beams 19, 041002 (2016)

Slides MOA3IO01 [2.164 MB]

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MOA3CO03

Bunch Shape Monitor Measurements at the LANSCE Linac

linac, electron, target, detector

25

I.N.D. Draganic, D. Baros, C.M. Fortgang, R.W. Garnett, R.C. McCrady, J.F. O'Hara, L. Rybarcyk, C.E. Taylor, H.A. Watkins
LANL, Los Alamos, New Mexico, USA
A. Feschenko, V. Gaidash, Yu.V. Kiselev
RAS/INR, Moscow, Russia

Two Bunch Shape Monitors (BSM) [1] have been developed, fabricated and assembled for the first direct longitudinal beam measurements at the Los Alamos Neutron Science Center (LANSCE) linear accelerator (linac). The BSM detectors use different radio frequencies for the deflecting field: first harmonic (201.25 MHz) and second harmonic (402.5 MHz) of fundamental accelerator radio frequency. The first BSM is designed to record the proton beam longitudinal phase distribution after the new RFQ accelerator at a beam energy of 750 keV with phase resolution of 1.0 degree and covering phase range of 180 degree at 201.25 MHz. The second BSM is installed between DTL tanks 3 and 4 of the LANSCE linac in order to scan both H⁺ and H⁻ beams at a beam energy of 73 MeV with a phase resolution up to 0.5 degree in the phase range of 90 degree at 201.25 MHz. Preliminary results of bunch shape measurements for both beams under different beam gates (pulse length of 150 us, 1 Hz repetition rate, etc.) will be presented and compared high performance simulation results (HPSIM) [2].
[1] A. Feschenko, Proc. of RUPAC2012, FRXOR01, Saint Petersburg, Russia, pp. 181 - 185.
[2] X. Pang, L. Rybarcyk, and S. Baily, Proc. of HB2014, MOPAB30, East Lansing, MI, USA, pp. 99-102.

Slides MOA3CO03 [4.942 MB]

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MOA3CO04

Operational Experience with Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

undulator, operation, site, kicker

28

J.C. Dooling, K.C. Harkay, V. Sajaev, H. Shang
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-m-long SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps* by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.
K. Harkay et al., these proceedings

Slides MOA3CO04 [1.188 MB]

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MOB3IO01

Commissioning of the Phase-I SuperKEKB B-Factory and Update on the Overall Status

electron, vacuum, emittance, coupling

32

Y. Ohnishi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, Y. Funakoshi, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong
KEK, Ibaraki, Japan
M.E. Biagini, M. Boscolo, S. Guiducci
INFN/LNF, Frascati (Roma), Italy
D. El Khechen
LAL, Orsay, France

The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented.

Slides MOB3IO01 [10.375 MB]

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MOB3IO02

LHC Operation at 6.5 TeV: Status and Beam Physics Issues

luminosity, operation, MMI, radiation

37

G. Papotti, M. Albert, R. Alemany-Fernandez, E. Bravin, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, G. Iadarola, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, T. Persson, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J. Wenninger
CERN, Geneva, Switzerland

LHC operation restarted in 2015 after the first Long Shutdown, planning for a 4-year long run until the end of 2018 (called Run 2). The beam energy was fixed at 6.5 TeV. The year 2015 was dedicated to establishing operation at the high energy and with 25 ns beams, in order to prepare production for the following three years. The year 2016 was the first one dedicated to production, and it turned out to be a record-breaking year, in which the goals in both peak and integrated luminosities with proton-proton beams were achieved and surpassed. This paper revisits 2015 and 2016, shortly highlighting the main facts in the timelines, recalling the parameters that characterized luminosity production, and sketching the main limitations and the main highlights of results for selected topics, including a particular focus on the beam physics issues.

Slides MOB3IO02 [15.183 MB]

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MOB3CO03

RHIC Au-Au Operation at 100 GeV in Run16

operation, cavity, luminosity, electron

42

X. Gu, J.G. Alessi, E.N. Beebe, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, J.P. Jamilkowski, J.S. Laster, V. Litvinenko, C. Liu, Y. Luo, M. Mapes, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, I. Pinayev, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, Q. Wu, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York, USA

In order to achieve higher instantaneous and integrated luminosities, the average Au bunch intensity in RHIC has been increased by 30% compared to the preceding Au run. This increase was accomplished by merging bunches in the RHIC injector AGS. Luminosity leveling for one of the two interaction points (IP) with collisions was realized by continuous control of the vertical beam separation. Parallel to RHIC physics operation, the electron beam commissioning of a novel cooling technique with potential application in eRHIC, Coherent electron Cooling as a proof of principle (CeCPoP), was carried out. In addition, a 56 MHz superconducting RF cavity was commissioned and made operational. In this paper we will focus on the RHIC performance during the 2016 Au-Au run.

Slides MOB3CO03 [2.173 MB]

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MOB3CO04

High Luminosity 100 TeV Proton-Antiproton Collider

proton, collider, antiproton, quadrupole

45

S.J. Oliveros, J.G. Acosta, L.M. Cremaldi, T.L. Hart, D.J. Summers
UMiss, University, Mississippi, USA

The energy scale for new physics is known to be in the multi-TeV range, signaling the potential need for a collider beyond the LHC. A 10³⁴ cm**−2 s**−1 luminosity 100 TeV proton-antiproton collider is explored. Prior engineering studies for 233 and 270 km circumference tunnels were done for Illinois dolomite and Texas chalk signaling manageable tunneling costs. At a ppbar the cross section for high mass states is of order 10x higher with antiproton collisions, where antiquarks are directly present rather than relying on gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets, because lower beam currents can produce the same rare event rates. In our design the increased momentum acceptance (11 ± 2.6 GeV/c) in a Fermilab-like antiproton source is used with septa to collect 12x more antiprotons in 12 channels. For stochastic cooling, 12 cooling systems would be used, each with one debuncher/momentum equalizer ring and two accumulator rings. One electron cooling ring would follow. Finally antiprotons would be recycled during runs without leaving the collider ring, by joining them to new bunches with synchrotron damping.

Slides MOB3CO04 [1.304 MB]

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MOA4IO01

Performance of the Low Charge State Laser Ion Source in BNL

laser, target, plasma, ion-source

49

M. Okamura, J.G. Alessi, E.N. Beebe, M.R. Costanzo, L. DeSanto, S. Ikeda, J.P. Jamilkowski, T. Kanesue, R.F. Lambiase, D. Lehn, C.J. Liaw, D.R. McCafferty, J. Morris, R.H. Olsen, A.I. Pikin, R. Schoepfer, A.N. Steszyn
BNL, Upton, Long Island, New York, USA

In March 2014, a Laser Ion Source (LIS) was commissioned which delivers high brightness low charge state heavy ions for the hadron accelerator complex in Brookhaven National Laboratory (BNL). Since then, the LIS has provided many heavy ion species successfully. The induced low charge state (mostly singly charged) beams are injected to the Electron Beam Ion Source (EBIS) where ions are then highly ionized to fit to the following accelerator's Q/M acceptance, like Au³²⁺. Last year, we upgraded the LIS to be able to provide two different beams into EBIS on a pulse-to- pulse basis. Now the LIS is simultaneously providing beams for both the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL). In the conference we present achieved performance and developed new techniques of the LIS.

Slides MOA4IO01 [7.796 MB]

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MOA4IO02

Recent Progress in High Intensity Operation of the Fermilab Accelerator Complex

proton, booster, target, experiment

54

M.E. Convery
Fermilab, Batavia, Illinois, USA

We report on the status of the Fermilab accelerator complex. Beam delivery to the neutrino experiments surpassed our goals for the past year. The Proton Improvement Plan is well underway with successful 15 Hz beam operation. Beam power of 700 kW to the NOvA experiment was demonstrated and will be routine in the next year. We are also preparing the Muon Campus to commission beam to the g-2 experiment.

Slides MOA4IO02 [3.574 MB]

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MOA4CO03

Complete Beam Dynamics of the JLEIC Ion Collider Ring Including Imperfections, Corrections, and Detector Solenoid Effects

dynamic-aperture, multipole, solenoid, detector

57

G.H. Wei, F. Lin, V.S. Morozov, F.C. Pilat, Y. Zhang
JLab, Newport News, Virginia, USA
Y.M. Nosochkov
SLAC, Menlo Park, California, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: This paper has been authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported also by the U.S. DOE Contract DE-AC02-76SF00515.
The JLEIC is proposed as a next-generation facility for the study of strong interaction (QCD). Achieving its goal luminosity of up to 1034 cm^-2s⁻¹ requires good dynamical properties and a large dynamic aperture (DA) of ~ ±10 σ of the beam size. The limit on the DA comes primarily from non-linear dynamics, element misalignments, magnet multipole components, and detector solenoid effect. This paper presents a complete simulation including all of these effects. We first describe an orbit correction scheme and determine tolerances on element misalignments. And beta beat, betatron tunes, coupling, and linear chromaticity perturbations also be corrected. We next specify the requirements on the multipole components of the interaction region magnets, which dominate the DA in the collision mode. Finally, we take special care of the detector solenoid effects. Some of the complications are an asymmetric design necessary for a full acceptance detector with a crossing angle of 50 mrad. Thus, in addition to coupling, the solenoid causes closed orbit excursion and excites dispersion. It also breaks the figure-8 spin symmetry. We present a scheme with correction of all of these effects.

Slides MOA4CO03 [1.502 MB]

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MOA4CO04

Compact Carbon Ion Linac

linac, DTL, rfq, accelerating-gradient

61

P.N. Ostroumov, A. Goel, B. Mustapha, A. Nassiri, A.S. Plastun
ANL, Argonne, USA
L. Faillace, S.V. Kutsaev, E.A. Savin
RadiaBeam, Marina del Rey, California, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under Accelerator Stewardship Grant, Proposal No. 0000219678.
Argonne National Laboratory is developing an Advanced Compact Carbon Ion Linac (ACCIL) in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver up to 10⁹ carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. To optimize the linac design in this energy range both backward traveling wave and coupled cell standing wave S-band structures were analyzed. To achieve the required accelerating gradients our design uses accelerating structures excited with short RF pulses (~500 ns flattop). The front-end accelerating structures such as the RFQ, DTL and Coupled Cell DTL are designed to operate at lower frequencies to maintain high shunt impedance. In parallel with our design effort ANL's RF test facility has been upgraded and used for the testing of an S-band high-gradient structure designed and built by Radiabeam for high pulsed RF power operation. The 5-cell S-band structure demonstrated 52 MV/m acceleration field at 2 μs 30 Hz RF pulses. A detailed physics design, including a comparison of different accelerating structures and end-to-end beam dynamics simulations of the ACCIL will be presented.

Slides MOA4CO04 [3.531 MB]

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MOB4IO02

ERL-Ring and Ring-Ring Designs for the eRHIC Electron-Ion Collider

electron, luminosity, proton, linac

64

V. Ptitsyn
BNL, Upton, Long Island, New York, USA

An overview of the eRHIC project.

Slides MOB4IO02 [6.001 MB]

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MOB4CO03

Design of Muon Collider Lattices

collider, sextupole, quadrupole, factory

69

Y.I. Alexahin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
A Muon Collider promises unique opportunities both as an energy frontier machine and as a factory for detailed study of the Higgs boson and other particles. However, in order to achieve a competitive level of luminosity a number of demanding requirements to the collider optics should be satisfied arising from short muon lifetime and relatively large values of the transverse emittance and momentum spread in muon beams that can realistically be obtained with ionization cooling. Basic solutions which make possible to achieve these goals with Nb3Sn magnet parameters are presented.

Slides MOB4CO03 [0.794 MB]

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MOB4CO04

Design of the Room-Temperature Front-End for a Multi-Ion Linac Injector

rfq, linac, light-ion, heavy-ion

73

A.S. Plastun, Z.A. Conway, B. Mustapha, P.N. Ostroumov
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S.DOE, Office of Science, Office of Nuclear Physics, contract DE-AC02-06CH11357. This research used resources of ANL's ATLAS, which is a DOE Office of Science User Facility.
A pulsed multi ion injector linac is being developed by ANL for Jefferson Laboratory's Electron Ion Collider (JLEIC). The linac is designed to deliver both polarized and non polarized ion beams to the booster synchrotron at energies ranging from 135 MeV for hydrogen to 43 MeV/u for lead ions. The linac is composed of a 5 MeV/u room temperature section and a superconducting section with variable velocity profile for different ion species. This paper presents the results of the RF design of the main components and the beam dynamics simulations of the linac front-end with the goal of achieving design specifications cost-effectively.

Slides MOB4CO04 [2.545 MB]

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MOPOB05

Tokamak Accelerator

plasma, vacuum, ECR, experiment

76

G. Li
ASIPP, Hefei, People's Republic of China

Tokamak accelerator within plasma is analyzed to be implemented in existing machines for speeding the development of fusion energy with seeding fast particles from high current accelerators - the so-called two-component reactor approach [J. M. Dawson, H. P. Furth, and F. H. Tenney, Phys. Rev. Lett. 26, 1156 (1971)]. All plasma particles are heated at the same time by inductively-coupled power transfer (IPT) within an energy confinement time. This could facilitate the attainment of ignition in tokamak by forming high-gain high-field (HGHF) fusion plasma suggested in [Li. G., Sci. Rep.5, 15790 (2015)]. HGHF mechanism is validated by the flux-conserving process existed in discharges of tokamak plasma at normal operation with long pulses or at compression process within an energy confinement time. Differences between HGHF plasma and former unity-beta plasma are discussed. Tokamak as an accelerator could scale down the design capacity of fusion power plant by simply inserting in-vacuum vertical field coils (IVC) within its vacuum vessel, such as China Fusion Engineering Test Reactor (CFETR).

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MOPOB06

MAX IV and Solaris Linac Magnets Production Series Measurement Results

linac, gun, storage-ring, septum

79

M.A.G. Johansson
MAX IV Laboratory, Lund University, Lund, Sweden
R. Nietubyć
NCBJ, Świerk/Otwock, Poland

The linacs of the MAX IV and Solaris synchrotron radiation light sources, currently in operation in Lund, Sweden, and Kraków, Poland, use various conventional magnet designs. The production series of totally more than 100 magnets of more than 10 types or variants, which were all outsourced to industry, with combined orders for the types that are common to both MAX IV and Solaris, were completed in 2013 with mechanical and magnetic QA conforming to specifications. This article presents an overview of the different magnet types installed in these machines, and mechanical and magnetic measurement results of the full production series.

Poster MOPOB06 [2.535 MB]

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MOPOB07

Off-Orbit Ray Tracing Analysis for the APS-Upgrade Storage Ring Vacuum System

vacuum, photon, storage-ring, site

82

J.A. Carter, K.C. Harkay, B.K. Stillwell
ANL, Argonne, Illinois, USA

Funding: Argonne National Laboratory's work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357.
A MatLab program has been created to investigate off-orbit ray tracing possibilities for the APS-Upgrade stor-age ring vacuum system design. The goals for the pro-gram include calculating worst case thermal loading conditions and finding minimum shielding heights for photon absorbers. The program computes the deviation possibilities of synchrotron radiation rays emitted along bending magnet paths using discretized local phase space ellipses. The sizes of the ellipses are computed based on multi-bend achromat (MBA) lattice parameters and the limiting aperture size within the future storage ring vacuum system. For absorber height calculations, rays are projected from each point in the discretized ellipse to the locations of downstream absorbers. The absorber heights are mini-mized while protecting downstream components from all possible rays. For heat loads, rays are projected until they hit a vacuum chamber wall. The area and linear power densities are calculated based on a ray's distance trav-elled and striking incidence angle. A set of worse case local heat loads is collected revealing a maximum condi-tion that each vacuum component must be designed to withstand.

Poster MOPOB07 [12.749 MB]

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MOPOB08

Streak Camera Measurements of the APS PC Gun Drive Laser

laser, factory, gun, optics

85

J.C. Dooling
ANL, Argonne, Illinois, USA
A.H. Lumpkin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic (SH, 527 nm) and fourth harmonic (FH. 263 nm) wavelengths. The drive laser is a Nd:Glass-based CPA with the IR wavelength (1053 nm) twice doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay employs an etalon with known spacing between reflecting surfaces; this etalon is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.

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MOPOB10

Design of the HGVPU Undulator Vacuum Chamber for LCLS-II

vacuum, alignment, undulator, operation

89

J.E. Lerch, J.A. Carter, P.K. Den Hartog, G.E. Wiemerslage
ANL, Argonne, Illinois, USA

A vacuum chamber has been designed and prototyped for the new Horizontal Gap Vertically Polarization Undulator (HGVPU) as part of the LCLS-II upgrade project. Numerous functional requirements for the HGVPU assembly constrained the vacuum chamber design. These constraints included spatial restrictions to achieve small magnet gaps, narrow temperature and alignment specifications, and minimization of wall erosion and pressure drop within the cooling channels. This led to the design of a 3.5-meter length, thin walled, extruded aluminium chamber with interior water cooling. FEA stress analysis was performed to ensure the chamber will not fail under vacuum and water pressure. A cooling scheme was optimized to ensure water flow is sufficient to maintain temperature without the risk of erosion and to minimize pres-sure drop across the chamber.

Poster MOPOB10 [60.628 MB]

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MOPOB11

Research and Development on the Storage Ring Vacuum System for the APS Upgrade Project

photon, vacuum, storage-ring, impedance

92

B.K. Stillwell, B. Brajuskovic, J.A. Carter, H. Cease, R.M. Lill, G. Navrotski, J. R. Noonan, K.J. Suthar, D.R. Walters, G.E. Wiemerslage, J. Zientek
ANL, Argonne, Illinois, USA
M.P. Sangroula
IIT, Chicago, Illinois, USA

Funding: UChicago Argonne, LLC, operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
A number of research and development activities are underway at Argonne National Laboratory to build confidence in the designs for the storage ring vacuum system required for the Advanced Photon Source Upgrade project (APS-U) [1]. The predominant technical risks are: excessive residual gas pressures during operation, insufficient beam position monitor stability, excessive beam impedance, excessive heating by induced electrical surface currents, and insufficient operational reliability. Present efforts to mitigate these risks include: building and evaluating mock-up assemblies, performing mechanical testing of chamber weld joints, developing computational tools, investigating design alternatives, and performing electrical bench measurements. Status of these activities and some of what has been learned to date will be shared.
*B. Stillwell et al., Conceptual Design of a Storage Ring Vacuum System Compatible with Implementation of a Seven Bend Achromat Lattice at the APS, in Proc. IPAC'14, Dresden, Germany, 2409-2411.

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MOPOB12

A High Bandwidth Bipolar Power Supply for the Fast Correctors in the APS Upgrade

power-supply, controls, ISOL, interface

96

J. Wang, G.S. Sprau
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Upgrade of a multi-bend achromat (MBA) storage ring requires a fast bipolar power supply for the fast correction magnets. The key performance requirement of the power supply includes a small-signal bandwidth of 10 kHz for the output current. This requirement presents a challenge to the design because of the high inductance of the magnet load and a limited input DC voltage. A prototype DC/DC power supply utilizing a MOSFET H-bridge circuit with a 500 kHz PWM has been developed and tested successfully. The prototype achieved a 10-kHz bandwidth with less than 3-dB attenuation for a signal 0.5% of the maximum operating current of 15 amperes. This paper presents the design of the power circuit, the PWM method, the control loop, and the test results.

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MOPOB13

Post Irradiation Examination Results of the NT-02 Graphite Fins Numi Target

target, radiation, proton, operation

99

K. Ammigan, P. Hurh, V.I. Sidorov, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
D. Asner, A.M. Casella, D.J. Edwards, A.L. Schemer-Kohrn, D.J. Senor
PNNL, Richland, Washington, USA

Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The NT-02 neutrino target in the NuMI beamline at Fermilab is a 95 cm long target made up of segmented graphite fins. It is the longest running NuMI target, which operated with a 120 GeV proton beam with maximum power of 340 kW, and saw an integrated total proton on target of 6.1 x 1020. Over the last half of its life, gradual degradation of neutrino yield was observed until the target was replaced. The probable causes for the target performance degradation are attributed to radiation damage, possibly including cracking caused by reduction in thermal shock resistance, as well as potential localized oxidation in the heated region of the target. Understanding the long-term structural response of target materials exposed to proton irradiation is critical as future proton accelerator sources are becoming increasingly more powerful. As a result, an autopsy of the target was carried out to facilitate post-irradiation examination of selected graphite fins. Advanced microstructural imaging and surface elemental analysis techniques were used to characterize the condition of the fins in an effort to identify degradation mechanisms, and the relevant findings are presented in this paper.

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MOPOB14

Experimental Results of Beryllium Exposed to Intense High Energy Proton Beam Pulses

experiment, proton, target, radiation

102

K. Ammigan, B.D. Hartsell, P. Hurh, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
A.R. Atherton
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
M.E.J. Butcher, M. Calviani, M. Guinchard, R. Losito
CERN, Geneva, Switzerland
O. Caretta, T.R. Davenne, C.J. Densham, M.D. Fitton, P. Loveridge, J. O'Dell
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
V.I. Kuksenko, S.G. Roberts
University of Oxford, Oxford, United Kingdom
S.G. Roberts
CCFE, Abingdon, Oxon, United Kingdom

Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Beryllium is extensively used in various accelerator beam lines and target facilities as material for beam windows, and to a lesser extent, as secondary particle production targets. With increasing beam intensities of future accelerator facilities, it is critical to understand the response of beryllium under extreme conditions to reliably operate these components as well as avoid compromising particle production efficiency by limiting beam parameters. As a result, an exploratory experiment at CERN's HiRadMat facility was carried out to take advantage of the test facility's tunable high intensity proton beam to probe and investigate the damage mechanisms of several beryllium grades. The test matrix consisted of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. This paper outlines the experimental measurements, as well as findings from Post-Irradiation-Examination (PIE) work where different imaging techniques were used to analyze and compare surface evolution and microstructural response of the test matrix specimens.

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MOPOB16

Higher Order Modes Analysis of Fermilab's Recycler Cavity

impedance, cavity, dipole, HOM

106

M.H. Awida, J.E. Dey, T.N. Khabiboulline, V.A. Lebedev, R.L. Madrak
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Two recycler cavities are being employed in Fermilab's Recycler Ring for the purpose of slip stacking proton bunches, where 6 batches of 8 GeV protons coming from the Booster are stacked on top of 6 circulating batches. Slip stacking requires two RF cavities operating at 52.809 and 51.545 MHz. In this paper, we report on the analysis of higher order modes in the Recycler cavity, presenting the values for R/Q and shunt impedances. Knowing the frequencies and properties of higher order modes is particularly critical for beam physics and avoidance of beam instabilities.

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MOPOB17

Resonant Frequency Control for the PIP-II Injector Test RFQ: Control Framework and Initial Results

controls, rfq, framework, operation

109

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
D.L. Bowring, B.E. Chase, J.P. Edelen, D.J. Nicklaus, J. Steimel
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359.
For the PIP-II Injector Test (PI-Test) at Fermilab, a four-vane radio frequency quadrupole (RFQ) is designed to accelerate a 30-keV, 1-mA to 10-mA H' beam to 2.1 MeV under both pulsed and continuous wave (CW) RF operation. The available headroom of the RF amplifiers limit the maximum allowable detuning to 3 kHz, and the detuning is controlled entirely via thermal regulation. Fine control over the detuning, minimal manual intervention, and fast trip recovery is desired. In addition, having active control over both the walls and vanes provides a wider tuning range. For this, we intend to use model predictive control (MPC). To facilitate these objectives, we developed a dedicated control framework that handles higher-level system decisions as well as executes control calculations. It is written in Python in a modular fashion for easy adjustments, readability, and portability. Here we describe the framework and present the first control results for the PI-Test RFQ under pulsed and CW operation.

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MOPOB20

Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators

cavity, induction, accelerating-gradient, ECR

113

M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
Fermilab, Batavia, Illinois, USA
M. Martinello
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.

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MOPOB23

The Radiation Damage In Accelerator Target Environments (RaDIATE) Collaboration R&D Program - Status and Future Activities

radiation, target, proton, experiment

117

P. Hurh
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The RaDIATE collaboration (Radiation Damage In Accelerator Target Environments), founded in 2012, has grown to over 50 participants and 11 institutions globally. The primary objective is to harness existing expertise in nuclear materials and accelerator targets to generate new and useful materials data for application within the accelerator and fission/fusion communities. Current activities include post-irradiation examination of materials taken from existing beamlines (such as the NuMI primary beam window from Fermilab) as well as new irradiations of candidate target materials at low energy and high energy beam facilities. In addition, the program includes thermal shock experiments utilizing high intensity proton beam pulses available at the HiRadMat facility at CERN. Status of current RaDIATE activities as well as future plans will be discussed, including special focus on the upcoming RaDIATE irradiation at the Brookhaven Linac Isotope Producer facility (BLIP) in which multiple materials of interest (e.g. beryllium, graphite, silicon, titanium, iridium) will simultaneously be exposed to 120 - 181 MeV proton beam to relevant radiation damage levels.

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MOPOB24

Design of Main Coupler for 650 MHz SC Cavities of PIP-II Project

cavity, vacuum, cryomodule, proton

121

O.V. Pronitchev, S. Kazakov
Fermilab, Batavia, Illinois, USA

Proton Improvement Plan-II at Fermilab has designed an 800MeV superconducting pulsed linac which is also capable of running in CW mode. The high energy section from 185MeV to 800MeV will be using cryomodules with two types of 650MHz elliptical cavities. Both types of cryomodules will include six 5-cell elliptical cavities. Each cavity will have one coupler. Updated design of the 650 MHz main coupler is reported.

Poster MOPOB24 [1.016 MB]

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MOPOB25

The Use of KF Style Flanges in Low Particlulate Applications

vacuum, diagnostics, hardware, cavity

124

K.R. Kendziora, J.J. Angelo, C.M. Baffes, D. Franck, R.J. Kellett
Fermilab, Batavia, Illinois, USA

Funding: Fermilab, Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
As SCRF particle accelerator technology advances the need for 'low particulate' and 'particle free' vacuum systems becomes greater and greater. In the course of the operation of these systems, there comes a time when vari-ous instruments have to be temporarily attached for diag-nostic purposes: RGAs, leak detectors, and additional pumps. In an effort to make the additions of these instru-ments easier and more time effective, we propose to use KF style flanges for these types of temporary diagnostic connections. This document will describe the tests used to compare the particles generated using the assembly of the, widely accepted for 'particle free' use, conflat flange to the proposed KF style flange, and demonstrate that KF flanges produce less particles.

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MOPOB27

Superconducting Coil Winding Machine Control System

controls, FPGA, operation, software

127

J.M. Nogiec, S. Kotelnikov, A. Makulski, K. Trombly-Freytag, D.G.C. Walbridge
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract no. DE-AC02-07CH11359.
The Spirex magnet coil winder has been equipped with an automation system, which allows operation from both a computer and a remote control unit. This machine is about 6m long with a bridge that moves along a track and supports a rotating boom holding a spool of cable and providing cable tension. The machine control system is distributed between three layers: PC, RTOS, and FPGA providing respectively HMI, operational logic and controls. The PC stores the history of operation, shows the machine positions, status, and their history. Keeping cable tension constant is non-trivial in situations where the length of the cable changes with varying speeds. This has been addressed by a PID controller with feed forward augmentation and low-pass filters. Another challenging problem, synchronizing multiple servo motors, has been solved by designing an innovative decentralized algorithm. Extra attention was given to the safety aspects; a fail-safe, redundant safety system with interlocks has been developed, including protection for the operator and the superconducting cable against such situations as accidental over tension, or fast movement of the cable due to operational errors.

Poster MOPOB27 [1.952 MB]

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MOPOB28

Progress on the Design of a Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster

cavity, booster, simulation, injection

130

R.L. Madrak, J.E. Dey, K.L. Duel, J. Kuharik, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine
Fermilab, Batavia, Illinois, USA

A perpendicular biased 2nd harmonic cavity is being designed and built for the Fermilab Booster. Its purpose is to flatten the bucket at injection and thus change the longitudinal beam distribution to decrease space charge effects. It can also help with transition crossing. The cavity frequency range is 76 - 10⁶ MHz. It is modeled using CST microwave studio and COMSOL. The power amplifier will use the same tetrode as is used for the fundamental mode cavities in the Fermilab Booster (Y567B). We discuss recent progress on the cavity design, plans for testing the tuner's garnet material, and tests of the power source.

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MOPOB29

Measurements of the Properties of Garnet Material for Tuning a 2nd Harmonic Cavity for the Fermilab Booster

cavity, solenoid, resonance, ISOL

134

R.L. Madrak, W. Pellico, G.V. Romanov, C.-Y. Tan, I. Terechkine
Fermilab, Batavia, Illinois, USA

A perpendicular biased 2nd harmonic cavity is being designed and built for the Fermilab Booster, to help with injection and transition. The frequency range is 76 - 10⁶ MHz. The garnet material chosen for the tuner is AL800. To reliably model the cavity, its static permeability and loss tangent must be well known. We present our measurements of these properties.

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MOPOB30

Development and Comparison of Mechanical Structures for FNAL 15 T Nb3Sn Dipole Demonstrator

dipole, operation, collider, controls

137

A.V. Zlobin, I. Novitski
Fermilab, Batavia, Illinois, USA

Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Main design challenges for 15 T accelerator magnets are large Lorentz forces at this field level. The large Lorentz forces generate high stresses in the coil and mechanical structure and, thus, need stress control to maintain them at the acceptable level for brittle Nb3Sn coils and other elements of magnet mechanical structure. To provide these conditions and achieve the design field in the FNAL 15 T dipole demonstrator, several mechanical structures have been developed and analysed. The possibilities and limitations of these designs are discussed in this paper.

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MOPOB32

Design and Test of the Prototype Tuner for 3.9 GHz SRF Cavity for LCLS II Project

cavity, SRF, cryomodule, FEL

140

Y.M. Pischalnikov, E. Borissov, J.C. Yun
Fermilab, Batavia, Illinois, USA

Fermilab is responsible for the design of the 3.9GHz cryomodule for the LCLS-II that will operate in continuous wave (CW) mode. Bandwidth of the SRF cavities will be in the range of the 180Hz. In our tuner design, we adopted as the slow tuner-mechanism slim blade tuner originated by INFN for the European XFEL 3.9GHz. At the same time bandwidth of the SRF cavities for LCLS II will be in the range of the 180Hz and fine/fast tuning of the cavity frequency required. We added to the design fast/fine tuner made with 2 encapsulated piezos. First prototype tuner has been built and went through testing at warm conditions. Details of the design and summary of the tests will be presented in this paper.

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MOPOB33

LCLS-II Tuner Assembly for the Prototype Cryomodule at FNAL

cavity, cryomodule, SRF, operation

143

Y.M. Pischalnikov, E. Borissov, T.N. Khabiboulline, J.C. Yun
Fermilab, Batavia, Illinois, USA

The tuner design for LCLS-II has been thoroughly verified and fabricated for used in the LCLS-II prototype modules. This paper will present the lessons learned during the installation of these tuners for the prototype modules at FNAL, including installation procedures, best practices, and challenges encountered.

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MOPOB35

Design of the LBNF Beamline Target Station

target, shielding, radiation, focusing

146

S. Tariq, K. Ammigan, K. Anderson, S.A. Buccellato, C.F. Crowley, B.D. Hartsell, P. Hurh, J. Hylen, P.H. Kasper, G.E. Krafczyk, A. Lee, B.G. Lundberg, A. Marchionni, N.V. Mokhov, C.D. Moore, V. Papadimitriou, D. Pushka, I.L. Rakhno, S.D. Reitzner, V.I. Sidorov, A.M. Stefanik, I.S. Tropin, K. Vaziri, K.E. Williams, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
C.J. Densham
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Long Baseline Neutrino Facility (LBNF) project will build a beamline located at Fermilab to create and aim an intense neutrino beam of appropriate energy range toward the DUNE detectors at the SURF facility in Lead, South Dakota. Neutrino production starts in the Target Station, which consists of a solid target, magnetic focusing horns, and the associated sub-systems and shielding infrastructure. Protons hit the target producing mesons which are then focused by the horns into a helium-filled decay pipe where they decay into muons and neutrinos. The target and horns are encased in actively cooled steel and concrete shielding in a chamber called the target chase. The reference design chase is filled with air, but nitrogen and helium are being evaluated as alternatives. A replaceable beam window separates the decay pipe from the target chase. The facility is designed for initial operation at 1.2 MW, with the ability to upgrade to 2.4 MW, and is taking advantage of the experience gained by operating Fermilab's NuMI facility. We discuss here the design status, associated challenges, and ongoing R&D and physics-driven component optimization of the Target Station.

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MOPOB36

Design of the High Beta 650 MHz Cryomodule - PIP II

cavity, cryomodule, vacuum, cryogenics

149

V. Roger, T.H. Nicol, Y.O. Orlov
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy
In this paper the design of the high beta 650 MHz cryomodule will be presented. This cryomodule is composed of six 5-cell 650 MHz elliptical cavities, designed for β=0.92. These cryomodules are the last elements of the Super Conducting (SC) linac architecture which is the main component of the Proton Improvement Plan-II (PIP-II) at Fermilab. This paper summarizes the design choices which have been done. Mechanical, thermal and cryogenic analyses have been performed to ensure the proper operation. First the concept of having a strong-back at room temperature has been validated. Then the heat loads have been estimated and all the components have been integrated inside the cryomodule by designing the supports, the beam line, the thermal shield and the cryogenic lines. All these elements and the calculations leading to the design of this cryomodule will be described in this paper.

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MOPOB39

A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch

linac, electron, ECR, operation

152

G.W. Saewert, D. Frolov, H. Pfeffer
Fermilab, Batavia, Illinois, USA

Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.

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MOPOB40

Quench Training Analysis of Nb3Sn Accelerator Magnets

dipole, quadrupole, operation, magnet-design

155

S. Stoynev, K.H. Riemer, A.V. Zlobin
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Nb3Sn accelerator magnet technology has made significant progress during the past decades. Thanks to that 11-12 T Nb3Sn dipoles and quadrupoles are planned to be used in accelerators such as LHC in near future for the luminosity upgrade and in longer term for the LHC energy upgrade or a future Very High Energy pp Collider. However, all the state of the art Nb3Sn accelerator magnets show quite long training. This specific feature significantly raises the required design margin or limit the nominal operation field of Nb3Sn accelerator magnets and, thus, increases their cost. To resolve this problem Fermilab has launched a study aiming to analyze the relatively large amount of Nb3Sn magnet training data accumulated at Fermilab magnet test facility. The ultimate goal is to correlate magnet design and manufacturing features and magnet material properties with training performance parameters which will eventually allow us to optimize both the magnet design, fabrication and the training processes. This paper describes the general strategy of the analysis and presents the first results based on partial data processing. Conclusions and further steps are also outlined and discussed.

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MOPOB41

Field Quality Measurements in the FNAL Twin-Aperture 11 T Dipole for LHC Upgrades

dipole, quadrupole, magnet-design, ion-effects

158

T. Strauss, G. Apollinari, E.Z. Barzi, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, S. Stoynev, D. Turrioni, G. Velev, A.V. Zlobin
Fermilab, Batavia, Illinois, USA
B. Auchmann, S. Izquierdo Bermudez, M. Karppinen, L. Rossi, F. Savary, D. Smekens
CERN, Geneva, Switzerland

Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404
FNAL and CERN magnet groups are developing a twin-aperture Nb3Sn 11 T dipole suitable for installation in the LHC to provide room for additional collimators in the dispersion suppressor (DS) areas. Two of these magnets with a collimator in between will replace one regular MB dipole. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been assembled and tested at FNAL in 2012-2014. The 1 m long collared coils were then assembled into the twin-aperture configuration and tested in 2015. The first magnet test was focused on the quench performance of twin-aperture magnet configuration including magnet training, ramp rate sensitivity and temperature dependence of magnet quench current. In the second test performed in July 2016 field quality in one of the two magnet apertures has been measured and compared with the data for the single-aperture models. These results are reported and discussed in this paper.

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MOPOB44

Thyratron Replacement

operation, klystron, network, linear-collider

162

I. Roth, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: *Work supported by US Department of Energy under contract DE-SC0011292
Semiconductor thyristors have long been used as a replacement for thyratrons in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. It is, however, possible to assemble these devices in arrays to reach the required performance levels without sacrificing their inherent speed. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6μs, and 120 Hz.

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MOPOB46

Long Pulse Solid-State Pulsed Power Systems Built to ESS Specifications

klystron, operation, high-voltage, power-supply

165

I. Roth, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J. Domenge
Sigma Phi Electronics, Wissembourg, France
J.L. Lancelot
Sigmaphi, Vannes, France

Diversified Technologies, Inc. (DTI), in partnership with SigmaPhi Electronics (SPE) has built three long pulse solid-state klystron transmitters to meet spallation source requirements. Two of the three units are installed at CEA Saclay and the National Institute of Nuclear and Particle Physics (IN2P3), where they will be used as test stands for the European Spallation Source (ESS). The systems delivered to CEA and IN2P3 demonstrate that the ESS klystron modulator specifications (115 kV, 25 A per klystron, 3.5 ms, 14 Hz) have been achieved in a reliable, manufacturable, and cost-effective design. There are only minor modifications required to support transition of this design to the full ESS Accelerator, with up to 100 klystrons. The systems will accommodate the recently-determined increase in average power (~660 kW), can offer flicker-free operation, are equally-capable of driving Klystrons or MBIOTs, and are designed for an expected MTBCF of over ten years, based on operational experience with similar systems.

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MOPOB47

Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade

impedance, cavity, HOM, coupling

167

T.H. Luo, K.M. Baptiste, M. Betz, J.M. Byrd, S. De Santis, S. Kwiatkowski, S. Persichelli, Y. Yang
LBNL, Berkeley, California, USA

The ALS upgrade to a diffraction-limited light source (ALS-U) depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. In order to achieve lengthening in excess of fourfold necessary to this end, we are investigating the use of the same passive 1.5 GHz normal-conducting RF cavities currently used on the ALS. While the upgraded ring RF parameters and fill pattern make it easier as long as the beam-induced phase transient is concerned, the large lengthening factor and the strongly non-linear lattice require particular attention to the cavities contribution to the machine overall impedance budget. In this paper we present our estimates of the narrow-band impedance obtained by numerical simulation and bench measurements of the cavities' resonant modes.

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MOPOB49

Persistent Current Effects in RHIC Arc Dipole Magnets Operated at Low Currents

dipole, operation, ion-effects, detector

170

X. Wang, S. Caspi, S.A. Gourlay, G.L. Sabbi
LBNL, Berkeley, California, USA
A.K. Ghosh, R.C. Gupta, A.K. Jain, P. Wanderer
BNL, Upton, Long Island, New York, USA

Funding: BNL work was supported by Brookhaven Science Associates, LLC under Contract# DESC0012704 with the U.S. DOE. LBNL work was supported by the U.S. DOE under Contract# DEAC02- 05CH11231.
The Relativistic Heavy Ion Collider (RHIC) arc dipoles at Brookhaven National Laboratory are operated at low field for low energy Au-Au studies. Indications of strong nonlinear magnetic fields have been observed at these low currents due to the persistent current effects of superconducting NbTi filaments. We report the details of the measurement and calculation of the field errors due to persistent current effect. The persistent current induced field errors calculated with a model based on the strand magnetization data agree well with the measurements of a spare arc dipole magnet. The dependence of the persistent current effects on the park current is calculated based on the validated model.

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MOPOB51

High-Efficiency 500-W RF-Power Modules for UHF

operation, klystron, ISOL, proton

174

F.H. Raab
Green Mountain Radio Research, Boone, USA

Funding: U.S. DoE DE-SC0002548, DE-SC0006200, and DE-SC0006237. GMRR IR&D.
GMRR has developed solid-state RF-power modules that deliver up to 650 W at frequencies from 325 to 704 MHz. The nominal output of 500 W is delivered with an overall efficiency from 79% at 704 MHz to 83% percent at 325 MHz. In contrast to conventional solid-state power amplifiers, high efficiency is maintained over a wide range of output powers; e.g., 70 percent or better for outputs of 30 W or higher. Each 500-W module contains five 120-W RF power amplifiers (PAs) and a Gysel* splitter and combiner. The class-F** PAs employ GaN FETs and produce over 120 W with efficiencies from 82-86%. A class-S modulator maintains high efficiency over nearly the entire range of amplitudes. Supporting hardware includes a control computer, DSP, low-level RF amplifiers, and drivers. The 500-W modules are intended to be building blocks of a multi-kW RF power source. A system based these modules will consume 1/3 to 1/2 of the prime power required by a system based upon klystrons or conventional solid-state amplifiers and will have significantly lower cooling requirements.
* U. H. Gysel, Int. Microwave Symp. Digest, May 12 - 14, 1975.
** F. H. Raab et al., IEEE Trans. Microwave Theory Tech., March 2002.

