NAPAC2016 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOA2CO04	MICE Operation and Demonstration of Muon Ionization Cooling	ion, emittance, optics, cavity	10
	A. Liu Fermilab, Batavia, Illinois, USA
	Funding: DOE, NSF, STFC, INFN, CHEPP and more The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling, the only technique that, given the short muon lifetime, can reduce the phase-space volume occupied by a muon beam quickly enough. MICE will demonstrate cooling in two steps. In the first one, Step IV, MICE will study the multiple Coulomb scattering in liquid hydrogen (LH₂) and lithium hydride (LiH). A focus coil module will provide focusing on the absorber. The transverse emittance will be measured upstream and downstream of the absorber in two spectrometer solenoids (SS). Magnetic fields generated by two match coils in the SSs allow the beam to be matched into flat-field regions in which the tracking detectors are installed. This paper will present preliminary results and present plans for data taking of MICE Step IV, together with the design of the MICE Cooling Demonstration Step (Step DEMO), which requires addition of RF systems in the current setup.
	Slides MOA2CO04 [10.025 MB]
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, cavity, luminosity, 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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MOPOB28	Progress on the Design of a Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster	ion, cavity, booster, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB28
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MOPOB53	Simulation of Ping-Pong Multipactor with Continuous Electron Seeding	ion, electron, multipactoring, resonance	181
	M. Siddiqi, R.A. Kishek UMD, College Park, Maryland, USA
	Funding: National Science Foundation grant No. PHY1535519 Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics . In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented. R.A. Kishek, Physics of Plasmas 20, 056702 (2013).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB53
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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, cavity, GUI, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB56
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MOPOB69	Wire Stretching Technique for Measuring RF Crabbing/Deflecting Cavity Electrical Center and a Demonstration Experiment on Its Accuracy	ion, cavity, experiment, cryomodule	225
	H. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The fabrication accuracy of a superconducting RF crab cavity for the Large Hadron Collider High Luminosity Upgrade and the future Electron Ion Collider requires the cavity's electric center line relative to the crabbing plane within sub mm offset and sub degree in rotation. It is very hard for the cavity's niobium sheet formation, high temperature bake and chemistry processes and finally cooling down in cryomodule to satisfy such tight tolerance. A new wire stretching technique combining with the RF measurement in the deflecting modes has been demonstrated on the bench to detect less than 10um resolution on the RF signal when the wire is moving away from the ideal electric center line. The foundation of this technique and its difference from the use in other applications will be reviewed. Based on this principle, the possible implementations for detecting RF leakage to the higher older mode couplers, cavity string alignment and cryomodule assembly will be discussed.
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MOPOB71	Consideration on Determination of Coupling Factors of Waveguide Iris Couplers	cavity, ion, DTL, coupling	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, cavity, electron, SRF	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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TUB2CO03	Fokker-Planck Analysis of Transverse Collective Instabilities in Electron Storage Rings	ion, damping, impedance, synchrotron	290
	R.R. Lindberg ANL, Argonne, Illinois, USA
	Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357 We analyze single bunch transverse instabilities due to wakefields using a Fokker-Planck model. We expand on the work of Suzuki, writing out the linear matrix equation including chromaticity, both dipolar and quadrupolar transverse wakefields, and the effects of damping and diffusion due to the synchrotron radiation. The eigenvalues and eigenvectors determine the collective stability of the beam, and we show that the predicted threshold current for transverse instability and the profile of the unstable agree well with tracking simulations. In particular, we find that predicting collective stability for high energy electron beams at moderate to large values of chromaticity requires the full Fokker-Planck analysis to properly account for the effects of damping and diffusion due to synchrotron radiation. T. Suzuki, Particle Accel., 12, 237 (1982)
	Slides TUB2CO03 [1.717 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB2CO03
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TUPOA36	Computed Tomography of Transverse Phase Space	ion, quadrupole, instrumentation, optics	358
	A.C. Watts, C. Johnstone, J.A. Johnstone Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Reserach Alliance, LLC under Contract no. DE-AC02-07CH11359 with the United States Department of Energy. Two computed tomography techniques are explored to reconstruct beam transverse phase space using both simulated beam and multi-wire profile data in the Fermilab Muon Test Area ("MTA") beamline. Both Filtered Back-Projection ("FBP") and Simultaneous Algebraic Reconstruction Technique ("SART") algorithms are considered and compared. Errors and artifacts are compared as a function of each algorithm's free parameters, and it is shown through simulation and MTA beamline profiles that SART is advantageous for reconstructions with limited profile data. awatts@fnal.gov, cjj@fnal.gov, jjohnstone@fnal.gov
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TUPOA52	Updates to the Low-Level RF Architecture for Fermilab	ion, controls, LLRF, hardware	394
	J. Einstein, B.E. Chase, E. Cullerton, P. Varghese Fermilab, Batavia, Illinois, USA S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA D. Sharma RRCAT, Indore (M.P.), India
	Fermilab has teamed with Colorado State University on several projects in LLRF controls and architecture. These projects include new LLRF hardware, updated controls techniques, and new system architectures. Here we present a summary of our work to date.
