NAPAC2016 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOA2CO04	MICE Operation and Demonstration of Muon Ionization Cooling	ion, emittance, simulation, optics	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOA2CO04
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MOB2CO04	Multiphysics Analysis of Crab Cavities for High Luminosity LHC Upgrade	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOB2CO04
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MOB3CO03	RHIC Au-Au Operation at 100 GeV in Run16	ion, operation, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOB3CO03
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MOPOB16	Higher Order Modes Analysis of Fermilab's Recycler Cavity	impedance, ion, 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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MOPOB20	Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators	ion, 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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MOPOB24	Design of Main Coupler for 650 MHz SC Cavities of PIP-II Project	ion, 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	ion, vacuum, diagnostics, hardware	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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MOPOB28	Progress on the Design of a Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster	ion, 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	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB29
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MOPOB32	Design and Test of the Prototype Tuner for 3.9 GHz SRF Cavity for LCLS II Project	ion, 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	ion, 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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MOPOB36	Design of the High Beta 650 MHz Cryomodule - PIP II	ion, 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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MOPOB47	Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade	ion, impedance, 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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MOPOB52	Dielectric Loaded High Pressure Gas Filled RF Cavities for Use in Muon Cooling Channels	ion, 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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MOPOB56	Frequency Domain Simulations of Rf Cavity Structures and Coupler Designs for Co-Linear X-Band Energy Booster (CXEB) with ACE3P	ion, 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	ion, 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	ion, interaction-region, 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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MOPOB60	Performance of the Cornell Main Linac Prototype Cryomodule for the CBETA Project	ion, 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, ion, 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	ion, 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	ion, 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	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB65
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MOPOB69	Wire Stretching Technique for Measuring RF Crabbing/Deflecting Cavity Electrical Center and a Demonstration Experiment on Its Accuracy	ion, 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	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB71
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MOPOB76	Field Emission Dark Current Simulation for eRHIC ERL Cavities	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB76
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TUA1CO04	Simulation of Beam Dynamics in a Strong Focusing Cyclotron	ion, cyclotron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA1CO04
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TUA2CO03	A Novel Technique of Power Control in Magnetron Transmitters for Intense Accelerators	ion, controls, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA2CO03
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TUA2CO04	Vacuum Breakdown at 110 GHz	ion, experiment, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA2CO04
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TUPOA17	A Longitudinal Digital Mode Damper System for the Fermilab Booster	ion, booster, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA17
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TUPOA18	Low Level RF Control for the PIP-II Injector Test RFQ	ion, rfq, controls, LLRF	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA18
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TUPOA19	50-MeV Run of the IOTA/FAST Electron Accelerator	ion, electron, gun, emittance	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA19
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TUPOA31	Fermilab Cryomodule Test Stand RF Interlock System	ion, controls, monitoring, interlocks	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA31
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TUPOA40	Low Noise Digitizer Design for LCLS-II LLRF	ion, FPGA, LLRF, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA40
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TUPOA41	FPGA Control of Coherent Pulse Stacking	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA41
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TUPOA42	Multicavity Coherent Pulse Stacking Using Herriott Cells	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA42
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TUPOA44	Future Prospects of RF Hadron Beam Profile Monitors for Intense Neutrino Beam	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA44
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TUPOA64	Effects of Low Frequency Buncher Field (LFB) Variation on an H⁻ Beam Phase-Energy	ion, 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
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA64
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TUPOA67	Helium Pressure Vessel Jacketing of the Fermilab SSR1 Single Spoke SC Cavities	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA67
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TUPOA74	The Design and Construction of a Resonance Control System for the IOTA RF Cavity	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA74
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TUB3IO01	Commissioning of the Max IV Light Source	ion, storage-ring, MMI, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB3IO01
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TUPOB02	Development of the Method for Evaluation of a Super-Conducting Traveling Wave Cavity With a Feedback Waveguide	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB02