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MOPOB52

Dielectric Loaded High Pressure Gas Filled RF Cavities for Use in Muon Cooling Channels

cavity, solenoid, plasma, accelerating-gradient

177

B.T. Freemire
IIT, Chicago, Illinois, USA
M. Backfish, D.L. Bowring, A. Moretti, D.W. Peterson, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, Illinois, USA
R.P. Johnson
Muons, Inc, Illinois, USA
A.V. Kochemirovskiy
University of Chicago, Chicago, Illinois, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
High brightness muon beams require significant six dimensional cooling. One cooling scheme, the Helical Cooling Channel, employs high pressure gas filled radio frequency cavities, which provide both the absorber needed for ionization cooling, and a means to mitigate RF breakdown. The cavities are placed along the beam's trajectory, and contained within the bores of superconducting solenoid magnets. Gas filled RF cavities have been shown to successfully operate within multi-Tesla external magnetic fields, and not be overcome with the loading resulting from beam-induced plasma. The remaining engineering hurdle is to find a way to fit 325 and 650 MHz single cell pillbox cavities within the bores of the magnets using modern technology. One method to accomplish this is to partially fill the cavities with a dielectric material. Alumina (Al2O3) is an ideal dielectric, and the experimental test program to determine its performance under high power in a gas filled cavity has concluded. The final results, and their implications for the design of a muon cooling channel based on gas filled RF cavities will be discussed.

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MOPOB53

Simulation of Ping-Pong Multipactor with Continuous Electron Seeding

simulation, electron, multipactoring, resonance

181

M. Siddiqi, R.A. Kishek
UMD, College Park, Maryland, USA

Funding: National Science Foundation grant No. PHY1535519
Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics *. In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented.
*R.A. Kishek, Physics of Plasmas 20, 056702 (2013).

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MOPOB54

Superferric Arc Dipoles for the Ion Ring and Booster of JLEIC

dipole, multipole, quadrupole, collider

184

P.M. McIntyre, J. Breitschopf, T. Elliott, R. Garrison, J. Gerity, J.N. Kellams, A. Sattarov
Texas A&M University, College Station, USA
D. Chavez
DCI-UG, León, Mexico

Funding: This work was supported by a grant from the NP Division of the US Dept. of Energy.
The JLEIC project requires 3 T superferric dipoles and quadrupoles for the half-cell arcs of its Ion Ring and Booster. A superferric design using NbTi cable-in-conduit conductor is being developed. A mockup winding has been completed, with the objectives to develop and evaluate the coil structure and the winding tooling and methods, and to measure errors in the position of each cable turn in the dipole body. The results of the mockup winding study are presented. The CIC design is now ready for construction and testing of a first model dipole.

Poster MOPOB54 [1.147 MB]

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MOPOB55

Room Temperature Magnets in FRIB Driver Linac

linac, quadrupole, alignment, dipole

188

Y. Yamazaki, N.K. Bultman, E.E. Burkhardt, F. Feyzi, K. Holland, A. Hussain, M. Ikegami, F. Marti, S.J. Miller, T. Russo, J. Wei, Q. Zhao
FRIB, East Lansing, USA
W.J. Yang, Q.G. Yao
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
The FRIB Driver Linac* is to accelerate all the stable ions beyond 200 MeV/nucleon with a beam power of 400 kW. The linac is unique, being compactly folded twice. In this report, the room temperature magnets, amounting 147 in total, after Front End with a 0.5-MeV RFQ, are detailed, emphasizing the rotating coil field measurements and fiducialization.
*E. Pozdeyev et al., "Status of FRIB" in this conference.
T. Xu, "Superconducting Cryomodule Development and Production for the FRIB Linac" in this conference.

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MOPOB56

Frequency Domain Simulations of Rf Cavity Structures and Coupler Designs for Co-Linear X-Band Energy Booster (CXEB) with ACE3P

cavity, GUI, simulation, electron

191

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

Due to their higher intrinsic shunt impedance X-band accelerating structures offer significant gradients with relatively modest input powers, and this can lead to more compact light sources. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3-GHz, L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the frequency domain simulation results using the ACE3P Electromagnetic Suite's OMEGA3P and S3P for our proposed Co-linear X-band Energy Booster (CXEB) system that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structures while driven solely by the beam from the L-band system.

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MOPOB57

Wakefield Excitation in Power Extraction Cavity of Co-Linear X-Band Energy Booster in Time Domain With ACE3P

cavity, wakefield, impedance, extraction

195

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

We provide the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB). Here, using the time domain solver T3P of the ACE3P Suite we provide the single bunch and multiple bunch wakefield excitation mechanism for the power build up when using a symmetric Gaussian bunch distribution in our traveling wave (TW) X-band power extraction cavity (PEC). Finally, we determine the achievable X-band power at the end of the PEC structure.

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MOPOB58

Eddy Current Calculations for a 1.495 GHz Injection-Locked Magnetron

interaction-region, cavity, injection, klystron

198

S.A. Kahn, A. Dudas, R.P. Johnson, M.L. Neubauer
Muons, Inc, Illinois, USA
H. Wang
JLab, Newport News, Virginia, USA

An injection-locked amplitude modulated magnetron is being developed as a reliable, efficient RF source that could replace klystrons used in particle accelerators. The magnetron amplitude is modulated using a trim magnetic coil to alter the magnetic field in conjunction with the anode voltage to suppress the emittance growth due to microphonics and changing beam loads. The rate for microphonic noise can have frequencies in the range 10-50 Hz. This is competitive to the inductive decay time of the trim coil. Eddy currents will be induced in the copper anode of the magnetron that will buck the field from the trim coil in the interaction region. This paper will describe the magnetic circuit of the proposed magnetron as well as the calculation and handling of the Eddy currents on the magnetic field.

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MOPOB59

Magnet Design for the Splitter/Combiner Regions of CBETA, the Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator

quadrupole, dipole, linac, magnet-design

201

J.A. Crittenden, D.C. Burke, Y.L.P. Fuentes, C.E. Mayes, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and New York State.
The Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator (CBETA) will provide a 150-MeV electron beam using four acceleration and four deceleration passes through the Cornell Main Linac Cryomodule housing six 1.3-GHz superconducting RF cavities. The return path of this 76-m-circumference accelerator will be provided by 10⁶ fixed-field alternating-gradient (FFAG) cells which carry the four beams of 42, 78, 114 and 150-MeV. Here we describe magnet designs for the splitter and combiner regions which serve to match the on-axis linac beam to the off-axis beams in the FFAG cells, providing the path-length adjustment necessary to energy recovery for each of the four beams. The path lengths of the four beamlines in each of the splitter and combiner regions are designed to be adapted to 1-, 2-, 3-, and 4-pass staged operations. Design specifications and modeling for the 24 dipole and 32 quadrupole electromagnets in each region are presented. The CBETA project will serve as the first demonstration of multi-pass energy recovery using superconducting RF cavities with FFAG cell optics for the return loop.

Poster MOPOB59 [8.982 MB]

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MOPOB60

Performance of the Cornell Main Linac Prototype Cryomodule for the CBETA Project

cavity, linac, HOM, cryomodule

204

F. Furuta, N. Banerjee, J. Dobbins, R.G. Eichhorn, M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The main linac prototype cryomodule (MLC) is a key component for the Cornell-BNL ERL Test Accelerator (CBETA), which is a 4-turn FFAG ERL under construction at Cornell University. The MLC has been designed for high current and efficient continuous wave (CW) SRF cavity operation, and houses six high Q0 7-cell SRF cavities with individual beamline higher order-modes (HOMs) absorbers for strong HOM suppression in high beam current operation. Cavities have achieved specification values of 16.2MV/m with high Q0 of 2.0·10¹⁰ at 1.8K in CW operation after cooldown optimizations and RF processing. Damping of the HOMs has been measured in detail, indicating that the loaded quality-factors of all critical modes are low enough to avoid BBU in high current, multi-turn ERL operation. Microphonics measurements have been carried out as well, and vibration sources have been determined and eliminated. Here we report on these cryomodule performance studies.

Poster MOPOB60 [3.321 MB]

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MOPOB61

Updates of Vertical Electropolishing Studies at Cornell with KEK and Marui Galvanizing Co. Ltd .

cathode, cavity, SRF, target

208

F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, T. Saeki
KEK, Ibaraki, Japan

Cornell, KEK, and Marui Galvanizing Co. Ltd (MGI) have started new Vertical Electro-Polishing (VEP) R&D collaboration in 2014. MGI and KEK has developed their original VEP cathode named 'i-cathode Ninja'® which has four retractable wing-shape parts per cell for single-/9-cell cavities. One single cell cavity had processed with VEP using i-cathode Ninja at Cornell. Cornell also performed the vertical test on that cavity. We will present the details of process and RF test result at Cornell.

Poster MOPOB61 [2.251 MB]

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MOPOB62

SRF Half Wave Resonator Activities at Cornell for the RAON Project

cavity, SRF, pick-up, heavy-ion

211

M. Ge, F. Furuta, T. Gruber, S.W. Hartman, C. Henderson, M. Liepe, S. Lok, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Joo, J.-W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

The RAON heavy-ion accelerator requires ninety-eight 162.5MHz Half-Wave-Resonators (HWR) with a geometrical β=0.12. Cornell University will test a prototype HWR as well as develop a frequency tuner for this cavity. In this paper we report on the progress in designing, fabricating, and commissioning of new HWR preparation and testing infrastructure at Cornell. The HWR infrastructure work includes new input and pick-up couplers, a modified vertical test insert with a 162.5MHz RF system, a new High-Pressure-Water-Rinsing (HPR) setup, and a modified chemical etching system.

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MOPOB63

Impact of Cooldown Procedure and Ambient Magnetic Field on the Quality Factor of State-of-the-Art Nb3Sn Single-Cell ILC Cavities

cavity, site, experiment, factory

215

D.L. Hall, M. Ge, J.J. Kaufman, M. Liepe, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: DOE
Single-cell Nb3Sn cavities coated at Cornell University have demonstrated quality factors of 10¹⁰ at 16 MV/m and 4.2 K in vertical tests, achieving the performance requirements of contemporary modern accelerator designs. In this paper, we present results demonstrating the impact of the cooldown procedure and ambient magnetic fields on the cavity's ability to achieve these quality factors and accelerating gradients. The impact of the magnetic fields from thermoelectric currents, generated by thermal gradients across the cavity during cooldown, are shown to be equivalent to the impact of magnetic fields trapped from ambient sources. Furthermore, the increase in the residual surface resistance due to trapped magnetic flux, from both ambient sources and thermoelectric currents, is found to be a function of the applied RF magnetic field amplitude. A hypothesis for this observation is given, and conclusions are drawn regarding the demands on the cooldown procedure and ambient magnetic fields necessary to achieve quality factors of 10¹⁰ at 4.2 K and 16 MV/m or higher.

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MOPOB65

Investigation of the Origin of the Anti-Q-Slope

cavity, ECR, experiment, SRF

218

J.T. Maniscalco, M. Ge, D. Gonnella, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The surface resistance of a superconductor, a property very relevant to SRF accelerators, has long been known to depend on the strength of the surface magnetic field. A recent discovery showed that, for certain surface treatments, microwave cavities can be shown to have an inverse field dependence, dubbed the ‘‘anti-Q-slope'', in which the surface resistance decreases over an increasing field. Here we present an investigation into what causes the anti-Q-slope in nitrogen-doped niobium cavities, drawing a direct connection between the electron mean free path of the SRF material and the magnitude of the anti-Q-slope. Further, we incorporate residual resistance due to flux trapping to calculate an optimal mean free path for a given trapped flux.

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MOPOB68

A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films

laser, niobium, controls, electron

221

J. Musson, K. Macha, H.L. Phillips
JLab, Newport News, Virginia, USA
W. Cao, H. Elsayed-Ali
ODU, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University
Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.

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MOPOB69

Wire Stretching Technique for Measuring RF Crabbing/Deflecting Cavity Electrical Center and a Demonstration Experiment on Its Accuracy

cavity, experiment, simulation, cryomodule

225

H. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The fabrication accuracy of a superconducting RF crab cavity for the Large Hadron Collider High Luminosity Upgrade and the future Electron Ion Collider requires the cavity's electric center line relative to the crabbing plane within sub mm offset and sub degree in rotation. It is very hard for the cavity's niobium sheet formation, high temperature bake and chemistry processes and finally cooling down in cryomodule to satisfy such tight tolerance. A new wire stretching technique combining with the RF measurement in the deflecting modes has been demonstrated on the bench to detect less than 10um resolution on the RF signal when the wire is moving away from the ideal electric center line. The foundation of this technique and its difference from the use in other applications will be reviewed. Based on this principle, the possible implementations for detecting RF leakage to the higher older mode couplers, cavity string alignment and cryomodule assembly will be discussed.

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MOPOB71

Consideration on Determination of Coupling Factors of Waveguide Iris Couplers

cavity, DTL, coupling, simulation

229

S.W. Lee, M.S. Champion, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE.
Waveguide iris couplers are frequently used to power accelerating cavities in low beta sections of ion accelerators. In ORNL Spallation Neutron Source (SNS), six drift tube linac (DTL) cavity structures have been operating. An iris input coupler with a tapered ridge waveguide and a waveguide ceramic disk window feeds each cavity. The original couplers and cavities have been in service for more than a decade. Since all DTL cavity structures are fully utilized for neutron production, none of the cavity structures is available as a test cavity or a spare. Maintaining spares of the iris couplers for operations and future system upgrade without using the full DTL structure, a test setup for precision tuning is needed. A smaller single-cell cavity may be used for pretuning of the coupling irises as the test cavity and high power RF conditioning of the iris couplers as the bridge waveguide. In this paper, study of using a single-cell cavity for the iris tuning and the conditioning is presented with 3D simulations. A single-cell test cavity has been built and used for low power bench measurement with the iris couplers to demonstrate the approach.

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MOPOB72

Update on CW 8 kW 1.5 GHz Klystron Replacement

klystron, operation, ISOL, controls

232

A.V. Smirnov, S. Boucher
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, D.I. Gavryushkin, J.J. Hartzell, K.J. Hoyt, A.Y. Murokh, T.J. Villabona
RadiaBeam, Santa Monica, California, USA
G.R. Branner, K.S. Yuk
UC Davis, Davis, USA
V. Khodos
Sierra Nevada Corporation, Irvine, USA

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC0013136).
JLAB upgrade program requires a ~8 kW, 1497 MHz amplifier operating at more than 55-60% efficiency, and 8 kW CW power to replace up to 340 klystrons. One of possibilities for the klystron replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. Design features and challenges related to amplifier modules and radial multi-way dividers/combiners are discussed including HFSS simulations and measurements.

Poster MOPOB72 [1.199 MB]

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MOPOB76

Field Emission Dark Current Simulation for eRHIC ERL Cavities

cavity, electron, SRF, simulation

235

C. Xu, I. Ben-Zvi, Y. Hao, V. Ptitsyn, K.S. Smith, B. P. Xiao, W. Xu
BNL, Upton, Long Island, New York, USA

The eRHIC project will be a electron and proton collider proposed in BNL. These high repetition rates will require Super-Conducting Radio-Frequency cavities with fundamental frequency of 650MHZ for high current applications. Each with a string of two of those cavities. The strong electromagnetic fields in the SRF cavities will extract electrons from the cavity walls and will accelerate those. Most dark current will be deposited locally, although some electrons may reach several neighbour cyromodules, thereby gaining substantial energy before they hit a collimator or other aperture. Simulation of these effects is therefore crucial for the design of the machine. Track3P code was used to simulate field-emission electrons from different SRF cavities setup to optimize the field emission dark current characterizes.

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MOPOB81

Deposition of Non-Evaporative Getters R&D Activity for HEPS-TF

vacuum, cathode, site, distributed

238

P. He, D.Z. Guo, B. Liu, Y. Ma, Y.C. Yang, L. Zhang
IHEP, Beijing, People's Republic of China

Non Evaporable Getter(NEG) coating technology was widely used around the world's ultra-low emittance storage rings. It will provide the distributed pumping which is the obvious solution to solve the conductance limitation of narrow vacuum chamber at small magnet aperture. The HEPS-TF is the R&D project of HEPS (High Energy Photon Source), it will cover all of the key technology for HEPS accelerator system and beamlines. In order to meet the small aperture vacuum chamber distributed pumping requirement, the NEG coating R&D for HEPS vacuum chamber is under the way. Getter films deposited on the inner surface of the chamber would transform the vacuum chamber from an outgassing source into a pump. The coating test bench will be shown here and coating procedure will be presented.

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TUA1IO02

Status Report on the SPIRAL2 Facility at GANIL

rfq, linac, proton, experiment

240

E. Petit
GANIL, Caen, France

The GANIL SPIRAL2 project is based on the construction of a superconducting ion CW LINAC with two experimental areas named S3 ('Super Separator Spectrometer') and NFS ('Neutron For Science'). This status will report the construction of the facility and the first beam commissioning results. The perspectives of the SPIRAL2 project, with the future construction of the low energy RIB experimental hall called DESIR and with the construction of a new injector with q/A>1/6 or 1/7, will also be presented.

Slides TUA1IO02 [22.004 MB]

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TUA1IO03

Technological Challenges in the Path to 3.0 MW at the SNS Accelerator

operation, target, neutron, rfq

246

K.W. Jones
ORNL, Oak Ridge, Tennessee, USA

This talk discusses the design and anticipated challenges associated with upgrading the SNS beam power from the original 1.4 MW baseline design to the upgrade goal of 3 MW.

Slides TUA1IO03 [22.843 MB]

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TUA1CO04

Simulation of Beam Dynamics in a Strong Focusing Cyclotron

cyclotron, cavity, space-charge, focusing

251

P.M. McIntyre, J. Gerity, A. Sattarov
Texas A&M University, College Station, USA
S. Assadi
HiTek ESE LLC, Madison, USA
K.E. Badgley
Fermilab, Batavia, Illinois, USA
N. Pogue
LLNL, Livermore, California, USA

Funding: This work is supported by the US Dept. of Energy Accelerator Stewardship Program.
The strong-focusing cyclotron is an isochronous sector cyclotron in which slot-geometry superconducting half-cell cavities are used to provide sufficient energy gain per turn to fully separate orbits and superconducting quadrupoles are located in the aperture of each sector dipole to provide strong focusing and control betatron tune. The SFC offers the possibility to address the several effects that most limit beam current in a CW cyclotron: space charge, bunch-bunch interactions, resonance-crossing, and wake fields. Simulation of optical transport and beam dynamics entails several new challenges: the combined-function fields in the sectors must be properly treated in a strongly curving geometry, and the strong energy gain induces continuous mixing of horizontal betatron and synchrotron phase space. We present a systematic simulation of optical transport using modified versions of MAD-X and SYNERGIA. We report progress in introducing further elements that will set the stage for studying dynamics of high-current bunches.

Slides TUA1CO04 [15.462 MB]

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TUA1CO05

Conceptual Design of a Ring for Pulse Structure Manipulation of Heavy Ion Beams at the MSU NSCL

rfq, extraction, acceleration, linac

255

A.N. Pham, R. Ready, C.Y. Wong
NSCL, East Lansing, Michigan, USA
S.M. Lund
FRIB, East Lansing, USA
M.J. Syphers
Northern Illinois University, DeKalb, Illinois, USA

Funding: Research supported by Michigan State University, MSU NSCL, ReA Project, and NSF Award PHY-1415462.
The Reaccelerator (ReA) Facility at the National Superconducting Cyclotron Laboratory (NSCL) located at Michigan State University (MSU) offers the low-energy nuclear science community unique capabilities to explore wider ranges of nuclear reactions and the structure of exotic nuclei. Future sensitive time-of-flight experiments on ReA will require the widening of pulse separation for improved temporal resolution in single bunch detection while minimizing loss of rare isotopes and cleaning of beam decay products that might pollute measurements. In this proceedings, we present a preliminary design of a heavy ion ring that will address the task of bunch compression, bunch separation enhancement, satellite bunches elimination, cleaning of decay products, beam loss mitigation, and improvement of beam transmission.

Slides TUA1CO05 [4.991 MB]

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TUB1CO02

Operating Synchrotron Light Sources with a High Gain Free Electron Laser

FEL, undulator, electron, emittance

259

S. Di Mitri, M. Cornacchia
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption*. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality.
* S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006

Slides TUB1CO02 [2.353 MB]

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TUB1CO03

ALS-U: A Soft X-Ray Diffraction Limited Light Source

emittance, undulator, injection, impedance

263

C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, S. Persichelli, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y.C. Yang
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source (ALS-U). The upgrade proposal will reuse much of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. We will report on the accelerator design progress as well as the details of the ongoing R+D program.

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TUA2IO01

AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN

plasma, proton, electron, wakefield

266

A. Caldwell
MPI-P, München, Germany

It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.

Slides TUA2IO01 [24.428 MB]

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TUA2CO03

A Novel Technique of Power Control in Magnetron Transmitters for Intense Accelerators

controls, cavity, operation, power-supply

271

G.M. Kazakevich, R.P. Johnson, M.L. Neubauer
Muons, Inc, Illinois, USA
V.A. Lebedev, W. Schappert, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

A novel concept of a high-power magnetron transmitter allowing dynamic phase and power control at the frequency of locking signal is proposed. The transmitter compensating parasitic phase and amplitude modulations inherent in Superconducting RF (SRF) cavities within closed feedback loops is intended for powering of the intensity-frontier superconducting accelerators. The concept uses magnetrons driven by a sufficient resonant (injection-locking) signal and fed by the voltage which can be below the threshold of self-excitation. This provides an extended range of power control in a single magnetron at highest efficiency minimizing the cost of RF power unit and the operation cost. Proof-of-principle of the proposed concept demonstrated in pulsed and CW regimes with 2.45 GHz, 1kW magnetrons is discussed here. A conceptual scheme of the high-power transmitter allowing the dynamic wideband phase and mid-frequency power controls is presented and discussed.

Slides TUA2CO03 [0.714 MB]

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TUA2CO04

Vacuum Breakdown at 110 GHz

experiment, cavity, vacuum, GUI

275

S.C. Schaub
MIT, Cambridge, Massachusetts, USA
M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

A 1.5 MW, 110 GHz gyrotron is used to produce a linearly polarized quasioptical beam in 3 μs pulses. The beam is concentrated in vacuum to produce strong electric fields on the surfaces of dielectric and metallic samples, which are being tested for breakdown threshold at high fields. Dielectrics are tested in the forms of both windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Currently, visible light emission, absorbed/scattered microwave power, and vacuum pressure diagnostics are used to detect discharges on dielectric surfaces. Future experiments will include dark current diagnostics for direct detection of electrons. Dielectrics to be tested include crystal quartz, fused quartz, sapphire, high resistivity float-zone silicon, and alumina. Metallic accelerator structures will also be tested in collaboration with SLAC. These tests will require shortening of the microwave pulse length to the nanosecond scale.

Slides TUA2CO04 [1.826 MB]

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TUB2IO01

Accelerator Physics Challenges in the Design of Multi Bend Achromat Based Storage Rings

lattice, emittance, storage-ring, injection

278

M. Borland
ANL, Argonne, Illinois, USA
R.O. Hettel
SLAC, Menlo Park, California, USA
S.C. Leemann
MAX IV Laboratory, Lund University, Lund, Sweden
D. Robin
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
With the recent success in commissioning of MAX IV, the multi-bend achromat (MBA) lattice has begun to deliver on its promise to usher in a new generation of higher-brightness synchrotron light sources. In this paper, we begin by reviewing the challenges, recent success, and lessons learned of the MAX-IV project. Drawing on these lessons, we then describe the physics challenges in even more ambitious rings and how these can be met. In addition, we touch on engineering issues and choices that are tightly linked with the physics design.

Slides TUB2IO01 [3.723 MB]

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TUB2IO02

Advanced Concepts for Seeded FELs

FEL, electron, controls, laser

284

E. Ferrari, E. Allaria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The use of an external laser to seed an electron beam at the beginning of the Free Electron Laser process has been proposed as a way to improve temporal coherence of modern short wavelength FELs. More recent studies and experiments have shown that electron beam manipulation through interaction with a seed laser can be exploited for tailoring FEL properties to specific users requests. Recently, experiment for phase control, multi-color emission and coherent control have been reported.

Slides TUB2IO02 [15.975 MB]

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TUB2CO03

Fokker-Planck Analysis of Transverse Collective Instabilities in Electron Storage Rings

damping, impedance, simulation, synchrotron

290

R.R. Lindberg
ANL, Argonne, Illinois, USA

Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357
We analyze single bunch transverse instabilities due to wakefields using a Fokker-Planck model. We expand on the work of Suzuki*, writing out the linear matrix equation including chromaticity, both dipolar and quadrupolar transverse wakefields, and the effects of damping and diffusion due to the synchrotron radiation. The eigenvalues and eigenvectors determine the collective stability of the beam, and we show that the predicted threshold current for transverse instability and the profile of the unstable agree well with tracking simulations. In particular, we find that predicting collective stability for high energy electron beams at moderate to large values of chromaticity requires the full Fokker-Planck analysis to properly account for the effects of damping and diffusion due to synchrotron radiation.
* T. Suzuki, Particle Accel., 12, 237 (1982)

Slides TUB2CO03 [1.717 MB]

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TUB2CO04

Corrugated Structure Insertion to Extend SASE Bandwidth Up to 3% at the European XFEL

radiation, undulator, FEL, electron

293

I. Zagorodnov, G. Feng, T. Limberg
DESY, Hamburg, Germany

The usage of x-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth could be useful in order to obtain and to index a larger number of Bragg peaks used for determination of crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that usage of corrugated structures allows for a considerable increase in radiation bandwidth. It allows for data collection with a 3% bandwidth, a few micrjoule radiation pulse energy, a few fs pulse duration, and a photon energy 4.1 keV.

Slides TUB2CO04 [5.848 MB]

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TUPOA04

Study on THz Imaging by Using the Coherent Cherenkov Radiation

radiation, electron, experiment, detector

296

M. Nishida, M. Brameld, M. Washio
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

THz frequency is a special electromagnetic wave which is categorized between a radio wave and a light wave. It can pass through the various materials like a radio wave and can be transported with optical components like a light wave. Thus, it's suitable for imaging application of materials. At Waseda University, it's possible to generate a high-quality electron beam using Cs-Te photocathode RF-Gun and the electron beam is applied to several application researches. As an application of this electron beam, we generate a coherent Cherenkov radiation, and succeed in observing a high power THz light. The successful results of high power THz radiation encourage us to perform the THz imaging with transmission and reflection imaging using some materials, cross-section imaging using a simple material. On studying the THz imaging, it is necessary to clarify the spatial resolution. So, we tried to evaluate the spatial resolution in our device. Furthermore, our target is to get the three-dimensional THz images. We will introduce the CT technique in order to obtain the clear cross-section image. In this conference, we report the recent results of the THz imaging and future prospective.

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TUPOA05

Development of a Fiber Laser for Improving the Pulse Radiolysis System

laser, electron, radiation, gun

299

Y. Saito, S.Y. Soeta, M. Washio
Waseda University, Tokyo, Japan
Y. Hosaka, K. Sakaue
RISE, Tokyo, Japan

When material is irradiated by the ionizing radiation, short-lived and highly reactive substance intermediate active species are made and then react with substances. The chemical reaction is determined by intermediate active species in early process. Proving the behavior of intermediate active species is important for understanding and controlling radiation chemical reaction. In Waseda university we been developing a Pulse Radiolysis System, a method to measure the behavior of intermediate species, for radiation chemical analysis with RF electron gun. Currently we are developing a Supercontinuum ray(SC ray)as a probe ray to improve Pulse Radiolysis System. We have introduced a SC ray using Yb fiver laser and PCF(Photonic Crystal Fiber). But this type of prove light isn't stable enough in the visible light region. Therefore we started to study Er fiber laser oscillator as new prove ray source. We have succeeded to oscillate a Er fs laser pulse, second harmonic generation and measurement of hydrated electron in ns time resolution. In this presentation we will report current research about generation of SC ray, Er fiber laser system and dose rate effect against the hydrated electron.

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TUPOA07

IoT Application in the Control System of the BEPCII Power Supplies

controls, power-supply, status, operation

302

C.H. Wang, L.F. Li, X.L. Wang
IHEP, Beijing, People's Republic of China
C.P. Chu
MSU, East Lansing, Michigan, USA

Funding: This prject is support by NSFC(1137522)
In recent years in the development of Internet technology, the Internet of things (IoT) has begun to apply to each domain. The paper introduces the idea how to apply IoT to the accelerator control system and take the existing control system of the BEPCII power supplies as an example for IoT application. It not only introduce the status of the control system of the BEPCII power supplies, but also present a solution how to apply IoT to the existing control system. The purpose is to make the control system more intelligent and automatically identify what and where problem when the alarm of the control system of the power supplies. That means that IoT can help to automatically identify which crate and which PSC board inserted in the crates and which PSI sittiing in the power supply crates as well as the optic fiber cables between the PSCs and the PSIs. It is great convenient for the maintainer to use a mobile phone to diagnose faults and create the electronic maintenance record.

Poster TUPOA07 [0.762 MB]

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TUPOA10

Cyclotrons for Accelerator-Driven Systems

cyclotron, proton, neutron, target

305

T.-Y. Lee, J. Lee, S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea
C.U. Choi, M. Chung
UNIST, Ulsan, Republic of Korea

Accelerator-Driven system (ADS) can transmute long lived nuclear waste to short lived species. For this system to be fully realizable, a very stable high energy and high power proton beam (typically, 1 GeV beam energy and 10 MW beam power) is required, and preparing such a powerful and stable proton beam is very costly. Currently, the most promising candidate is superconducting linear accelerators. However, high power cyclotrons may be used for ADS particularly at the stage of demonstrating proof of principle of ADS. This paper discusses how cyclotrons can be used to demonstrate ADS.

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TUPOA12

An Updated LLRF Control System for the TLS Linac

controls, linac, EPICS, LLRF

308

C.Y. Wu, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Liao
NSRRC, Hsinchu, Taiwan

The amplitude and phase of the RF field at the linear accelerator (LINAC) decides the beam quality. To study and to improve the performance of the LINAC system for Taiwan Light Source (TLS), a new design of a low-level radio-frequency (LLRF) control system was developed and set up for the TLS LINAC. The main components of the LLRF control system are an I/Q modulator, an Ethernet-based arbitrary waveform generator, a digital oscilloscope and an I/Q demodulator; these are essential parts of the LLRF feed-forward control. This paper presents the efforts to improve the LLRF control system. The feasibility of the RF feed-forward control will be studied at the linear accelerator of TLS.

Poster TUPOA12 [1.425 MB]

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TUPOA13

First Test Run for High Density Material Imaging Experiment Using Relativistic Electron Beam at the Argonne Wakefield Accelerator

electron, target, experiment, diagnostics

311

Y.R. Wang
AAI/ANL, Argonne, Illinois, USA
S. Cao, X.K. Shen, Z.M. Zhang, Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China
M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA

A test facility, AWA, has been commissioned and in operation since last year. It can provide beam of several bunches in a train of nano-seconds and 10s of nC with energy up to 70 MeV. In addition, the AWA can accommodate various beamlines for experiments. One of the proposed experiments is to use the AWA beam as a diagnostics for time resolved high density material, typically a target with high Z and time dependent, imaging experiments. When electron beam scatters after passing through the target, and the angular and energy distribution of beam will depend on the density and thickness of the target. A small aperture is used to collimate the scattered electron beam for off axis particles, and the target image will be detected by imaging plate. By measuring the scatted angle and energy at the imaging plate would yield information of the target. In this paper, we report on the AWA electron imaging (EI) system setup, which consist of a target, imaging optics and drift transport. The AWA EI beam line was installed on June, 2016 and the first test run was performed on August, 2016. This work will have implication on the high energy density physics and even future nuclear fusion studies.

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TUPOA14

An Internet Rack Monitor-Controller for APS LINAC RF Electronics Upgrade

controls, linac, network, klystron

314

H. Ma, A. Nassiri, T.L. Smith, Y. Sun
ANL, Argonne, Illinois, USA
L.R. Doolittle, A. Ratti
LBNL, Berkeley, California, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences
To support the current research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rack-mount digital electronics platform 'Internet Rack Monitor-Controller (or IRMC) to replace the existing analog ones on the legacy crate/backplane-based hardware. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance processor in the mid- layer to handle the general digital signal processing (DSP). The custom FPGA IP's in the bottom layer handle the high-speed, real-time, low-latency DSP tasks, and provide the interface ports. A network communication gateway, in conjunction with an embedded event receiver (EVR), in the top layer merges the Internet Rack Monitor-Controller device into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today's Internet-of-Things (IoT), this implementation has actually been used in accelerators for over two decades.

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TUPOA16

A VME and FPGA Based Data Acquisition System for Intensity Monitors

software, data-acquisition, controls, instrumentation

317

J.S. Diamond, A. Ibrahim, N. Liu, E.S.M. McCrory, A. Semenov
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
A universal data acquisition system supporting toroids, DCCTs, Faraday cups, srapers and other types of instru-mentation has been developed for reporting beam inten-sity measurements to the Fermilab Accelerator Controls System (ACNet). Instances of this front end, supporting dozens of intensity monitor devices have been deployed throughout the Fermilab accelerator complex in the Main Injector, Recycler, Fermilab Accelerator Science and Technology (FAST) facility and the PIP-II Injector Exper-iment (PXIE). Each front end consists of a VME chassis containing a single board computer (SBC), timing and clock module and one or more 8 to 12-channel digitizer modules. The digitizer modules are based on a Cyclone III FPGA with firmware developed in-house allowing a wide range of flexibility and digital signal processing capability. The front end data acquisition software adds a list of new features to the previous generation allowing users to: take beam intensity measurements at custom points in the acceleration cycle, access waveform data, control machine protection system (MPS) parameters and calculate beam energy loss.

Poster TUPOA16 [1.532 MB]

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TUPOA17

A Longitudinal Digital Mode Damper System for the Fermilab Booster

booster, cavity, damping, feedback

320

N. Eddy, W. Pellico, A. Semenov, D.C. Voy, A.M. Waller
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.
The Fermilab Booster accelerates bunches and accelerates proton beams from 400 MeV to 8 GeV. During the acceleration the Radio Frequency (RF) cavities are swept from 38MHz to 52.8MHz and requires crossing through transition where accelerating phase is shifted 90 degrees. In order to keep the beam stable and minimize losses and emittance growth a longitudinal damping system is required. This has traditionally been done by dedicated analog electronics designed to operate on specific beam modes for frequencies of instabilities. A complete digital implementation has been developed for this same purpose. The new digital system features and performance are detailed.

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TUPOA18

Low Level RF Control for the PIP-II Injector Test RFQ

rfq, controls, LLRF, cavity

323

J.P. Edelen, B.E. Chase, E. Cullerton, J. Einstein, P. Varghese
Fermilab, Batavia, Illinois, USA

The PIP-II injector test radio frequency quadrupole (RFQ) arrived at Fermilab in the fall of 2015. The RFQ is a 162.5MHz H⁻ accelerator with a nominal drive power of 100kW, which produces a bunched H⁻ beam at 2.1MeV. In this paper we discuss commissioning, operational performance, and improvements to the low level RF (LLRF) control system for the RFQ. We begin by describing the general system configuration and initial simulation results. We will then highlight temperature related issues in the high power RF system, which necessitate active control over the phase balance of the two amplifiers. Finally we demonstrate performance of the RF feedback and feed-forward compensation needed to meet specification during a 20-microsecond beam pulse.

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TUPOA19

50-MeV Run of the IOTA/FAST Electron Accelerator

electron, gun, emittance, cavity

326

D.R. Edstrom, C.M. Baffes, C.I. Briegel, D.R. Broemmelsiek, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, B.J. Fellenz, E.R. Harms, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, D.J. Nicklaus, E. Prebys, P.S. Prieto, J. Reid, A.L. Romanov, J. Ruan, J.K. Santucci, T. Sen, V.D. Shiltsev, Y.-M. Shin, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner, S.J. Wesseln
Fermilab, Batavia, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA
A. Halavanau, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

Funding: Supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC.
The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin-Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.

Poster TUPOA19 [4.636 MB]

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TUPOA24

Beam Intensity Monitoring System for the PIP-II Injector Test Accelerator

pick-up, FPGA, interface, linac

330

N. Liu, J.S. Diamond, N. Eddy, A. Ibrahim, N. Patel, A. Semenov
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.
The PIP-II injector test accelerator is an integrated systems test for the front-end of a proposed CW-compatible, pulsed H⁻ superconducting RF linac. This linac is part of Fermilab's Proton Improvement Plan II (PIP-II) upgrade. This injector test accelerator will help minimize the technical risk elements for PIP-II and validate the concept of the front-end. Major goals of the injector accelerator are to test a CW RFQ and H⁻ source, a bunch-by-bunch MEBT beam chopper and stable beam acceleration through low-energy superconducting cavities. Operation and characterization of this injector places stringent demands on the types and performance of the accelerator beam diagnostics. This paper discusses the beam intensity monitor systems as well as early commissioning measurements of beam transport through the Medium-Energy Beam Transport (MEBT) beamline.

Poster TUPOA24 [1.039 MB]

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TUPOA25

Initial Demonstration of 9-MHz Framing Camera Rates on the FAST Drive Laser Pulse Trains*

laser, electron, optics, radiation

333

A.H. Lumpkin, D.R. Edstrom, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy.
Although beam centroid information at the MHz-micropulse-repetition rate has routinely been achieved at various facilities with rf BPMS, the challenge of recording beam size information at that rate is more daunting. The Integrable Optics Test Accelerator (IOTA) ring being planned at Fermilab has ~8 MHz revolution rates. To simulate the IOTA synchrotron radiation source temporal structure, we have used the UV component of the drive laser of the Fermilab Accelerator Science and Technology (FAST) Facility. This laser is normally set at 3 MHz, but has also been run at 9 MHz. We have configured our Hamamatsu C5680 streak camera in a framing camera mode using a slow vertical sweep plugin unit with the dual axis horizontal sweep unit**. A two-dimensional array of images sampled at the MHz rate can then be displayed on the streak tube phosphor and recorded by the CCD readout camera at up to 10 Hz. As an example, by using the 10 microsecond vertical sweep with the 100 microsecond horizontal sweep ranges, 49 of the 300 micropulses at 3 MHz are displayed for a given trigger delay in each of six images. Example 2D image arrays with profiling examples will be presented.
**Hamamatsu C5680 product web page.

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TUPOA26

Initial Observations of Micropulse Elongation of Electron Beams in a SCRF Accelerator*

electron, laser, gun, MMI

337

A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy
Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane bypass beamline allowed the measurements of the bunch length without the compression stage at the downstream beamline location using OTR and the streak camera. The UV component of the drive laser had previously been characterized with a Gaussian fit σ of 3.5-3.7 ps**. However, the uncompressed electron beam is expected to elongate due to space charge forces in an initial 1.5-m drift from the gun to the first SCRF accelerator cavity. We have observed electron beam bunch lengths from 5 to 14 ps (σ) for micropulse charges of 60 pC to 800 pC, respectively. Commissioning of the system and initial results with uncompressed and compressed beam will be presented.
**A.H. Lumpkin et al., Proceedings of FEL14, MOP021, Basel, Switzerland, www. JACoW.org

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TUPOA27

From Relativistic Electrons to X-ray Phase Contrast Imaging

electron, linac, GUI, software

341

A.H. Lumpkin
Fermilab, Batavia, Illinois, USA
M.A. Anastasio, A.B. Garson
Washington University in St. Louis, St. Louis, Missouri, USA

Funding: Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No.DE-AC02-07CH11359 with the U.S.DoE. Work at Washington Univ. in St. Louis was supported in part by NSF CBET1263988.
X-ray phase contrast (XPC) imaging is an emerging technology that holds great promise for biomedical applications due to its ability to provide information about soft tissue structure *. The need for high spatial resolution at the boundaries of the tissues is noted for this process. Based on results from imaging of relativistic electron beams with single crystals **, we proposed transferring single-crystal imaging technology to this bio-imaging issue. Using a microfocus x-ray tube (17 kVp) and the exchangeable phosphor feature of the camera system, we compared the point spread function (PSF) of the system with the reference P43 phosphor to that with several rare earth garnet single crystals of varying thickness. Based on single Gaussian peak fits to the collimated x-ray images, we observed a four times smaller system PSF (21 microns (FWHM)) with the 25-mm diameter single crystals than with the reference polycrystalline phosphor's 80-micron value. Initial images of 33-micron diameter carbon fibers have also been obtained with small crystals installed. Tests with a full-scale 88-mm diameter single crystal (patent-pending configuration) are being planned.
*A. Appel, M.A. Anastasio, and E.M. Brey, Tissue Eng. Part B Rev 17 (5), 321 (2011).
**A.H. Lumpkin, et al., Phys. Rev. ST-AB 14 (6), 060704 (2011).