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TUPOA57	Using High Precision Beam Position Monitors at the Cornell Electron Storage Ring (CESR) to Measure the One Way Speed of Light Anisotropy	ion, electron, positron, dipole	399
	W.F. Bergan, M.J. Forster, N.T. Rider, D. L. Rubin, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.A. Schmookler MIT, Cambridge, Massachusetts, USA B. Wojtsekhowski CMU, Pittsburgh, Pennsylvania, USA
	Funding: NSF PHY-1416318 NSF DGE-1144153 The Cornell Electron Storage Ring (CESR) has been equipped with a number of high-precision beam position monitors which are capable of measuring the orbit of a circulating beam with a precision of a few microns. This technology will enable a precision measurement of deviations in the one-way speed of light. An anisotropic speed of light will alter the beam momentum as it travels around the ring, resulting in a change of orbit over the course of a sidereal day. Using counter-circulating electron and positron beams, we will be able to suppress many of the systematics such as those relating to variations in RF voltage or magnet strength. We show here initial feasibility studies to measure the stability of our beam position monitors and the various systematic effects which may hide our signal and discuss ways in which we can minimize their impact.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA57
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TUPOA58	Minimization of Emittance at the Cornell Electron Storage Ring With Sloppy Models	ion, emittance, storage-ring, lattice	402
	W.F. Bergan, A.C. Bartnik, I.V. Bazarov, H. He, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.P. Sethna Cornell University, Ithaca, New York, USA
	Funding: DOE DE-SC0013571 NSF DGE-1144153 Our current method to minimize the vertical emittance of the beam at the Cornell Electron Storage Ring (CESR) involves measurement and correction of the dispersion, coupling, and orbit of the beam and lets us reach emittances of 10 pm, but is limited by finite dispersion measurement resolution.* For further improvement in the vertical emittance, we propose using a method based on the theory of sloppy models.** The storage ring lattice permits us to identify the dependence of the dispersion and emittance on our corrector magnets, and taking the singular value decomposition of the dispersion/corrector Jacobian gives us the combinations of these magnets which will be effective knobs for emittance tuning, ordered by singular value. These knobs will permit us to empirically tune the emittance based on direct measurements of the vertical beam size. Simulations show that when starting from a lattice with realistic alignment errors which has been corrected by our existing method to have an emittance of a few pm, this new method will enable us to reduce the emittance to nearly the quantum limit, assuming that vertical dispersion is the primary source of our residual emittance. * J. Shanks, D.L. Rubin, and D. Sagan, Phys. Rev. ST Accel. Beams 17, 044003 (2014). ** K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
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TUPOA68	Design, Simulations and Experimental Demonstration of an Intra-Pulse Ramped-Energy Travelling Wave Linac for Cargo Inspection	ion, linac, electron, beam-loading	421
	S.V. Kutsaev, R.B. Agustsson, A. Arodzero, R.D.B. Berry, S. Boucher, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A. Laurich, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A. Verma RadiaBeam, Santa Monica, California, USA
	Funding: This work has been supported by the US Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contract HSHQDC-13-C-B0019. Novel radiographic imaging techniques [1] based on adaptive, intra-pulse ramped-energy short X-ray packets of pulses, a new type of fast X-ray detectors, and advanced image processing are currently some of the most promising methods for real-time cargo inspection systems. RadiaBeam Technologies is currently building the high-speed Adaptive Railroad Cargo Inspection System (ARCIS), which will enable better than 5 mm line pair resolution, penetration greater than 450 mm of steel equivalent, material discrimination over the range of 6 mm to 250 mm, 100% image sampling rate at speed 45 km/h, and minimal average dose. One of the core elements of ARCIS is a new S-band travelling wave linac with a wide range of energy control that allows energy ramping from 2 to 9 MeV within a single 16 μs RF pulse using the beam loading effect. In this paper, we will discuss the linac design approach and its principal components, as well as engineering and manufacturing aspects. The results of the experimental demonstration of intra-pulse energy ramping will be presented. [1] A. Arodzero, S. Boucher, A. Murokh, S. Vinogradov, S.V. Kutsaev. System and Method for Adaptive X-ray Cargo Inspection. US Patent Application 2015/1472051.