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TUPOB61	Recent Improvements to TAPAs, the Android Application for Accelerator Physics and Engineering Calculations	ion, lattice, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB61
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WEB1CO02	Investigation of Structural Development in the Two-Step Diffusion Coating of Nb3Sn on Niobium	ion, niobium, SRF, experiment	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO02
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WEB1CO03	Surface Impurity Content Optimization to Maximize Q-factors of Superconducting Resonators	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO03
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WEB2IO02	Compact Crabbing Cavity Systems for Particle Colliders	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB2IO02
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WEPOA11	Frequency Manipulation of Half-Wave Resonators During Fabrication and Processing	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA11
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WEPOA13	RF Design and Simulation of a Non-Periodic Lattice Photonic Band Gap (PBG) Accelerating Structure	ion, lattice, 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	ion, impedance, 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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WEPOA25	Fermilab Accelerator R&D Program Towards Intensity Frontier Accelerators: Status and Progress	ion, proton, target, radiation	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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WEPOA28	A Recirculating Proton Linac Design	ion, linac, 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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WEPOA33	Novel Metallic Structures for Wakefield Acceleration	ion, wakefield, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA33
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WEPOA54	Simulation of a Skew Parametric Resonance Ionization Cooling Channel	ion, resonance, simulation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA54
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WEPOA60	Design Considerations for the Fermilab PIP-II 800 MeV Superconducting Linac	ion, linac, 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	ion, brightness, electron, 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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WEB3IO01	SRF Devlopment and Cryomodule Production for the FRIB Linac	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB3IO01
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WEB3CO03	650 MHz Elliptical Superconducting RF Cavities for PIP-II Project	ion, 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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WEA4CO05	Accelerator Physics Design Requirements and Challenges of RF Based Electron Cooler LEReC	ion, electron, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA4CO05
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WEB4CO03	RF Calibration of CEBAF Linac Cavities Through Phase Shifts	ion, 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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WEPOB11	Tuning of the APS Linac Accelerating Cavities After Structural Re-Alignment	ion, linac, 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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WEPOB27	Modification of 3rd Harmonic Cavity for CW Operation in LCLS-II Accelerator	ion, HOM, 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	ion, electron, 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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WEPOB41	Quality Factor in High Power Tests of Cryogenic Copper Accelerating Cavities	ion, 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	ion, 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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WEPOB54	DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC).	ion, gun, electron, laser	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	ion, electron, cathode, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB55
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WEPOB59	Performance of CEC Pop Gun During Commissioning	ion, cathode, gun, laser	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	ion, 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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WEPOB66	NSLS-II Post Mortem Function Development and Data Analysis of Beam Dump	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB66
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WEPOB69	Impedance Simulation for LEReC Booster Cavity Transformed from ERL Gun Cavity	ion, impedance, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB69
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THA1IO02	Results of the 2015 Helium Processing of CEBAF Cryomodules	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THA1IO02
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THA2CO04	Bench Measurements of a Multi-Frequency Prototype Cavity for the Fast Kicker in the JLEIC Circulator Cooler Ring	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THA2CO04
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THPOA20	Simulation of Multipacting with Space Charge Effect in PIP-II 650 MHz Cavities	ion, simulation, space-charge, multipactoring	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	ion, HOM, multipactoring, 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	ion, lattice, experiment, 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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THPOA33	A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL	ion, impedance, 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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THPOA50	Development of an Optical Cavity for LCS Sources at the Compact ERL	ion, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA50
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THPOA58	Multiple Bunch Length Operation Mode Design at HLS-II Storage Ring	ion, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA58
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THA3IO01	FNAL Accelerator Complex Upgrade Possibilities	ion, proton, booster, linac	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THA3IO01
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THA3IO02	The ESS Accelerator: Moving into Construction	ion, 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]