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TUPOA28

Feasibility of OTR Imaging for Laser-Driven Plasma Accelerator Electron-Beam Diagnostics

electron, polarization, laser, plasma

345

A.H. Lumpkin
Fermilab, Batavia, Illinois, USA
M. Downer
The University of Texas at Austin, Austin, Texas, USA
D.W. Rule
Private Address, Silver Spring, USA

Funding: * Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. DoE. ** Work at the Univ. of Texas supported by DoE grant DE-SC0011617.
Recent measurements of betatron x-ray emission from quasi-monoenergetic electrons accelerating to 500 MeV within a laser plasma accelerator (LPA) enabled estimates of normalized transverse emittance well below 1 mm-mrad and divergences of order 1/gamma [1]. Such unprecedented LPA beam parameters can, in principle, be addressed by utilizing the properties of linearly polarized optical transition radiation (OTR) that provide additional beam parameter sensitivity. We propose a set of complementary measurements of beam size and divergence with near-field and far-field OTR imaging, respectively, on LPA electron beams ranging in energy from 100 MeV [2] to 2 GeV [3]. The feasibility is supported by analytical modeling for beam size sensitivity and divergence sensitivity. In the latter case, the calculations indicate that the parallel polarization component of the far-field OTR pattern is sensitive to divergences from 0.1 to 0.4 mrad (σ) at 2 GeV, and it is similarly sensitive to divergences from 1 to 5 mrad (σ) at 100 MeV. We anticipate the signal levels from charges of 100 pC will require a 16-bit cooled CCD camera. Other practical challenges in the LPA will also be discussed.
1.G. R. Plateau et al., Phys. Rev. Lett. 109, 064802 (2012).
2.Hai-EnTsai, Chih-Hao Pai, and M.C. Downer, AIP Proc. 1507, 330 (2012)
3.Xiaoming Wang et al., Nature Communications 4,1988(2013).

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TUPOA29

Beam Position Monitoring System for the PIP-II Injector Test Accelerator

pick-up, electronics, electron, linac

349

N. Patel, C.I. Briegel, J.S. Diamond, N. Eddy, B.J. Fellenz, J. Fitzgerald, V.E. Scarpine
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.
The Proton Improvement Plan II (PIP-II) injector test accelerator is an integrated systems test for the front-end of a proposed continuous-wave (CW) compatible, pulsed H⁻ superconducting RF linac. This linac is part of Fermilab's PIP-II upgrade. This injector test accelerator will help minimize the technical risk elements for PIP-II and validate the concept of the front-end. Major goals of the injector accelerator are to test a CW RFQ and H⁻ source, a bunch-by-bunch Medium-Energy Beam Transport (MEBT) beam chopper and stable beam acceleration through low-energy superconducting cavities. Operation and characterization of this injector places stringent demands on the types and performance of the accelerator beam diagnostics. A beam position monitor (BPM) system has been developed for this application and early commissioning measurements have been taken of beam transport through the beamline.

Poster TUPOA29 [0.469 MB]

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TUPOA30

Fermilab Switchyard Resonant Beam Position Monitor Electronics Upgrade Results

electron, electronics, controls, power-supply

352

T.B. Petersen, J.S. Diamond, N. Liu, P.S. Prieto, D. Slimmer, A.C. Watts
Fermilab, Batavia, Illinois, USA

The readout electronics for the resonant beam position monitors (BPMs) in the Fermilab Switchyard (SY) have been upgraded, utilizing a low noise amplifier transition board and Fermilab designed digitizer boards. The stripline BPMs are estimated to have an average signal output of between -110 dBm and -80 dBm, with an esti-mated peak output of -70 dBm. The external resonant circuit is tuned to the SY machine frequency of 53.10348 MHz. Both the digitizer and transition boards have vari-able gain in order to accommodate the large dynamic range and irregularity of the resonant extraction spill. These BPMs will aid in auto-tuning of the SY beamline as well as enabling operators to monitor beam position through the spill.

Poster TUPOA30 [0.833 MB]

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TUPOA31

Fermilab Cryomodule Test Stand RF Interlock System

controls, monitoring, interlocks, cavity

355

T.B. Petersen, J.S. Diamond, D. McDowell, D.J. Nicklaus, P.S. Prieto, A. Semenov
Fermilab, Batavia, Illinois, USA

An interlock system has been designed for the Fermilab Cryomodule Test Stand (CMTS), a test bed for the cryomodules to be used in the upcoming Linac Coherent Light Source 2 (LCLS-II) project at SLAC. The interlock system features 8 independent subsystems, consisting of a superconducting RF cavity, a coupler, and solid state amplifier (SSA). Each system monitors several devices to detect fault conditions such as arcing in the waveguides or quenching of the SRF system. Additionally each system can detect fault conditions by monitoring the RF power seen at the cavity coupler through a directional coupler. In the event of a fault condition, each system is capable of removing RF signal to the amplifier (via a fast RF switch) as well as turning off SSA. Additionally, each input signal is available for remote viewing and recording via a Fermilab designed digitizer board.

Poster TUPOA31 [0.762 MB]

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TUPOA36

Computed Tomography of Transverse Phase Space

simulation, quadrupole, instrumentation, optics

358

A.C. Watts, C. Johnstone, J.A. Johnstone
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Reserach Alliance, LLC under Contract no. DE-AC02-07CH11359 with the United States Department of Energy.
Two computed tomography techniques are explored to reconstruct beam transverse phase space using both simulated beam and multi-wire profile data in the Fermilab Muon Test Area ("MTA") beamline. Both Filtered Back-Projection ("FBP") and Simultaneous Algebraic Reconstruction Technique ("SART") algorithms are considered and compared. Errors and artifacts are compared as a function of each algorithm's free parameters, and it is shown through simulation and MTA beamline profiles that SART is advantageous for reconstructions with limited profile data.
awatts@fnal.gov, cjj@fnal.gov, jjohnstone@fnal.gov

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TUPOA38

Real-Time Magnetic Electron Energy Spectrometer for Use With Medical Linear Acceletors

electron, linac, detector, real-time

361

P.E. Maggi, H.R. Hogstrom, K.L. Matthews II
LSU, Baton Rouge, USA
R.L. Carver
Mary Bird Perkins Cancer Center, Our Lady of the Lake, Baton Rouge, USA

Accelerator characterization and quality assurance is an integral part of electron linear accelerator (linac) use in a medical setting. The current clinical method for radia-tion metrology of electron beams (dose on central axis versus depth in water) only provides a surrogate for the underlying performance of the accelerator and does not provide direct information about the electron energy spectrum. We have developed an easy to use real-time magnetic electron energy spectrometer for characterizing the electron beams of medical linacs. Our spectrometer uses a 0.57 T permanent magnet block as the dispersive element and scintillating fibers coupled to a CCD camera as the position sensitive detector. The goal is to have a device capable of 0.12 MeV energy resolution (which corresponds to a range shift of 0.5 mm) with a minimum readout rate of 1 Hz, over an energy range of 5 to 25 MeV. This work describes the real-time spectrometer system, the detector response model, and the spectrum unfolding method. Measured energy spectra from multi-ple electron beams from an Elekta Infinity Linac are presented.

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TUPOA40

Low Noise Digitizer Design for LCLS-II LLRF

FPGA, LLRF, cavity, hardware

364

G. Huang, L.R. Doolittle, Y.L. Xu, J. Yang
LBNL, Berkeley, California, USA
Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China

Modern accelerators use a digital low level RF controller to stabilize the fields in accelerator cavities. The noise in the receiver chain and analog to digital conversion (ADC) for the cavity probe signal is critically important. Within the closed-loop bandwidth, it will eventually become part of the field noise seen by the beam in the accelerator. Above the open-loop cavity bandwidth, feedback processes transfer that noise to the high power drive amplifiers. The LCLS-II project is expected to use an undulator to provide soft X-rays based on a stable electron beam accelerated by a superconducting linac. Project success depends on a low noise, low crosstalk analog to digital conversion. We developed a digitizer board with 8 ADC channels and 2 DAC channels. The broadband phase noise of this board is measured at <-151\thinspace dBc/Hz, and the adjacent channel crosstalk is measured at <-80\thinspace dB. In this paper we describe the digitizer board design, performance test procedures, and bench-test results.

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TUPOA41

FPGA Control of Coherent Pulse Stacking

cavity, controls, FPGA, feedback

367

Y.L. Xu, J.M. Byrd, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, Y. Yang
LBNL, Berkeley, California, USA
J. Dawson
LLNL, Livermore, California, USA
A. Galvanauskas, J.M. Ruppe
University of Michigan, Ann Arbor, Michigan, USA

Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy from fiber lasers. Due to advantages of precise timing and fast processing, we use an FPGA to process digital signals and do feedback control so as to realize stacking-cavity stabilization. We develop a hardware and firmware design platform to support the coherent pulse stacking application. A firmware bias control module stabilizes the amplitude modulator at the minimum of its transfer function. A cavity control module ensures that each optical cavity is kept at a certain individually-prescribed and stable round-trip phase with 2.5 deg rms phase error.

Poster TUPOA41 [5.546 MB]

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TUPOA42

Multicavity Coherent Pulse Stacking Using Herriott Cells

cavity, laser, controls, experiment

370

Y. Yang, J.M. Byrd, L.R. Doolittle, G. Huang, W. Leemans, Q. Qiang, R.B. Wilcox
LBNL, Berkeley, California, USA
J. Dawson
LLNL, Livermore, California, USA
A. Galvanauskas, J.M. Ruppe
University of Michigan, Ann Arbor, Michigan, USA
Y.L. Xu
TUB, Beijing, People's Republic of China

Coherent Pulse Stacking provides a promising way to generate a single high-intensity laser pulse by stacking a sequence of phase and amplitude modulated laser pulses using multiple optical cavities. Optical misalignment and phase stability are two critical issues that need to be addressed. Herriott cells are implemented for their relaxed alignment tolerance and a phase stabilization method based on cavity output pattern matching has been developed. A single pulse with intensity enhancement factor over 7.4 has been generated by stacking 13 modulated pules through a four-cavity stacking system. This can be a possible path for generating TW KHz laser pulses for a future laser-driven plasma accelerator.

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TUPOA44

Future Prospects of RF Hadron Beam Profile Monitors for Intense Neutrino Beam

cavity, plasma, radiation, proton

373

Q. Liu
Case Western Reserve University, Cleveland, USA
M. Backfish, A. Moretti, V. Papadimitriou, A.V. Tollestrup, K. Yonehara, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, R.P. Johnson, G.M. Kazakevich
Muons, Inc, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
A novel beam monitor based on a gas-filled RF resonator is proposed to measure the precise profile of secondary particles downstream of a target in the LBNF beam line at high intensity. The RF monitor is so simple that it promises to be radiation robust in extremely high-radiation environment. When a charged beam passes through a gas-filled microwave RF cavity, it produces electron-ion pairs in the RF cavity. The induced plasma changes the gas permittivity in proportion to the beam intensity. The permittivity shift can be measured by the modulated RF frequency and quality factor. The beam profile can thus be reconstructed from the signals from individual RF cavity pixels built into the beam profile monitor. A demonstration test is underway, and the current results has shown technical feasibility. The next phase consists of two stages, (1) to build and test a new multi-cell 2.45 GHz RF cavity that can be used for the NuMI beamline, and (2) to build and test a new multi-cell 9.3 GHz RF cavity that can be put in service in a future beamline at the LBNF for spatial resolution. These two resonant frequencies are chosen since they are the standard frequencies for magnetron RF source.

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TUPOA46

Development of a Python-Based Emittance Calculator at Fermilab Science & Technology (FAST) Facility

emittance, quadrupole, experiment, solenoid

376

A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA
Y.-M. Shin
Fermilab, Batavia, Illinois, USA
Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA

Beam emittance is an important characteristic which helps to describe a charged particle beam. In linear accelerators (linac), it is critical to characterize the beam phase space parameters and, in particular, to precisely measure transverse beam emittance. The quadrupole scan (quad-scan) is a well established technique used to characterize transverse beam parameters in four-dimensional phase space. Quad-scans are very time consuming and off-line analysis is needed to extrapolate the beam phase space parameters. We have developed a computational algorithm with Python scripts to automatically estimate beam parameters, in particular beam emittance, using the quadrupole scan technique in the electron linac of Fermilab Accelerator Science and Technology (FAST) facility. These Python scripts have decreased the time it takes to perform a single quad scan from a few hours to a few minutes. From the experimental data, the emittance calculator quickly delivers various results including: transverse emittance, Courant-Snyder parameters, and Beam Size (squared) vs Quadrupole field strength plots, among others.

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TUPOA47

Development of Short Undulators for Electron-Beam-Radiation Interaction Studies

undulator, radiation, laser, electron

380

P. Piot
Fermilab, Batavia, Illinois, USA
M.B. Andorf, G. Fagerberg, M. Figora
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the US DOE contract DE-SC0013761 with Northern Illinois University
Interaction of an electron beam with external field or its own radiation has widespread applications ranging from coherent radiation generation, phase space cooling or formation of time-structured beam. An efficient coupling mechanism between an electron beam and radiation field relies on the use of a magnetic undulator. In this contribution we detail the construction and magnetic measurements of short (11 period) undulators with 7-cm period built using parts of the ALADDIN U3 undulator*. Possible use of these undulators at two accelerator test facilities to support experiment relevant to cooling techniques and radiation souces are discussed.
* F. C. Younger, W. Jorge Pearce, B. Ng, Nucl. Instrum. Meth Phys. Res. A 347, pp. 96-101 (1994).

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TUPOA48

A High-Level Python Interface to the Fermilab ACNET Control System

quadrupole, controls, emittance, interface

383

P. Piot
Fermilab, Batavia, Illinois, USA
A. Halavanau
Northern Illinois University, DeKalb, Illinois, USA

This paper discusses the implementation of a PYTHON-based high-level interface to the Fermilab ACNET control system. We will especially present examples of applications which include the interfacing of an ELEGANT beam-dynamics model to assist lattice matching and an automated emittance measurement via the quadrupole-scan method.

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TUPOA49

A General Model of Vacuum Arcs in Linacs

plasma, experiment, laser, vacuum

387

J. Norem
Nano Synergy, Inc., Downers Grove, Illinois, USA
Z. Insepov
Purdue University, West Lafayette, Indiana, USA

We are developing a general model of breakdown and gradient limits that applies to accelerators, along with other high field applications such as power grids and laser ablation. Our recent efforts have considered failure modes of integrated circuits, sheath properties of dense, non-Debye plasmas and applications of capillary wave theory to rf breakdown in linacs. In contrast to much of the rf breakdown effort that considers one physical mechanism or on e experimental geometry, we are finding that there is an enormous volume of relevant material in the literature that helps to constrain our model and suggest experimental tests.

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TUPOA51

First Steps Toward Incorporating Image Based Diagnostics into Particle Accelerator Control Systems Using Convolutional Neural Networks

gun, network, controls, solenoid

390

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
J.P. Edelen
Fermilab, Batavia, Illinois, USA

At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.

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TUPOA52

Updates to the Low-Level RF Architecture for Fermilab

controls, LLRF, simulation, hardware

394

J. Einstein, B.E. Chase, E. Cullerton, P. Varghese
Fermilab, Batavia, Illinois, USA
S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
D. Sharma
RRCAT, Indore (M.P.), India

Fermilab has teamed with Colorado State University on several projects in LLRF controls and architecture. These projects include new LLRF hardware, updated controls techniques, and new system architectures. Here we present a summary of our work to date.

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TUPOA54

Examination of Out-of-Field Dose and Penumbral Width of Flattening Filter Free Beams in Medical Linear Accelerators

photon, linac, ECR, radiation

396

L.C. Bennett, O.N. Vassiliev
M.D.A.C.C., Houston, Texas, USA

Medical linear accelerators (LINACS) have traditionally used a flattening filter to ensure that the photon spectrum entering the patient was homogeneous within a given field size. Recently, leading manufacturers of medical accelerators have begun including an option for Flattening Filter Free (FFF) beams on their accelerators. These beams are characterized by a softer spectrum (lower average energy), peaked profiles, and less side scatter. Previous work with Monte Carlo models has shown that the elimination of the flattening filter from the beam path has the potential to greatly reduce scatter in regions immediately adjacent to the primary field (Kry 2010); however, systematic in-depth investigation of these effects has yet to be done using actual measurements from a linac equipped with FFF beams. We have examined and compared measurements of different energy pairings of FFF and FF beams from the Varian TrueBeam accelerators and found reductions of peripheral dose at upwards of 30% for the FFF beams and nearly 5% reduction in penumbral width at nearly all depths and field sizes; reductions were greatest for shallow depths and small field size.
Kry et al. Out-of-field photon dose following removal of the flattening filter from a medical accelerator. Physics in Medicine and Biology. vol. 55, no. 8, 2010. pp 2155-2166.

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TUPOA57

Using High Precision Beam Position Monitors at the Cornell Electron Storage Ring (CESR) to Measure the One Way Speed of Light Anisotropy

electron, positron, dipole, simulation

399

W.F. Bergan, M.J. Forster, N.T. Rider, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.A. Schmookler
MIT, Cambridge, Massachusetts, USA
B. Wojtsekhowski
CMU, Pittsburgh, Pennsylvania, USA

Funding: NSF PHY-1416318 NSF DGE-1144153
The Cornell Electron Storage Ring (CESR) has been equipped with a number of high-precision beam position monitors which are capable of measuring the orbit of a circulating beam with a precision of a few microns. This technology will enable a precision measurement of deviations in the one-way speed of light. An anisotropic speed of light will alter the beam momentum as it travels around the ring, resulting in a change of orbit over the course of a sidereal day. Using counter-circulating electron and positron beams, we will be able to suppress many of the systematics such as those relating to variations in RF voltage or magnet strength. We show here initial feasibility studies to measure the stability of our beam position monitors and the various systematic effects which may hide our signal and discuss ways in which we can minimize their impact.

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TUPOA58

Minimization of Emittance at the Cornell Electron Storage Ring With Sloppy Models

emittance, simulation, storage-ring, lattice

402

W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.P. Sethna
Cornell University, Ithaca, New York, USA

Funding: DOE DE-SC0013571 NSF DGE-1144153
Our current method to minimize the vertical emittance of the beam at the Cornell Electron Storage Ring (CESR) involves measurement and correction of the dispersion, coupling, and orbit of the beam and lets us reach emittances of 10 pm, but is limited by finite dispersion measurement resolution.* For further improvement in the vertical emittance, we propose using a method based on the theory of sloppy models.** The storage ring lattice permits us to identify the dependence of the dispersion and emittance on our corrector magnets, and taking the singular value decomposition of the dispersion/corrector Jacobian gives us the combinations of these magnets which will be effective knobs for emittance tuning, ordered by singular value. These knobs will permit us to empirically tune the emittance based on direct measurements of the vertical beam size. Simulations show that when starting from a lattice with realistic alignment errors which has been corrected by our existing method to have an emittance of a few pm, this new method will enable us to reduce the emittance to nearly the quantum limit, assuming that vertical dispersion is the primary source of our residual emittance.
* J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014).
** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).

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TUPOA59

Successful Laboratory-Industrial Partnerships: the Cornell-Friatec Segmented Insulator for High Voltage DC Photocathode Guns

gun, electron, vacuum, high-voltage

405

K.W. Smolenski, B.M. Dunham
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D.L. Barth, M. Muehlbauer, S. Wacker
FRIATEC AG, Mannheim, Germany
J.M. Maxson
UCLA, Los Angeles, California, USA

High voltage DC photocathode guns currently offer the most reliable path to electron beams with high current and brightness. The performance of a gun is directly dependent on its vacuum and high voltage capabilities, determined in large part by the ceramic insulators. The insulator must meet XHV standards, bear the load of pressurized SF6 on its exterior, support the massive electrode structures as well as holding off DC voltages up to 750kV. Construction of UHV and high voltage capable insulators require high purity ceramics and metal components proven to minimize thermal stress between the brazed ceramic rings and metal guard rings. The use of replaceable guard rings is a critical way of controlling manufacturing costs while extending the life cycle of the insulator. Successful fabrication requires proven manufacturing methods in flatness, parallelism, and maintaining alignment of many parts during the brazing process. Taking a scalable, modular approach, the insulator design can be applied to a variety of gun voltages and can be used by other projects. The Cornell-Friatec insulator was designed collaboratively and has now been produced in quantity for Cornell and elsewhere.

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TUPOA61

Integrated Control System for an X-Band-Based Laser-Compton X-Ray Source

controls, laser, FPGA, LabView

408

D.J. Gibson, G.G. Anderson, C.P.J. Barty, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
LLNL's compact, tunable, laser-Compton x-ray source has been built around an advanced X-band photogun and accelerator sections and two independent laser systems. In support of this source, the control system has evolved from a minimal, isolated control points to an integrated architecture that continues to grow to simplify operation of the system and to meet new needs of this research capability. In addition to a PLC-based machine protection component, a custom, LabView-based suite of control software monitors systems including low level and high power RF, vacuum, magnets, and beam imaging cameras. This system includes a comprehensive operator interface, automated arc detection and rf processing to optimize rf conditioning of the high-gradient structures, and automated quad-scan-based emittance measurements to explore the beam tuning parameter space. The latest upgrade to the system includes a switch from real-time OS to FPGA-based low-level RF generation and arc detection. This offloads processing effort from the main processor allowing for arbitrary expansion of the monitored points. It also allows the possibility of responding to arcs before the pulse is complete.

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TUPOA63

Preliminary Study of Advanced LLRF Controls at LANSCE for Beam Loading Compensation in the MaRIE X-FEL

controls, beam-loading, LLRF, FPGA

411

A. Scheinker, S.A. Baily, J.T. Bradley III, L.J. Castellano, J.O. Hill, D.J. Knapp, S. Kwon, J.T.M. Lyles, M.S. Prokop, D. Rees, P.A. Torrez
LANL, Los Alamos, New Mexico, USA

The analog low level RF (LLRF) control system of the Los Alamos Neutron Science Center is being upgraded to a Field Programmable Gate Array (FPGA)-based digital system (DLLRF). In this paper we give an overview of the FPGA design and the overall DLLRF system. We also present preliminary performance measurements including results utilizing model-independent iterative feedforward for beam-loading transient minimization, which is being studied for utilization in the future MaRIE X-FEL, which will face difficult beam loading conditions.

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TUPOA64

Effects of Low Frequency Buncher Field (LFB) Variation on an H⁻ Beam Phase-Energy

cavity, DTL, emittance, bunching

414

P.K. Roy, Y.K. Batygin
LANL, Los Alamos, New Mexico, USA

Funding: This work supported by the United States Department of Energy under contract DE-AC52-06NA25396
Beam bunching optimization at low energy (750keV) before injecting into a DTL (100MeV) is essential for beam transport, emittance reduction, and focusing on to a target. The LANSCE simultaneously utilizes H⁺ and H⁻ beam (with a timing variation) for many important national security sciences. In addition to quadrupole, several bunchers are utilized in the transport. A technique with pre-bunching at lower frequency and main bunching at higher frequency is utilized for beam injection into the linac. The buncher parameters (voltage and frequency) are well established for operations. However, there is the possibility that the parameters vary with time due to electrical malfunction or adverse tuning during a beam development activity. Some effort is needed to correct the parameters as a non-optimized pre-bunching setup can alter the beam phase space and the nominal beam intensity at a desired location. Here, we examine emittance and phase space distribution variation for H⁻ beam due to variation of the low frequency (16 MHz) buncher voltage, which typically operates at 25 kV peak. Beam phase dynamics with buncher voltage variation is also examined using the beam transport code Parmila.
LA-UR-16-23822
LANSCE: Los Alamos Neutron Science Center
DTL: Drift Tube Linac

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TUPOA67

Helium Pressure Vessel Jacketing of the Fermilab SSR1 Single Spoke SC Cavities

cavity, real-time, feedback, cryomodule

418

E.C. Bonnema, E.K. Cunningham
Meyer Tool & MFG, Oak Lawn, Illinois, USA

Meyer Tool recently completed the welding of the liquid helium pressure vessel jackets around ten (10) superconducting single spoke niobium cavities for Fermilab. The SSR1 cavities are intended for use in the PIP-II Injector Experiment Cryomodule. Meyer Tool's scope of supply included review of the Fermilab Pressure Rating Analysis Document and the development of fabrication details and a fabrication sequence to meet that document's requirements, while minimizing the effects of jacketing cavity frequency, and the actual jacketing of the cavities. This paper will focus on the development of the fabrication details and sequence and how the details and sequence evolved over the course of welding and final machining of the ten (10) jackets. As the frequency of these cavities is critical the fabrication sequence accommodated numerous in process frequency checks, a frequency tuning step prior to the final weld, the use of thermal cameras to monitor weld heat input into the cavity, and post welding final machining of critical features. Lessons learned from this fabrication will be discussed.

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TUPOA68

Design, Simulations and Experimental Demonstration of an Intra-Pulse Ramped-Energy Travelling Wave Linac for Cargo Inspection

linac, simulation, electron, beam-loading

421

S.V. Kutsaev, R.B. Agustsson, A. Arodzero, R.D.B. Berry, S. Boucher, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A. Laurich, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A. Verma
RadiaBeam, Santa Monica, California, USA

Funding: This work has been supported by the US Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contract HSHQDC-13-C-B0019.
Novel radiographic imaging techniques [1] based on adaptive, intra-pulse ramped-energy short X-ray packets of pulses, a new type of fast X-ray detectors, and advanced image processing are currently some of the most promising methods for real-time cargo inspection systems. RadiaBeam Technologies is currently building the high-speed Adaptive Railroad Cargo Inspection System (ARCIS), which will enable better than 5 mm line pair resolution, penetration greater than 450 mm of steel equivalent, material discrimination over the range of 6 mm to 250 mm, 100% image sampling rate at speed 45 km/h, and minimal average dose. One of the core elements of ARCIS is a new S-band travelling wave linac with a wide range of energy control that allows energy ramping from 2 to 9 MeV within a single 16 μs RF pulse using the beam loading effect. In this paper, we will discuss the linac design approach and its principal components, as well as engineering and manufacturing aspects. The results of the experimental demonstration of intra-pulse energy ramping will be presented.
[1] A. Arodzero, S. Boucher, A. Murokh, S. Vinogradov, S.V. Kutsaev. System and Method for Adaptive X-ray Cargo Inspection. US Patent Application 2015/1472051.

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TUPOA71

Beam Stability During Top Off Operation at NSLS-II Storage Ring

feedback, injection, operation, storage-ring

425

W.X. Cheng, B. Bacha, Y. Li, O. Singh, Y. Tian
BNL, Upton, Long Island, New York, USA

NSLS-II storage ring started top off operation since Oct 2015. User operation current has been gradually increased to 250mA. Observations of beam stabilities during top-off operations will be presented. Total beam current was typically maintained within ±0.5% and bunch to bunch current variation was less than 20%. Injection transition during top-off was measured bunch by bunch digitizer, and BPM to analyze the orbit motion at various bandwidths (turn by turn, 10kHz and 10Hz rate). Coupled bunch unstable motions were monitored. As the vacuum pressure improves, fast-ion instability is not as severe compared to early stage of commissioning/operation, but still observed as the dominant instability. Resistive wall instability is noticed as more in-vacuum-undulator (IVU) gaps closed. xBPM measured photon stability and electron beam stability at top off injection have been evaluated. Short term and long term orbit stabilities will be reported.

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TUPOA73

Commissioning and First Results From a Channeling-Radiation Experiment at FAST

detector, electron, gun, radiation

428

J. Hyun
Sokendai, Ibaraki, Japan
D.R. Broemmelsiek, D.R. Edstrom, A.L. Romanov, J. Ruan, T. Sen, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA
A. Halavanau, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

X-rays have widespread applications in science. Developing compact and high-quality X-ray sources, easy to disseminate, has been an on going challenge. Our group has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays (photon energy from 40 keV to 140 keV). In this contribution we present the simulated X-ray spectrum including the background bremsstrahlung contribution, and optimization of the relevant electron-beam parameters required to maximize the X-ray brilliance. The results of experiments carried out at Fermilab's FAST facility – which include a 50 MeV superconducting linac and a high-brightness photoinjector – are also discussed. The average brilliance in our experiment is expected to be about one order of magnitude higher than that in previous experiments.

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TUPOA74

The Design and Construction of a Resonance Control System for the IOTA RF Cavity

cavity, controls, bunching, proton

432

G.M. Bruhaug
ISU, Pocatello, Idaho, USA
K. Carlson
Fermilab, Batavia, Illinois, USA

The IOTA ring will be an advanced storage ring used for non-linear beam dynamics experiments to assist in the construction of future accelerators. This ring is being built in conjunction with the FAST electron LINAC and the HINS RFQ proton source, at Fermilab, for injection into the ring. These accelerators will generate +150 MeV electron beams and 2.5 MeV proton beams respectively. As the beams are injected into the IOTA storage ring their longitudinal profile will begin to smear out and become more uniform. This will prevent detection of beam position with a Beam Position Monitoring system (BPM). To combat this a ferrite loaded bunching cavity is being constructed. This paper details the design and construction of an automatic resonance control system for this bunching cavity.

Poster TUPOA74 [2.604 MB]

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TUA3CO03

Compact Ring-Based X-Ray Source With on-Orbit and on-Energy Laser-Plasma Injection

electron, laser, plasma, radiation

435

M. Turner
CERN, Geneva, Switzerland
J.R. Cheatam, A.L. Edelen
CSU, Fort Collins, Colorado, USA
J. Gerity
Texas A&M University, College Station, USA
A. Lajoie, C.Y. Wong
NSCL, East Lansing, Michigan, USA
G. Lawler
UCLA, Los Angeles, California, USA
O. Lishilin
DESY Zeuthen, Zeuthen, Germany
K. Moon
UNIST, Ulsan, Republic of Korea
A. A. Sahai, A. Seryi
JAI, London, United Kingdom
K. Shih
SBU, Stony Brook, New York, USA
B. Zerbe
MSU, East Lansing, Michigan, USA

Funding: We acknowledge the stimulating atmosphere and support of US Particle Accelerator School, class of June 2016, where this design study was performed.
We report here the results of a one week long investigation into the conceptual design of an X-ray source based on a compact ring with on-orbit and on-energy laser-plasma accelerator (mini-project 10.4 from [1]). We performed these studies during the June 2016 USPAS class "Physics of Accelerators, Lasers, and Plasma…" applying the art of inventiveness TRIZ. We describe three versions of the light source with the constraints of the electron beam with energy 1 GeV or 3 GeV and a magnetic lattice design being normal conducting (only for the 1 GeV beam) or superconducting (for either beam). The electron beam recirculates in the ring, to increase the effective photon flux. We describe the design choices, present relevant parameters, and describe insights into such machines.
[1] Unifying physics of accelerators, lasers and plasma, A. Seryi, CRC Press, 2015.

Slides TUA3CO03 [8.411 MB]

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TUB3IO01

Commissioning of the Max IV Light Source

storage-ring, MMI, cavity, vacuum

439

P.F. Tavares, E. Al-Dmour, Å. Andersson, M. Eriksson, M.J. Grabski, M.A.G. Johansson, S.C. Leemann, L. Malmgren, M. Sjöström, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility, currently under commissioning in Lund, Sweden, features two electron storage rings operated at 3 GeV and 1.5 GeV and optimized for the hard X-ray and soft X-ray/VUV spectral ranges, respectively. A 3 GeV linear accelerator serves as a full-energy injector into both rings as well as a driver for a short-pulse facility, in which undulators produce X-ray pulses as short as 100 fs. In this paper, we briefly review the overall facility layout and design concepts and focus on recent results obtained in commissioning of the accelerators with an emphasis on the ultralow emittance 3 GeV ring, the first light source using a multibend achromat.

Slides TUB3IO01 [6.269 MB]

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TUB3IO02

Overview of Electron Source Development for High Repetition Rate FEL Facilities

gun, cathode, electron, emittance

445

F. Sannibale
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 'fsannibale@lbl.gov
An increasing science demand for high-repetition rate (MHz-class) FEL facilities, from IR to X-rays, has been pushing institutions and groups around the world to develop proposals addressing such a need, and some of them have been already funded and are under construction. Such facilities require the development of high-brightness high-repetition rate electron guns, and a number of groups worldwide started to develop R&D programs to develop electron guns capable of operating at this challenging regime. Here we describe the approaches and technologies used by the different programs and discuss advantages and challenges for each of them. A review of the present achievements is included, as well as a brief analysis to understand if the present technology performance is sufficient to operate present and future high repetition rate FEL facilities.

Slides TUB3IO02 [7.951 MB]

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TUB3CO03

Demonstration of fresh slice self seeding in a hard X-ray free electron laser

electron, experiment, simulation, FEL

450

C. Emma, C. Pellegrini
UCLA, Los Angeles, USA
M.W. Guetg, A.A. Lutman, A. Marinelli, J. Wu
SLAC, Menlo Park, California, USA

We discuss the first demonstration of fresh slice self seeding (FSSS) in a hard X-ray Free Electron Laser (XFEL). The FSSS method utilizes a single electron beam to generate a strong seed pulse and amplify it with a small energy spread electron slice. This extends the capability of self seeded XFELs by producing short pulses, not limited by the duration set by the self-seeding monochromator system, with high peak intensity. The scheme relies on using a parallel plate dechirper to impart a spatial chirp on the beam, and appropriate orbit control to lase with different electron beam slices before and after the self-seeding monochromator. The performance of the FSSS method is analyzed with start-to-end simulations for the Linac Coherent Light Source (LCLS). The simulations include the effect of the parallel plate dechirper and propagation of the radiation field through the monochromator. We also present results of the first successful demonstration of FSSS at LCLS. The radiation properties of FSSS X-ray pulses are compared with the Self-Amplified Spontaneous Emission (SASE) mode of FEL operation for the same electron beam parameters.

Slides TUB3CO03 [10.423 MB]

Poster TUB3CO03 [3.275 MB]

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TUB3CO04

A New Thermionic RF Electron Gun for Synchrotron Light Sources

gun, cathode, coupling, electron

453

S.V. Kutsaev, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A.V. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, J.J. Hartzell, A. Verma
RadiaBeam, Santa Monica, California, USA
A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
ANL, Argonne, Illinois, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Science, under contract DE-SC0015191 and contract No. DE-AC02-06CH11357.
A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source of Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity, and report the progress towards high power tests of the cathode assembly of the new gun.

Slides TUB3CO04 [2.661 MB]

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TUA4CO03

Loading of Wakefields in a Plasma Accelerator Section Driven by a Self-Modulated Proton Beam

plasma, simulation, proton, wakefield

457

V.K.B. Olsen, E. Adli
University of Oslo, Oslo, Norway
P. Muggli
MPI-P, München, Germany
J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

Using parameters from the AWAKE project and particle-in-cell simulations we investigate beam loading of a plasma wake driven by a self-modulated proton beam. Addressing the case of injection of an electron witness bunch after the drive beam has already experienced self-modulation in a previous plasma, we optimise witness bunch parameters of size, charge and injection phase to maximise energy gain and minimise relative energy spread and emittance of the accelerated bunch.

Slides TUA4CO03 [3.103 MB]

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TUA4CO04

Simulation of High-Power Tunable THz Generation in Corrugated Plasma Waveguides

plasma, laser, radiation, GUI

460

C.M. Miao, T.M. Antonsen
UMD, College Park, Maryland, USA
J. Palastro
NRL, Washington,, USA

Intense, short laser pulses propagating through inhomogeneous plasmas generate terahertz (THz) radiation. We consider the excitation of THz radiation by the interaction between an ultra short laser pulse and a miniature plasma waveguide. Such corrugated plasma waveguides support electromagnetic (EM) channel modes with subluminal phase velocities, thus allowing the phasing matching between the generated THz modes and the ponderomotive potential associated with laser pulse, making significant THz generation possible. Full format PIC simulations and theoretical analysis are conducted to investigate this slow wave phase matching mechanism. We find the generated THz is characterized by lateral emission and a coherent, narrow band spectrum. A range of realistic laser pulse and plasma profile parameters are considered with the goal of increasing the conversion efficiency of optical energy to THz radiation. As an example, a fixed driver pulse (1.66 J) with spot size of 15 μ m and pulse duration of 50 fs excites approximately 83.7 μ J of THz radiation in a 500-μ m-long corrugated waveguide with on axis average density of 10¹⁸ cm^-3.

Slides TUA4CO04 [3.569 MB]

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TUB4IO01

Status of the Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes

FEL, electron, experiment, linac

464

J.L. Erickson, R.W. Garnett
LANL, Los Alamos, New Mexico, USA

The Matter-Radiation Interactions in Extremes (MaRIE) project will provide capability that will address the control of performance and production of materials at the mesoscale. MaRIE will characterize the behavior of interfaces, defects, and microstructure between the spatial scales of atomic structures and those of the engineering continuum where there is a current capability gap. The mission need is well-met with an x-ray source, coherent to optimize disordered imaging capability, brilliant and high-rep-rate to provide time-dependent information, and high enough energy to see into and through the mesoscale of materials of interest. It will be designed for time-dependence from electronic motion (picosecond) through sound waves (nanosecond) through thermal diffusion (millisecond) to manufacturing (seconds and above). The mission need, the requirements, a plausible alternative reference design of a 12-GeV linac-based 42-keV x-ray free-electron laser, and the status of the project will be described.

Slides TUB4IO01 [16.013 MB]

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TUB4IO02

Accelerator Technical Progress and First Commissioning Results from the European XFEL

linac, FEL, MMI, electron

469

R. Wichmann
DESY, Hamburg, Germany

The construction of the European XFEL is coming to an end. The linac tunnel will be closed and commissioning of the main linac will start. The status of the construction project is reviewed. Commissioning of the injector of the European XFEL was already performed in 2016 while construction of the main linac was continuing. The commissioning goals and achievements for the XFEL injector will be reviewed.
Proposed Speaker: W. Decking, DESY

Slides TUB4IO02 [13.428 MB]

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TUB4CO03

Optimization of Compton Source Performance Through Electron Beam Shaping

electron, radiation, brightness, photon

474

A. Malyzhenkov, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA

We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of these sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary. We find the optimal uncorrelated electron beam phase space distribution resulting in the highest brightness of the ICS source for the simple on axis case as an example.

Slides TUB4CO03 [1.673 MB]

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TUB4CO04

Progress on the Magnetic Performance of Planar Superconducting Undulators

undulator, photon, quadrupole, octupole

477

M. Kasa, C.L. Doose, J.D. Fuerst, E. Gluskin, Y. Ivanyushenkov
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
One of the primary goals of the superconducting undulator (SCU) program at the Advanced Photon Source (APS) is to achieve a high quality undulator magnetic field without the need for magnetic shimming to tune the device. Over the course of two years, two SCUs were designed, manufactured, assembled, and tested at the APS. Both SCUs were one meter in length with a period of 1.8 cm. After magnetic measurements of the first undulator were completed, several design changes were made in order to improve the quality of the undulator magnetic field. The design modifications were implemented during construction and assembly of the second SCU. The details of the design modifications along with a comparison of the magnetic measurement results will be described.

Slides TUB4CO04 [6.426 MB]

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TUPOB02

Development of the Method for Evaluation of a Super-Conducting Traveling Wave Cavity With a Feedback Waveguide

cavity, GUI, simulation, feedback

480

R.A. Kostin
LETI, Saint-Petersburg, Russia
P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: DOE SBIR # DE-SC0006300
Euclid Techlabs is developing a superconducting traveling wave (SCWT) cavity with a feedback waveguide [1] and has demonstrated a traveling wave at room temperature [2] in a 3-cell SCTW cavity [3]. A special method described in this paper was developed for cavity evaluation. It is based on an S-matrix approach. The cavity tuning procedure based on this method is described.