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TUB3CO03	Demonstration of fresh slice self seeding in a hard X-ray free electron laser	ion, electron, experiment, FEL	450
	C. Emma, C. Pellegrini UCLA, Los Angeles, USA M.W. Guetg, A.A. Lutman, A. Marinelli, J. Wu SLAC, Menlo Park, California, USA
	We discuss the first demonstration of fresh slice self seeding (FSSS) in a hard X-ray Free Electron Laser (XFEL). The FSSS method utilizes a single electron beam to generate a strong seed pulse and amplify it with a small energy spread electron slice. This extends the capability of self seeded XFELs by producing short pulses, not limited by the duration set by the self-seeding monochromator system, with high peak intensity. The scheme relies on using a parallel plate dechirper to impart a spatial chirp on the beam, and appropriate orbit control to lase with different electron beam slices before and after the self-seeding monochromator. The performance of the FSSS method is analyzed with start-to-end simulations for the Linac Coherent Light Source (LCLS). The simulations include the effect of the parallel plate dechirper and propagation of the radiation field through the monochromator. We also present results of the first successful demonstration of FSSS at LCLS. The radiation properties of FSSS X-ray pulses are compared with the Self-Amplified Spontaneous Emission (SASE) mode of FEL operation for the same electron beam parameters.
	Slides TUB3CO03 [10.423 MB]
	Poster TUB3CO03 [3.275 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB3CO03
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TUA4CO03	Loading of Wakefields in a Plasma Accelerator Section Driven by a Self-Modulated Proton Beam	ion, plasma, proton, wakefield	457
	V.K.B. Olsen, E. Adli University of Oslo, Oslo, Norway P. Muggli MPI-P, München, Germany J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	Using parameters from the AWAKE project and particle-in-cell simulations we investigate beam loading of a plasma wake driven by a self-modulated proton beam. Addressing the case of injection of an electron witness bunch after the drive beam has already experienced self-modulation in a previous plasma, we optimise witness bunch parameters of size, charge and injection phase to maximise energy gain and minimise relative energy spread and emittance of the accelerated bunch.
	Slides TUA4CO03 [3.103 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA4CO03
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TUPOB02	Development of the Method for Evaluation of a Super-Conducting Traveling Wave Cavity With a Feedback Waveguide	ion, cavity, GUI, 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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TUPOB09	Solid-State Pulsed Power System for a Stripline Kicker	ion, kicker, ISOL, operation	500
	N. Butler, M.P.J. Gaudreau, M.K. Kempkes, M.G. Munderville, F.M. Niell, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: *Work supported by US Department of Energy contract DE-SC0004255 Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers.
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TUPOB13	Simulations of Space Charge Neutralization in a Magnetized Electron Cooler	ion, electron, collider, experiment	511
	J. Gerity, P.M. McIntyre Texas A&M University, College Station, USA D.L. Bruhwiler, C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA V. Moens EPFL, Lausanne, Switzerland C.S. Park, G. Stancari Fermilab, Batavia, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-SC0015212. Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.
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TUPOB14	An Accurate and Efficient Numerical Integrator for Pair-Wise Interaction	ion, proton, software, operation	514
	A.A. Al Marzouk, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	We are developing a new numerical integrator based on Picard iteration method for Coulomb collisions. The aim is to achieve a given prescribed accuracy most efficiently. The integrator is designed to have adaptive time stepping, variable order, and dense output. It also has an automatic selection of the order and the time step. We show that with a good estimation of the radius of convergence of the expansion, we can obtain the optimal time step size. We also show how the optimal order of the integration is chosen to maintain the required accuracy. For efficiency, particles are distributed over time bins and propagated accordingly.