Paper

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MOA2CO04

MICE Operation and Demonstration of Muon Ionization Cooling

ion, emittance, simulation, optics

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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MOB2CO04

Multiphysics Analysis of Crab Cavities for High Luminosity LHC Upgrade

ion, 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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MOB3CO03

RHIC Au-Au Operation at 100 GeV in Run16

ion, operation, 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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MOPOB16

Higher Order Modes Analysis of Fermilab's Recycler Cavity

impedance, ion, 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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MOPOB20

Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators

ion, 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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MOPOB24

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

ion, 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

ion, vacuum, diagnostics, hardware

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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MOPOB28

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

ion, 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

ion, 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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MOPOB32

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

ion, 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

ion, 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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MOPOB36

Design of the High Beta 650 MHz Cryomodule - PIP II

ion, 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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MOPOB47

Beam Coupling Impedance Characterization of Third Harmonic Cavity for ALS Upgrade

ion, impedance, 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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MOPOB52

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

ion, 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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MOPOB56

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

ion, 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

ion, 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

ion, interaction-region, 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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MOPOB60

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

ion, 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, ion, 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

ion, 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

ion, 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

ion, 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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MOPOB69

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

ion, 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

ion, 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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MOPOB76

Field Emission Dark Current Simulation for eRHIC ERL Cavities

ion, 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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TUA1CO04

Simulation of Beam Dynamics in a Strong Focusing Cyclotron

ion, cyclotron, 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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TUA2CO03

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

ion, controls, 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

ion, experiment, 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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TUPOA17

A Longitudinal Digital Mode Damper System for the Fermilab Booster

ion, booster, 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

ion, rfq, controls, LLRF

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

ion, electron, gun, emittance

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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TUPOA31

Fermilab Cryomodule Test Stand RF Interlock System

ion, controls, monitoring, interlocks

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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TUPOA40

Low Noise Digitizer Design for LCLS-II LLRF

ion, FPGA, LLRF, 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

ion, 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

ion, 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

ion, 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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TUPOA64

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

ion, 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

ion, 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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TUPOA74

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

ion, 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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TUB3IO01

Commissioning of the Max IV Light Source

ion, storage-ring, MMI, 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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TUPOB02

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

ion, 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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TUPOB61

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

ion, lattice, 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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WEB1CO02

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

ion, niobium, SRF, experiment

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

ion, 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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WEB2IO02

Compact Crabbing Cavity Systems for Particle Colliders

ion, 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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WEPOA11

Frequency Manipulation of Half-Wave Resonators During Fabrication and Processing

ion, 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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WEPOA13

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

ion, lattice, 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

ion, impedance, 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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WEPOA25

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

ion, proton, target, radiation

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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WEPOA28

A Recirculating Proton Linac Design

ion, linac, 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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WEPOA33

Novel Metallic Structures for Wakefield Acceleration

ion, wakefield, 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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WEPOA54

Simulation of a Skew Parametric Resonance Ionization Cooling Channel

ion, resonance, simulation, 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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WEPOA60

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

ion, linac, 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

ion, brightness, electron, 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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WEB3IO01

SRF Devlopment and Cryomodule Production for the FRIB Linac

ion, 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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WEB3CO03

650 MHz Elliptical Superconducting RF Cavities for PIP-II Project

ion, 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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WEA4CO05

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

ion, electron, 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

ion, 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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WEPOB11

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

ion, linac, 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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WEPOB27

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

ion, HOM, 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

ion, electron, 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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WEPOB41

Quality Factor in High Power Tests of Cryogenic Copper Accelerating Cavities

ion, 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

ion, 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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WEPOB54

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

ion, gun, electron, laser

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

ion, electron, cathode, 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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WEPOB59

Performance of CEC Pop Gun During Commissioning

ion, cathode, gun, laser

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

ion, 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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WEPOB66

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

ion, 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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WEPOB69

Impedance Simulation for LEReC Booster Cavity Transformed from ERL Gun Cavity

ion, impedance, 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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THA1IO02

Results of the 2015 Helium Processing of CEBAF Cryomodules

ion, 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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THA2CO04

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

ion, 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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THPOA20

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

ion, simulation, space-charge, multipactoring

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

ion, HOM, multipactoring, 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

ion, lattice, experiment, 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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THPOA33

A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL

ion, impedance, 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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THPOA50

Development of an Optical Cavity for LCS Sources at the Compact ERL

ion, 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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THPOA58

Multiple Bunch Length Operation Mode Design at HLS-II Storage Ring

ion, 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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THA3IO01

FNAL Accelerator Complex Upgrade Possibilities

ion, proton, booster, linac

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

ion, 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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THB3CO03

Thermoacoustic Range Verification for Ion Therapy

ion, proton, target, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THB3CO03

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FRA1CO05

Progress of Gas-Filled Multi-RF-Cavity Beam Profile Monitor for Intense Neutrino Beams

ion, plasma, electron, 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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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-FRA1CO05

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FRA2IO02

High Precision RF Control for the LCLS-II

ion, 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

ion, 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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