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TUPOB04

A More Compact Design for the JLEIC Ion Pre-Booster Ring

booster, injection, dipole, linac

483

B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL
The original design of the JLEIC pre-booster was a 3-GeV figure-8 shaped synchrotron with a circumference of about 240 m. In the current baseline design, the 3-GeV pre-booster was converted into an 8-GeV booster of the same shape and size but using super-ferric magnets with fields up to 3 Tesla. In order to limit the foot-print of the JLEIC ion complex and reduce its total cost, we have designed a more compact and cost-effective octagonal 3-GeV ring about half the size of the original one. At 3 GeV, the figure-8 shape is not required to preserve ion polarization; Siberian snakes with reasonable magnetic fields can be used for spin correction. As the ion collider ring requires an injection energy of at least 8 GeV, we propose to use the existing electron storage ring, which is part of the electron complex, as a large booster for the ions up to 11 GeV. The design optimization of the pre-booster ring will be presented leading to the final octagonal ring design. Preliminary beam simulations will also be presented and discussed.

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TUPOB05

An Alternative Approach for the JLEIC Ion Accelerator Complex

booster, collider, linac, proton

486

B. Mustapha, Z.A. Conway, P.N. Ostroumov, A.S. Plastun
ANL, Argonne, USA
Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The current baseline design for the JLab EIC (JLEIC) ion accelerator complex is based on a pulsed superconducting linac, an 8-GeV booster followed by a dual function 20-100 GeV booster and collider ring. Both the 8-GeV booster and collider ring will use super-ferric magnets with fields up to 3 Tesla. We here propose an alternative cost-effective and low-risk design where the 8-GeV booster is replaced with a more compact 3-GeV booster using room-temperature magnets. The electron storage ring, which is part of the electron complex, will also serve as large booster for the ions, up to 11 GeV. We also propose two stages for the JLEIC. A first low-energy stage up to 60 GeV, where room-temperature magnets (up to 1.6 Tesla) will be used for the ion collider ring, to be later replaced with 6 Tesla superconducting magnets in a second stage of the project providing up to 200 GeV energy. In this second stage, the 1.6 T room-temperature magnets will replace the PEP-II magnets in the electron storage ring to boost the ions to higher energies (25 GeV or higher) for appropriate injection into the higher energy collider. Details and feasibility of the proposed plan will be presented and discussed.

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TUPOB06

Accomplishments of the Heavy Electron Particle Accelerator Program

collider, factory, proton, experiment

489

D.V. Neuffer, D. Stratakis
Fermilab, Batavia, Illinois, USA
M.A. Cummings
Muons, Inc, Illinois, USA
J.-P. Delahaye
SLAC, Menlo Park, California, USA
M.A. Palmer
BNL, Upton, Long Island, New York, USA
R.D. Ryne
LBNL, Berkeley, California, USA
D.J. Summers
UMiss, University, Mississippi, USA

Funding: Work supported by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359
The Muon Accelerator Program has completed a four-year study on the feasibility of muon colliders and on using stored muon beams for neutrinos. That study was broadly successful in its goals, establishing the feasibility of lepton colliders from the 125 GeV Higgs Factory to more than 10 TeV, as well as exploring using μ storage rings for neutrinos. The key components of the muon collider scenarios are a high-intensity proton source, a multi MW target and transport system for π capture, a front end system for bunching, energy compression and initial cooling of μ's, muon cooling systems to obtain intense μ+ and μ- bunches, acceleration up to multiTeV energies, and a collider ring with detectors for high luminosity collisions. For a neutrino factory a similar system could be used but with a racetrack storage ring for ν production and without the cooling needed for high luminosity collisions. Feasible designs and detailed simulations of all of these components have been obtained, including some initial hardware component tests, setting the stage for future implementation where resources are available and clearly associated physics goals become apparent.

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TUPOB07

Considerations on Energy Frontier Colliders After LHC

collider, luminosity, plasma, hadron

493

V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

The future of the world-wide HEP community critically depends on the feasibility of possible post-LHC colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosiity and feasibility of cost. The talk will give on overview of all current options for post-LHC colliders from such perspective (ILC, CLIC, Muon Collider, plasma colliders, CEPC, FCC, HE-LHC, etc) and discuss major challenges and accelerator R&D required to claim these machines feasible.

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TUPOB08

Beam Extraction from the Recycler Ring to P1 Line at Fermilab

extraction, proton, kicker, MMI

497

M. Xiao
Fermilab, Batavia, Illinois, USA

The transfer line for beam extraction from the Recycler ring to P1 line provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. It was designed in 2012. The kicker magnets at RR520 and the lambertson magnet at RR522 in the RR were installed in 2014 Summer Shutdown, the elements of RR to P1 Stub (permanent quads, trim quads, correctors, BPMs, the toroid at 703 and vertical bending dipole at V703 (ADCW) ) were installed in 2015 Summer Shutdown. On Tuesday, June 21, 2016, beam line from the Recycler Ring to P1 line was commissioned. The detailed results will be presented in this report.

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TUPOB09

Solid-State Pulsed Power System for a Stripline Kicker

kicker, ISOL, operation, simulation

500

N. Butler, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, F.M. Niell, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: *Work supported by US Department of Energy contract DE-SC0004255
Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers.

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TUPOB11

Quantification of Octupole Magnets at the University of Maryland Electron Ring

octupole, quadrupole, multipole, lattice

503

H. Baumgartner, B. Beaudoin, S. Bernal, I. Haber, T.W. Koeth, D.B. Matthew, K.J. Ruisard, M.R. Teperman
UMD, College Park, Maryland, USA

Funding: Funding for this project is provided by DOE-HEP and the NSF Accelerator Science Program
The intensity frontier is limited by the ability to propagate substantial amounts of beam current without resulting in particle scrapping and/or losses from resonant growth and halo formation. Modern accelerators are based on the theories developed in the 1950's that assume particle motion is bounded and subject to linear forces. Recent theoretical developments have demonstrated that a strongly nonlinear lattice can be used to stably transport an intense beam has resulted in a fundamental rethinking of the conventional wisdom. A lattice composed of strong nonlinear magnets is predicted by theory to damp resonances while maintaining dynamic aperture. Results of rotating coil measurements, magnetic field scans and simulations will be presented, quantifying the multi-pole moments and fringe fields in the 1st generation Printed Circuit Board (PCB) octupoles for UMER's nonlinear lattice experiments.

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TUPOB12

Experimental Plans for Single-Channel Strong Octupole Fields at the University of Maryland Electron Ring

lattice, octupole, quadrupole, focusing

507

K.J. Ruisard, H. Baumgartner, B. Beaudoin, I. Haber, T.W. Koeth, M.R. Teperman
UMD, College Park, Maryland, USA

Funding: Funding for this project and travel is provided by DOE-HEP, NSF GRFP and NSF Accelerator Science Program
Nonlinear quasi-integrable optics is a promising development on the horizon of high-intensity ring design. Large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, lead to decoupling from incoherent tune resonances. This reduces intensity-driven beam loss while quasi-integrability ensures a well-contained beam. In this paper we discuss on-going work to install and interrogate a long-octupole channel at the University of Maryland Electron Ring (UMER). This is a discrete insert that occupies 20 degrees of the ring, consisting of independently powered printed circuit octupole magnets. Transverse confinement is obtained with quadrupoles external to this insert. Operating UMER as a non-FODO lattice, in order to meet the beam-envelope requirements of the quasi-integrable lattice, is a challenge. We discuss efforts to match the beam and optimize steering solutions. We also discuss our experiences operating a distributed strong octupole lattice.

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TUPOB13

Simulations of Space Charge Neutralization in a Magnetized Electron Cooler

electron, simulation, collider, experiment

511

J. Gerity, P.M. McIntyre
Texas A&M University, College Station, USA
D.L. Bruhwiler, C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
V. Moens
EPFL, Lausanne, Switzerland
C.S. Park, G. Stancari
Fermilab, Batavia, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-SC0015212.
Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.

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TUPOB14

An Accurate and Efficient Numerical Integrator for Pair-Wise Interaction

proton, software, operation, simulation

514

A.A. Al Marzouk, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

We are developing a new numerical integrator based on Picard iteration method for Coulomb collisions. The aim is to achieve a given prescribed accuracy most efficiently. The integrator is designed to have adaptive time stepping, variable order, and dense output. It also has an automatic selection of the order and the time step. We show that with a good estimation of the radius of convergence of the expansion, we can obtain the optimal time step size. We also show how the optimal order of the integration is chosen to maintain the required accuracy. For efficiency, particles are distributed over time bins and propagated accordingly.

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TUPOB15

Implementing the Fast Multipole Boundary Element Method With High-Order Elements

multipole, simulation, controls, lattice

518

A.J. Gee, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

The next generation of beam applications will require high-intensity beams with unprecedented control. For the new system designs, simulations that model collective effects must achieve greater accuracies and scales than conventional methods allow. The fast multipole method is a strong candidate for modeling collective effects due to its linear scaling. It is well known the boundary effects become important for such intense beams. We implemented a constant element fast boundary element method (FMBEM) * as our first step in studying the boundary effects. To reduce the number of elements and discretization error, our next step is to allow for curvilinear elements. In this paper we will present our study on a quadratic and a cubic parametric method to model the surface.
* A.Gee and B.Erdelyi, "A Differential Algebraic Framework for the Fast Indirect Boundary Element Method," in Proc. IPAC'16. Busan, South Korea.

Poster TUPOB15 [1.727 MB]

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TUPOB16

A Simple Method for Measuring the Electron-Beam Magnetization

solenoid, electron, cathode, emittance

521

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
G. Qiang
TUB, Beijing, People's Republic of China

There are a number of projects that require magnetized beams, such as electron cooling or aiding in flat beam transforms. Here we explore a simple technique to characterize the magnetization, observed through the angular momentum of magnetized beams. These beams are produced through photoemission. The generating drive laser first passes through microlens arrays (fly-eye light condensers) to form a transversely modulated pulse incident on the photocathode surface. The resulting charge distribution is then accelerated from the photocathode. We explore the evolution of the pattern via the relative shearing of the beamlets, providing information about the angular momentum. This method is illustrated through numerical simulations and preliminary measurements carried out at the Argonne Wakefield Accelerator (AWA) facility are presented.

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TUPOB17

Simulations in Support of Wire Beam-Beam Compensation Experiment at the LHC

simulation, experiment, emittance, optics

525

A.S. Patapenka
Northern Illinois University, DeKalb, Illinois, USA
R. De Maria, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Valishev
Fermilab, Batavia, Illinois, USA

The compensation of long-range beam-beam interaction with current wires is considered as a possible technology for the HL-LHC upgrade project. A demonstration experiment is planned in the present LHC machine starting in 2018. This paper summarizes the tracking studies of long range beam-beam effect compensation in the LHC aimed to aid in planning the demonstration experiment. The impact of wire compensators is demonstrated on the tune footprints, dynamic aperture, beam emittance and beam intensity degradation. The simulations are performed with SIXTRACK code. The symplectic transport map for the wire element, its verification and implementation into the code are also discussed.

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TUPOB18

Beam Test of Masked-Chicane Micro-Buncher

simulation, electron, bunching, controls

528

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA
D.R. Broemmelsiek, D.J. Crawford, D.R. Edstrom, A.H. Lumpkin, J. Ruan, J.K. Santucci, J.C.T. Thangaraj, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA

Funding: This work was supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. We also thank the FAST Department team for the helpful discussion and technical supports.
Masking a dispersive beamline such as a dogleg or a chicane [1, 2] is a simple way to shape a beam in the longitudinal and transverse space. This technique is often employed to generate arbitrary bunch profiles for beam/laser-driven accelerators and FEL undulators or even to reduce a background noise from dark currents in electron linacs. We have been investigating a beam-modulation of a slit-masked chicane, which was deployed for crystal-channeling experiments at the injector beamline of the Fermilab Accelerator Science and Technology (FAST) facility. With a nominal beam of 3 ps bunch length, Elegant simulations showed that a slit-mask with slit period 900 um and aperture width 300 um induces a modulation with bunch-to-bunch space of about 187 um (0.25 nC), 270 um (1 nC) and 325 um (3.2 nC) with 3 ~ 6% correlated energy spread: An initial energy modulation pattern has been observed in the electron spectrometer downstream of the masked chicane using a micropulse charge of 260 pC and 40 micropulses. Investigations of the beam longitudinal modulation are planned with a Martin-Puplett interferometer and a synchro-scan streak camera at a station between the chicane and spectrometer.
[1] D.C.Nguyen, B.E.Carlsten, NIMA 375, 597 (1996)
[2] P.Muggli, V.Yakimeno, M.Babzien, et al., PRL 101, 054801 (2008)

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TUPOB19

FEL Wiggler Bussbar Field Compensation

wiggler, storage-ring, FEL, electron

532

B. Li, H. Hao, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Abstract The Duke storage ring is a dedicated driver for the storage ring based free-electron laser (FEL) and the High Intensity Gamma-ray Source (HIGS). The high intensity gamma-ray beam is produced using Compton scattering between the electron and FEL photon beams. The beam displacement and angle at the collision point need to be maintained constant during the gamma-ray beam production. The magnetic field of the copper bussbars carrying the current to the FEL wigglers can impact the beam orbit. The compensation scheme in-general is complicated. In this work, we report preliminary results of a bussbar compensation scheme for one of the wiggler and power supply configurations. Significant reductions of the orbit distortions have been realized using this compensation.

Poster TUPOB19 [3.693 MB]

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TUPOB21

MuSim, A Graphical User Interface for Multiple Simulation Codes

simulation, interface, resonance, proton

535

T.J. Roberts, Y. Bao
Muons, Inc, Illinois, USA
Y. Bao
UCR, Riverside, California, USA

MuSim is a user-friendly program designed to interface to many different particle simulation codes, regardless of their data formats or geometry descriptions. It presents the user with a compelling graphical user interface that includes a flexible 3-D view of the simulated world plus powerful editing and drag-and-drop capabilities. All aspects of the design can be parameterized so that parameter scans and optimizations are easy. It is simple to create plots and display events in the 3-D viewer, allowing for an effortless comparison of different simulation codes. Simulation codes: G4beamline 3.02, MCNP 6.1, and MAD-X; more are coming. Many accelerator design tools and beam optics codes were written long ago, with primitive user interfaces by today's standards. MuSim is specifically designed to make it easy to interface to such codes, providing a common user experience for all, and permitting the construction and exploration of models with very little overhead. For today's technology-driven students, graphical interfaces meet their expectations far better than text-based tools, and education in accelerator physics is one of our primary goals.

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TUPOB22

Dependence of the Coupling of Dipole Motion From Bunch to Bunch Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity

electron, damping, positron, dipole

538

M.G. Billing, L.Y. Bartnik, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA
E.C. Runburg
University of Notre Dame, Indiana, USA

The Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) has been utilized to probe the interaction of the electron cloud with a 2.1 GeV stored positron beam. Recent experiments have characterized any dependence of beam'electron cloud (EC) interactions on the bunch length (or synchrotron tune) and the vertical chromaticity. The measurements were performed on a 30-bunch positron train with 14 nsec spacing between bunches, at a fixed current of 0.75 mA/bunch. The dynamics of the stored beam, in the presence of the EC, was quantified using 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion. In this paper we report on the observations from these experiments and analyze the coupling of di-pole motion from bunches within the train to subsequent bunches, caused by the EC.

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TUPOB23

Electron Cloud Simulations for the Low-Emittance Upgrade at the Cornell Electron Storage Ring

electron, operation, positron, synchrotron

542

J.A. Crittenden, Y. Li, S. Poprocki, J.E. San Soucie
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the National Science Foundation DMR 13-32208
The Cornell Electron Storage Ring operations group is planning a major upgrade of the storage ring performance as an X-ray user facility. The principal modification foresees replacing the former e⁻e⁺ interaction region with six double-bend achromats, reducing the emittance by a factor of four. The beam energy will increase from 5.3 to 6.0 GeV and single-beam operation will replace the present two-beam e⁻e⁺ operation. The initial phase of the project will operate a single positron beam, so electron cloud buildup may contribute to performance limitations. This work describes a synchrotron radiation analysis of the new ring, and employs its results to provide ring-wide estimates of cloud buildup and consequences for the lattice optics.

Poster TUPOB23 [4.832 MB]

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TUPOB24

Optimization of Linear Induction Radiography Accelerator with Electron Beam with Energy Variation

electron, target, solenoid, induction

546

Y.H. Wu, Y.J. Chen
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The current interest for the next generation linear induction radiography accelerator (LIA) is to generate multiple electron beam pulses with high peak currents. The beam energy and current may vary from pulse to pulse. Conse-quently, the transport and control of multi-pulsing intense electron beams through a focus-ing lattice over a long distance on such machine becomes challenging. Simulation studies of multi-pulse LIAs using AMBER [1] and BREAKUP Code [2] are described. These include optimized focusing magnetic tune for beams with energy and current variations, and steering correction for corkscrew motion. The impact of energy variation and accelerating voltage error on radiograph performance are discussed.

Poster TUPOB24 [1.419 MB]

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TUPOB25

Unfolding Electron Beam Parameters Using Spot Size Measurement From Magnet Scan

electron, target, emittance, beam-transport

549

Y.H. Wu, Y.J. Chen, J. Ellsworth
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The Flash X-ray Radiography (FXR) [1] line-ar induction accelerator at Lawrence Livermore National Laboratory produces x-ray bursts for radiographs. The machine is able to produce x-ray spot sizes less than 2mm. Using the spot sizes measured from the magnet scanning, the beam parameters are unfolded by modelling the FXR LINAC with the simulation code AMBER [2] and the envelope code XENV [3]. In this study, the most recent spot size measurement results and techniques used to extract the beam parameters are described. Using the unfolded beam parameters as the initial condition, the backstreaming ions' neutralization factor f = 0.3 is found by comparing the calculated spot sizes with measured spot sizes at the target.

Poster TUPOB25 [0.576 MB]

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TUPOB26

Dynamics of Intense Beam in Quadrupole-Duodecapole Lattice Near Sixth Order Resonance

resonance, quadrupole, focusing, lattice

552

Y.K. Batygin, T.T. Fronk
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract DE-AC52-06NA25396
The presence of duodecapole components in quadrupole focusing field results in excitation of sixth-order single-particle resonance if the phase advance of the particles transverse oscillation is close to 60 deg. This phenomenon results in intensification of beam losses. We present analytical and numerical treatment of particle dynamics in the vicinity of sixth-order resonance. The topology of resonance in phase space is analyzed. Beam emittance growth due to crossing of resonance islands is determined. Halo formation of intense beams in presence of resonance conditions is examined.

Poster TUPOB26 [3.523 MB]

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TUPOB29

Simulations of Nonlinear Beam Dynamics in the JLEIC Electron Collider Ring

sextupole, emittance, electron, dynamic-aperture

555

F. Lin, Y.S. Derbenev, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov, M.K. Sullivan
SLAC, Menlo Park, California, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
The short lengths of colliding bunches in the proposed Jefferson Lab Electron-Ion Collider (JLEIC) allow for small beta-star values at the interaction point (IP) yielding a high luminosity. The strong focusing associated with the small beta-stars results in high natural chromaticities and potentially a beam smear at the IP. Rapid growth of the electron equilibrium emittances and momentum spread with energy further complicates the situation. We investigated nonlinear dynamics correction schemes that overcome these problems and allow for stable beam dynamics and sufficient beam lifetime at the highest electron energy. In this paper, we present and compare tracking simulation results for various schemes considering their emittance contributions.

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TUPOB30

Spin Flipping System in the JLEIC Collider Ring

collider, polarization, controls, solenoid

558

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The figure-8 JLEIC collider ring opens wide possibilities for manipulating proton and deuteron spin directions during an experiment. Using 3D spin rotators, one can, at the same time, efficiently control the polarization direction as well as the spin tune value. The 3D spin rotators allow one to arrange a system for reversals of the spin direction in all beam bunches during an experiment, i.e. a spin-flipping system. To preserve the polarization, one has to satisfy the condition of adiabatic change of the spin direction. When adjusting the polarization direction, one can stabilize the spin tune value, which completely eliminates resonant beam depolarization during the spin manipulation process. We provide the results of numerical modeling of a spin-flipping system in the JLEIC ion collider ring. The presented results demonstrate the feasibility of organizing a spin-flipping system using a 3D rota-tor. The figure-8 JLEIC collider provides a unique capability of doing high-precision experiments with polarized ion beams.

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TUPOB31

Compensation of Chromaticity in the JLEIC Electron Collider Ring

sextupole, emittance, electron, dipole

561

Y.M. Nosochkov, Y. Cai, M.K. Sullivan
SLAC, Menlo Park, California, USA
Y.S. Derbenev, F. Lin, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
The Jefferson Lab Electron-Ion Collider (JLEIC) is being designed to achieve a high luminosity of up to 10³⁴ 1/(cm²*sec). The latter requires a small beam size at the interaction point demanding a strong final focus (FF) quadrupole system. The strong beam focusing in the FF unavoidably creates a large chromaticity which has to be compensated in order to avoid a severe degradation of momentum acceptance. This has to be done while preserving sufficient dynamic aperture. An additional design requirement for the chromaticity compensation optics in the electron ring is preservation of the low beam emittance. This paper reviews the development and selection of a chromaticity correction scheme for the electron collider ring.

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TUPOB35

Progress on Skew Parametric Resonance Ionization Cooling Channel Design and Simulation

coupling, multipole, resonance, optics

565

A.V. Sy, Y.S. Derbenev, V.S. Morozov
JLab, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
Y. Bao
UCR, Riverside, California, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Skew Parametric-resonance Ionization Cooling (Skew PIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. Properties of the linear beam dynamics have been previously reported and good agreement exists between theory, analytic solutions, and simulations. Progress on aberration compensation in the coupled correlated optics channel is presented and discussed.

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TUPOB36

Simulation Study on JLEIC High Energy Bunched Electron Cooling

electron, emittance, simulation, collider

568

H. Zhang, S.V. Benson, J. Chen, Y.S. Derbenev, R. Li, Y. Roblin, Y. Zhang
JLab, Newport News, Virginia, USA
H. Huang, L. Luo
ODU, Norfolk, Virginia, USA

Funding: * Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance.

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TUPOB37

Diffusion Measurement From Transverse Echoes

quadrupole, dipole, simulation, octupole

572

Y.S. Li
Carleton College, Northfield, Minnesota, USA

Beam diffusion is an important measure of stability in high intensity beams. Traditional methods of diffusion characterization (e.g. beam scraping) can be very time-consuming. In this study, we investigate the transverse beam echo as a novel technique for measuring beam diffusion. Numerical analysis of maximum echo amplitude was compared with theoretical predictions with and without diffusion. We succeeded in performing a self-consistent measurement of the linear diffusion coefficient via a parameter scan over delay time. We also demonstrated the effectiveness of pulsed quadrupoles as a means to boost echo amplitude. Finally, multi-echo sequences were also briefly investigated. Results from this study will support planned experiments at the IOTA proton ring under construction at Fermilab.

Poster TUPOB37 [2.109 MB]

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TUPOB38

Implementation of MAD-X into MuSim

simulation, interface, detector, resonance

575

Y. Bao
UCR, Riverside, California, USA
T.J. Roberts
Muons, Inc, Illinois, USA

Funding: This work is supported by Muons, Inc.
MuSim is a new and innovative graphical system that allows the user to design, optimize, analyze, and evaluate accelerator and particle systems efficiently. It is designed for both students and experienced physicists to use in dealing with the many modeling tools and their different description languages and data formats. G4beamline [1] and MCNP [2] have been implemented into MuSim in previous studies. In this work, we implement MAD-X [3] into MuSim so that the users can easily use the graphical interface to design beam lines with MAD-X and compare the modeling results of different codes.

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TUPOB39

Mechanical Design and Manufacturing of a Two Meter Precision Non-Linear Magnet System

vacuum, alignment, optics, simulation

578

J.D. McNevin
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, F.H. O'Shea
RadiaBeam, Santa Monica, California, USA

Funding: Department of Energy Office of Science DE-SC0009531
RadiaBeam Technologies is currently developing a non-linear magnet insert for Fermilab's Integrable Optics Test Accelerator (IOTA), a 150 MeV circulating electron beam storage ring designed for investigating advanced beam physics concepts. The physics requirements of the insert demand a high level of precision in magnet geometry, magnet axis alignment, and corresponding alignment of the vacuum chamber geometry within the magnet modules to maximize chamber aperture size. Here we report on the design and manufacturing of the vacuum chamber, magnet manufacturing, and kinematic systems.

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TUPOB40

Fundamental Properties of a Novel, Metal-Dielectric, Tubular Structure with Magnetic RF Compensation

linac, impedance, coupling, simulation

582

A.V. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: Supported by DoE Contract # DE-SC0011370
A number of electron beam vacuum devices such as small radiofrequency (RF) linear accelerators (linacs) and microwave traveling wave tubes (TWTs) utilize slow wave structures which are usually rather complicated in production and may require multi-step brazing and time consuming tuning. Fabrication of these devices becomes challenging at centimeter wavelengths, at large number of cells, and when a series or mass production of such structures is required. A hybrid, metal-dielectric, periodic structure for low gradient, low beam current applications is introduced here as a modification of Andreev's disk-and-washer (DaW) structure. Compensated type of coupling between even and odd TE01 modes in the novel structure results in negative group velocity with absolute values as high as 0.1c-0.2c demonstrated in simulations. Sensitivity to material imperfections and electrodynamic parameters of the disk-and-ring (DaR) structure are considered numerically using a single cell model.

Poster TUPOB40 [1.447 MB]

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TUPOB41

Bi-Complex Toolbox Applied to Gyromagnetic Beam Break-Up

polarization, dipole, experiment, linac

585

A.V. Smirnov
RadiaBeam, Santa Monica, California, USA

Transverse instability of a multi-bunch beam in the presence of a longitudinal magnetostatic field and hybrid dipole modes is considered analytically within a single-section model. It incorporates resonant interaction with beam harmonics and eigenmodes, degenerated waves of different polarizations, and the Lorentz RF force contribution. The analysis is performed in a very compact form using a bi-complex i,j-space including four-component collective frequency of the instability. Rotating polarization of the collective field is determined by ImiImj part of the bi-complex collective frequency in agreement with available data. The other three components represent detuning of the collective frequency ReiRej, the left-hand, and right-hand increments ImiRej±ReiImj of the gyro-magnetic BBU effect. The scalar hyper-complex toolbox can be applied to designing of non-ferrite non-reciprocal devices, spin transport, and for characterization of complex transverse dynamics in gyro-devices such as Gyro-TWTs.

Poster TUPOB41 [0.526 MB]

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TUPOB43

Magnetic Cloaking of Charged Particle Beams

electron, detector, superconducting-magnet, dipole

588

K.G. Capobianco-Hogan, A.A. Adhyatman, G. Arrowsmith-Kron, G. Bello Portmann, D.B. Bhatti, R. Cervantes, B.D. Coe, A. Deshpande, N. Feege, S.P. Jeffas, T.C. Krahulik, J.J. LaBounty, T.M. LaByer, A. Oliveira, H.A. Powers, R.S. Sekelsky, V.D. Shethna, N. Ward, H.J. van Nieuwenhuizen
Stony Brook University, Stony Brook, USA
R. Cervantes
University of Washington, CENPA, Seattle, USA
B.D. Coe
BNL, Upton, Long Island, New York, USA

In order to measure the momentum of particles produced by asymmetric collisions in the proposed Electron Ion Collider, a magnetic field should be introduced perpendicular to the path of the beam to increase momentum resolution without bending or depolarizing it. A magnetic cloak consisting of a superconducting magnetic shield surrounded by a ferromagnetic layer is capable of shielding the interior from a magnetic field – thereby protecting the beam – without distorting the field outside of the cloak – permitting detector coverage at high pseudorapidity.

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TUPOB44

Final 6d Muon Ionization Cooling Using Strong Focusing Quadrupoles

emittance, quadrupole, betatron, collider

592

T.L. Hart, J.G. Acosta, L.M. Cremaldi, S.J. Oliveros, D.J. Summers
UMiss, University, Mississippi, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Low emittance muon beam lines and muon colliders are potentially a rich source of BSM physics for future experimenters. A normalized transverse muon emittance of 280 microns has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL, G4Beamline, and MAD-X to explore using a flat 400 MeV/c muon beam and strong focusing quadrupoles to achieve a normalized transverse emittance of 100 microns and finish 6D cooling. The low beta regions, as low as 5 mm, produced by the quadrupoles are occupied by dense, low Z absorbers, such as lithium hydride or beryllium, that cool the beam. Equilibrium transverse emittance is linearly proportional to the beta function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 microns at the expense of longitudinal emittance for a high energy lepton collider. Cooling challenges include chromaticity correction, momentum passband overlap, quadrupole acceptance, and staying in phase with RF.

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TUPOB45

A Model to Simulate the Effect of a Transverse Feedback System on Single Bunch Instability Thresholds

simulation, feedback, kicker, damping

596

G. Bassi, A. Blednykh, V.V. Smaluk
BNL, Upton, Long Island, New York, USA
Z. Yang
Auburn University, Auburn, USA

Funding: DOE Contract No. DE-AC02-98CH10886
A model to simulate the effect of a transverse feedback system is implemented in SPACE, a parallel, self-consistent code for collective effects. As an application, we discuss single bunch instability thresholds in the NSLS-II storage ring and compare the numerical results with measurements.

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TUPOB50

Beam-Induced Heating of the Kicker Ceramics Chambers at NSLS-II

kicker, impedance, ECR, injection

599

A. Blednykh, B. Bacha, G. Bassi, G. Ganetis, C. Hetzel, H.-C. Hseuh, T.V. Shaftan, V.V. Smaluk, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
First experience with the beam-induced heating of the ceramics chambers in the NSLS-II storage ring has been discussed. Total five ceramics chambers are considered to be replaced due to overheating concern during of upcoming I_av=500mA operations. The air cooling fans has been installed as a temporarily solution to remove heat.

Poster TUPOB50 [1.629 MB]

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TUPOB51

A NUMERICAL STUDY OF THE MICROWAVE INSTABILITY AT APS

storage-ring, simulation, vacuum, experiment

602

A. Blednykh, G. Bassi, V.V. Smaluk
BNL, Upton, Long Island, New York, USA
R.R. Lindberg
ANL, Argonne, Illinois, USA

Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
Two particle tracking codes, ELEGANT and SPACE, have been used to simulate the microwave instability in the APS storage ring. The total longitudinal wakepotential for the APS vacuum components, computed by GdfidL, has been used as the input file for the simulations. The numerical results have been compared with bunch length and the energy spread measurements for different single-bunch intensities.

Poster TUPOB51 [1.032 MB]

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TUPOB52

Linear Optics Characterization and Correction Method Using Turn-By-Turn BPM Data Based on Resonance Driving Terms with Simultaneous BPM Calibration Capability

lattice, coupling, experiment, quadrupole

605

Y. Hidaka, B. Podobedov
BNL, Upton, Long Island, New York, USA
J. Bengtsson
J B Optima, LLC, Rocky Point, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886.
A fast new linear lattice characterization / correction method based on turn-by-turn (TbT) beam position monitor (BPM) data in storage rings has been recently developed and experimentally demonstrated at NSLS-II. This method performs least-square fitting iteratively on the 4 frequency components extracted from TbT data and dispersion functions. The fitting parameters include the errors for normal/skew quadrupole strength and 4 types of BPM errors (gain, roll, and deformation). The computation of the Jacobian matrix for this system is very fast as it utilizes analytical expressions derived from the resonance driving terms (RDT), from which the method name DTBLOC (Driving-Terms-Based Linear Optics Characterization/Correction) originates. At NSLS-II, a lattice corrected with DTBLOC was estimated to have beta-beating of <1%, dispersion errors of ~1 mm, and emittance coupling ratio on the order of 10^-4.

Poster TUPOB52 [2.206 MB]

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TUPOB54

Using Square Matrix to Realize Phase Space Manipulation and Dynamic Aperture Optimization

resonance, lattice, sextupole, dynamic-aperture

609

Y. Li, L. Yu
BNL, Upton, Long Island, New York, USA

We introduce a new method of using square matrix to realize phase space manipulation and dynamic aperture optimization in storage rings. Both the tracking simulation and the experimental observation in the NSLS-II ring lattice are presented.

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TUPOB55

Optimize the Algorithm for the Global Orbit Feedback at Fixed Energies and During Acceleration in RHIC

feedback, acceleration, proton, lattice

612

C. Liu, R.L. Hulsart, K. Mernick, R.J. Michnoff, M.G. Minty
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
To combat triplets vibration, the global orbit feedback system with frequency about 10 Hz was developed and en- gaged in operation at injection and top energy in 2010, dur- ing beam acceleration in 2012 at RHIC. The system has performed well with keeping 6 out of 12 eigenvalues for the orbit response matrix. However, we observed correc- tor current transients with the lattice for polarized proton program in 2015 which resulted in corrector power supply trips. In this report, we will present the observation, an- alyze the cause and also optimize the feedback algorithm to overcome the newly emerged problem with the feedback system.

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TUPOB56

The eRHIC Ring-Ring Design

electron, proton, luminosity, dipole

616

C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A.V. Fedotov, W. Fischer, Y. Hao, A. Hershcovitch, Y. Luo, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, S. Seletskiy, T.V. Shaftan, V.V. Smaluk, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu
BNL, Upton, Long Island, New York, USA

The ring-ring version of the eRHIC electron-ion collider design aims at providing electron-proton collisions with a center-of-mass energy ranging from 32 to 141 GeV at a luminosity reaching 10³³ cm^-2 sec^-1. This design of the double-ring collider also supports electron-ion collisions with similar electron-nucleon luminosities, and is upgradeable to 10³⁴ cm^-2 sec^-1 using bunched beam electron cooling of the hadron beam. The baseline luminosities are achievable using existing technologies and beam parameters that have been routinely achieved at RHIC in hadron-hadron collisions or elsewhere in e⁺e⁻ collisions. This minimizes the risk associated with the challenging luminosity goal and is keeping the technical risk of the e-RHIC electron-ion collider low. The latest design status will be presented.

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TUPOB57

The Role of Adami Information in Beam Cooling

kicker, pick-up, experiment, beam-cooling

619

V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy under contract number DE-SC0012704
We re-consider stochastic cooling as type of information engine using the Adami definition of information *. We define information as data which can permit the cooling system to predict the individual trajectories better than purely random prediction and then act on that data to modify the trajectories of an ensemble of particles. In this study we track the flow of this type of information through the closed system and consider the limits based on sampling and correction as well as the role of the underlying model.
* Adami C. 2016 ‘‘What is information?'' Phil. Trans. R. Soc. A 374:20150230.

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TUPOB60

Permanent Magnets for High Energy Nuclear Physics Accelerators

quadrupole, electron, permanent-magnet, dipole

622

N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy
The proposed eRHIC accelerator1 will collide 20 GeV polarized electrons with 250 GeV polarized protons or 100 GeV/n polarized 3He ions or other unpolarized heavy ions. The electron accelerator of the eRHIC will be based on a 1.665 GeV Energy Recovery Linac (ERL) placed in the RHIC tunnel and two Fixed Field Alternating Gradient (FFAG) recirculating rings placed alongside the RHIC accelerator. The electron bunches reach the 20 GeV energy after passing 12 times through the ERL by recirculation in the FFAG rings. The FFAG rings consist of FODO cells comprised of one focusing and one defocusing quadrupoles made of permanent magnet material. Similarly other sections of the electron accelerator will utilize permanent magnets. In this presentation we will discuss details on the design of these magnets and their advantages over the current-excited magnets.
1. <http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf>

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TUPOB61

Recent Improvements to TAPAs, the Android Application for Accelerator Physics and Engineering Calculations

lattice, cavity, emittance, storage-ring

625

M. Borland
Private Address, Westmont, USA

The Android application TAPAs, the Toolkit for Accelerator Physics on Androids, was released in 2012 and at present has over 300 users. TAPAs provides over 50 calculations, many of which are coupled together. Updates are released about once a month and have provided many new capabilities. Calculations for electron storage rings are a particular emphasis, and have expanded to include CSR threshold, ion trapping, Laslett tune shift, and emittance dilution. Other additions include helical superconducting undulators, rf cavity properties, Compton backscattering, and temperature calculations for mixing water.

Poster TUPOB61 [2.925 MB]

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TUPOB62

Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design

proton, electron, simulation, emittance

628

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
Y. Hao
BNL, Upton, Long Island, New York, USA

The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.

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TUPOB63

POSINST Simulation on Fermilab Main Injector and Recycler Ring

electron, dipole, simulation, proton

632

Y. Ji
IIT, Chicago, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA
R.M. Zwaska
Fermilab, Batavia, Illinois, USA

The Fermilab accelerator complex is currently undergoing an upgrade from 400kW to 700kW. This intensity could push operations into the region where electron cloud (e-cloud) generation could be observed and even cause instabilities. The POSINST simulation code was used to study how in- creasing beam intensities will affect electron cloud genera- tion. Threshold simulations show how the e-cloud density depend on the beam intensity and secondary electron yield (SEY) in the Main Injector (MI) and Recycler Ring (RR).

Poster TUPOB63 [1.542 MB]

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TUPOB64

Beam Measurements at the PIP-II Injector Test LEBT

solenoid, emittance, simulation, ion-source

636

J.-P. Carneiro, B.M. Hanna, L.R. Prost, V.E. Scarpine, A.V. Shemyakin
Fermilab, Batavia, Illinois, USA

This paper presents the main results obtained during a series of beam measurements performed on the PIP-II Injector Test LEBT from November 2014 to June 2015. The measurements which focus on beam transmission, beam size and emittance at various locations along the beamline are compared with the beam dynamics code TRACK. These studies were aimed at preparing the beam for optimal operation of the RFQ, while evaluating simulation tools with respect to experimental data.

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TUPOB66

Procedure for the Alignment of the Beam in the Electrical Axes of the Pi-Test RFQ

rfq, alignment, solenoid, emittance

639

J.-P. Carneiro, L.R. Prost, J. Steimel
Fermilab, Batavia, Illinois, USA

The PI-Test Radio-Frequency Quadrupole (RFQ) has been in operation with beam at Fermilab since March 2016. The RFQ accelerates H⁻ beam from 30 keV to 2.1 MeV currently with 20 mus pulses and a maximum current of 10 mA. Once fully conditioned, the RFQ is expected to enable CW operation. Simulations with the beam dynamics code TRACK predict that a misalignment of the beam at the RFQ entrance can possibly deteriorate the transverse and longitudinal emittance at the RFQ exit without necessarily impacting the beam transmission. This paper discusses the procedure developed at Fermilab to align the beam in the electrical axes of the RFQ. Experimental results are shown together with predictions from TRACK.

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WEA1IO02

Computation of Electromagnetic Fields Generated by Relativistic Beams in Complicated Structures

simulation, electromagnetic-fields, vacuum, wakefield

642

I. Zagorodnov
DESY, Hamburg, Germany

We discuss recent developments of numerical methods for computation of wakefields excited by short bunches in accelerators. They include a low-dispersive computational algorithm, conformal approximation of the boundaries, surface conductivity, and indirect wake potential integration. The implementation of these methods in the electromagnetic code ECHO for 2D and 3D problems are presented with a special emphasis on a new ECHO2D code for fast calculations of wakefields in rectangular geometries. Several examples of application of the code to calculation of wakefields for the European Free Electron Laser project and in the Linac Coherent Light Source (LCLS) project are considered.

Slides WEA1IO02 [4.461 MB]

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WEA1CO03

Simulations of Booster Injection Efficiency for the APS-Upgrade

booster, lattice, injection, simulation

647

J.R. Calvey, M. Borland, K.C. Harkay, R.R. Lindberg, C. Yao
ANL, Argonne, Illinois, USA

The APS-Upgrade will require the injector chain to provide high single bunch charge for swap-out injection. One possible limiting factor to achieving this is an observed reduction of injection efficiency into the booster synchrotron at high charge. We have simulated booster injection using the particle tracking code elegant, including a model for the booster impedance and beam loading in the RF cavities. The simulations point to two possible causes for reduced efficiency: energy oscillations leading to losses at high dispersion locations, and a vertical beam size blowup caused by ions in the particle accumulator ring. We also show that the efficiency is much higher in an alternate booster lattice with smaller vertical beta function and zero dispersion in the straight sections.