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TUPOB15	Implementing the Fast Multipole Boundary Element Method With High-Order Elements	ion, multipole, controls, lattice	518
	A.J. Gee, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	The next generation of beam applications will require high-intensity beams with unprecedented control. For the new system designs, simulations that model collective effects must achieve greater accuracies and scales than conventional methods allow. The fast multipole method is a strong candidate for modeling collective effects due to its linear scaling. It is well known the boundary effects become important for such intense beams. We implemented a constant element fast boundary element method (FMBEM) * as our first step in studying the boundary effects. To reduce the number of elements and discretization error, our next step is to allow for curvilinear elements. In this paper we will present our study on a quadratic and a cubic parametric method to model the surface. * A.Gee and B.Erdelyi, "A Differential Algebraic Framework for the Fast Indirect Boundary Element Method," in Proc. IPAC'16. Busan, South Korea.
	Poster TUPOB15 [1.727 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB15
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TUPOB17	Simulations in Support of Wire Beam-Beam Compensation Experiment at the LHC	ion, experiment, emittance, optics	525
	A.S. Patapenka Northern Illinois University, DeKalb, Illinois, USA R. De Maria, Y. Papaphilippou CERN, Geneva, Switzerland A. Valishev Fermilab, Batavia, Illinois, USA
	The compensation of long-range beam-beam interaction with current wires is considered as a possible technology for the HL-LHC upgrade project. A demonstration experiment is planned in the present LHC machine starting in 2018. This paper summarizes the tracking studies of long range beam-beam effect compensation in the LHC aimed to aid in planning the demonstration experiment. The impact of wire compensators is demonstrated on the tune footprints, dynamic aperture, beam emittance and beam intensity degradation. The simulations are performed with SIXTRACK code. The symplectic transport map for the wire element, its verification and implementation into the code are also discussed.
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TUPOB18	Beam Test of Masked-Chicane Micro-Buncher	ion, electron, bunching, controls	528
	Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA D.R. Broemmelsiek, D.J. Crawford, D.R. Edstrom, A.H. Lumpkin, J. Ruan, J.K. Santucci, J.C.T. Thangaraj, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA
	Funding: This work was supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. We also thank the FAST Department team for the helpful discussion and technical supports. Masking a dispersive beamline such as a dogleg or a chicane [1, 2] is a simple way to shape a beam in the longitudinal and transverse space. This technique is often employed to generate arbitrary bunch profiles for beam/laser-driven accelerators and FEL undulators or even to reduce a background noise from dark currents in electron linacs. We have been investigating a beam-modulation of a slit-masked chicane, which was deployed for crystal-channeling experiments at the injector beamline of the Fermilab Accelerator Science and Technology (FAST) facility. With a nominal beam of 3 ps bunch length, Elegant simulations showed that a slit-mask with slit period 900 um and aperture width 300 um induces a modulation with bunch-to-bunch space of about 187 um (0.25 nC), 270 um (1 nC) and 325 um (3.2 nC) with 3 ~ 6% correlated energy spread: An initial energy modulation pattern has been observed in the electron spectrometer downstream of the masked chicane using a micropulse charge of 260 pC and 40 micropulses. Investigations of the beam longitudinal modulation are planned with a Martin-Puplett interferometer and a synchro-scan streak camera at a station between the chicane and spectrometer. [1] D.C.Nguyen, B.E.Carlsten, NIMA 375, 597 (1996) [2] P.Muggli, V.Yakimeno, M.Babzien, et al., PRL 101, 054801 (2008)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB18
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TUPOB21	MuSim, A Graphical User Interface for Multiple Simulation Codes	ion, interface, resonance, proton	535
	T.J. Roberts, Y. Bao Muons, Inc, Illinois, USA Y. Bao UCR, Riverside, California, USA
	MuSim is a user-friendly program designed to interface to many different particle simulation codes, regardless of their data formats or geometry descriptions. It presents the user with a compelling graphical user interface that includes a flexible 3-D view of the simulated world plus powerful editing and drag-and-drop capabilities. All aspects of the design can be parameterized so that parameter scans and optimizations are easy. It is simple to create plots and display events in the 3-D viewer, allowing for an effortless comparison of different simulation codes. Simulation codes: G4beamline 3.02, MCNP 6.1, and MAD-X; more are coming. Many accelerator design tools and beam optics codes were written long ago, with primitive user interfaces by today's standards. MuSim is specifically designed to make it easy to interface to such codes, providing a common user experience for all, and permitting the construction and exploration of models with very little overhead. For today's technology-driven students, graphical interfaces meet their expectations far better than text-based tools, and education in accelerator physics is one of our primary goals.