Slides WEA1CO03 [0.682 MB]

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WEA1CO04

Hollow Electron Beam Collimation for HL-LHC - Effect on the Beam Core

simulation, experiment, emittance, electron

651

M. Fitterer, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
R. Bruce, S. Papadopoulou, G. Papotti, D. Pellegrini, S. Redaelli, D. Valuch, J.F. Wagner
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

Slides WEA1CO04 [1.830 MB]

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WEA1CO05

Microwave Instability Studies in NSLS-II

lattice, simulation, wiggler, electron

655

A. Blednykh, B. Bacha, G. Bassi, Y. Chen-Wiegart, W.X. Cheng, O.V. Chubar, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
The microwave instability in the NSLS-II has been studied for the current configuration of insertion devices, 9 In-Vacuum Undulators (IVU's), 3EPU's, 3 Damping Wigglers. The energy spread as a function of single bunch current has been measured based on the frequency spectrum of IVU for X-Ray Spectroscopy (SRX) beam line. The results for two lattices, bare lattice with nominal energy spread 0.0005 and a lattice with one DW magnet gap closed (nominal energy spread 0.0007) are compared. In addition we used a Spectrum Analyzer to measure the beam spectrum. The instability thresholds for two different lattices cross-checked numerically using the particle tracking code SPACE and longitudinal impedance.

Slides WEA1CO05 [2.380 MB]

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WEB1CO02

Investigation of Structural Development in the Two-Step Diffusion Coating of Nb3Sn on Niobium

niobium, SRF, experiment, cavity

659

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA

Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475.
The potential for higher operating temperatures and increased accelerating gradient has attracted SRF researchers to Nb3Sn coatings on niobium for nearly 50 years. The two-step tin vapor diffusion: nucleation followed by deposition appears to be a promising technique to prepare Nb3Sn coatings on interior cavity surface. We have undertaken a fundamental materials study of the nucleation and deposition steps. Nucleation was accomplished within parameter ranges: 300 - 500 °C, 1 - 5 hrs duration, 5 mg - 1 g SnCl2 and 1 g Sn. The resulting deposit consists of (< 10%) coverage of tin particles, as determined by SEM/EDS, while XPS and SAM discovered extra tin film between these particles. Preliminary results by EBSD show no evident effect of substrate crystallography on the crystallography of the final coating. Substantial topography was found to develop during the coating growth.

Slides WEB1CO02 [3.299 MB]

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WEB1CO03

Surface Impurity Content Optimization to Maximize Q-factors of Superconducting Resonators

cavity, SRF, factory, niobium

663

M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA
M. Checchin
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of trapped flux, depends on the mean free path. A systematic study of a variety of 1.3 GHz cavities with different surface treatments (EP, 120 ^°C bake and different N-doping) is carried out. A bell shaped trend appears for the range of mean free path studied. Over-doped cavities fall at the maximum of this curve defining the largest values of sensitivity. In addition, we have studied the trend of the BCS surface resistance contribution as a function of mean free path, showing that N-doped cavities follow close to the theoretical minimum. Adding these results together we show that the 2/6 N-doping treatment gives the highest Q-factor values at 2 K and 16 MV/m, as long as the magnetic field fully trapped during the cavity cooldown is lower than 10 mG.

Slides WEB1CO03 [4.500 MB]

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WEA2IO01

Calculating Spin Lifetime

resonance, polarization, lattice, synchrotron

667

V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy under contract number DE-SC0012704.
We have extended a lattice independent code to integrate the Thomas-BMT equation over 2 hours of beam time in the presence of two orthogonal Siberian snakes. In tandem to this we have recast the Thomas-BMT equation in the presences of longitudinal dynamics, into the parametric resonance formalism recently developed to understand overlapping spin resonances *
* V. H. Ranjbar, "Approximations for crossing two nearby spin
resonances," Phys. Rev. ST Accel. Beams 18, no. 1, 014001
(2015). doi:10.1103/PhysRevSTAB.18.014001

Slides WEA2IO01 [2.252 MB]

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WEA2CO03

Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA

simulation, electron, dipole, positron

672

S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538.
We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Complementary data with an electron beam were obtained to distinguish EC effects from other sources of tune shifts and emittance growth. High resolution electric field maps are computed with EC buildup simulation codes (ECLOUD) in the small region around the beam as the bunch passes through the cloud. These time-sliced field maps are input to a tracking simulation based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong). Tracking through the full lattice over multiple radiation damping times with electron cloud elements in the dipole and field-free regions predict vertical emittance growth, and tune shifts in agreement with the measurements.

Slides WEA2CO03 [1.227 MB]

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WEA2CO04

Vlasov Analysis of Microbunching Gain for Magnetized Beams

bunching, electron, simulation, radiation

675

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
Y.S. Derbenev, D. Douglas, R. Li, C. Tennant
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE- AC05-06OR23177.
For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring* for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design.
*Ya. Derbenev and Y. Zhang, COOL'09 (FRM2MCCO01)

Slides WEA2CO04 [4.662 MB]

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WEB2IO02

Compact Crabbing Cavity Systems for Particle Colliders

cavity, HOM, dipole, collider

679

S.U. De Silva
ODU, Norfolk, Virginia, USA

In circular or ring-based particle colliders, crabbing cavities are used to increase the luminosity. The first superconducting crabbing cavity system was successfully implemented at KEKB electron-positron collider that have demonstrated the luminosity increase with overlapping bunches. Crabbing systems are an essential component in the future colliders with intense beams, such as the LHC high luminosity upgrade and proposed electron-ion colliders. Novel compact superconducting cavity designs with improved rf properties, at low operating frequencies have been prototyped successfully that can deliver high operating voltages. We present single cavity and multi-cell crabbing cavities proposed for future particle colliders and addresses the challenges in those cavity systems.

Slides WEB2IO02 [13.985 MB]

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WEPOA01

Effect of Proton Bunch Parameter Variation on AWAKE

wakefield, injection, plasma, electron

684

N. Savard
University of Victoria, Victoria BC, Canada
P. Muggli
MPI, Muenchen, Germany
J. Vieira
IPFN, Lisbon, Portugal

In AWAKE, long proton bunches propagate through a plasma, generating wakefields through the self-modulation instability (SMI). The phase velocity of these wakefields changes during the first 4 m of propagation and growth of the SMI, after which it stabilizes at the proton bunch velocity. This means that the ideal injection point for electrons to be accelerated is after 4 m into the plasma. Using the PIC code OSIRIS, we study how small changes in the initial proton bunch parameters (such as charge, radial and longitudinal bunch length, etc) to be expected in the experiment affect the phase velocity of the wakefields, primarily by looking at the difference in the phase of the wakefields at the point of injection (along the bunch and along the plasma) when changing these parameters by a small amount (±5%). We also look for the region of optimal acceleration/focusing for electron injection. Ultimately, it is found that small changes in the initial proton bunch parameters are not expected to significantly impact electron injection experiments in the future.

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WEPOA02

Progress Toward an Experiment at AWAKE*

laser, plasma, diagnostics, experiment

687

P. Muggli
MPI, Muenchen, Germany

The AWAKE experimental program is scheduled to start at the end of 2016. The aim of the first experiments is to detect and study the self-modulation instability (SMI) of the long proton bunch ~12cm in a plasma with wakefields of period of ~1.2mm. The occurrence of SMI results in the formation of a charge core surrounded by a halo in the time-integrated images of the proton bunch transverse profile. Transverse profiles are obtained from scintillator screens and from optical transition radiation (OTR). The OTR is time resolved using a ps-resolution streak camera to determine the start of the wakefields along the bunch on a slow time scale (~ns), i.e., the location of the seeding of the SMI generated by the ionizing laser pulse. The modulation period is measured using the faster time scale (~ps). Coherent transition radiation (CTR) is analyzed by a heterodyne system to also yield the modulation frequency. Later experiments will sample the wakefields generated by externally injecting low-energy (~15MeV) electrons expected to be accelerated to the GeV energy level over the 10m-long plasma. Progress toward the completion of the experimental set-up will be presented.
*for the AWAKE Collaboration

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WEPOA03

Synchrotron Oscillation Derived From Three Components Hamiltonian

synchrotron, betatron, heavy-ion, closed-orbit

690

K. Jimbo
Kyoto University, Kyoto, Japan
H. Souda
Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan

The Hamiltonian, which was composed of coasting, synchrotron and betatron motions, clarified the synchro-betatron resonant coupling mechanism in a storage ring*. The equation for the synchrotron motion was also obtained from the Hamiltonian. It shows that the so-called synchrotron oscillation is an oscillation around the revolution frequency as well as of the kinetic energy of the on-momentum particle. The detectable synchrotron oscillation is a horizontal oscillation on the laboratory frame.
*K.Jimbo, Physical Review Special Topics - Accelerator and Beams 19, 010102 (2016).

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WEPOA04

Design of Front End for RF Synchronized Short Pulse Laser Ion Source

laser, rfq, ion-source, plasma

693

Y. Fuwa, Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan

A short pulse laser ion source is under development. In this ion source, ions are produced by femto-second laser in RF electric field and produced ion bunch with a few nanosecond pulse length. This feature can eliminate bunching section of RFQ and beam can be accelerated from the first cell of RFQ. In this presentation, results of design study for the RFQ without bunching section will be presented.

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WEPOA05

EBIS Charge Breeder for RAON Facility

electron, vacuum, gun, ISOL

696

S.A. Kondrashev, J.-W. Kim, Y.K. Kwon, Y.H. Park, H.J. Son
IBS, Daejeon, Republic of Korea

New large scale accelerator facility called RAON is under design in Institute for Basic Science (IBS, Daejeon, Korea). Both technics of rare isotope production Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) will be combined within one facility for the first time to provide wide variety of rare isotope ion beams for nuclear physics experiments and applied research. Electron Beam Ion Source (EBIS) charge breeder will be used to prepare rare isotope ion beams produced by ISOL method for efficient acceleration. Beams of different rare isotopes will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ 1/4 and accelerated by linac post-accelerator to energies of 18.5 MeV/u. RAON EBIS charge breeder will provide the next step in the development of breeder technology by implementation of electron beam with current up to 3 A and utilization of wide (8') warm bore of 6 T superconducting solenoid. The design of RAON EBIS charge breeder and results of dumping of high power DC and pulsed electron beam into collector will be presented and discussed.

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WEPOA06

New Coolers for Ion Ion Colliders

electron, collider, gun, proton

700

V.V. Parkhomchuk
BINP SB RAS, Novosibirsk, Russia

For crucial contributions in the proof of principle of electron cooling, for leading contribution to the experimental and theoretical development of electron cooling, and for achievement of the planned parameters of coolers for facilities in laboratories around the world the 2016 "Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators" was awarded to Vasili Parkhomchuk. In this paper new future coolers for ion*ion collider will be discussed.

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WEPOA07

Neutrons and Photons Fluences in the DTL Section of the ESS Linac

DTL, linac, proton, neutron

703

L. Lari, R. Bevilacqua, R. Miyamoto, C. Pierre, L. Tchelidze
ESS, Lund, Sweden
F. Cerutti, L.S. Esposito, L. Lari, A. Mereghetti
CERN, Geneva, Switzerland
L.S. Esposito
ADAM SA, Geneva, Switzerland

The last section of the normal conducting front end of the ESS accelerator is composed by a train of 5 DTL tanks. They accelerate the proton beam from 3.6 until 90 MeV. The evaluation of the radiation field around these beam elements gives a valuable piece of information to define the layout of the electronic devices to be installed in the surrounding tunnel area. Indeed the risk of SEE and long term damage has to be considered in order to max-imize the performance of the ESS accelerator and to avoid possible long down time. A conservative loss distribution is assumed and FLUKA results in term of neutrons and photon fluence are presented.

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WEPOA09

Proton Beam Defocusing as a Result of Self-Modulation in Plasma

proton, plasma, wakefield, focusing

707

M. Turner, E. Gschwendtner, A.V. Petrenko
CERN, Geneva, Switzerland
K.V. Lotov, A. Sosedkin
Budker INP & NSU, Novosibirsk, Russia

Funding: CERN
The AWAKE experiment will use a 400 GeV/c proton beam with a longitudinal bunch length of sigmq_z = 12 cm to create and sustain GV/m plasma wakefields over 10 meters. A 12 cm long bunch can only drive strong wakefields in a plasma with n_pe = 7 x 10¹⁴ electrons/cm³ after the self-modulation instability (SMI) developed and microbunches formed, spaced at the plasma wavelength. The fields present during SMI focus and defocus the protons in the transverse plane. We show that by inserting two imaging screens downstream the plasma, we can measure the maximum defocusing angle of the defocused protons for plasma densities above n_pe = 5 x10¹⁴ electrons/cm³. Measuring maximum defocusing angles around 1 mrad indirectly proves that SMI developed successfully and that GV/m plasma wakefields were created. In this paper we present numerical studies on how and when the wakefields defocus protons in plasma, the expected measurement results of the two screen diagnostics and the physics we can deduce from it.

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WEPOA11

Frequency Manipulation of Half-Wave Resonators During Fabrication and Processing

cavity, cryomodule, target, linac

710

Z.A. Conway, R.L. Fischer, C.S. Hopper, M. Kedzie, M.P. Kelly, S.H. Kim, P.N. Ostroumov, T. Reid
ANL, Argonne, Illinois, USA
V.A. Lebedev, A. Lunin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and High-Energy Physics, under Contract No. DE-AC02-76-CH03000 and DE-AC02-06CH11357.
Argonne National Laboratory is developing a super-conducting resonator cryomodule for the acceleration of 2 mA H⁻ beams from 2.1 to 10.3 MeV for Fermi National Accelerator Laboratory's Proton Improvement Plan II. The cryomodule contains 8 superconducting half-wave resonators operating at 162.500 MHz with a 120 kHz tuning window. This paper reviews the half-wave resonator fabrication techniques used to manipulate the resonant frequency to the design goal of 162.500 MHz at 2.0 K. This also determines the target frequency at select stages of resonator construction, which will be discussed and supported by measurements.
This research used resources of ANL's ATLAS facility, which is a DOE Office of Science User Facility.

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WEPOA12

Interleaving Lattice Design for APS Linac

lattice, linac, electron, gun

713

S. Shin, Y. Sun, A. Zholents
ANL, Argonne, Illinois, USA

In order to realize and test advanced accelerator concepts and hardware, the existing beamline with both old and new components are being reconfigured in Linac Extension Area (LEA) of APS linac. Photo injector, which had been installed in the beginning of APS linac, will provide low emittance electron beam into the LEA. The thermionic RF gun beam for storage ring and photo-cathode RF gun beam for LEA will be operated though the LINAC in an interleaved fashion. In this presentation, technical issues as well as beam dynamics on the design for interleaving operation will be described.

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WEPOA13

RF Design and Simulation of a Non-Periodic Lattice Photonic Band Gap (PBG) Accelerating Structure

lattice, cavity, photon, wakefield

716

N. Zhou, A. Nassiri
ANL, Argonne, Illinois, USA

Photonic Band Gap (PBG) structures (metallic and or dielectric) have been proposed for accelerators. These structures act like a filter, allowing RF field at some frequencies to be transmitted through, while rejecting RF fields in some (unwanted) frequency range. Additionally PBG structures are used to support selective field patterns (modes) in a resonator or waveguide. In this paper, we will report on the RF design and simulation results of an X-band PBG structure, including lattice optimization, to improve RF performance.

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WEPOA14

Resistive Wall Growth Rate Measurements in the Fermilab Recycler

impedance, cavity, operation, injection

719

R. Ainsworth, P. Adamson, A.V. Burov, I. Kourbanis
Fermilab, Batavia, Illinois, USA

Impedance could represent a limitation of running high intensity beams in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this, studies have been performed measuring the growth rate of presumably the resistive wall instability. The growth rates at varying intensities and chromaticities are shown. The measured growth rates are compared to ones calculated with the resistive wall impedance.

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WEPOA15

Installation Progress at the PIP-II Injector Test at Fermilab

rfq, controls, MMI, linac

722

C.M. Baffes, M.L. Alvarez, R. Andrews, A.Z. Chen, J. Czajkowski, P. Derwent, J.P. Edelen, B.M. Hanna, B.D. Hartsell, K.R. Kendziora, D.V. Mitchell, L.R. Prost, V.E. Scarpine, A.V. Shemyakin, J. Steimel, T.J. Zuchnik
Fermilab, Batavia, Illinois, USA
A.L. Edelen
CSU, Fort Collins, Colorado, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
A CW-compatible, pulsed H⁻ superconducting linac 'PIP-II' is being planned to upgrade Fermilab's injection complex. To validate the concept of the front-end of such a machine, a test accelerator (The PIP-II Injector Test, formerly known as "PXIE") is under construction. The warm part of this accelerator comprises a 10 mA DC 30 keV H⁻ ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, and a 10-m long MEBT that is capable of creating a large variety of bunch structures. The paper will report on the installation of the RFQ and the first sections of the MEBT and related mechanical design considerations.

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WEPOA16

Fermilab Recycler Collimation System Design

collimation, proton, operation, radiation

726

B.C. Brown, P. Adamson, R. Ainsworth, D. Capista, K.J. Hazelwood, I. Kourbanis, N.V. Mokhov, D.K. Morris, M.J. Murphy, V.I. Sidorov, E.G. Stern, I.S. Tropin, M.-J. Yang
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
To provide 700 kW proton beams for neutrino production in the NuMI facility, we employ slip stacking in the Recycler with transfer to the Main Injector for recapture and acceleration. Slip stacking with 12 Booster batches per 1.33 sec cycle of the Main Injector has been implemented and extensive operation with 8 batches and 10 batches per MI cycle has been demonstrated. Operation in this mode since 2013 shows that loss localization is an essential component for long term operation. Beam loss in the Recycler will be localized in a collimation region with design capability for absorbing up to 2 kW of lost protons in a pair of 20-Ton collimators (absorbers). This system will employ a two stage collimation with a thin Mo scattering foil to define the bottom edge of both the injected and decelerated-for-slipping beams. Optimization and engineering design of the collimator components and radiation shielding are based on comprehensive MARS15 simulations predicting high collimation efficiency as well as tolerable levels of prompt and residual radiation. The system installation during the Fermilab 2016 facility shutdown will permit commissioning in the subsequent operating period.

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WEPOA17

On the Possibility of Using Nonlinear Elements for Landau Damping in High-Intensity Beams

octupole, insertion, optics, electron

729

E. Gianfelice-Wendt, Y.I. Alexahin, V.A. Lebedev, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
Direct space-charge force shifts the incoherent tunes down from the coherent ones switching off Landau damping of coherent oscillations at high beam intensity. To restore it the nonlinear elements can be employed which move back tunes of large amplitude particles. In the present report we consider the possibility of creating a "nonlinear integrable optics" insertion in the Fermilab Recycler to host either octupoles or hollow electron lens for this purpose. For comparison we also consider the classic scheme with distributed octupole families. It is shown that for the Proton Improvement Plan II parameters the required nonlinear tuneshift can be created without destroying the dynamic aperture.

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WEPOA18

Experimental Studies of Beam Collimation System in the Fermilab Booster

booster, collimation, proton, radiation

732

V.V. Kapin, S. Chaurize, N.V. Mokhov, W. Pellico, M. Slabaugh, T. Sullivan, R. Tesarek, A.K. Triplett
Fermilab, Batavia, Illinois, USA

A two-stage collimation (2SC) system was installed in Fermilab Booster around 2004 and consists of 2 primary collimators (PrC), one for each of the horizontal and vertical planes and 3 secondary collimators (SC) each capable of acting in both planes. Presently, only SC are used as the single-stage collimation (1SC). Part of the Fermilab Proton Improvement Plan (PIP) includes a task to test 2SC for Booster operations. In this paper we describe preparatory steps to fix SC motion issues and installation of a 380μm thick aluminum foil PrC and post-processing software for beam orbit and beam loss measurements. The initial experimental results for 2SC in the vertical plane are also presented. The tuning of 2SC system was performed using fast loss monitors allowing much higher time-resolution than existing BLMs. Analysis of losses and beam transmission efficiency allow for the comparison of 1SC and 2SC schemes.

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WEPOA20

Numerical Simulations of Collimation Efficiency for Beam Collimation System in the Fermilab Booster

proton, booster, collimation, simulation

735

V.V. Kapin, V.A. Lebedev, N.V. Mokhov, S.I. Striganov, I.S. Tropin
Fermilab, Batavia, Illinois, USA

A two-stage beam collimation (2SC) system has been installed in the Fermilab Booster more than 10 years ago. It consists of two primary collimators (horizontal and vertical) and three 1.2m-long secondary collimators. The two-stage collimation has never been used in Booster operations due to uncontrolled beam orbit variations produced by radial cogging (it is required for beam accumulation in Recycler). Instead, only secondary collimators were used in the single-stage collimation (1SC). Recently introduced magnetic cogging resulted in orbit stabilization in the course of almost entire accelerating cycle and created a possibility for the 2SC. In this paper, the 2SC performance is evaluated and compared the 1SC. Several parameters characterizing collimation efficiency are calculated in order to compare both schemes. A combination of the MADX and MARS15 codes is used for proton tracking in the Booster with their scattering in collimators being accounted. The dependence of efficiency on the primary collimators foil thickness is presented. The efficiency dependence on the proton energy is also obtained for the optimal foil. The feasibility of the 2SC scheme for the Booster is discussed.

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WEPOA22

nuPIL - Neutrinos from a PIon Beam Line

lattice, optics, proton, detector

739

A. Liu, A.D. Bross
Fermilab, Batavia, Illinois, USA
J.-B. Lagrange
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The Fermilab Deep Underground Neutrino Experiment (DUNE) was proposed to determine the neutrino mass hierarchy and demonstrate leptonic CP violation. The current design of the facility that produces the neutrino beam (LBNF) uses magnetic horns to collect pions and a decay pipe to allow them to decay. In this paper, a design of a possible alternative for the conventional neutrino beam in LBNF is presented. In this design, an FFAG magnet beam line is used to collect the pions from the downstream face of a horn, bend them by ∼ 5.8 degrees and then transport them in either a LBNF-like decay pipe, or a straight FODO beam line where they decay to produce neutrinos. Using neutrinos from this PIon beam Line (nuPIL) provides flavor-pure neutrino beams that can be well understood by implementing standard beam measurement technology. The neutrino flux and the resulting δ_CP sensitivity from the current version of nuPIL design are also presented in the paper.

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WEPOA24

Installation and Commissioning of an Ultrafast Electron Diffraction Facility as Part of the ATF-II Upgrade

operation, experiment, MMI, electron

742

M.A. Palmer, M. Babzien, M.G. Fedurin, C. Folz, M. Fulkerson, K. Kusche, J.J. Li, R. Malone, T.V. Shaftan, J. Skaritka, L. Snydstrup, C. Swinson, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: This work was funded by the US Department of Energy under contract DE-SC0012704.
The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is presently carrying out an upgrade, ATF-II, which will provide significantly expanded experimental space and capabilities for its users. One of the new capabilities being integrated into the ATF-II program is an Ultrafast Electron Diffraction (UED) beam line, which was originally deployed in the BNL Source Development Laboratory. Inclusion of the UED in the ATF-II research portfolio will enable ongoing development and extension of the UED capabilities for use in materials research. We discuss the design, installation and commissioning of the UED beam line at ATF-II as well as plans for future upgrades.

Poster WEPOA24 [18.332 MB]

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WEPOA25

Fermilab Accelerator R&D Program Towards Intensity Frontier Accelerators: Status and Progress

proton, target, radiation, cavity

745

V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Fermilab actively carries out broad R&D program toward future Intensity Frontier accelerators which includes novel beam physics approaches tests in IOTA ring at FAST, research on cost-effective SRF and development of multi-MW beam targets. This presentation gives a high level overview of the program, motivation, status and progress.

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WEPOA26

Fermilab Muon Campus as a Potential Probe to Study Neutrino Physics

detector, experiment, target, simulation

749

D. Stratakis, Z. Pavlovic
Fermilab, Batavia, Illinois, USA
J.M. Grange
ANL, Argonne, Illinois, USA
S-C. Kim
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Miceli
Stony Brook University, Stony Brook, USA
J.A. Zennamo
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
In the next decade the Fermilab Muon Campus will host two world class experiments dedicated to the search for signals of new physics. The Muon g-2 experiment will determine with unprecedented precision the anomalous magnetic moment of the muon. The Mu2e experiment will improve by four orders of magnitude the sensitivity on the search for the as-yet unobserved Charged Lepton Flavor Violation process of a neutrinoless conversion of a muon to an electron. In this paper, we will discuss the possibility for extending the Muon Campus capabilities for neutrino research. With the aid of numerical simulations, we estimate the number of produced neutrinos at various locations along the beamlines as well along the Small Baseline Neutrino Detector which faces one of the straight sections of the delivery ring. Finally, we discuss diagnostics required for realistic implementation of the experiment.

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WEPOA28

A Recirculating Proton Linac Design

linac, cavity, proton, space-charge

752

K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

The acceleration efficiency of the recirculating RF linac was demonstrated by operating electron machines. The acceleration concept of recirculating proton beam was recently proposed and is currently under study. In this paper, we present a 6D lattice design and beam dynamics tracking for a two-pass recirculating proton linac from 150 MeV to 500 MeV, which is the first section of the three acceleration steps proposed earlier. Issues covered are optimization of simultaneous focusing of two beams passing the same structure and achromatic condition under space-charge potential.

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WEPOA29

Recent Experiments at NDCX-II: Irradiation of Materials Using Short, Intense Ion Beams

experiment, target, plasma, focusing

755

P.A. Seidl, E. Feinberg, Q. Ji, B.A. Ludewigt, A. Persaud, T. Schenkel, M. Silverman, A.A. Sulyman, W.L. Waldron
LBNL, Berkeley, California, USA
J.J. Barnard, A. Friedman, D.P. Grote
LLNL, Livermore, California, USA
E.P. Gilson, I. Kaganovich, A.D. Stepanov
PPPL, Princeton, New Jersey, USA
F. Treffert, M. Zimmer
TU Darmstadt, Darmstadt, Germany

Funding: This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0205CH11231 (LBNL), DE-AC52- 07NA27344 (LLNL) and DE-AC02-09CH11466 (PPPL).
We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and summarize recent studies of material properties created with nanosecond and millimeter-scale ion beam pulses. The scientific topics being explored include the dynamics of ion induced damage in materials, materials synthesis far from equilibrium, warm dense matter and intense beam-plasma physics. We summarize the improved accelerator performance, diagnostics and results of beam-induced irradiation of thin samples of, e.g., tin and silicon. Bunches with over 3x10¹⁰ ions, 1-mm radius, and 2-30 ns FWHM duration have been created. To achieve these short pulse durations and mm-scale focal spot radii, the 1.2 MeV He⁺ ion beam is neutralized in a drift compression section which removes the space charge defocusing effect during final compression and focusing. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing accelerator performance; these keep pace with the accelerator repetition rate of ~1/minute.

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WEPOA30

High-Performance Modeling of Plasma-Based Acceleration and Laser-Plasma Interactions.

plasma, simulation, laser, GPU

758

J.-L. Vay, G. Blaclard, R. Lehé, M. Lobet, H. Vincenti
LBNL, Berkeley, California, USA
B.B. Godfrey
UMD, College Park, Maryland, USA
M. Kirchen
University of Hamburg, Hamburg, Germany
P. Lee
CNRS LPGP Univ Paris Sud, Orsay, France

Funding: Work supported by US-DOE Contracts DE-AC02-05CH11231 and by the European Commission through the Marie Slowdoska-Curie actions. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
Large-scale numerical simulations are essential to the design of plasma-based accelerators and laser-plasma interations for ultra-high intensity (UHI) physics. The electromagnetic Particle-In-Cell (PIC) approach is the method of choice for self-consistent simulations, as it is based on first principles, and captures all kinetic effects, and also scales easily (for uniform plasmas) to many cores on supercomputers. The standard PIC algorithm relies on second-order finite-difference discretizations of the Maxwell and Newton-Lorentz equations. We present here novel PIC formulations, based on the use of very high-order pseudo-spectral Maxwell solvers, which enable near-total elimination of the numerical Cherenkov instability and increased accuracy over the standard PIC method. We also discuss the latest implementations in the PIC modules Warp-PICSAR and FBPIC on the Intel Xeon Phi and GPU architectures. Examples of applications are summarized on the simulation of laser-plasma accelerators and high-harmonic generation with plasma mirrors.

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WEPOA33

Novel Metallic Structures for Wakefield Acceleration

wakefield, cavity, acceleration, electron

762

X.Y. Lu, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: US DOE, Office of High Energy Physics
Three novel ideas for wakefield acceleration (WFA) of electrons with metallic periodic subwavelength structures will be presented. The first idea is a deep corrugation structure for collinear WFA. A design for the Argonne Wakefield Accelerator is shown. An analytical model is developed and it agrees with the CST wakefield solver. A scaling study has been performed, and ways to increase the gradient will be discussed. The deep corrugation structure can generate a higher gradient than a dielectric tube with the same beam aperture when excited by the same bunch. The second idea is an elliptical structure for two-beam acceleration (TBA). The unit cell is an elliptical cavity, and the drive beam hole and the witness beam hole are located around the two focal points. The TBA process has been calculated and will be presented. The third idea is a metamaterial ‘wagon wheel' structure for a power extractor design. The fundamental mode is a TM mode with a negative group velocity. A power extractor at 11.7 GHz based on the structure can reach a GW power level when a train of 40 nC bunches with 1.3 GHz rep rate are sent in.

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WEPOA34

Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices

plasma, simulation, emittance, scattering

765

J.S. Ellison
IIT, Chicago, Illinois, USA
P. Snopok
Fermilab, Batavia, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: Work supported by the U.S. Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.

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WEPOA35

Wedge Absorbers for Muon Cooling with a Test Beam at MICE

emittance, collider, experiment, simulation

768

D.V. Neuffer
Fermilab, Batavia, Illinois, USA
J.G. Acosta, D.J. Summers
UMiss, University, Mississippi, USA
T.A. Mohayai
IIT, Chicago, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359
Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented.

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WEPOA36

Simulated Measurements of Beam Cooling in Muon Ionization Cooling Experiment

emittance, solenoid, experiment, lattice

771

T.A. Mohayai
IIT, Chicago, Illinois, USA
D.V. Neuffer, D.V. Neuffer, P. Snopok
Fermilab, Batavia, Illinois, USA
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Science Graduate Student Research (SCGSR) under contract No. DE-AC05-06OR23100.
Cooled muon beams are essential to enable future Neutrino Factory and Muon Collider facilities. The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate muon beam cooling through ionization energy loss in material. A figure of merit for muon beam cooling in MICE is the transverse root-mean-square (RMS) emittance reduction and to measure this, the individual muon positions and momenta are reconstructed using two scintillating-fiber tracking detectors housed in spectrometer solenoid modules. The reconstructed positions and momenta before and after a low-Z absorbing material are then used for constructing the covariance matrix and measuring normalized transverse RMS emittance of MICE muon beam. However, RMS emittance is sensitive to nonlinear effects in beam optics. In this study, the direct measurement of phase-space density as an alternative approach to measuring the muon beam cooling using the novel Kernel Density Estimation (KDE) method, is described.

Poster WEPOA36 [1.855 MB]

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WEPOA37

Hybrid Methods for Simulation of Muon Ionization Cooling Channels

simulation, scattering, collider, experiment

775

J.D. Kunz, P. Snopok
IIT, Chicago, Illinois, USA
M. Berz
MSU, East Lansing, Michigan, USA
J.D. Kunz
Anderson University, Anderson, USA
P. Snopok
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. Department of Energy
COSY Infinity is an arbitrary-order beam dynamics simulation and analysis code. It uses high-order transfer maps of combinations of particle optical elements of arbitrary field configurations. New features have been developed and implemented in COSY to follow charged particles through matter. To study in detail the properties of muons passing through a material, the transfer map approach alone is not sufficient. The interplay of beam optics and atomic processes must be studied by a hybrid transfer map–Monte Carlo approach in which transfer map methods describe the average behavior of the particles including energy loss, and Monte Carlo methods are used to provide small corrections to the predictions of the transfer map, accounting for the stochastic nature of scattering and straggling of particles. This way the vast majority of the dynamics is represented by fast application of the high-order transfer map of an entire element and accumulated stochastic effects. The gains in speed simplify the optimization of muon cooling channels which are usually very computationally demanding. Progress on the development of the required algorithms is reported.

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WEPOA38

Optically Based Diagnostics for Optical Stochastic Cooling

pick-up, kicker, undulator, radiation

779

M.B. Andorf
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

An Optical Stochastic Cooling (OSC) experiment with electrons is planned in the Integrable Optics Test Accelerator (IOTA) ring currently in construction at Fermilab. OSC requires timing the arrival of an electron and its radiation generated from the upstream pickup undulator into the downstream kicker undulator to a precision on the order of less than a fs. The interference of the pickup and kicker radiation suggests a way to diagnose the arrival time to the required precision.

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WEPOA39

Theoretical and Numerical Study on Plasmon-Assisted Channeling Interactions in Nanostructures

laser, plasma, target, acceleration

782

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC.
A plasmon-assisted channeling acceleration can be realized with a large channel possibly in a nanometer scale. Carbon nanotubes are the most typical example of nano-channels that can confine a large amount of channeled particles and confined plasmon in a coupling condition. This paper presents theoretical and numerical study on the concept of the laser-driven surface-plasmon (SP) acceleration in a carbon nanotube (CNT) channel. Analytic description of the SP-assisted laser acceleration is detailed with practical acceleration parameters, in particular with specifications of a typical tabletop femto-second laser system. The maximally achievable acceleration gradients and energy gains within dephasing lengths and CNT lengths are discussed with respect to laser-incident angles and CNT-filling ratios.

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WEPOA40

Construction Status of a RF-Injector with a CNT-Tip Cathode for High Brightness Field-Emission Tests

cathode, electron, gun, emittance

785

Y.-M. Shin, G. Fagerberg, M. Figora
Northern Illinois University, DeKalb, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA

We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed Sband klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 microsecond pulse length and 1 Hz repetition rate. A single-cell RFgun is designed to produce with 0.5 - 1 pC electron bunches in a photo-emission mode within a 50 fs - 3 ps at 0.5- 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOAjitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.

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WEPOA42

RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source

cathode, gun, electron, simulation

789

N. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.

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WEPOA43

Simulations of High Current Magnetic Horn Striplines at Fermilab

simulation, site, experiment, proton

792

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
J. Hylen, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Both the NuMI (Neutrinos and the Main Injector) beam line, that has been providing intense neutrino beams for several Fermilab experiments (MINOS, MINERVA, NOVA), and the newly proposed LBNF (Long Baseline Neutrino Facility) beam line, which plans to produce the highest power neutrino beam in the world for DUNE (the Deep Underground Neutrino Experiment), need pulsed magnetic horns to focus the mesons that decay to produce the neutrinos. The high-current horn and stripline design has been evolving as NuMI reconfigures for higher beam power and to meet the needs of the future LBNF program. We evaluated the two existing high-current striplines for NuMI and NOvA at Fermilab by producing Electromagnetic simulations of the magnetic horns and the required high-current striplines. In this paper, we present the comparison of these two designs using the ANSYS Electric and ANSYS Maxwell 3D codes with special attention on the critical stress points. These results are being used to support the development of evolving horn stripline designs to handle increased electrical current and higher beam power for NuMI upgrades and for the LBNF experiment.

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WEPOA44

Accleration System of Beam Brightness Booster

space-charge, brightness, proton, electron

796

V.G. Dudnikov
Muons, Inc, Illinois, USA
A.V. Dudnikov
BINP SB RAS, Novosibirsk, Russia

The brightness and intensity of a circulating proton beam now can be increased up to space charge limit by means of charge exchange injection or by an electron cooling but cannot be increased above this limit. Significantly higher brightness can be produced by means of the charge exchange injection with the space charge compensation [1]. The brightness of the space charge compensated beam is limited at low level by development of the electron-proton (e-p) instability [2]. Fortunately, e-p instability can be self-stabilized at a high beam density. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. Accelerating system with a space charge compensation is proposed and described. The superintense beam production can be simplified by developing of nonlinear nearly integrable focusing system with broad spread of betatron tune and the broadband feedback system for e-p instability suppression .
[1] V. Dudnikov, in Proceedings of the Particle Accelerator Conference, Chicago, 2001..
[2] G. Budker, et al., Sov. Atomic Energy 22, 384 (1967);

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WEPOA45

Positive and Negative Ions Radio Frequency Sources with Solenoidal Magnetic Field

plasma, solenoid, ion-source, electron

799

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Illinois, USA
G. Dudnikova
ICT SB RAS, Novosibirsk, Russia
B. Han, S. Murrey, C. Stinson
ORNL RAD, Oak Ridge, Tennessee, USA
T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: The work was supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant, DE-SC0011323.
Operation of Radio Frequency surfaces plasma sources (RF SPS) with a solenoidal magnetic field are described. RF SPS with solenoidal and saddle antennas are discussed. Dependences of beam current and extraction current on RF power, gas flow, solenoidal magnetic field and filter magnetic field are presented.

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WEPOA46

The Muon Injection Simulation Study for the Muon g-2 Experiment at Fermilab

kicker, storage-ring, simulation, injection

803

S-C. Kim
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
N.S. Froemming
University of Washington, CENPA, Seattle, USA
D. L. Rubin
Cornell University, Ithaca, New York, USA
D. Stratakis
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
The new experiment, under construction at Fermilab, to measure the muon magnetic moment anomaly, aims to reduce measurement uncertainty by a factor of four to 140 ppb. The required statistics depend on efficient production and delivery of the highly polarized muon beams from production target into the g-2 storage ring at the design "magic"-momentum of 3.094 GeV/c, with minimal pion and proton contamination. We have developed the simulation tools for the muon transport based on G4Beamline and BMAD, from the target station, through the pion decay line and delivery ring and into the storage ring, ending with detection of decay positrons. These simulation tools are being used for the optimization of the various beam line guide field parameters related to the muon capture efficiency, and the evaluation of systematic measurement uncertainties. We describe the details of the model and some key findings of the study.

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WEPOA51

Update on Photonic Band Gap Accelerating Structure Experiment

experiment, wakefield, higher-order-mode, photon

807

J. Upadhyay, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Photonic band gap (PBG) structures have great potential in filtering higher order modes (HOMs) without perturbing the fundamental mode and in suppressing the wakefields. An efficient PBG structure would help a lot in terms of beam quality for high beam current future free-electron lasers (FEL). An improved design of X-band normal conducting PBG accelerating structure with elliptical rods will be presented. A comparison of cavity parameters between cylindrical and elliptical shape rod PBG structures will be shown. This new optimized PBG structure would be fabricated and tested at Argonne Wakefield Accelerator (AWA) test facility. The status of the test will be reported.

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WEPOA52

Modeling and Simulation of RFQs for Analysis of Fields and Frequency Deviations with Respect to Internal Dimensional Errors

rfq, simulation, resonance, operation

810

Y.W. Kang, S.W. Lee
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE.
Performance of radio frequency quadrupole (RFQ) is sensitive to the errors in internal dimensions which shift resonance frequency and distort field distribution on the beam axis along the structure. The SNS RFQ has been retuned three times to compensate the deviations in frequency and field flatness with suspected dimensional changes since the start of the project for continuous operation with H⁻ ion beams. SNS now has a new RFQ as a spare that is installed in beam test facility (BTF), a low energy test accelerator. In order to understand and predict the performance deviation, full 3D modeling and simulation were performed for the SNS RFQs. Field and frequency errors from hypothetical transverse vane perturbations, and vane erosion (and metal deposition such as Cesium introduced by the ion source operation) at the low energy ends are discussed.

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WEPOA54

Simulation of a Skew Parametric Resonance Ionization Cooling Channel

resonance, simulation, cavity, collider

813

Y. Bao
UCR, Riverside, California, USA
A. Afanasev
GWU, Washington, USA
Y.S. Derbenev, V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
R.P. Johnson
Muons, Inc, Illinois, USA

Skew Parametric-resonance Ionization Cooling (Skew-PIC) is designed for the final 6D cooling of a high-luminosity muon collider. Tracking of muons in such a channel has been modeled in MAD-X in previous studies. However, the ionization cooling process has to be simulated with a code that can handle matter dominated beam lines. In this paper we present the simulation of a Skew-PIC channel using G4beamline. We implemented the required magnetic field components into G4beamline and compare the tracking of muons by the two different codes. We optimize the cooling channel and present the muon cooling effect in the Skew-PIC channel for the first time.

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WEPOA55

Modulator Simulations for Coherent Electron Cooling

electron, simulation, quadrupole, plasma

816

J. Ma, X. Wang
SBU, Stony Brook, New York, USA
V. Litvinenko, V. Samulyak, G. Wang, K. Yu
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
V. Samulyak
SUNY SB, Stony Brook, New York, USA

Highly resolved numerical simulations of the modulator, the first section of the proposed coherent electron cooling (CEC) device, have been performed using the code SPACE. The beam parameters for simulations are relevant to the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Numerical convergence has been studied using various numbers of macro-particles and mesh refinements of computational domain. A good agreement of theory and simulations has been obtained for the case of stationary and moving ions in uniform electron clouds with realistic distribution of thermal velocities. The main result of the paper is the prediction of modulation processes for ions with reference and off-reference coordinates in realistic Gaussian electron bunches with quadrupole field.

Poster WEPOA55 [1.510 MB]

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WEPOA56

Design of RFQ Linac to Accelerate High Current Lithium Ion Beam from Laser Ion Source for Compact Neutron Source

neutron, rfq, linac, ion-source

820

S. Ikeda, T. Kanesue, M. Okamura
BNL, Upton, Long Island, New York, USA

Accelerator-driven compact neutron sources have been developed to conduct nondestructive inspection more conveniently and/or on the spot with lower cost than other neutron sources, such as spallation sources and nuclear reactors. In typical compact source, proton or deuteron are injected into Li or Be. To develop a higher flax source than conventional ones, we propose a source with 7Li beam generated by laser ion source using direct injection scheme (DPIS) into RFQ linac. Because of the higher velocity of center of mass than that in the case of proton beam injection, generated neutrons are more collimated. In addition, laser ion source with DPIS is expected to accelerate mA class fully ionized 7Li beam stably with simple setup, while it is difficult for conventional ion sources. The high collimation and high current are expected to lead to higher neutron flax. In this presentation, we present a design of RFQ linac optimized to accelerate such a high current beam with shorter distance.

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WEPOA57

Stabilized Operation Mode of Laser Ion Source Using Pulsed Magnetic Field

laser, ion-source, solenoid, electron

823

S. Ikeda, M.R. Costanzo, T. Kanesue, R.F. Lambiase, C.J. Liaw, M. Okamura
BNL, Upton, Long Island, New York, USA

A laser ion source (LIS) provides several types of singly charged ions into an electron beam ion source (EBIS) followed by linear accelerator injectors for the Relativistic Heavy Ion Collider (RHIC) and the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory. In the present set-up of the LIS, beam current shape varies with time drastically. It is expected that the present current shape is not optimal for the ion trap of the EBIS. However, there are no knobs to modify the shape flexibly. Therefore, as an upgrade of the LIS, we install a coil and a pulsed circuit* that generates a fast-rising pulsed magnetic field to tailor the beam current shape. In this presentation, the effect of the magnetic field on the beam profile from the LIS and the performance of the injectors, such as the transmission and the charge injected into an accelerator downstream, are described.

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WEPOA60

Design Considerations for the Fermilab PIP-II 800 MeV Superconducting Linac

linac, cavity, focusing, operation

826

A. Saini
Fermilab, Batavia, Illinois, USA

Proton Improvement Plan (PIP)-II is a proposed upgrade of existing proton accelerator complex at Fermilab. It is primarily based on construction of a superconducting (SC) linear accelerator (linac) that would be capable to operate in the continuous wave and pulsed modes. It will accelerate 2 mA H⁻ ion beam up to 800 MeV. Among the various technical and beam optics issues associated with high beam power ion linacs, beam mismatch, uncontrolled beam losses, halo formation and potential element's failures are the most critical elements that largely affect performance and reliability of the linac. This paper reviews these issues in the framework of PIP-II SC linac and discusses experience accumulated in the course of this work.

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WEPOA62

The Center for Bright Beams

brightness, electron, cavity, cathode

830

J.R. Patterson, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Y.K. Kim
University of Chicago, Chicago, Illinois, USA

Funding: National Science Foundation award PHY-1549132.
The Center for Bright Beams (CBB) is a new National Science Foundation-supported Science and Technology Center. CBB's research goal is to increase the brightness of electron beams while reducing the cost and size of key technologies. To achieve this, it will augment the capabilities of accelerator physicists with those of physical chemists, materials scientists, condensed matter physicists, plasma physicists, and mathematicians. This approach has the potential to increase the brightness of electron sources through better photocathodes, the efficiency and gradient of SRF cavities through deeper understanding of superconducting compounds and their surfaces, and better understanding of beam storage and transport and the associated optics by using new mathematical techniques.

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WEA3IO01

Emittance Growth from Modulated Focusing in Bunched Beam Cooling

emittance, electron, simulation, betatron

833

M. Blaskiewicz
BNL, Upton, Long Island, New York, USA

The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This is the primary source of heating when the cooling is well tuned. An analytic theory of this process is presented and compared with simulations.

Slides WEA3IO01 [4.160 MB]

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WEA3IO02

Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators

linac, controls, electron, FEL

838

J. Qiang
LBNL, Berkeley, California, USA

State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm*. The most recent developments will be described, together with applications to the modeling of LCLS-II**.
*J. Qiang, et al, http://www.optimization-online.org/DB_FILE/2015/03/4796.pdf, submitted
**J. Qiang, et al, in preparation

Slides WEA3IO02 [10.928 MB]

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WEA3CO04

Impedance Characterization and Collective Effects in the MAX IV 3 GeV Ring

impedance, synchrotron, feedback, experiment

843

G. Skripka, Å. Andersson, P.F. Tavares
MAX IV Laboratory, Lund University, Lund, Sweden
F.J. Cullinan, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

Collective instabilities in the MAX IV 3 GeV storage ring are enhanced by the combination of high beam current, ultralow emittance and small vacuum chamber aperture. To mitigate instabilities by Landau damping and improve lifetime three passive harmonic cavities are installed to introduce synchrotron tune spread and bunch lengthening respectively. We present the results of studies of collective effects driven by the machine impedance. Bunch lengthening and detuning were measured to characterize the effective impedance and estimate the effect of the harmonic cavity potential. Investigations of collective effects as a function of parameters such as beam current and chromaticity are discussed.

Slides WEA3CO04 [3.845 MB]

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WEB3IO01

SRF Devlopment and Cryomodule Production for the FRIB Linac

cavity, cryomodule, linac, SRF

847

T. Xu, H. Ao, B. Bird, N.K. Bultman, E.E. Burkhardt, F. Casagrande, C. Compton, J.L. Crisp, K.D. Davidson, K. Elliott, A. Facco, V. Ganni, A. Ganshyn, P.E. Gibson, W. Hartung, M. Ikegami, P. Knudsen, S.M. Lidia, I.M. Malloch, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, G. Shen, M. Shuptar, S. Stark, J. Wei, J.D. Wenstrom, M. Xu, T. Xu, Y. Xu, Y. Yamazaki, Z. Zheng
FRIB, East Lansing, Michigan, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy
K. Hosoyama
KEK, Ibaraki, Japan
M.P. Kelly
ANL, Argonne, Illinois, USA
R.E. Laxdal
TRIUMF, Vancouver, Canada
M. Wiseman
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy Office of Sci-ence under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams' heavy ion con-tinuous-wave (CW) linac extends superconducting RF to low beam energy of 500 keV/u. 332 low-beta cavities are housed in 48 cryomodules. Technical development of high performance subsystems including resonator, cou-pler, tuner, mechanical damper, solenoid and magnetic shielding is necessary. In 2015, the first innovatively designed FRIB bottom-up prototype cryomodule was tested meeting all FRIB specifications. In 2016, the first full production cryomodule is constructed and tested. The preproduction and production cryomodule procurements and in-house assembly are progressing according to the project plan.

Slides WEB3IO01 [15.765 MB]

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WEB3IO02

First Test Results of the 150 mm Aperture IR Quadrupole Models for the High Luminosity LHC

quadrupole, luminosity, dipole, alignment

853

G. Ambrosio, G. Chlachidze
Fermilab, Batavia, Illinois, USA
P. Ferracin
CERN, Geneva, Switzerland
G.L. Sabbi
LBNL, Berkeley, California, USA
P. Wanderer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP) and by the High Luminosity LHC project at CERN.
The High Luminosity upgrade of the LHC at CERN will use large aperture (150 mm) quadrupole magnets to focus the beams at the interaction points. The high field in the coils requires Nb3Sn superconductor technology, which has been brought to maturity by the LHC Accelerator Research Program (LARP) over the last 10 years. The key design targets for the new IR quadrupoles were established in 2012, and fabrication of model magnets started in 2014. This paper discusses the results from the first single short coil test and from the first short quadrupole model test. Remaining challenges and plans to address them are also presented and discussed.

Slides WEB3IO02 [15.312 MB]

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WEB3CO03

650 MHz Elliptical Superconducting RF Cavities for PIP-II Project

cavity, SRF, linac, simulation

859

V. Jain, E. Borissov, I.V. Gonin, C.J. Grimm, S. Kazakov, T.N. Khabiboulline, V.A. Lebedev, C.S. Mishra, D.V. Mitchell, T.H. Nicol, Y.M. Pischalnikov, A.M. Rowe, N.K. Sharma, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Proton Improvement Plan-II at Fermilab is an 800 MeV superconducting pulsed linac which is also capable of running in CW mode. The high energy section operates from 185 MeV to 800 MeV instigated using 650 MHz elliptical cavities. The low-beta (LB) βG =0.61 portion will accelerate protons from 185 MeV-500 MeV, while the high-beta (HB) βG = 0.92 portion of the linac will acceler-ate from 500 to 800 MeV. The development of both LB and HB cavities is taking place under the umbrella of the Indian Institutions Fermilab Collaboration (IIFC). This paper presents the design methodology adopted for both low-beta and high-beta cavities starting from the RF design yielding mechanical dimensions of the cavity cells and, then moving to the workable dressed cavity design. Designs of end groups (main coupler side and field probe side), helium vessel, coupler, and tuner are the same for both cavities everywhere where it is possible. The design, analysis and integration of dressed cavity are presented in detail.

Slides WEB3CO03 [11.396 MB]

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WEA4CO03

Intrinsic Landau Damping of Space Charge Modes at Coupling Resonance

resonance, damping, coupling, ECR

863

A. Macridin, J.F. Amundson, A.V. Burov, P. Spentzouris, E.G. Stern
Fermilab, Batavia, Illinois, USA

Funding: This work was performed at Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Using Synergia accelerator modeling package and Dynamic Mode Decomposition technique, the properties of the first transverse dipole mode in Gaussian bunches with space charge are compared at transverse coupling resonance and off-resonance. The Landau damping at coupling resonance and in the strong space charge regime is a factor of two larger, while the mode's tune and shape are nearly the same. While the damping mechanism in the off-resonance case fits well with the classical Landau damping paradigm, the enhancement at coupling resonance is due to a higher order mode-particle coupling term which is modulated by the amplitude oscillation of the resonance trapped particles.

Slides WEA4CO03 [3.422 MB]

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WEA4CO05

Accelerator Physics Design Requirements and Challenges of RF Based Electron Cooler LEReC

electron, cavity, cathode, emittance

867

A.V. Fedotov, M. Blaskiewicz, W. Fischer, D. Kayran, J. Kewisch, S. Seletskiy, J.E. Tuozzolo
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A Low Energy RHIC electron Cooler (LEReC) is presently under construction at BNL to improve the luminosity of the Relativistic Heavy Ion Collider (RHIC). The required electron beam will be provided by a photoemission electron gun and accelerated by a RF linear accelerator. As a result, LEReC will be first bunched beam electron cooler. In addition, this will be the first electron cooler to cool beams under collisions. The achievement of very tight electron beam parameters required for cooling is very challenging and is being addressed by a proper beam transport and engineering design. In this paper, we describe accelerator physics requirements, design considerations and parameters, as well as associated challenges of such electron cooling approach.

Slides WEA4CO05 [4.866 MB]

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WEB4CO03

RF Calibration of CEBAF Linac Cavities Through Phase Shifts

cavity, linac, optics, simulation

870

A. Carpenter, J. F. Benesch, C.J. Slominski
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
This paper describes a new beam-based method of cavity energy gain calibration based on varying the cavity phase. This method can be fully automated and allows a larger range of momentum excursions during measurement than previous calibration approaches. Monte Carlo simulations suggest that a calibration precision of 2-3% could be realistically achieved using this method. During the commissioning of the Continuous Electron Beam Accelerator Facility's (CEBAF) energy upgrade to 12 GeV, 876 measurements were performed on 375 of the 400 linac cavities in Fall 2015 and applied December 2015. Linac optics appears to be closer to design as a result. The resulting ensemble proved to be 2% over the value needed to get the desired energy in the arcs. Continued offline analysis of the data has allowed for error analysis and better understanding of the process.

Slides WEB4CO03 [2.413 MB]

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WEB4CO04

100 kW Very Compact Pulsed Solid-State RF Amplifier. Development and Tests

controls, rf-amplifier, vacuum, power-supply

873

G.B. Sharkov, A.A. Krasnov, S.A. Polikhov
NIITFA, Moscow, Russia
R. Cisneros, R.J. Patrick
TMD Technologies, Middlesex, United Kingdom

A high power solid-state RF amplifier system has been developed and tested. The modular scalable architecture of the system allows to build megawatt-range compact, robust, cost effective RF amplifiers/generators with high plug efficiency. Using a special designed technology of RF power on-board combination for several LDMOS transistors and very compact high power RF combiners, the amplifier with output power of 100 kW and duty cycle of 5% has been fit into a single 19" cabinet. The system has been tested at the output power up to 104 kW with 3.5 ms pulses. The overview of the technologies, the design of the machine, and its main subsystems is given in this talk. The test results and the market perspectives are also presented.

Slides WEB4CO04 [19.504 MB]

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WEPOB01

Lower Emittance Lattice for the Advanced Photon Source Upgrade Using Reverse Bending Magnets

lattice, emittance, quadrupole, damping

877

M. Borland, T.G. Berenc, R.R. Lindberg, V. Sajaev, Y.P. Sun
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
he Advanced Photon Source (APS) is pursuing an upgrade to the storage ring to a hybrid seven-bend-achromat design*. The nominal design provides a natural emittance of 67 pm. By adding reverse dipole fields to several quadrupoles**, we can reduce the natural emittance to 41 pm while simultaneously providing more optimal beta functions in the insertion devices. The improved emittance results from a combination of increased energy loss per turn and a change in the damping partition. At the same time, the nonlinear dynamics performance is very similar, thanks in part to increased dispersion in the sextupoles. This paper describes the properties, optimization, and performance of the new lattice.
* L. Farvacque et al., IPAC13, 79 (2013).
** J.P. Delahaye \em et al., PAC89, 1611 (1990); A. Streun, NIM A 737, 148 (2014).

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WEPOB02

Simulation of Swap-Out Reliability for the Advance Photon Source Upgrade

operation, injection, simulation, lattice

881

M. Borland
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The proposed upgrade of the Advanced Photon Source (APS) to a multibend achromat lattice relies on the use of swap-out injection to accommodate the small dynamic acceptance, allow use of unusual insertion devices, and minimize collective effects at high single-bunch charge. This, combined with the short beam lifetime, will make injector reliability even more important than it is for top-up operation. We used historical data for the APS injector complex to obtain probability distributions for injector up-time and down-time durations. Using these distributions, we simulated several years of swap-out operation for the upgraded lattice for several operating modes. The results indicate that obtaining very high availability of beam in the storage ring will require improvements to injector reliability.

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WEPOB03

Magnetic Measurements of Storage Ring Magnets for the APS Upgrade Project

alignment, quadrupole, MMI, sextupole

884

R.J. Dejus, H. Cease, J.T. Collins, G. Decker, A.T. Donnelly, C.L. Doose, W.G. Jansma, M.S. Jaski, J. Liu
ANL, Argonne, Illinois, USA
J. DiMarco
Fermilab, Batavia, Illinois, USA
A.K. Jain
BNL, Upton, Long Island, New York, USA

Funding: * Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357, and contract number DE-SC0012704 for work associated with Brookhaven National Laboratory.
Extensive prototyping of storage ring magnets is ongoing at the Advanced Photon Source (APS) in support of the APS Multi-Bend Achromat upgrade (APS-U) project. As part of the R&D activities 4 quadrupole magnets with slightly different geometries and pole tip materials, and one sextupole magnet with vanadium permendur pole tips were designed, built and tested. Magnets were measured individually using a rotating coil and a Hall probe for detailed mapping of the magnetic field. Magnets were then assembled and aligned relative to each other on a steel support plate and concrete plinth using precision machined surfaces to gain experience with the alignment method chosen for the APS-U storage ring magnets. The required alignment of magnets on a common support structure is 30 micron rms. Measurements of magnetic field quality, strength and magnet alignment after subjecting the magnets and assemblies to different tests will be presented.

Poster WEPOB03 [1.242 MB]

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WEPOB04

Beamline-Controlled Steering of Source-Point Angle at the Advanced Photon Source

EPICS, controls, feedback, operation

887

L. Emery, G.I. Fystro, H. Shang, M.L. Smith
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
An EPICS-based steering software system has been implemented for beamline personnel to directly steer the angle of the synchrotron radiation sources at the Advanced Photon Source. A script running on a workstation monitors "start steering" beamline EPICS records, and effects a steering by the value of "angle request" EPICS records that beamlines have set. The new system effectively bypasses floor coordinators and MCR operators, and makes the steering process much faster than before, although these older protocols can still be used. As with the original steering there are EPICS alarm limits that prevent large steering from occurring and avoid other problems. Error messages and statuses, OPI windows and alarm configurations are provided to the beamlines and the accelerator operators. Underpinning this new steering protocol is the recent refinement of the global orbit feedback process whereby feedforward of dipole corrector set points and orbit set points are used to create a local steering bump in a rapid and seamless way. In principle and in practice, many simultaneous steering commands from many beamlines are possible. We report on a complete 3-month run of experience.

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WEPOB05

Operational Experience With Beam Abort System for Superconducting Undulator Quench Mitigation

kicker, simulation, beam-losses, operation

890

K.C. Harkay, J.C. Dooling, V. Sajaev, J. Wang
ANL, Argonne, Illinois, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance of the abort system–kick amplitudes and loss distributions of all bunches–was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss diagnostics described elsewhere [1]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described.
[1] J. Dooling et al., these proceedings.

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WEPOB06

Parameterization of Helical Superconducting Undulator Magnetic Field*

undulator, software, factory, radiation

894

S.H. Kim
ANL, Argonne, Illinois, USA

Using a scaling law, the magnetic fields of helical superconducting undulators (HSCUs) for a period range of 10 ' 50 mm are parameterized from the field calculations of one reference HSCU with a period of 30 mm. The on-axis fields are calculated at the critical current densities of the NbTi and Nb3Sn superconducting coils at 4.2 K. The parametrized on-axis fields for the period range are expressed in terms of the period and inner radius of the helical coils. The corresponding critical current densities and coil maximum fields are also included. The parameterization procedures are described in detail and some field deviations are discussed.
*Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Associate of Seville, Advanced Photon Source
'shkim@aps.anl.gov, shkim242@gmail.com

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WEPOB07

Dielectrically-Loaded Waveguide as a Short Period Superconducting Microwave Undulator

undulator, operation, GUI, brightness

897

R. Kustom, A. Nassiri, K.J. Suthar, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. The waveguide is designed to operate near its cutoff frequency where the wavelength and phase velocity vary significantly to enable tuning of the equivalent undulator wavelength. The operating frequency would range from 18 - 24 GHz. It would be possible to generate coherent, high-energy 45 - 65 KeV x-rays from the fundamental mode which are tunable over a 20% energy range by changing the source frequency while maintaining constant field strengths. The x-ray brilliance of the microwave undulator would be 3 times higher at 56-KeV and 7 times higher at 66 KeV than what is available with the APS 1.8 cm period Superconducting Wire Undulator. Since the loss factor of sapphire is very low at cryogenic temperatures, it is possible to consider a superconducting microwave undulator, although resistive losses of ~200 to 700 W/m may be a bit too high for CW operation.

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WEPOB08

Collective Effects at Injection for the APS-U MBA Lattice

feedback, injection, collective-effects, lattice

901

R.R. Lindberg, M. Borland
ANL, Argonne, Illinois, USA
A. Blednykh
BNL, Upton, Long Island, New York, USA

Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357
The Advanced Photon Source has proposed an upgrade to a multi-bend achromat (MBA) with a proposed timing mode calls for 48 bunches of 15 nC each. In this mode of operation we find that phase space mismatch from the booster can drive large wakefields that in turn may limit the current below that of the nominal collective instability threshold. We show that collective effects at injection lead to emittance growth that makes usual off-axis accumulation very challenging. On-axis injection ameliorates many of these issues, but we find that transverse feedback is still required. We explore the role of impedance, feedback, and phase-space mismatch on transverse instabilities at injection.

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WEPOB09

Field Quality from Tolerance Stack Up in R&D Quadrupoles for the Advanced Photon Source Upgrade

quadrupole, lattice, alignment, multipole

904

J. Liu, M. Borland, R.J. Dejus, A.T. Donnelly, C.L. Doose, J.S. Downey, M.S. Jaski
ANL, Argonne, Illinois, USA
A.K. Jain
BNL, Upton, Long Island, New York, USA

Funding: *Work supported by U.S. Department of Energy, Office of Science, under contract No. DE-AC02-06CH11357 and contract number DE-SC0012704 for work associated with Brookhaven National Laboratory.
The Advanced Photon Source (APS) at Argonne National Laboratory (ANL) is considering upgrading the current double-bend, 7-GeV, 3rd generation storage ring to a 6-GeV, 4th generation storage ring with a Multibend Achromat (MBA) lattice. In this study, a novel method is proposed to determine fabrication and assembly tolerances through a combination of magnetic and mechanical tolerance analyses. Mechanical tolerance stackup analyses using Teamcenter Variation Analysis are carried out to determine the part and assembly level fabrication tolerances. Finite element analyses using OPERA are conducted to estimate the effect of fabrication and assembly errors on the magnetic field of a quadrupole magnet and to determine the allowable tolerances to achieve the desired magnetic performance. Finally, results of measurements in R&D quadrupole prototypes are compared with the analysis results.

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WEPOB10

Simulation Study of the Helical Superconducting Undulator Installation at the Advanced Photon Source

lattice, undulator, sextupole, injection

907

V. Sajaev, M. Borland, Y.P. Sun, A. Xiao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator is planned for installation at the APS. Such an installation would be first of its kind – helical devices were never installed in synchrotron light sources before. Due to its reduced horizontal aperture, a lattice modification is required to accommodate for large horizontal oscillations during injection. We describe the lattice change details and show the new lattice experimental test results. To understand the effect of the undulator on single-particle dynamics, first, its kick maps were computed using different methods. We have found that often-used Elleaume formula* for kick maps gives wrong results for this undulator. We then used the kick maps obtained by other methods to simulate the effect of the undulator on injection and lifetime.
*P. Elleaume, EPAC 1992

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WEPOB11

Tuning of the APS Linac Accelerating Cavities After Structural Re-Alignment

linac, cavity, cathode, photon

910

T.L. Smith, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

A new S-band LCLS type Photo-cathode (PC) gun was recently installed in the APS linac. As a consequence, it was recognized that many of the linac accelerating structures were out of their 1mm straightness tolerances. In order to reduce the effects of wakefield on the beam, several of the misaligned structures were straightened. This paper discusses the bead-pull RF measurements, the effect of the straightening efforts on rf and the cell to cell retuning efforts that were performed.

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WEPOB12

Multi-Objective Online Optimization of Beam Lifetime at APS

sextupole, lattice, simulation, storage-ring

913

Y.P. Sun
ANL, Argonne, Illinois, USA

In this paper, online optimization of beam lifetime at the APS (Advanced Photon Source) storage ring is presented. A general genetic algorithm (GA) is developed and employed for some online optimizations in the APS storage ring. Sextupole magnets in 40 sectors of the APS storage ring are employed as variables for the online nonlinear beam dynamics optimization. The algorithm employs several optimization objectives and is designed to run with topup mode or beam current decay mode. Up to 50\% improvement of beam lifetime is demonstrated, without affecting the transverse beam sizes and other relevant parameters. In some cases, the top-up injection efficiency is also improved.

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WEPOB13

Online Minimization of Vertical Beam Sizes at APS

storage-ring, operation, lattice, photon

916

Y.P. Sun
ANL, Argonne, Illinois, USA

In this paper, online minimization of vertical beam sizes along the APS (Advanced Photon Source) storage ring is presented. A genetic algorithm (GA) was developed and employed for the online optimization in the APS storage ring. A total of 59 families of skew quadrupole magnets were employed as knobs to adjust the coupling and the vertical dispersion in the APS storage ring. Starting from initially zero current skew quadrupoles, small vertical beam sizes along the APS storage ring were achieved in a short optimization time of one hour. The optimization results from this method are briefly compared with the one from LOCO (Linear Optics from Closed Orbits) response matrix correction.

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WEPOB14

APS-U Lattice Design for Off-Axis Accumulation

lattice, emittance, injection, quadrupole

920

Y.P. Sun, M. Borland, R.R. Lindberg, V. Sajaev
ANL, Argonne, Illinois, USA

A 67-pm hybrid-seven-bend achromat (H7BA) lattice is being proposed for a future Advanced Photon Source (APS) multi-bend-achromat (MBA) upgrade project. This lattice design pushes for smaller emittance and requires use of a swap-out (on-axis) injection scheme due to limited dynamic acceptance. Alternate lattice design work has also been performed for the APS upgrade to achieve better beam dynamics performance than the nominal APS MBA lattice, in order to allow off-axis accumulation. Two such alternate H7BA lattice designs, which target a still-low emittance of 90 pm, are discussed in detail in this paper. Although the single-particle-dynamics performance is good, simulations of collective effects indicate that surprising difficulty would be expected accumulating high single-bunch charge in this lattice. The brightness of the 90-pm lattice is also a factor of two lower than the 67-pm H7BA lattice.

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WEPOB15

Comparison of Nonlinear Dynamics Optimization Methods for APS-U

lattice, sextupole, octupole, optics

924

Y.P. Sun, M. Borland
ANL, Argonne, Illinois, USA

Many different objectives and genetic algorithms have been proposed for storage ring nonlinear dynamics performance optimization. These optimization objectives include nonlinear chromaticities and driving/detuning terms, on-momentum and off-momentum dynamic acceptance, chromatic detuning, local momentum acceptance, variation of transverse invariant, Touschek lifetime, etc. In this paper, the effectiveness of several different optimization methods and objectives are compared for the nonlinear beam dynamics optimization of the Advanced Photon Source upgrade (APS-U) lattice. The optimized solutions from these different methods are preliminarily compared in terms of the dynamic acceptance, local momentum acceptance, chromatic detuning, and other performance measures.

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WEPOB16

Simulation Studies of a Prototype Stripline Kicker for the APS-MBA Upgrade

kicker, impedance, simulation, high-voltage

928

X. Sun, C. Yao
ANL, Argonne, Illinois, USA

Funding: *Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A prototype dual-blade stripline kicker for the APS multi-bend achromat (MBA) upgrade has been designed and developed. It was optimized with 3D CST Micro-wave Studio. The high voltage (HV) feedthrough and air-side connector were designed and optimized. The elec-tromagnetic fields along the beam path, deflecting angle and high electric fields with their locations were calculat-ed with 15 kV differential pulse voltage applied to the kicker blades through the feedthroughs. The beam im-pedance and power dissipation on different parts of the kicker and external loads were studied for a 48-bunch fill pattern. Our simulation results show that the prototype kicker with its HV feedthroughs meets the specified re-quirements. The results of TDR (time-domain reflectome-ter) test, high voltage pulse test and beam test of the pro-totype kicker assembly agreed with the simulations.

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WEPOB18

Bend Magnet Head Loads and Out of Orbit Scenarios

photon, software, electron, lattice

931

T.T. Valicenti, J.A. Carter, P.K. Den Hartog, K.J. Suthar
ANL, Argonne, Illinois, USA

This paper presents an analytical calculation of the spatial power spectrum emitted from relativistic electrons passing through a series of bend magnets. Using lattice files from the software Elegant, both the ideal and missteered trajectories taken by the beam are considered in determination of the power profile. Calculations were performed for the Advanced Photon Source Upgrade multi-bend-achromat storage-ring. Results were validated with Synrad, a monte-carlo based program designed at CERN. The power distribution and integrated total power values are in agreement with Synrad's results within one percent error. The analytic solution used in this software gives a both quick and accurate tool for calculating the heat load on a photon absorber. The location and orientation can be optimized in order to reduce the peak intensity and thus the maximum thermal stress. This can be used with any optimization or FEA software and gives rise to a versatile set of uses for the developed program.

Poster WEPOB18 [2.491 MB]

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WEPOB19

Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun

cathode, gun, operation, wakefield

934

E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months.

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WEPOB20

Multiple Scattering Effects on a Short Pulse Electron Beam Travelling Through Thin Beryllium Foils

experiment, scattering, vacuum, simulation

937

E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
Q. Gao
TUB, Beijing, People's Republic of China
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The Argonne Wakefield Accelerator beamlines have stringent vacuum requirements (100 picotorr) necessitated by the Cesium telluride photoinjector. In direct conflict with this, the structures-based wakefield accelerator research program sometimes includes worthy but complex experimental installations with components or structures unable to meet the vacuum standards. A proposed chamber to sequester such experiments safely behind a thin beryllium (Be) window is described and the results of a study of beam-quality issues due to the multiple scattering of the beam through the window are presented and compared to GEANT4 simulations via G4beamline. Three thicknesses of Be foil were used: 30, 75 and 127 micron, probed by electron beams of three different energies: 25, 45, and 65 MeV. Multiple scattering effects were evaluated by comparing the measured transverse rms beam size for the scattered vs. unscattered beam. The experimental results are presented and compared to simulations. Results are discussed along with the implications and suggestions for the future sequestered vacuum chamber design.

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WEPOB21

Benchmarking of Touschek Beam Lifetime Calculations for the Advanced Photon Source

synchrotron, scattering, coupling, storage-ring

940

A. Xiao, B.X. Yang
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Particle loss from Touschek scattering is one of the most significant issues faced by present and future synchrotron light source storage rings. For example, the predicted, Touschek-dominated beam lifetime for the Advanced Photon Source (APS) Upgrade lattice in 48-bunch, 200-mA timing mode is only ~2 h. In order to understand the reliability of the predicted lifetime, a series of measurements with various beam parameters was performed on the present APS storage ring. This paper first describes the entire process of beam lifetime measurement, then compares measured lifetime with the calculated one by applying the measured beam parameters. The results show very good agreement.

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WEPOB22

Beam Loss Simulation and Collimator System Configurations for the Advanced Photon Source Upgrade

simulation, beam-losses, shielding, injection

943

A. Xiao, M. Borland
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The proposed multi-bend achromat lattice for the Advanced Photon Source upgrade (APS-U) has a design emittance of less than 70 pm. The Touschek loss rate is high: compared with the current APS ring, which has an average beam lifetime ∼ 10 h, the simulated beam lifetime for APS-U is only ~2 h when operated in the high flux mode (I=200 mA in 48 bunches). An additional consequence of the short lifetime is that injection must be more frequent, which provides another potential source of particle loss. In order to provide information for the radiation shielding system evaluation and to avoid particle loss in sensitive locations around the ring (for example, insertion device straight sections), simulations of the detailed beam loss distribution have been performed. Several possible collimation configurations have been simulated and compared.

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WEPOB23

Performance of the Full-Length Vertical Polarizing Undulator Prototype for LCLS-II

undulator, FEL, operation, electron

946

N.O. Strelnikov, E. Gluskin, I. Vasserman, J.Z. Xu
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
As part of the LCLS-II R&D program, a novel 3.4-meter long undulator prototype with horizontal main magnetic field and dynamic force compensation - called the horizontal gap vertical polarization undulator (HGVPU) - has recently been developed at the Advanced Photon Source (APS). Initial steps of the project included designing, building, and a testing 0.8-meter long prototype. Extensive mechanical testing of the HGVPU has been carried out. The magnetic tuning was accomplished by applying a set of magnetic shims. As a result, the performance of the HGVPU meets all the stringent requirements for the LCLS-II insertion device, which includes limits on the field integrals and phase errors for all operational gaps, as well as the reproducibility and accuracy of the gap settings. The HGVPU has been included in the baseline of the LCLS-II project for the hard x-ray undulator line.

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WEPOB24

Preliminary Test Results of a Prototype Fast Kicker for APS MBA Upgrade

kicker, simulation, high-voltage, impedance

950

C. Yao, A. Barcikowski, A.R. Brill, J. Carwardine, T.K. Clute, Z.A. Conway, A.R. Cours, G. Decker, R.T. Keane, F. Lenkszus, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS multi-bend achromatic (MBA) upgrade storage ring plans to support two bunch fill patterns: a 48-bunch and a 324-bunch. A "swap out" injection scheme is required. In order provide the required kick to injected beam, to minimize the beam loss and residual oscillation of injected beam, and to minimize the perturbation to stored beam during injection, the rise, fall, and flat-top parts of the kicker pulse must be within a 16.9-ns interval. Stripling-type kickers are chosen for both injection and extraction. We developed a prototype kicker that supports a ±15kV differential pulse voltage. We performed high voltage discharge, TDR measurement, high voltage pulse test and beam test of the kicker. We report the design of the fast kicker and the test results.

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WEPOB25

Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns

gun, cathode, electron, simulation

953

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

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WEPOB26

Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

cathode, gun, electron, experiment

956

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.

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WEPOB27

Modification of 3rd Harmonic Cavity for CW Operation in LCLS-II Accelerator

HOM, cavity, FEL, linac

960

T.N. Khabiboulline, M.H. Awida, I.V. Gonin, A. Lunin, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

A 3.9 GHz 3rd harmonic cavity was developed at FNAL and it is currently used in the FLASH accelerator at DESY in order to improve FEL operation. The European XFEL accelerator in Hamburg also adapted the same cavity design for a pulsed linac operation. The 3rd harmonic cavity for the LCLS-II accelerator at SLAC will operate in a continuous wave (CW) regime. A CW operation and a high average current in the LCLS-II linac result in in-creased heat loads to main and HOM couplers of the cavity. Several cavity design modifications were pro-posed and investigated for improving a cavity perfor-mance in the CW regime. In this paper we present results of the design review for proposed modifications

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WEPOB29

Modeling of Dark Current Generation and Transport Using the IMPACT-T Code

electron, cavity, cathode, space-charge

964

J. Qiang, K. Hwang
LBNL, Berkeley, California, USA

Dark current from unwanted electrons in photoinjector can present significant danger to the accelerator operation by causing damage to photocathode and power deposition onto conducting wall. In this paper, we present numerical models of dark current generation from the field emission and from the electron impact ionization of the residual gas that were recently developed in the IMPACT-T code. We also report on the application of above numerical model to an LCLS-II like photoinjector.

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WEPOB30

Simulation of the Shot-Noise Driven Microbunching Instability Experiment at the LCLS

simulation, laser, electron, bunching

967

J. Qiang
LBNL, Berkeley, California, USA
Y. Ding, P. Emma, Z. Huang, D.F. Ratner, T.O. Raubenheimer, F. Zhou
SLAC, Menlo Park, California, USA

The shot-noise driven microbunching instability can significantly degrade electron beam quality in next generation light sources. Experiments were carried out at the Linac Coherent Light Source (LCLS) to study this instability. In this paper, we will present start-to-end simulation of the shot-noise driven microbunching instability experiment at the LCLS.

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WEPOB31

Dark Current Study of a Standing Wave Disk-Loaded Waveguide Structure at 17 GHz

electron, simulation, experiment, multipactoring

971

H. Xu, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: US DoE, Office of High Energy Physics
We present calculations of the dark current in a high gradient accelerator with the intent of understanding its role in breakdown. The initial source of the dark current is the field emission of electrons. For a 17 GHz single-cell standing wave disk-loaded waveguide structure, the 3D particle-in-cell simulation shows that only a small portion of the charge emitted reaches the current monitors at the ends of the structure, while most of the current collides on the structure surfaces, causing secondary electron emission. In the simulation, a two-point multipactor process is observed on the side wall of the cell due to the low electric field on the surface. The multipactor approaches a steady state within nanoseconds when the electric field is suppressed by the electron cloud formed so that the average secondary electron yield is reduced. This multipactor current can cause the ionization of the metal material and surface outgassing, leading to breakdown. We report first results from an experiment designed to extract dark current directly from an accelerator cell from the side through two slits. First results show that the dark current behavior deviates from the field emission theory.

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WEPOB32

Performance of a Combined System Using an X-Ray FEL Oscillator and a High-Gain FEL Amplifier

FEL, radiation, simulation, laser

974

L. Gupta
University of Chicago, Chicago, Illinois, USA
K.-J. Kim, R.R. Lindberg
ANL, Argonne, Illinois, USA

Funding: [5] R. R. Lindberg, K.-J. Kim, "Intense, coherent x-rays at 40 keV or higher by combining an XFELO and a high-gain harmonic generation," (in prep) US DOE contract DE-AC02-06CH11357 & NSF PHY-1535639
The LCLS-II at SLAC will feature a 4 GeV CW superconducting (SC) RF linac [1] that can potentially drive a 5th harmonic X-Ray FEL Oscillator to produce fully coherent, 1 MW photon pulses with a 5 meV bandwidth at 14.4 keV [2]. The XFELO output can serve as the input seed signal for a high-gain FEL amplifier employing fs electron beams from the normal conducting SLAC linac, thereby generating coherent, fs x-ray pulses with ~TW peak powers using a tapered undulator after saturation [3]. Coherent, intense output at several tens of keV will also be feasible if one considers a harmonic generation scheme. Thus, one can potentially reach the 42 keV photon energy required for the MaRIE project [4] by beginning with an XFELO operating at the 5th harmonic to produce 8.4 keV photons using a 3.1 GeV SCRF linac, and then subsequently using the high-gain harmonic generation scheme to generate and amplify the 5th harmonic at 42 keV [5]. We report extensive GINGER simulations that determine an optimized parameter set for the combined system. [1] "Linac Coherent Light Source-II Conceptual Design Report," SLAC-R-978 (2011)
[2] T. J. Maxwell, et al., "Feasibility Study for an X-Ray FEL Oscillator at the LCLS-II," IPAC, Richmond, VA (May, 2015)
[3] K.-J. Kim, et al., IPAC 2016
[4] http://www.lanl.gov

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WEPOB35

LLNL Laser-Compton X-Ray Characterization

electron, laser, simulation, scattering

977

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344
30 keV Compton-scattered X-rays have been produced at LLNL. The flux, bandwidth, and X-ray source focal spot size have been characterized using an X-ray ICCD camera and results agree very well with modeling predictions. The RMS source size inferred from direct electron beam spot size measurement is 17 um , while imaging of the penumbra yields an upper bound of 42 um. The accuracy of the latter method is limited by the spatial resolution of the imaging system, which has been characterized as well, and is expected to improve after the upgrade of the X-ray camera later this year.

Poster WEPOB35 [37.648 MB]

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WEPOB36

Upgrade of the Cornell Electron Storage Ring as a Synchrotron Light Source

undulator, lattice, injection, emittance

980

D. L. Rubin, J.A. Crittenden, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF-DMR 13-32208
The planned upgrade of the Cornell Electron Storage Ring as an X-ray source for CHESS will include an increase in beam energy and decrease in emittance from 100 nm-rad at 5.3 GeV to 30 nm-rad at 6 GeV, increase in beam current from 120 to 200 mA, continuous top-off injection of the single circulating beam, and four new zero dispersion inser- tion straights that can each accommodate a pair of canted undulators. The existing sextant of the storage ring arc that serves as the source for all of the CHESS X-ray beam lines will be reconfigured with 6 double-bend achromats, each consisting of two pairs of horizontally focusing quadrupoles, and a single pair of combined-function gradient bend magnets. The chromaticity will be compensated by the existing sextupoles in the legacy FODO arcs. We describe details of the linear optics, sextupole distributions to maximize dynamic aperture and injection efficiency, and characterization of magnetic field and alignment error tolerance.

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WEPOB39

Photo-Injector Optimization and Validation Study with the OPAL Beam Simulation Code

emittance, simulation, booster, FEL

984

L.D. Duffy, K. Bishofberger, J.W. Lewellen, S.J. Russell, D.Y. Shchegolkov
LANL, Los Alamos, New Mexico, USA

A 42 keV x-ray free electron laser (XFEL) is a plausible technology alternative for the Matter Radiation Interactions in Extremes (MaRIE) experimental project, a concept developed by Los Alamos National Laboratory. An early pre-conceptual design for such an XFEL calls for 100 pC electron bunches with very low emittance and energy spread. High fidelity simulations that capture all beamline physics will be required to ensure a successful design. We expect to use the beam simulation code OPAL as one of the tools in this process. In this study, we validate OPAL as a photo-injector design tool by comparing its performance with published PITZ experimental data and simulations.

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WEPOB41

Quality Factor in High Power Tests of Cryogenic Copper Accelerating Cavities

cavity, ECR, experiment, GUI

987

A.D. Cahill, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V.A. Dolgashev, M.A. Franzi, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Research made possible by DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Recent SLAC experiments with cryogenically cooled 11.4 GHz standing wave copper accelerating cavities have shown evidence of 250 MV/m accelerating gradients with low breakdown rates. The gradient depends on the circuit parameters of the accelerating cavity, such as the intrinsic and external quality factors (Q0, QE). In our studies we see evidence that Q₀ decreases during rf pulse at 7-70 K. This paper discusses experiments that are directed towards understanding the change of Q0 at high power.

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WEPOB42

High Gradient S-Band Cryogenic Accelerating Structure for RF Breakdown Studies

cavity, cryogenics, coupling, experiment

991

A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
G.B. Bowden, V.A. Dolgashev, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515 and DOE SCGSR Fellowship
Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdowns. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape, cavity temperature, and material. Experimental and theoretical study of the effects of these parameters on the breakdown physics is ongoing at SLAC. As of now, most of the data has been obtained at 11.4 GHz. We are extending this research to S-band. We have designed a single cell accelerating structure, based on the extensively tested X-band cavities. The setup uses matched TM01 mode launcher to feed rf power into the test cavity. Our ongoing study of the physics of rf breakdown in cryogenically X-band accelerating cavities shows improved breakdown performance. Therefore, this S-band experiment is designed to cool the cavity to cryogenic temperatures. We use operating frequencies near 2.856 GHz. We present the rf design and discuss the experimental setup.

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WEPOB47

Development of a Short Period Cryogenic Undulator at RadiaBeam

undulator, cryogenics, electron, simulation

995

F.H. O'Shea, R.B. Agustsson, Y.C. Chen, A.J. Palmowski, E. Spranza
RadiaBeam, Santa Monica, California, USA

Funding: Work supported by DOE under contracts DE-SC0006288 and NNSA SSAA DE-NA0001979.
RadiaBeam Technologies has developed a 7-mm period length cryogenic undulator prototype to test fabrications techniques in cryogenic undulator production. We present here our first prototype, the production techniques used to fabricate it, its magnetic performance at room temperature and the temperature uniformity after cool down.

Poster WEPOB47 [2.725 MB]

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WEPOB48

THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

radiation, undulator, electron, experiment

998

A.V. Smirnov, R.B. Agustsson, S. Boucher, T.J. Campese, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A.Y. Murokh, F.H. O'Shea, E. Spranza
RadiaBeam, Santa Monica, California, USA
W. Berg, M. Borland, J.C. Dooling, L. Erwin, R.R. Lindberg, S.J. Pasky, N. Sereno, Y. Sun, A. Zholents
ANL, Argonne, Illinois, USA
W. Bruns
WBFB, Berlin, Germany
M.J. de Loos, S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC-FOA-0007702).
Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes including conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.
[1] A. V. Smirnov, R. Agustsson, W. J. Berg et al., Phys. Rev. ST Accel. Beams 18, 090703(2015)

Poster WEPOB48 [1.335 MB]

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WEPOB49

LCLS Injector Laser Profile Shaping Using Digital Micromirror Device

laser, electron, cathode, target

1001

S. Li
Stanford University, Stanford, California, USA
S.C. Alverson, D.K. Bohler, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou
SLAC, Menlo Park, California, USA

In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The emittance of the beam is highly related to the transverse profile of the injector laser. Currently the LCLS injector laser has undesired features, such as hot spots, which carry over to the electron beam. These undesired features increase electron emittance, degrade the FEL performance, and complicate operations. The injector laser shaping project at LCLS aims to produce arbitrary electron beam profiles, such as cut-Gaussian, uniform, and parabolic, and to study the effect of spatial profiles on beam emittance and FEL performance. Effectively it also allows easy transition between the two spare lasers, where the operators can use the spatial shaper to achieve identical profiles for the two lasers. In this paper, we describe the experimental methods to achieve laser profile shaping and electron beam profile shaping respectively, and demonstrate promising results.

Poster WEPOB49 [1.850 MB]

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WEPOB53

Computation of Synchrotron Radiation

undulator, radiation, simulation, synchrotron

1005

D.A. Hidas
BNL, Upton, Long Island, New York, USA

This presentation introduces a new open-source software development for the computation of radiation from charged particles and beams in magnetic and electric fields. The computations are valid in the near-field regime for both relativistic and non-relativistic scenarios. This project is being developed, and is currently in use, at Brookhaven National Laboratory's National Synchrotron Light Source II. Primary applications include, but are not limited to, the computation of spectra, photon flux densities, and power density distributions from undulators, wigglers, and bending magnets on arbitrary shaped surfaces in 3D making possible detailed study of sensitive accelerator and beam-line equipment. Application interfaces are available in Python, Mathematica, and C. Practical use cases are demonstrated and benchmarked. Additionally, future upgrades will be elaborated on.

Poster WEPOB53 [27.003 MB]

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WEPOB54

DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC).

gun, electron, laser, cavity

1008

D. Kayran, Z. Altinbas, D.R. Beavis, S. Bellavia, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, J. Halinski, K. Hamdi, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, G.J. Mahler, T.A. Miller, S.K. Nayak, T. Rao, S. Seletskiy, B. Sheehy, J.E. Tuozzolo, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
Non-magnetized bunched electron cooling of low-energy RHIC requires electron beam energy in range of 1.6-2.6 MeV, with average current up to 45 mA, very small energy spread, and low emittance [1]. A 400 kV DC gun equipped with photocathode and laser delivery system will serve as a source of high-quality electron beam. Acceleration will be achieved by an SRF 704 MHz booster cavity and other RF components that are scheduled to be operational in early 2018. The DC gun testing in its installed location in RHIC will start in early 2017. During this stage we plan to test the critical equipment in close to operation conditions: laser beam delivery system, cathode QE lifetime, DC gun, beam instrumentation, high power beam dump system, and controls. In this paper, we describe the gun test set up, major components, and parameters to be achieved and measured during the gun beam test.
[1] A. Fedotov. Bunched beam electron cooling for Low Energy RHIC operation. ICFA Beam Dynamics letter, No. 65, p. 22 (December 2014)

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WEPOB55

Simulation of Stray Electrons in the RHIC Low Energy Cooler

electron, cathode, cavity, SRF

1012

J. Kewisch
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Low Energy RHIC electron Cooler, under construction at BNL, accelerates electrons with a 400 kV DC gun and a 2.2 MeV SRF booster cavity. Electrons which leave the cathode at the wrong time will not be accelerated to the correct energies and will not reach the beam dump at the end of the accelerator. Thy may impact the beam pipe after incorrect deflection in dipoles or after being slowed down longitudinally in the booster while the transverse momentum is not affected. In some cases their direction is reversed in the booster and they will impact the cathode. We simulated the trajectories of these electrons using the GPT tracking code. The results are qualitative, not quantitative, since the sources and numbers of the stray electrons are unknown.

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WEPOB56

Beam Optics for the RHIC Low Energy Electron Cooler (LEReC)

electron, booster, emittance, space-charge

1015

J. Kewisch, A.V. Fedotov, D. Kayran, S. Seletskiy
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A Low-energy RHIC Electron Cooler (LEReC) system is presently under construction at Brookhaven National Laboratory. This device shall enable gold ion collisions at energies below the design injection energy with sufficient luminosity. Electron beam with energies between 1.6, 2.0 and 2.6 MeV are necessary. This machine will be the first to attempt electron cooling using bunched electron beam, using a 703 MHz SRF cavity for acceleration. Special consideration must be given to the effect of space charge forces on the transverse and longitudinal beam quality. We will present the current layout of the cooler and beam parameter simulations using the computer codes PARMELA.

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WEPOB57

Magnetic Optimization of Long EPUs at NSLS-II

undulator, MMI, insertion-device, insertion

1018

C.A. Kitegi, P.L. Cappadoro, O.V. Chubar, T.M. Corwin, H.C. Fernandes, D.A. Harder, D.A. Hidas, W. Licciardi, M. Musardo, J. Rank, C. Rhein, T. Tanabe
BNL, Upton, Long Island, New York, USA

The Soft Inelastic X-ray scattering (SIX) and the Elec-tron-Spectro-Microscopy (ESM) are two beamlines under construction at National Synchrotron Light Source-II (NSLS-II). The specifics of these two beamlines requested the use of two long Advanced Planar Polarized Light Emitter-II (APPLE-II) undulators, as a source that provides circularly and vertically polarized radiation. Thus we designed 3.5 m and 2.7m long APPLE-II type undulators for SIX and ESM. The NSLS-II ID group is responsible for the magnetic optimization of these two long undulators. In this paper, we first summarize the APPLE-II magnetic and mechanical design. Then, we discuss the magnetic performance of the first APPLE-II achieved with the shimming performed at BNL.

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WEPOB58

Cathode Puck Insertion System Design for the LEReC Photoemission DC Electron Gun

cathode, gun, vacuum, insertion

1021

C.J. Liaw, V. De Monte, L. DeSanto, K. Hamdi, M. Mapes, T. Rao, A.N. Steszyn, J.E. Tuozzolo, J. Walsh
BNL, Upton, Long Island, New York, USA
K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. DOE.
The operation of LEReC is to provide an electron cooling to improve the luminosity of the RHIC heavy ion beam at lower energies in a range of 2.5-25 GeV/nucleon. The electron beam is generated in a DC Electron Gun (DC gun) designed and built by the Cornell High Energy Synchrotron Source Group. This DC gun will operate around the clock for at least two weeks without maintenance. This paper presents the design of a reliable cathode puck insertion system, which includes a multi-pucks storage device, a transfer mechanism, a puck insertion device, a vacuum/control system, and a transport scheme.

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WEPOB59

Performance of CEC Pop Gun During Commissioning

cathode, gun, laser, cavity

1024

I. Pinayev, W. Fu, Y. Hao, M. Harvey, T. Hayes, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, G. Narayan, M.C. Paniccia, W.E. Pekrul, T. Rao, F. Severino, B. Sheehy, J. Skaritka, K.S. Smith, J.E. Tuozzolo, E. Wang, G. Wang, W. Xu, A. Zaltsman, Z. Zhao
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment employs a high-gradient CW photo-injector based on the superconducting RF cavity. Such guns operating at high accelerating gradients promise to revolutionize many sciences and applications. They can establish the basis for super-bright monochromatic X-ray and gamma ray sources, high luminosity hadron colliders, nuclear waste transmutation or a new generation of microchip production. In this paper we report on our operation of a superconducting RF electron gun with a high accelerating gradient at the CsK2Sb photo-cathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (above 4 nC). We give short description of the system and then detail our experimental results.

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WEPOB60

Commissioning of CeC PoP Accelerator

cavity, electron, hadron, gun

1027

I. Pinayev, Z. Altinbas, J.C.B. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, W. Fu, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, R.J. Michnoff, K. Mihara, T.A. Miller, G. Narayan, P. Orfin, M.C. Paniccia, D. Phillips, T. Rao, F. Severino, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, V. Soria, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, W. Xu, A. Zaltsman, Z. Zhao
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling is new cooling technique to be tested at BNL. Presently we are in the commissioning stage of the accelerator system. In this paper we present status of various systems and achieved beam parameters as well as operational experience. Near term future plans are also discussed.

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WEPOB61

Magnetic Shielding of LEReC Cooling Section

shielding, solenoid, simulation, electron

1030

S. Seletskiy, A.V. Fedotov, D.M. Gassner, D. Kayran, G.J. Mahler, W. Meng
BNL, Upton, Long Island, New York, USA

The transverse angle of the electron beam trajectory in the low energy RHIC Electron Cooling (LEReC) accelerator cooling section (CS) must be much smaller than 100 urad. This requirement sets 2.3 mG limit on the ambient transverse magnetic field. The maximum ambient field in the RHIC tunnel along the cooling section was measured to be 0.52 G. In this paper we discuss the design of the proposed LEReC CS magnetic shielding, which is capable of providing required attenuation.

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WEPOB62

Absolute Energy Measurement of the LEReC Electron Beam

dipole, simulation, electron, HOM

1033

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, T.A. Miller, P. Thieberger
BNL, Upton, Long Island, New York, USA

The goal of future operation of the low energy RHIC Electron Cooling (LEReC) accelerator is to cool the RHIC ion beams. To provide successful cooling, the velocities of the RHIC ion beam and the LEReC electron beam must be matched with 10^-4 accuracy. While the energy of ions will be known with the required accuracy, the e-beam energy can have an initial offset as large as 5%. The final setting of the e-beam energy will be performed by observing either the Schottky spectrum of debunched ions co-traveling with the e-beam or the recombination signal. Yet, to start observing such signals one has to set the absolute energy of the electron beam with an accuracy better than 10^-2, preferably better than 5·10^-3. In this paper we discuss how such accuracy can be reached by utilizing the LEReC 180 degree bend as a spectrometer.

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WEPOB65

Experiments of Lossless Crossing - Resonance With Tune Modulation by Synchrotron Oscillations

resonance, lattice, experiment, quadrupole

1036

G.M. Wang, B. Holub, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

It had become a standard practice to constrain particle's tune footprint while designing the storage ring lattice so that the tunes fit between harmful resonances that limit ring dynamic aperture (DA). However, in recent ultra-bright light source design, the nonlinearities of storage ring lattices are much enhanced as compared with the 3rd generation light source one. It is becoming more and more difficult to keep the off-momentum tune footprint confined and even more, the solution cannot be found to confine off-energy tune footprint in certain cases. The questions have been asked whether crossing of a resonance stopband from off-momentum particle will necessarily lead to particle loss. In NSLS-II, we modified the lattice working point to mimic machine tune footprint crossing half integer with beam synchrotron oscillation excitation and demonstrated that beam can cross a resonance without loss with control of stopband width and high order chromaticity.

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WEPOB66

NSLS-II Post Mortem Function Development and Data Analysis of Beam Dump

cavity, operation, status, synchrotron

1039

G.M. Wang, W.X. Cheng, J. Choi, L. Doom, K. Ha, T.V. Shaftan, R.M. Smith, J. Tagger, Y. Tian
BNL, Upton, Long Island, New York, USA
R.V. Madelon
University of Orleans, Orleans, France

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. The storage ring was commissioned in 2014 and transitioned to routine operations in the December of the same year. At this point the facility hosts 14 operating beam lines with beam current upto 250 mA. During beamline operation, various sources (protection system or subsystem malfunction) may cause beam dump. To identify the beam trip sources and improve the operation reliability, post mortem function was developed in NSLS-II to capture the sub-systems status and beam information prior and after beam dump, including RF system, power supply, BPMs and active interlock system. Most of the trip events have been identified and related source was improved. In this paper, we'll present the post mortem function and data application.

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WEPOB67

K2CsSb Photocathode Performance in QWR SRF Gun

cathode, gun, multipactoring, vacuum

1042

E. Wang, Y. Hao, Y.C. Jing, V. Litvinenko, I. Pinayev, T. Rao, J. Skaritka, G. Wang, T. Xin
BNL, Upton, Long Island, New York, USA

In 2016 run of Coherent Electron Cooling, we have successfully tested the performance of a number of K2CsSb cathodes. These cathodes with QE of 6%-10% were fabricated in Instrumentation Division, a few miles away, transported to RHIC tunnel under UHV conditions, attached to the CeC gun, kept in storage, and inserted in the gun as needed. A maximum bunch charge of 4.6 nC was generated in the gun when the QE was 1.8 %. With careful conditioning at increasing accelerating fields, it was possible to maintain the QE of several cathodes for more than a week. For the cathodes that experienced degradation, the primary cause was multipacting when the power into the gun was increased. In the initial runs, the entire 20 mm substrate face was coated with the cathode material causing cathode induced multipacting. For subsequent measurements, the substrate was masked to coat only the central 9 mm of the substrate. By optimizing the procedure for boosting the power to the gun and covering all viewports to minimize dark current, we were able to minimize QE degradation. In this paper we discuss the cathode preparation, transfer to the gun and operational experience with the cathodes in 112 MHz gun.

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WEPOB68

DESIGN AND SIMULATION OF EMITTANCE MEASUREMENT WITH MULTI-SLIT FOR LEREC

emittance, electron, simulation, space-charge

1045

C. Liu, A.V. Fedotov, J. Kewisch, M.G. Minty
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
To improve the luminosity of beam energy scan of low energy Au-Au collision, a electron machine is under con- struction to cool ion beams in both RHIC rings with pulsed electron beam. Over the course of the project, a multi- slit device is needed to characterize the transverse beam emittance of three energies, 0.4, 1.6 and 2.6 MeV. This re- port shows the optimization and compromise of the design, which include the slit width, slit spacing, and drift space from the multi-slit to the downstream profile monitor.

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WEPOB69

Impedance Simulation for LEReC Booster Cavity Transformed from ERL Gun Cavity

impedance, cavity, simulation, booster

1048

C. Liu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Wake impedance induced energy spread is a concern for the electron beam to be used for electron cooling of the low energy ion beams in RHIC. The impedance simulation of the booster cavity for the Low Energy RHIC electron cooling (LEReC) project is presented in this report. The simulation is done for both non-relativistic and ultra-relativistic cases. The space charge impedance in the first case is discussed. For an impedance budget consideration of the electron machine only a simulation of the geometrical impedance in the latter case is necessary since space charge is considered separately.

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WEPOB70

Mechanical Straightening of the 3-m Accelerating Structures at the Advanced Photon Source

linac, photon, operation, alignment

1051

D.J. Bromberek, W.G. Jansma, T.L. Smith, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

A project is underway at the Advanced Photon Source to mechanically straighten the thirteen 3 meter accelerating structures in the Linac in order to minimize transverse wakefield, and improve charge transport efficiency and beam quality. Flexure supports allow positioning of the structures in the X & Y directions. Mechanical design of the flexure support system, straightening techniques, mechanical measurement methods, and mechanical & RF results will be discussed.

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THA1IO02

Results of the 2015 Helium Processing of CEBAF Cryomodules

cavity, cryomodule, radiation, vacuum

1054

M.A. Drury, F. Humphry, L.K. King, M.D. McCaughan, A.D. Solopova
JLab, Newport News, Virginia, USA

The CEBAF accelerator at Jefferson Lab consists of an injector and two linacs connected by arcs. Each linac contains 25 cryomodules that are designed to deliver an integrated energy of 2.2 GeV per pass to an electron beam in order to meet 12 GeV energy requirements. Helium processing is a processing technique that is used to reduce field emission (FE) in SRF cavities. Helium processing of the 50 installed linac cryomodules was seen as necessary to support 12 GeV energy requirements. This paper will describe the processing procedure and summarize the results of this effort. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

Slides THA1IO02 [3.803 MB]

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THA1CO03

MAX IV and Solaris 1.5 GeV Storage Rings Magnet Block Production Series Measurement Results

storage-ring, synchrotron, lattice, magnet-design

1058

M.A.G. Johansson
MAX IV Laboratory, Lund University, Lund, Sweden
K. Karaś
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
R. Nietubyć
NCBJ, Świerk/Otwock, Poland

The magnet design of the MAX IV and Solaris 1.5 GeV storage rings replaces the conventional support girder + discrete magnets scheme of previous third-generation synchrotron radiation light sources with an integrated design having several consecutive magnet elements precision-machined out of a common solid iron block, with mechanical tolerances of ±0.02 mm over the 4.5 m block length. The production series of 12+12 integrated magnet block units, which was totally outsourced to industry, was completed in the spring of 2015, with mechanical and magnetic QA conforming to specifications. This article presents mechanical and magnetic field measurement results of the full production series.

Slides THA1CO03 [7.517 MB]

Poster THA1CO03 [1.117 MB]

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THA1CO04

Persistent Current Effect in 15-16 T Nb3Sn Accelerator Dipoles and its Correction

dipole, ion-effects, sextupole, collider

1061

A.V. Zlobin, V.V. Kashikhin
Fermilab, Batavia, Illinois, USA

Funding: * This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry.

Slides THA1CO04 [3.440 MB]

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THA1CO05

Thermal Modeling and Cryogenic Design of a Helical Superconducting Undulator Cryostat

cryogenics, undulator, operation, radiation

1064

Y. Shiroyanagi, J.D. Fuerst, Q.B. Hasse, Y. Ivanyushenkov
ANL, Argonne, Illinois, USA

A conceptual design for a helical superconducting undulator (HSCU) for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL) has been completed. The device differs sufficiently from the existing APS planar superconducting undulator (SCU) design to warrant development of a new cryostat based on value engineering and lessons learned from the existing planar SCU. Changes include optimization of the existing cryocooler-based refrigeration system and thermal shield as well as cost reduction through the use of standard vacuum hardware. The end result is a design that provides significantly larger 4.2 K refrigeration margin in a smaller package for greater installation flexibility in the APS storage ring. This paper presents ANSYS-based thermal analysis of the cryostat, including estimated static and dynamic (beam-induced) heating, and compares the new design with the existing planar SCU cryostat.
Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.

Slides THA1CO05 [3.905 MB]

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THA1CO06

Status of the Development of Superconducting Undulators for Storage Rings and Free Electron Lasers at the Advanced Photon Source

undulator, photon, vacuum, operation

1068

Y. Ivanyushenkov, C.L. Doose, J.F. Fuerst, E. Gluskin, K.C. Harkay, Q.B. Hasse, M. Kasa, Y. Shiroyanagi, D. Skiadopoulos, E. Trakhtenberg
ANL, Argonne, Illinois, USA
P. Emma
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Development of superconducting undulator (SCU) technology continues at the Advanced Photon Source (APS). Experience of building and successful operation of the first short-length, 16-mm period length superconducting undulator SCU0 paved a way for the second 1-m long, 18-mm period device, SCU1, which is in operation since May 2015. The APS SCU team has also built and tested a 1.5-m long, 21-mm period undulator as a part of LCLS SCU R&D program aiming at demonstration of SCU technology availability for free electron lasers. This undulator successfully achieved all the requirements including a phase error of 5 degree rms. Our team is currently completing one more 1-m, 18-mm period undulator that will replace the SCU0. We are also working on a helical SCU for the APS. The status of these projects will be presented.

Slides THA1CO06 [3.545 MB]

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THA2IO01

Specifics of Electron Dynamics in High Energy Circular e⁺e⁻ Colliders

collider, sextupole, luminosity, impedance

1071

Q. Qin, J. Gao, H. Geng, P. He, D. Wang, N. Wang, Y. Wang, Y. Zhang
IHEP, Beijing, People's Republic of China

At the energies envisioned for the FCC-ee the synchrotron radiation produces not only closed orbit effects but also some dynamics effects including strong "beta-synchrotron" coupling due to radiation in the final focus quadrupoles. Past experience with LEP and other machines as well as the implications for the new wave of circular electron collider proposals will be discussed.

Slides THA2IO01 [6.536 MB]

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THA2IO02

High Gradient PM Technology for Ultra-High Brightness Rings

quadrupole, storage-ring, HOM, radiation

1077

G. Le Bec, J. Chavanne
ESRF, Grenoble, France

Permanent magnets have long been major components in accelerator-based light sources, particularly as a part of insertion devices. However, their use as main lattice magnets (dipoles, quadrupoles) has been so far somewhat limited. The present trend towards small magnet apertures, exemplified by various multibend achromat designs currently under commissioning or design/construction opens up the discussion once more on the large-scale use of permanent magnets as a means to achieve extremely high gradients in future diffraction-limited storage rings. This paper will review the current R&D programs on the use of permanent magnets in the lattice of high brightness storage rings.

Slides THA2IO02 [5.770 MB]

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THA2CO03

New 1.4 Cell RF Photoinjector Design for High Brightness Beam Generation

cathode, brightness, laser, electron

1083

E. Pirez, P. Musumeci
UCLA, Los Angeles, California, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: This work was partially funded by NSF grant 145583
The new electromagnetic and mechanical designs of the S-band 1.4 cell photoinjector are discussed. A novel fabrication method is adopted to replace the brazing process with a clamping technique achieving lower breakdown probability. The photoinjector is designed to operate at a 120 MV/m gradient and an optimal injection phase of 70 degrees to improve the extraction field by a factor of 1.9 compared to standard 1.6 cell designs with the same peak field. New geometries and features are implemented to improve beam quality for the demand of high brightness beam applications.

Slides THA2CO03 [2.444 MB]

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THA2CO04

Bench Measurements of a Multi-Frequency Prototype Cavity for the Fast Kicker in the JLEIC Circulator Cooler Ring

cavity, simulation, kicker, electron

1087

Y.L. Huang
IMP/CAS, Lanzhou, People's Republic of China
J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177
A multi-frequency copper prototype cavity with 5 odd harmonic modes (from 95.26 MHz to 857.34 MHz) is fabricated and bench measured at JLab. This quarter wavelength resonator (QWR) based deflecting cavity is an half scale prototype of the five-mode cavity (from 47.63 MHz to 428.67 MHz) in the QWRs group developed for the ultrafast harmonic RF kicker in the proposed Jefferson Lab Electron Ion Collider (JLEIC, formerly MEIC). With this prototype cavity, several RF measurements are performed and the results show good agreement with the simulation results.

Slides THA2CO04 [7.286 MB]

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THB2IO02

Production of Medical Isotopes With Electron Linacs

target, radiation, electron, photon

1091

D.A. Rotsch, K. Alford, J.L. Bailey, D.L. Bowers, T. Brossard, M.A. Brown, S. Chemerisov, D. Ehst, J.P. Greene, R. Gromov, J.J. Grudzinski, L. Hafenrichter, A.S. Hebden, T.A. Heltemes, W.F. Henning, J. Jerden, C.D. Jonah, M. Kalensky, J.F. Krebs, V. Makarashvili, B.J. Micklich, J.A. Nolen, K.J. Quigley, J.F. Schneider, N.A. Smith, D.C. Stepinski, P. Tkac, G.F. Vandegrift, M. Virgo, K.A. Wesolowski, A.J. Youker
ANL, Argonne, Illinois, USA
Z. Sun
SCSU, Orangeburg, South Carolina, USA

Radioisotopes play important roles in numerous areas ranging from medical treatments to national security and basic research. Radionuclide production technology for medical applications has been pursued since the early 1900s both commercially and in nuclear science centers. Many medical isotopes are now in routine production and are used in day-to-day medical procedures. Despite these advancements, research is accelerating around the world to improve the existing production methodologies as well as to develop novel radionuclides for new medical applications. Electron linear accelerators (linacs) are unique sources of radioisotopes. Even though the basic technology has been around for decades, only recently have electron linacs capable of producing photons with sufficient energy and flux for radioisotope production become available. Housed in Argonne National Laboratory's building 211 is a newly upgraded 50 MeV/30-kW electron linear accelerator, capable of producing a wide range of radioisotopes. This talk will focus on the work being performed for the production of the medical isotopes 99Mo (99Mo/99mTc generator), 67Cu, and 47Sc.

Slides THB2IO02 [25.926 MB]

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THB2IO03

Fulfilling the Mission of Brookhaven ATF as DOE's Flagship User Facility in Accelerator Stewardship

laser, electron, acceleration, plasma

1096

I. Pogorelsky, I. Ben-Zvi, M.A. Palmer
BNL, Upton, Long Island, New York, USA

Funding: DOE
25 years ago, Brookhaven Accelerator Test Facility (ATF), sponsored by the U.S. Department of Energy's (DOE's) Office of High-Energy Physics (HEP), pioneered a concept of a proposal-driven user facility for advanced accelerator research using lasers and electron beams. Since then, the ATF became an internationally recognized destination for researchers to benefit from free access to unique equipment not affordable otherwise to individual institutions and businesses. We will show by examples how collaborative user research achieves high productivity when supported by the ATF's capabilities. Researchers from academia, industry and national laboratories coming to ATF successfully investigate wide range of topics. Recently endorsed as an Office of Science National User Facility and a flagship in Accelerator Stewardship, ATF continues broadening its user community. DOE is now planning a considerable expansion of the ATF's capabilities via simultaneously upgrading the parameters of the e-beam and laser.

Slides THB2IO03 [49.425 MB]

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THPOA04

Maximum Brightness of Linac-Driven Electron Beams in the Presence of Collective Effects

brightness, linac, electron, emittance

1101

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Linear accelerators capable of delivering high brightness electron beams are essential components of a number of research tools, such as free electron lasers (FELs) and elementary particle colliders. In these facilities the charge density is high enough to drive undesirable collective effects (wakefields) that may increase the beam emittance relative to the injection level, eventually degrading the nominal brightness. We formulate a limit on the final electron beam brightness, imposed by the interplay of geometric transverse wakefield in accelerating structures and coherent synchrotron radiation in energy dispersive regions*. Numerous experimental data of VUV and X-ray FEL drivers validate our model. This is then used to show that a normalized brightness of 10¹⁶ A/m², promised so far by ultra-low charge beams (1-10 pC), can in fact be reached with a 100 pC charge beam in the Italian FERMI FEL linac, with the existing machine configuration.**
*Physical Review Special Topics - Accelerators And Beams 17, 110702 (2014)
**Physical Review Special Topics - Accelerators And Beams 16, 050701 (2013)

Poster THPOA04 [0.828 MB]

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THPOA05

Intrabeam Scattering in High Brightness Electron Linacs

electron, emittance, linac, quadrupole

1104

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The role played by Intra-Beam Scattering (IBS) in high brightness electron linacs, like those driving free electron lasers, is studied analytically and with particle tracking. We found that IBS typically plays no significant role in the microbunching instability that develops in such accelerators*. A partial damping of the instability through IBS is envisaged, however, with dedicated magnetic insertions. The feasibility of linear and circular lattice designs to cumulate relevant IBS-induced energy spread, and the interplay with microbunching instability, are discussed theoretically, and with the help of tracking codes.
* S. Di Mitri, PRST-AB 17, 074401 (2014)

Poster THPOA05 [0.547 MB]

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THPOA06

CSR-Immune Arc Compressors for Recirculating Accelerators Driving High Brightness Electron Beams

optics, emittance, dipole, sextupole

1108

S. Di Mitri, M. Cornacchia
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The advent of short electron bunches in high brightness linear accelerators has raised the awareness of the accelerator community to the degradation of the beam transverse emittance by coherent synchrotron radiation (CSR) emitted in magnetic bunch length compressors, transfer lines and turnaround arcs. We reformulate the concept of CSR-driven beam optics balance, and apply it to the general case of varying bunch length in an achromatic cell*. The dependence of the CSR-perturbed emittance to beam optics, mean energy, and bunch charge is shown. The analytical findings are compared with particle tracking results**. Practical considerations on CSR-induced energy loss and nonlinear particle dynamics are included. As a result, we identify the range of parameters that allows feasibility of an arc compressor in a recirculating accelerator driving, for example, a free electron laser or a linear collider.
*S. Di Mitri and M. Cornacchia, EPL, 109 (2015) 62002
**S. Di Mitri, NIM A 806 (2016) 184'192

Poster THPOA06 [0.616 MB]

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THPOA07

Probablistic Estimation of Low Energy Electron Trapping in Quadrupoles

electron, quadrupole, storage-ring, simulation

1112

K.G. Sonnad
KEK, Ibaraki, Japan
J.A. Crittenden, K.G. Sonnad
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Electron cloud formation in quadrupoles is important for storage rings because they have the potential of being trapped for a time period that exceeds the revolution period of the beam. This can result in a turn by turn build up of cloud, that could potentially interfere with beam motion. The mechanism of electron trapping can be understood based on dynamics associated with the motion of an isolated charged particle in a magnetic field. In such a system, energy is conserved and so is the magnetic moment of the gyrating electron which is an adiabatic invariant. This leads to determination of a so called loss cone in velocity space. Using these principles we describe a method to estimate the probability distribution of trapping across the cross-section of a quadrupole for a given field gradient and electron energy. Such an estimate can serve as a precursor to more detailed numerical studies of electron cloud build and trapping in quadrupoles.

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THPOA08

Transformer Ratio Enhancement Experiment Based on Emittance Exchanger in Argonne Wakefield Accelerator

wakefield, experiment, GUI, emittance

1115

Q. Gao, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
S.P. Antipov
Euclid Beamlabs LLC, Bolingbrook, USA
M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

The transformer ratio is an important figure of merit in collinear wakefield acceleration, it indicates the efficiency of energy transferring from drive bunch to witness bunch. Higher transformer ratio will significantly reduce the length of accelerator thus reducing the cost of accelerator construction. However, for the gaussian bunch, this ratio has its limit of 2. To obtain higher transformer ratio, one possible method is to tailor the beam current profile to specific shapes. One method of beam shaping is based on emittance exchange, which has been demonstrated at the Argonne Wakefield Accelerator. Its principle is to tailor the beam transversely using a mask then exchange the beam's transverse profile and longitudinal profile. In this paper, we describe our efforts to optimize the beamline and mask in order to generate a triangular beam with quadratic head, which has a transformer ratio of 6.4. We also present our design of a dielectric slab based accelerating structure to measure the transformer ratio. Finally, we discuss an experiment for this high transformer ratio at Argonne Wakefield Accelerator Laboratory.

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THPOA13

Modeling of Dipole and Quadrupole Fringe-Field Effects for the Advanced Photon Source Upgrade Lattice

dipole, quadrupole, lattice, multipole

1119

M. Borland, R.R. Lindberg
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The proposed upgrade of the Advanced Photon Source (APS) to a multibend-achromat lattice requires shorter and much stronger quadrupole magnets than are present in the existing ring. This results in longitudinal gradient profiles that differ significantly from a hard-edge model. Additionally, the lattice assumes the use of five-segment longitudinal gradient dipoles. Under these circumstances, the effects of fringe fields and detailed field distributions are of interest. We evaluated the effect of soft-edge fringe fields on the linear optics and chromaticity, finding that compensation for these effects is readily accomplished. In addition, we evaluated the reliability of standard methods of simulating hard-edge nonlinear fringe effects in quadrupoles.

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THPOA14

Ion Effects in the APS Particle Accumulator Ring

simulation, vacuum, emittance, coherent-effects

1123

J.R. Calvey, K.C. Harkay, C. Yao
ANL, Argonne, Illinois, USA

Trapped ions in the APS Particle Accumulator Ring (PAR) lead to a positive coherent tune shift in both planes, which increases along the PAR cycle as more ions accumulate. This effect has been studied using an ion simulation code developed at SLAC. After modifying the code to include a realistic vacuum profile, multiple ionization, and the effect of shaking the beam to measure the tune, the simulation agrees well with our measurements. This code has also been used to evaluate the possibility of ion instabilities at the high bunch charge needed for the APS-Upgrade.

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THPOA15

Adaptive Space Charge Calculations in MADX-SC

emittance, simulation, optics, resonance

1126

Y.I. Alexahin, V.V. Kapin, A. Valishev
Fermilab, Batavia, Illinois, USA
F. Schmidt, R. Wasef
CERN, Geneva, Switzerland

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
Since a few years MAD-X allows to simulate beam dynamics with frozen space charge à la Basseti-Erskine. The limitation of simulation with a fixed distribution is somewhat overcome by an adaptive approach that consists of updating the emittances once per turn and by recalculating the Twiss parameters after certain intervals, typically every 1,000 turns to avoid an excessive slowdown of the simulations. The technique has been benchmarked for the PS machines over 800, 000 turns. MADX-SC code developments are being discussed that include the re-introduction of acceleration into MAD-X and more advanced beam σ calculations that will avoid code interruptions for the Twiss parameters calculation.

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THPOA16

Gaseous H2-Filled Helical FOFO Snake for Initial 6D Ionization Cooling of Muons

solenoid, emittance, focusing, dipole

1129

Y.I. Alexahin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
H2 gas-filled channel for 6D ionization cooling of muons is described which consists of periodically inclined solenoids of alternating polarity with 325MHz RF cavities inside them. To provide sufficient longitudinal cooling LiH wedge absorbers are placed at the minima of transverse beta-function between the solenoids. An important feature of such channel (called Helical FOFO snake) is that it can cool simultaneously muons of both signs. Theoretical considerations as well as results of simulations with G4beamline are presented.

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THPOA17

Computing Eigen-Emittances from Tracking Data

emittance, optics, simulation, controls

1132

Y.I. Alexahin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
In a strongly nonlinear system the particle distribution in the phase space may develop long tails which contribution to the covariance (σ) matrix should be suppressed for a correct estimate of the beam emittance. A method is offered based on Gaussian approximation of the original particle distribution in the phase space (Klimontovich distribution) which leads to an equation for the σ matrix which provides efficient suppression of the tails and cannot be obtained by introducing weights. This equation is easily solved by iterations in the multi-dimensional case. It is also shown how the eigen-emittances and coupled optics functions can be retrieved from the σ matrix in a strongly coupled system.

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THPOA18

Simulating Batch-on-Batch Slip-Stacking in the Fermilab Recycler Using a New Multiple Interacting Bunch Capability in Synergia

simulation, space-charge, collective-effects, wakefield

1135

E.G. Stern, R. Ainsworth, J.F. Amundson, Q. Lu
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy, contract DE-AC02-07CH11359
The Recycler is an 8 GeV/c proton storage ring at Fermilab. To achieve the 700 MW beam power goals for the NOvA neutrino oscillation experiment, the Recycler accumulates 12 batches of 80-bunch trains from the Booster using slip-stacking. One set of bunch trains are injected into the ring and decelerated, then a second set is injected at the nominal momentum. The trains slip past each other longitudinally due to their momenta difference. We have recently extended the multi-bunch portion of the Synergia beam simulation program to allow co-propagation of bunch trains at different momenta. In doing so, we have expanded the applicability of the massively parallel multi-bunch physics portion of Synergia to include new categories of bunch-bunch interactions. We present results from our first application of these capabilities to batch-on-batch slip stacking in the Recycler.

Poster THPOA18 [2.144 MB]

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THPOA19

Design Considerations for Proposed Fermilab Integrable RCS

lattice, booster, optics, proton

1138

J.S. Eldred, A. Valishev
Fermilab, Batavia, Illinois, USA

Integrable optics is an innovation in particle accelerator design that provides strong nonlinear focusing while avoiding parametric resonances. One promising application of integrable optics is to overcome the traditional limits on accelerator intensity imposed by betatron tune-spread and collective instabilities. The efficacy of high-intensity integrable accelerators will be undergo comprehensive testing over the next several years at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER). We propose an integrable RCS (iRCS) as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program. We provide a overview of the machine parameters and discuss an approach to lattice optimization. Integrable optics requires arcs with integer-pi phase advance followed by drifts with matched beta functions. We provide an example integrable lattice with features of a modern RCS - long dispersion-free drifts, low momentum compaction, superperiodicity, chromaticity correction, separate-function magnets, and bounded beta functions.

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THPOA20

Simulation of Multipacting with Space Charge Effect in PIP-II 650 MHz Cavities

simulation, space-charge, multipactoring, cavity

1142

G.V. Romanov
Fermilab, Batavia, Illinois, USA

The central element of the Proton Improvement Plan -II at Fermilab is a new 800 MeV superconducting linac, injecting into the existing Booster. Multipacting affects superconducting RF cavities in the entire range from high energy elliptical cavities to coaxial resonators for low-beta part of the linac. The extensive simulations of multipacting in the cavities with updated material properties and comparison of the results with experimental data are routinely performed during electromagnetic design at Fermilab. This work is focused on multipacting study in the low-beta and high-beta 650 MHz elliptical cavities. The new advanced computing capabilities made it possible to take the space charge effect into account in this study. The results of the simulations and new features of multipacting due to the space charge effect are discussed.

Poster THPOA20 [3.572 MB]

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THPOA21

Multipacting in HOM Coupler of LCLS-II 1.3 GHz SC Cavity

HOM, multipactoring, cavity, electron

1146

G.V. Romanov, T.N. Khabiboulline, A. Lunin
Fermilab, Batavia, Illinois, USA

During high power tests of the 1.3 GHz LCLS-2 cavity on the test stand at Fermilab an anomalous rise of temperature of the pickup antenna in the higher order mode (HOM) coupler was detected in accelerating gradient range of 5-10 MV/m. It was suggested that the multipacting in the HOM coupler may be a cause of this temperature rise. In this work the suggestion was studied, and the conditions and the location, where multipacting can develop, were found.

Poster THPOA21 [4.786 MB]

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THPOA22

Linear Lattice and Trajectory Reconstruction and Correction at FAST Linear Accelerator

lattice, experiment, cavity, solenoid

1149

A.L. Romanov, D.R. Edstrom
Fermilab, Batavia, Illinois, USA
A. Halavanau
Northern Illinois University, DeKalb, Illinois, USA

Low energy part of FAST linear accelerator based on 1.3 GHz superconducting RF cavities was successfully commissioned. During commissioning, beam based model dependent methods were used to correct linear lattice and trajectory. Lattice correction algorithm is based on analysis of beam shape from profile monitors and trajectory responses to dipole correctors. Trajectory responses to field gradient variations in quadrupoles and phase variations in superconducting RF cavities were used to correct bunch offsets in quadrupoles and accelerating cavities relative to its magnetic axes. Details of used methods and experimental results are presented.

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THPOA23

Adaptive Matching of the IOTA Ring Linear Optics for Space Charge Compensation

lattice, space-charge, insertion, experiment

1152

A.L. Romanov, A. Valishev
Fermilab, Batavia, Illinois, USA
D.L. Bruhwiler, N.M. Cook, C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA

Many present and future accelerators must operate with high intensity beams when distortions induced by space charge forces are among major limiting factors. Betatron tune depression of above approximately 0.1 per cell leads to significant distortions of linear optics. Many aspects of machine operation depend on proper relations between lattice functions and phase advances, and can be improved with proper treatment of space charge effects. We implement an adaptive algorithm for linear lattice re-matching with full account of space charge in the linear approximation for the case of Fermilab's IOTA ring. The method is based on a search for initial second moments that give closed solution and, at the same time, satisfy predefined set of goals for emittances, beta functions, dispersions and phase advances at and between points of interest. Iterative singular value decomposition based technique is used to search for optimum by varying wide array of model parameters.

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THPOA24

Testing of Advanced Technique for Linear Lattice and Closed Orbit Correction by Modeling Its Application for IOTA Ring at Fermilab

experiment, lattice, closed-orbit, insertion

1155

A.L. Romanov
Fermilab, Batavia, Illinois, USA

Many modern and most future accelerators rely on precise configuration of lattice and trajectory. Integrable Optics Test Accelerator (IOTA) at Fermilab that is coming to final stages of construction will be used to test advanced approaches of control over particles dynamics. Various experiments planned at IOTA require high flexibility of lattice configuration as well as high precision of lattice and closed orbit control. Dense element placement does not allow to have ideal configuration of diagnostics and correctors for all planned experiments. To overcome this limitations advanced method of lattice analysis is proposed that can also be beneficial for other machines. Developed algorithm is based on LOCO approach, extended with various sets of other experimental data, such as dispersion, BPM-to-BPM phase advances, beam shape information from synchrotron light monitors, responses of closed orbit bumps to variations of focusing elements and other. Extensive modeling of corrections for a big number of random seed errors is used to illustrate benefits from developed approach.

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THPOA26

Analysis of the Transport of Muon Polarization for the Fermilab G-2 Muon Experiment

proton, experiment, polarization, target

1158

D. Stratakis, K.E. Badgley, M.E. Convery, J.P. Morgan, M.J. Syphers, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA
J.D. Crnkovic, W. Morse
BNL, Upton, Long Island, New York, USA
M.J. Syphers
Northern Illinois University, DeKalb, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
The Muon g-2 experiment at Fermilab aims to measure the anomalous magnetic moment of the muon to a precision of 140 ppb ─ a fourfold improvement over the 540 ppb precision obtained in BNL experiment E821. Obtaining this precision requires controlling total systematic errors at the 100 ppb level. One form of systematic error on the measurement of the anomalous magnetic moment occurs when the muon beam injected and stored in the ring has a correlation between the muon's spin direction and its momentum. In this paper, we first analyze the creation and transport of muon polarization from the production target to the Muon g-2 storage ring. Then, we detail the spin-momentum and spin-orbit correlations and estimate their impact on the final measurement. Finally, we outline mitigation strategies that could potentially circumvent this problem.

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THPOA29

PIP-II Transfer Lines Design

booster, linac, dipole, optics

1161

A. Vivoli
Fermilab, Batavia, Illinois, USA

The U.S. Particle Physics Project Prioritization Panel (P5) report encouraged the realization of Fermilab's Proton Improvement Plan II (PIP-II) to support future neutrino programs in the United States. PIP-II aims at enhancing the capabilities of the Fermilab existing accelerator complex while simultaneously providing a flexible platform for its future upgrades. The central part of PIP-II project is the construction of a new 800 MeV H⁻ Superconducting (SC) Linac together with upgrades of the Booster and Main Injector synchrotrons. New transfer lines will also be needed to deliver beam to the downstream accelerators and facilities. In this paper we present the recent development of the design of the transfer lines discussing the principles that guided their design, the constraints and requirements imposed by the existing accelerator complex and the following modifications implemented to comply with a better understanding of the limitations and further requirements that emerged during the development of the project.

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THPOA30

SCHARGEV 1.0 - Strong Space Charge Vlasov Solver

space-charge, impedance, dipole, feedback

1164

T. Zolkin, A.V. Burov
Fermilab, Batavia, Illinois, USA

The space charge (SC) is known to be one of the major limitations for the collective transverse beam stability. When space charge is strong, i.e. SC tune shift much greater than synchrotron tune, the problem allows an exact analytical solution. For that practically important case we present a fast and effective Vlasov solver SCHARGEV (Space CHARGE Vlasov) which calculates a complete eigensystem (spatial shapes of modes and frequency spectra) and therefore provides the growth rates and the thresholds of instabilities. SCHARGEV 1.0 includes driving and detuning wake forces, and, any feedback system (damper). In the next version we will include coupled bunch interaction and Landau damping. Numerical examples for FermiLab Recycler and CERN SPS are presented.

Poster THPOA30 [1.493 MB]

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THPOA31

Sector Magnets or Transverse Electromagnetic Fields in Cylindrical Coordinates

multipole, dipole, HOM, electromagnetic-fields

1167

T. Zolkin
Fermilab, Batavia, Illinois, USA

Laplace's equation in normalized cylindrical coordinates is considered for scalar and vector potentials describing electric or magnetic fields with invariance along the azimuthal coordinate (arXiv:1603.03451). A series of special functions are found which when expanded to lowest order in power series in radial and vertical coordinates (rho=1 and y=0) replicate harmonic homogeneous polynomials in two variables. These functions are based on radial harmonics found by Edwin M. McMillan forty years ago. In addition to McMillan's harmonics, a second family of radial harmonics is introduced to provide a symmetric description between electric and magnetic fields and to describe fields and potentials in terms of the same functions. Formulas are provided which relate any transverse fields specified by the coefficients in the power series expansion in radial or vertical planes in cylindrical coordinates with the set of new functions. This result is important for potential theory and for theoretical study, design and proper modeling of sector dipoles, combined function dipoles and any general sector element for accelerator physics and spectrometry.

Poster THPOA31 [2.274 MB]

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THPOA32

Sensitivity of the Microbunching Instability to Irregularities in Cathode Current in the LCLS-II Beam Delivery System

cathode, bunching, undulator, emittance

1171

C.E. Mitchell, J. Qiang, M. Venturini
LBNL, Berkeley, California, USA
P. Emma
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract Numbers DE-AC02-76SF00515, DE-AC02-05CH11231, and the LCLS-II Project.
LCLS-II is a high-repetition rate (1 MHz) Free Electron Laser (FEL) X-ray light source now under construction at SLAC National Accelerator Laboratory. During transport to the FEL undulators, the electron beam is subject to a space charge-driven microbunching instability that can degrade the electron beam quality and lower the FEL performance if left uncontrolled. The present LCLS-II design is well-optimized to control the growth of this instability out of the electron beam shot noise. However, the instability may also be seeded by irregularities in the beam current profile at the cathode (due to non-uniformities in the temporal profile of the photogun drive laser pulse). In this paper, we describe the sensitivity of the microbunching instability to small-amplitude temporal modulations on the emitted beam current profile at the cathode, using high-resolution simulations of the LCLS-II beam delivery system.

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THPOA33

A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL

impedance, cavity, vacuum, simulation

1174

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang
LBNL, Berkeley, California, USA

The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.

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THPOA35

Analysis of Microbunching Structures in Transverse and Longitudinal Phase Spaces

bunching, simulation, electron, lattice

1177

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
R. Li
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Microbunching instability (MBI) has been a challenging issue in high-brightness electron beam transport for modern accelerators. The existing Vlasov analysis of MBI is based on single-pass configuration*. For multi-pass recirculation or a long beamline, the intuitive argument of quantifying MBI, by successive multiplication of MBI gains, was found to underestimate the effect**. More thorough analyses based on concatenation of gain matrices aimed to combine both density and energy modulations for a general beamline**. Yet, quantification still focuses on characterizing longitudinal phase space; microbunching residing in (x,z) or (x',z) was observed in particle tracking simulation. Inclusion of such cross-plane microbunching structures in Vlasov analysis shall be a crucial step to systematically characterize MBI for a beamline complex in terms of concatenating individual beamline segments. We derived a semi-analytical formulation to include the microbunching structures in longitudinal and transverse phase spaces. Having numerically implemented the generalized formulae, an example lattice*** is studied and reasonable agreement achieved when compared with particle tracking simulation.
* Heifets et al., PRSTAB 5, 064401 (2002), Huang and Kim, PRSTAB 5, 074401 (2002), and Vneturini, PRSTAB 10, 104401 (2007)
** Tsai et al., IPAC'16 (TUPOR020)
*** Di Mitri, PRSTAB 17, 074401 (2014)

Poster THPOA35 [4.710 MB]

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THPOA37

Study of 2D CSR Effects in a Compression Chicane

simulation, dipole, electron, FEL

1181

C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

The study of coherent synchrotron radiation (CSR) has been an area of great interest because of its negative impact on FEL performance. The modeling of CSR is frequently performed using a 1D approximation*, as 2D and 3D models can become extremely computational intensive. While experimental evidence is lacking in this area most studies show reasonable agreement between 1D and 2D CSR models for beam parameters in existing accelerators. In this work we focus on 2D modeling of CSR in a four-dipole chicane lattice based on the Jefferson Lab FEL. Comparison is shown between several models and measurement for energy loss due to CSR in the chicane. While good agreement is generally observed we also present investigation of several key differences observed in simulation. In particular, showing how the 1D and 2D CSR models deviate in regards to CSR and beam interaction within the drift spaces of the chicane and the downstream drift at the chicane end.
*E. Saldin, E. Schneidmiller, and M. Yurkov, Nucl. Instr. Meth. A398, 373 (1997).

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THPOA41

Simulations of Hole Injection in Diamond Detectors

electron, simulation, detector, injection

1184

G.I. Bell, D.A. Dimitrov, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, M. Gaowei, T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller
SBU, Stony Brook, New York, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences, under grant DE-SC0007577.
We present simulations of a semiconductor beam detector using the code VSIM. The 3D simulations involve the movement and scattering of electrons and holes in the semiconductor, voltages which may be applied to external contacts, and self-consistent electrostatic fields inside the device. Electrons may experience a Schottky barrier when attempting to move from the semiconductor into a metal contact. The strong field near the contact, due to trapped electrons, can result in hole injection into the semiconductor due to transmission of electrons from the valence band of the semiconductor into the metal contact. Injected holes are transported in the applied field leading to current through the detector. We compare our simulation results with experimental results from a prototype diamond X-ray detector.

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THPOA42

3D Modeling and Simulations of Electron Emission From Photocathodes With Controlled Rough Surfaces

electron, simulation, cathode, scattering

1187

D.A. Dimitrov, G.I. Bell, D.N. Smithe, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J. Smedley
BNL, Upton, Long Island, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Developments in materials design and synthesis have resulted in photocathodes that can have a high quantum efficiency (QE), operate at visible wavelengths, and are robust enough to operate in high electric field gradient photoguns, for application to free electron lasers and in dynamic electron microscopy and diffraction. However, synthesis often results in roughness, ranging from the nano to the microscale. The effect of this roughness in a high gradient accelerator is to produce a small transverse accelerating gradient, which therefore results in emittance growth. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking, and our work aims to bridge this gap. We report results on electron emission modeling and 3D simulations from photocathodes with controlled surface roughness similar to grated surfaces that have been fabricated by nanolithography. The simulations include both charge carrier dynamics in the photocathode material and a general electron emission modeling that includes field enhancement effects at rough surfaces. The models are being implemented in the VSim code.

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THPOA45

Update of the SEY Measurement at Fermilab Main Injector

electron, vacuum, proton, operation

1190

Y. Ji
IIT, Chicago, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA
R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Studies of in-situ Secondary electron yield (SEY) mea- surements of material samples at the Main Injector (MI) beam pipe wall location started in 2013. [2, 3] These studies aimed at understanding how the beam conditioning of differ- ent materials evolve if they function as MI vacuum chamber walls. The engineering run of the SEY measurement test stand was finished in 2014. From 2014 to 2016 the Fermilab accelerator intensity has increased from 24 × 10¹² protons to 42 × 1012 protons. The beam conditioning effect on SS316L and TiN coated SS316L has been observed throughout this period. [1] Improvement of the data acquisition procedure and hardware has been performed. A deconditioning pro- cess was observed during the accelerator annual shut down in 2016.

Poster THPOA45 [3.113 MB]

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THPOA46

Benchmark of RF Photoinjector and Dipole Using ASTRA, GPT, and OPAL

simulation, gun, emittance, dipole

1194

N.R. Neveu
IIT, Chicago, Illinois, USA
A. Adelmann
PSI, Villigen PSI, Switzerland
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
C.J. Metzger-Kraus
HZB, Berlin, Germany
N.R. Neveu, J.G. Power
ANL, Argonne, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S.J. Russell
LANL, Los Alamos, New Mexico, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Grant no. DE-SC0015479, and contract No. DE-AC02-06CH11357.
With the rapid improvement in computing resources and codes in recent years, accelerator facilities can now achieve and rely on accurate beam dynamics simulations. These simulations include single particle effects (e.g. particle tracking in a magnetic field) as well as collective effects such as space charge (SC), and coherent synchrotron radiation (CSR). Using portions of the Argonne Wakefield Accelerator (AWA) as the benchmark model, we simulated beam dynamics with three particle tracking codes. The AWA rf photoinjector was benchmarked, primarily to study SC, in ASTRA, GPT, and OPAL-T using a 1 nC beam. A 20° dipole magnet was used to benchmark CSR effects in GPT and OPAL-T by bending a 1nC beam at energies between 2 MeV and 100 MeV. In this paper we present the results, and discuss the similarities and differences between the codes.

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THPOA48

Model of Electron Cloud Instability in Fermilab Recycler

electron, proton, simulation, dipole

1197

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
A.V. Burov, S. Nagaitsev
Fermilab, Batavia, Illinois, USA

An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future in-tensity upgrades.

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THPOA49

Electron Cloud Trapping in Recycler Combined Function Dipole Magnets

electron, dipole, proton, vacuum

1200

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA

Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that combined function magnets trap the electron cloud with their magnetic field, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud in a combined function magnet is located at the beam center and up to 1% of the particles can be trapped by its magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulations allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a single clearing bunch of 1*10¹⁰ p at any position in the ring.

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THPOA50

Development of an Optical Cavity for LCS Sources at the Compact ERL

cavity, laser, electron, photon

1204

T. Akagi, S. Araki, Y. Honda, A. Kosuge, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
R. Hajima, M. Mori, R. Nagai, T. Shizuma
QST, Tokai, Japan

High-energy photons from the laser Compton scattering (LCS) sources are expected to be applied in various fields in a wide range photon energies from keV to GeV. High-flux and narrow-bandwidth LCS photon beam is realized in an energy recovery linac (ERL). An electron beam of high-average current and small-emittance collides with accumulating laser pulses in an enhancement cavity for generating high-flux LCS photon beam. We have developed the high-finesse bow-tie ring cavity for the LCS experiment at the Compact ERL (cERL) in KEK. In this presentation, we will report the detail of the optical cavity.

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THPOA51

Improvement of X-Ray Generation by Using Laser Compton Scattering in Laser Undulator Compact X-Ray Source(LUCX)

laser, gun, electron, photon

1207

M.K. Fukuda, S. Araki, Y. Honda, Y. Sumitomo, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source based on the laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. We have started to take X-ray images such as refraction contrast images and phase contrast imaging with Talbot interferometer. In this accelerator, 6-10keV X-rays are generated by LCS. An electron beam is produced by a 3.6cell RF-gun and accelerated to 18-24MeV by a 12cell accelerating tube. A laser pulse is stored in a 4-mirror planar optical cavity to enhance the power. To increase the flux of LCS X-rays, we perform an optimization of the beam-loading compensation, improvement of the intensity of an electron beam and a laser light at the collision point. We report the result of the X-ray generation in this accelerator.

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THPOA52

A Simulation for Bright THz Light Source from Wiggler Radiation at KEK LUCX

wiggler, radiation, simulation, experiment

1210

Y. Sumitomo, S. Araki, A. Aryshev, M.K. Fukuda, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A. Deshpande
SAMEER, Mumbai, India
N. Terunuma
Sokendai, Ibaraki, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We study a bright THz light source generated by a wiggler radiation at KEK LUCX THz experiment, where an injected four pre-micro-bunched electron beam with few hundreds femto-seconds separation plays a crucial role. The energy of pre-bunched beam reaches few MeV at an S-band 3.6 cell RF Gun, and hence the space-charge effect is not negligible. We simulate the beam optics by ASTRA code, a charged beam optics simulator with space-charge effect, and then the resultant particle distribution is passed to GENESIS, a FEL simulator to deal with the wiggler radiation. We also present an experimental result at KEK LUCX. The major advantage of this system is a compactness of total setup that is expected to generate a MW class peak power THz beam by the coherent radiation.

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THPOA53

Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method

electron, laser, luminosity, photon

1213

Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity and KEK (High Energy Accelerator Research Organization) has achieved the luminosity record in 2009. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher brightness X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed*, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected results of crab crossing laser-Compton scattering.
*V. Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

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THPOA56

Primary Study of the Photocathode Electron Gun With a Cone Cathode and Radial Polarization Laser

cathode, gun, laser, emittance

1216

R. Huang, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is partly supported by the National Nature Science Foundation of China under Grant No. 11375199.
The linearly polarized laser with oblique incidence can achieve a higher quantum efficiency (QE) of metal cathodes than that with the normal incidence, which however requires the wavefront shaping for better performance. To maintain the high QE and simplify the system, we propose a cone cathode electron gun with a radial polarization laser at normal incidence. The primary analytical estimation and numerical simulations are explored for its effect on the emittance of the electron beam.

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THPOA58

Multiple Bunch Length Operation Mode Design at HLS-II Storage Ring

cavity, lattice, radiation, storage-ring

1220

W.W. Gao
Fujian University of Technology, Fuzhou, People's Republic of China
W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: * Project supported by the National Natural Science Foundation of China (Grant No.11305170)
In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent THz radiation experiments, and the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and THz users to carry out their experiments simultaneously. Also we analyzed the physical properties such as the CSR effect, RF jitter and Touschek lifetime of this operating mode.

Poster THPOA58 [0.611 MB]

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THPOA60

Status of PLSII Operation

insertion, insertion-device, impedance, operation

1223

T.-Y. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

As the upgrade of PLS, PLSII is a 3 GeV light source in 12 super-periods (281.8 m circumference) with 5.8 nm design emittance and can store electron beam up to 400 mA with 3 superconducting RF cavities. Its most unique characteristic is that it has a short straight section and a long straight section for each cell (24 straight sections) and up to 20 insertion devices can be installed. But, as the installed insertion devices, particularly in-vacuum insertion devices, are sources of high impedance, these are quite challenging for high current operation. Current status of PLSII operation and future plans are described in this paper.

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THPOA61

A Possible Emittance Reduction Scheme for PLSII

lattice, emittance, quadrupole, electron

1226

T.-Y. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

As the upgrade of PLS, PLSII is a 3 GeV light source in 12 super-periods (281.8 m circumference) with 5.8 nm design emittance and can store electron beam up to 400 mA with 3 superconducting RF cavities. PLSII lattice is a double bend achromatic (DBA) lattice with 2 straight sections for each cell (24 straight sections). After comple-tion of PLSII, multi-bend achromatic lattice has widely been adopted to accomplish low emittance. This paper discusses how a minimal change can modify the PLSII's DBA to a quadruple bend achromatic (QBA) lattice and reduce the emittance to about a half value.

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THPOA62

Clearing Magnet Design for APS-U

storage-ring, electron, permanent-magnet, vacuum

1228

M. Abliz, J.H. Grimmer, Y. Jaski, M. Ramanathan, F. Westferro
ANL, Argonne, Illinois, USA

Abstract Advanced Photon Source is in the process of developing an upgrade of the storage ring. The Upgrade will be converting the current double bend lattice to a multi-bend lattice (MBA). In addition, the storage ring will be operated at 6 GeV and 200 mA with regular swap-out injection to keep the stored beam current constant. The swap-out injection will take place with beamline shutters open. For radiation safety to ensure that no electrons can exit the storage ring, a passive method of protecting the beamline and containing the electrons inside the storage ring tunnel is proposed. A clearing magnet will be located in all beamline front ends inside the storage ring tunnel. This article will discuss the principle, design and mechanical design of the clearing magnet scheme for the APS-Upgrade.

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THPOA63

Septum Magnet Design for APS-U

septum, injection, ECR, multipole

1231

M. Abliz, M. Borland, H. Cease, G. Decker, M.S. Jaski, J.S. Kerby, U. Wienands, A. Xiao
ANL, Argonne, Illinois, USA

Funding: * Work supported by the U. S. Department of Energy, Office of Science, under Contract No. DE AC02 06CH11357
The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring from a double-bend to a multi-bend lattice. A swap-out injection is planned for the APS-U lattice to keep a constant beam current and accommodate small, dynamic aperture. A septum magnet that has a minimum thickness of 2 mm with an injection field of 1.06 T has been designed. The stored beam chamber has an 8 mm x 6 mm super-ellipsoidal aperture. The required total deflecting angle is 89 mrad with a ring energy of 6 GeV. The magnet is straight, but is tilted in yaw, roll, and pitch from the stored beam chamber in order to meet the swap out injection requirements for the APS-U lattice. In order to minimize the leakage field inside the stored beam chamber, four different techniques were utilized in the design. As a result, the horizontal deflecting angle of the stored beam was held to only 5 μrad, and the integrated skew quadrupole inside the stored beam chamber was held to 0.09 T. The detailed techniques that were applied to the design, the field multipoles, and the resulting trajectories of the injected and stored beams are reported.

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THPOA64

MAX IV Storage Ring Magnet Installation Procedure

storage-ring, vacuum, MMI, operation

1234

K. Åhnberg, M.A.G. Johansson, P.F. Tavares, L. Thånell
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility consists of a 3 GeV storage ring, a 1.5 GeV storage ring and a full energy injector linac. The storage ring magnets are based on an integrated "magnet block" concept. Each magnet block holds several consecutive magnet elements. The 3 GeV ring consists of 140 magnet blocks and 1.5 GeV ring has 12 magnet blocks. During the installation, procedures were developed to guarantee block straightness. This article discusses the installation procedure from a mechanical point of view and presents measurement data of block straightness and ring performance.

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THPOA65

Double Triple Bend Achromat for Next Generation 3 GeV Light Sources

injection, lattice, optics, SRF

1237

A. Alekou, R. Bartolini
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Alekou, R. Bartolini
JAI, Oxford, United Kingdom
A. Alekou, R. Bartolini, T. Pulampong, R.P. Walker
DLS, Oxfordshire, United Kingdom
N. Carmignani, S.M. Liuzzo, P. Raimondi
ESRF, Grenoble, France

The Double Triple Bend Achromat (DTBA) is a newly designed cell for a next generation 3 GeV synchrotron light source. DTBA is inspired by the Double-Double Bend Achromat (DDBA) cell designed for Diamond and originates from a modification of the ESRF HMBA 6 GeV cell, combining in this way the best characteristics of each lattice. The lattice achieves a natural emittance as low as 131 pm, together with a sufficient Dynamic Aperture (DA) for injection and lifetime. Two cells are designed with different end-drift lengths providing two different Long Straight Sections (LSS) for insertion devices, 5 and 7.5 m long, in addition to a new middle-straight section of 3 m. The characteristics of the lattice together with the results on emittance, DA and Touschek lifetime are presented after extensive linear and non-linear optimisations, with and without the presence of errors and corrections.

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THPOA68

The First Particle-Based Proof of Principle Numerical Simulation of Electron Cooling

electron, proton, simulation, emittance

1241

S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Envisioned particle accelerators such as JLEIC demand unprecedented luminosities of 10³⁴ cm -2 s -1 and small emittances are key to achieve them. Electron cooling, where a 'cold' electron beam and the 'hot' proton or ion beam co-propagate in the cooling section of the accelerator, can be used to reduce the emittance growth. It is required to precisely calculate the cooling force among particles to estimate accurately the cooling time. There are different methods to simulate electron cooling. We have developed a novel code, Particles' High-order Adaptive Dynamics (PHAD), for electron cooling. This code differs from other established methods since it is the first particle-based simulation method employing full particle nonlinear dynamics. In this paper we present the first results obtained that establish electron cooling of heavy ions.

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THPOA69

Evolution of the Design of the Magnet Structure for the APS Planar Superconducting Undulators

undulator, photon, insertion-device, insertion

1245

E. Trakhtenberg, Y. Ivanyushenkov, M. Kasa
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
Abstract A number of superconducting planar undulators (SCU) with different pole gaps and periods were designed, manufactured, and successfully operated at the Advanced Photon Source (APS) storage ring. A key component of the project is the precision machining of the magnet structure and the precision of the coil winding. The design of the magnet core had a number of modifications during the evolution of the design in order to achieve the best magnetic performance. The current design of the magnet structure is based on the assembled jaws with individual poles, while previous designs utilized solid cores with machined coil grooves. The winding procedure also changed from the first test cores to the current final design. Details of the magnet structure's design, manufacturing, winding and jaw assembly, and changes made from the first prototype system to the production unit, are presented.
[1] Status of the First Planar Superconducting Undulator for the Advanced Photon Source, Y. Ivanyushenkov, E.M. Trakhtenberg et al., Proc. in IPAC-2012, New Orleans, May 2012.

Poster THPOA69 [1.287 MB]

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THA3IO01

FNAL Accelerator Complex Upgrade Possibilities

proton, booster, linac, cavity

1248

I. Kourbanis
Fermilab, Batavia, Illinois, USA

Proton Improvement Plan-II (PIP-II) is the centerpiece of Fermilab's plan for upgrading the accelerator complex to establish the leading facility in the world for particle physics research based on intense proton beams. PIP-II has been developed to provide 1.2 MW of proton beam power at the start of operations of the Long Baseline Neutrino Experiment (LBNE), while simultaneously providing a platform for eventual extension of LBNE beam power to >2 MW and enabling future initiatives in rare processes research based on high duty factor/higher beam power operations. PIP-II is based on the construction of a new 800 MeV superconducting linac, augmented by improvements to the existing Booster, Recycler, and Main Injector complex. PIP-II is currently in the development stage with an R&D program underway targeting the front end and superconducting RF acceleration technologies. This paper will describe the status of the PIP-II conceptual development, the associated technology R&D programs, and the strategy for project implementation.

Slides THA3IO01 [10.115 MB]

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THA3IO02

The ESS Accelerator: Moving into Construction

cavity, cryomodule, linac, ion-source

1252

J.G. Weisend
ESS, Lund, Sweden

The ESS accelerator construction has started and the tunnel and RF gallery will be handed over to the accelerator division in 2016 with the installation of the cryoplant starting later in the year. Beam should be delivered in June 2019 at 570 MeV and 1.5 MW with full 5 MW capability being available in 2023. The project is a highly contributed project with more than 50% of the total budget being contributed IK by more than 25 IK partners. The talk will review the project status reflecting the IK nature of the project with the many partners contributions and with some focus on the cryogenics systems.

Slides THA3IO02 [17.091 MB]

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THA3CO04

Space Charge Compensation Using Electron Columns and Electron Lenses at IOTA

electron, proton, space-charge, solenoid

1257

C.S. Park, D. Milana, V.D. Shiltsev, G. Stancari, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA
D. Milana
Politecnico/Milano, Milano, Italy

Funding: This work was supported by the United States Department of Energy under contract DE-AC02-07CH11359.
The ability to transport a high current proton beam in a ring is ultimately limited by space charge effects. Two novel ways to overcome this limit in a proton ring are by adding low energy, externally matched electron beams (electron lens, e-lens), and by taking advantage of residual gas ionization induced neutralization to create an electron column (e-column). Theory predicts that an appropriately confined electrons can completely compensate the space charge through neutralization, both transversely and longitudinally. In this report, we will discuss the current status of the Fermilab's e-lens experiment for the space charge compensation. In addition, we will show how the IOTA e-column compensates space charge with the WARP simulations. The dynamics of proton beams inside of the e-column isunderstood by changing the magnetic field of a solenoid, the voltage on the electrodes, and the vacuum pressure, and by looking for electron accumulation, as well as by considering various beam dynamics in the IOTA ring.

Slides THA3CO04 [42.834 MB]

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THB3IO01

Development of a High Brightness Source for Fast Neutron Imaging*

neutron, target, optics, linac

1260

B. Rusnak, S.G. Anderson, D.L. Bleuel, M.L. Crank, P. Fitsos, D.J. Gibson, M. Hall, M.S. Johnson, R.A. Marsh, J.D. Sain, R. Souza, A. Wiedrick
LLNL, Livermore, California, USA

Funding: *This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.
Lawrence Livermore National Lab is developing an intense, high-brightness fast neutron source to create high resolution neutron radiographs and images. An intense source (10¹¹ n/s/sr at 0 degrees) of fast neutrons (10 MeV) allows: penetrating very thick, dense objects; maintaining high scintillator response efficiency; and remaining below the air activation threshold for (n,p) reactions. Fast neutrons will be produced using a pulsed 7 MeV, 300 microamp average-current commercial ion accelerator that will deliver deuterons to a 3 atmosphere deuterium gas cell. To achieve high resolution, a small (1.5 mm diameter) beam spot size will be used, and to reduce scattering from lower energy neutrons, a transmission gas cell will be used to produce a quasi-monoenergetic neutron beam. Because of the high power density of such a tightly focused, modest-energy ion beam, the gas target is a major engineering challenge that combines a 'windowless' rotating aperture, a rotary valve to meter cross-flowing high pressure gases, a novel gas beam stop, and recirculating gas compressor systems. A summary of the progress of the system design and building effort shall be presented.

Slides THB3IO01 [6.998 MB]

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THB3CO03

Thermoacoustic Range Verification for Ion Therapy

proton, target, cavity, cyclotron

1265

S.K. Patch, Y.M. Qadadha
UWM, Milwaukee, Wisconsin, USA
R. Albright, P. Bloemhard, K. Campbell, A.P. Donoghue, T.L. Gimpel, A. Jackson, M.B. Johnson, M. Kireeff Covo, B. Ninemire, L. Phair, C.R. Siero, S.M. Small
LBNL, Berkeley, California, USA

Funding: We acknowledge support from a UWM Intramural Instrumentation Grant and by the Director, Office of Science, Office of Nuclear Physics, of the U.S. Dept. of Energy under Contract No. DE-AC02-05CH11231.
The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. We report correlation of the Bragg peak location with target structure, by overlaying thermoacoustic localization of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the inflector of the 88" cyclotron at Lawrence Berkeley National Lab. 2 Gy were delivered in 2 μs by a beam with peak current of 2 μA. Thermoacoustic emissions were detected by a clinical ultrasound array, which also generated a grayscale ultrasound image. Data was collected in a room temperature water bath and gelatin phantom with a cavity designed to mimic the intestine, where gas pockets can displace the Bragg peak. Experiments were performed with the cavity both empty and filled with olive oil. In the waterbath overlays of the Bragg peak agreed with Monte Carlo simulations to within 800±170 μm. Agreement within 1.3 ± 0.2 mm was achieved in the gelatin phantom, for which stopping power was estimated to first order from CT scans.

Slides THB3CO03 [1.156 MB]

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FRA1CO03

An Ultra-High Resolution Pulsed-Wire Magnet Measurement System

undulator, radiation, experiment, FEL

1268

A. D'Audney, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

The performance of a Free-Electron Laser (FEL) depends in part on the quality of the magnetic field in the undulator. Imperfections in the magnetic field of an undulator lead to an imperfect electron trajectory, both offset and angle, as well as a relative phase error between the oscillation phase of the electrons and the generated electromagnetic field. The result of such errors is a reduction of laser gain impacting overall FEL performance. A pulsed-wire method can be used to determine the profile of the magnetic field. This is achieved by sending a square-current pulse through a wire placed along the length of the axis that will induce a Lorentz-force interaction with the magnetic field. Measurement of the resulting displacement in the wire over time using a motion detector yields the first or second integrals of the magnetic field and so provides a measure of the local magnetic field strength. Dispersion in the wire can be corrected using algorithms, with a resulting increase in overall accuracy of the measurement. We have designed, constructed and tested a pulsed-wire magnetic measurement system and used this system to characterize the CSU FEL undulator.

Slides FRA1CO03 [4.318 MB]

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FRA1CO04

6D Phase Space Measurement of Low Energy, High Intensity Hadron Beam

simulation, electron, emittance, quadrupole

1271

B.L. Cathey
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The work has been partially supported by NSF grant 1535312
The goal of this project is to demonstrate a method for measuring the full 6D phase space of an low energy, high intensity hadron beam. This is done by combining 4D emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and phase space components. The measurement will be performed on new Beam Testing Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end.

Slides FRA1CO04 [8.295 MB]

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FRA1CO05

Progress of Gas-Filled Multi-RF-Cavity Beam Profile Monitor for Intense Neutrino Beams

plasma, electron, cavity, experiment

1275

K. Yonehara, M. Backfish, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
Q. Liu
Case Western Reserve University, Cleveland, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
A novel pressurized gas-filled multi-RF-cavity beam profile monitor has been studied that is simple and robust in high-radiation environments. Charged particles passing through each RF-cavity in the monitor produce intensity-dependent ionized plasma, which changes the gas permittivity. The sensitivity to beam intensity is adjustable using gas pressure and RF gradient. The performance of the gas-filled beam profile monitor has been numerically simulated to evaluate the sensitivity of permittivity measurements. The result indicates that the RF resonator will be useful to measure the beam profile with a charged beam intensity range from 10⁶ to 10¹³ protons/bunch. The range covers the expected beam intensities in NuMI and LBNF. The demonstration of the monitor with intense proton beams are taken place at Fermilab to validate the simulation result. The result will be given in this presentation.

Slides FRA1CO05 [3.750 MB]

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FRA1CO06

Measurement of Coherent Transition Radiation Using Interferometer and Photoconductive Antenna

electron, laser, linac, polarization

1279

K. Kan, M. Gohdo, T. Kondoh, I. Nozawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron beams are essential for light sources and time-resolved measurements. Electron beams can emit terahertz (THz) pulses using coherent transition radiation (CTR). Michelson interferometer* is one of candidates for analyzing the pulse width of an electron beam based on frequency-domain analysis. Recently, electron beam measurement using a photoconductive antenna (PCA)** based on time-domain analysis has been investigated. In this presentation, measurement of femtosecond electron beam with 35 MeV energy and < 1 nC from a photocathode based linac will be reported. Frequency- and time- domain analysis of THz pulse of CTR by combining the interferometer and PCA will be carried out.
* I. Nozawa, K. Kan et al., Phys. Rev. ST Accel. Beams 17, 072803 (2014).
** K. Kan et al., Appl. Phys. Lett. 102, 221118 (2013).

Slides FRA1CO06 [2.334 MB]

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FRB1IO02

LIGHT: A Linear Accelerator for Proton Therapy

linac, proton, rfq, MMI

1282

D. Ungaro, A. Degiovanni, P. Stabile
ADAM SA, Geneva, Switzerland

ADAM, Application of Detectors and Accelerators to Medicine is a Swiss Company based in Geneva Switzerland established on 20th December 2007. ADAM was founded to promote scientific know-how and innovations in medical technology for cancer treatment. In 2007 a first partnership agreement was signed with CERN and in 2011 ADAM has been officially recognized as CERN spin-off. After the first research results other partnership agreements were signed between ADAM and CERN with the main goal of establishing a framework within which the two parties can collaborate to develop novel technologies for detectors and accelerators. Currently ADAM research activity is mainly focused on the construction and testing of its first linear accelerator for medical application: LIGHT (Linac for Image-Guided Hadron Therapy). LIGHT is an innovative linear accelerator designed to revolutionise hadron therapy facilities by simplifying the infrastructure and make them profitable from an industrial point of view while providing a better quality beam. The current design allow LIGHT to accelerate proton beam up to 230MeV with several advantages comparing to the current solutions present in the market.

Slides FRB1IO02 [7.447 MB]

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FRA2IO01

Development and Application of Online Optimization Algorithms

injection, GUI, coupling, operation

1287

X. Huang
SLAC, Menlo Park, California, USA

Funding: DOE
Automated tuning is an online optimization process. It can be faster and more efficient than manual tuning and can lead to better performance. Automated tuning is an online optimization process. It is more efficient than manual tuning and can lead to better performance. It may also substitute or improve upon model based methods. Noise tolerance is a fundamental challenge to online optimization algorithms. We discuss our experience in developing a high efficiency, noise-tolerant optimization algorithm, the RCDS method, and the successful application of the algorithm to various real-life accelerator problems. Experience with a few other online optimization algorithms are also discussed. A performance stabilizer and an interactive optimization GUI are presented.

Slides FRA2IO01 [3.601 MB]

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FRA2IO02

High Precision RF Control for the LCLS-II

cavity, controls, LLRF, feedback

1292

G. Huang, K. Campbell, L.R. Doolittle, J.A. Jones, C. Serrano, V.K. Vytla
LBNL, Berkeley, California, USA
S. Babel, M. Boyes, G.W. Brown, D. Cha, B. Hong, A. Ratti, C.H. Rivetta
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, Q. Du, J. Einstein, D.W. Klepec
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
The LCLS-II is a CW superconducting linac under construction to drive an X-ray FEL. The energy and timing stability requirements of the FEL drive the need for very high precision RF control. This paper summarize the design considerations and early demonstration of the performance of the components and system we developed.

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FRA2CO03

Study of the Electrical Center of a Resonant Cavity Beam Position Monitor (RF-BPM) and Its Integration With the Main Beam Quadrupole for Alignment Purposes

cavity, alignment, quadrupole, scattering

1297

S. Zorzetti, M. Wendt
CERN, Geneva, Switzerland
L. Fanucci
Università di Pisa, Pisa, Italy

To achieve the luminosity goals in a next generation linear collider, acceleration and preservation of ultra-low emittance particle beams is mission critical and requires a precise alignment between the main accelerator components. PACMAN is an innovative doctoral training program, hosted by CERN, with the goal of developing high accuracy metrology and alignment methods and tools to integrate those components in a standalone, automatic test bench. The method will be validated on CLIC components, a proposed Compact Linear Collider currently studied at CERN. The alignment between the electrical center of the Beam Position Monitor (BPM) and the magnetic center of the associated Main Beam Quadrupole (MBQ) is of particular importance to minimize the emittance blow-up, and therefore in the focus of the PACMAN project. The two components have been independently characterized on separated test benches by stretched and vibrating wire techniques. Preliminary conclusions are presented in this paper, with emphasis on the characterization of the electrical center of the BPM.
The PACMAN project is funded by the European Union' s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 606839

Slides FRA2CO03 [7.920 MB]

Poster FRA2CO03 [1.570 MB]

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FRB2IO03

GEM*STAR Accelerator-Driven Subcritical System for Improved Safety, Waste Management, and Plutonium Disposition

neutron, proton, target, simulation

1300

M.A. Cummings, R.J. Abrams, R.P. Johnson, T.J. Roberts
Muons, Inc, Illinois, USA

Operation of high-power SRF particle accelerators at two US national laboratories allows us to consider a less-expensive nuclear reactor that operates without the need for a critical core, fuel enrichment, or reprocessing. A multipurpose reactor design that takes advantage of this new accelerator capability includes an internal spallation neutron target and high-temperature molten-salt fuel with continuous purging of volatile radioactive fission products. The reactor contains less than a critical mass and almost a million times fewer volatile radioactive fission products than conventional reactors like those at Fukushima. We describe GEMSTAR , a reactor that without redesign will burn spent nuclear fuel, natural uranium, thorium, or surplus weapons material. A first application is to burn 34 tonnes of excess weapons grade plutonium as an important step in nuclear disarmament under the 2000 Plutonium Management and Disposition Agreement **. The process heat generated by this W-Pu can be used for the Fischer-Tropsch conversion of natural gas and renewable carbon into 42 billion gallons of low-CO2-footprint, drop-in, synthetic diesel fuel for the DOD.

Slides FRB2IO03 [8.681 MB]

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