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TUPOB36	Simulation Study on JLEIC High Energy Bunched Electron Cooling	ion, electron, emittance, collider	568
	H. Zhang, S.V. Benson, J. Chen, Y.S. Derbenev, R. Li, Y. Roblin, Y. Zhang JLab, Newport News, Virginia, USA H. Huang, L. Luo ODU, Norfolk, Virginia, USA
	Funding: * Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance.
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TUPOB37	Diffusion Measurement From Transverse Echoes	ion, quadrupole, dipole, octupole	572
	Y.S. Li Carleton College, Northfield, Minnesota, USA
	Beam diffusion is an important measure of stability in high intensity beams. Traditional methods of diffusion characterization (e.g. beam scraping) can be very time-consuming. In this study, we investigate the transverse beam echo as a novel technique for measuring beam diffusion. Numerical analysis of maximum echo amplitude was compared with theoretical predictions with and without diffusion. We succeeded in performing a self-consistent measurement of the linear diffusion coefficient via a parameter scan over delay time. We also demonstrated the effectiveness of pulsed quadrupoles as a means to boost echo amplitude. Finally, multi-echo sequences were also briefly investigated. Results from this study will support planned experiments at the IOTA proton ring under construction at Fermilab.
	Poster TUPOB37 [2.109 MB]
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TUPOB38	Implementation of MAD-X into MuSim	ion, interface, detector, resonance	575
	Y. Bao UCR, Riverside, California, USA T.J. Roberts Muons, Inc, Illinois, USA
	Funding: This work is supported by Muons, Inc. MuSim is a new and innovative graphical system that allows the user to design, optimize, analyze, and evaluate accelerator and particle systems efficiently. It is designed for both students and experienced physicists to use in dealing with the many modeling tools and their different description languages and data formats. G4beamline [1] and MCNP [2] have been implemented into MuSim in previous studies. In this work, we implement MAD-X [3] into MuSim so that the users can easily use the graphical interface to design beam lines with MAD-X and compare the modeling results of different codes.
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TUPOB39	Mechanical Design and Manufacturing of a Two Meter Precision Non-Linear Magnet System	ion, vacuum, alignment, optics	578
	J.D. McNevin RadiaBeam Systems, Santa Monica, California, USA R.B. Agustsson, F.H. O'Shea RadiaBeam, Santa Monica, California, USA
	Funding: Department of Energy Office of Science DE-SC0009531 RadiaBeam Technologies is currently developing a non-linear magnet insert for Fermilab's Integrable Optics Test Accelerator (IOTA), a 150 MeV circulating electron beam storage ring designed for investigating advanced beam physics concepts. The physics requirements of the insert demand a high level of precision in magnet geometry, magnet axis alignment, and corresponding alignment of the vacuum chamber geometry within the magnet modules to maximize chamber aperture size. Here we report on the design and manufacturing of the vacuum chamber, magnet manufacturing, and kinematic systems.
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TUPOB40	Fundamental Properties of a Novel, Metal-Dielectric, Tubular Structure with Magnetic RF Compensation	ion, linac, impedance, coupling	582
	A.V. Smirnov RadiaBeam Systems, Santa Monica, California, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: Supported by DoE Contract # DE-SC0011370 A number of electron beam vacuum devices such as small radiofrequency (RF) linear accelerators (linacs) and microwave traveling wave tubes (TWTs) utilize slow wave structures which are usually rather complicated in production and may require multi-step brazing and time consuming tuning. Fabrication of these devices becomes challenging at centimeter wavelengths, at large number of cells, and when a series or mass production of such structures is required. A hybrid, metal-dielectric, periodic structure for low gradient, low beam current applications is introduced here as a modification of Andreev's disk-and-washer (DaW) structure. Compensated type of coupling between even and odd TE01 modes in the novel structure results in negative group velocity with absolute values as high as 0.1c-0.2c demonstrated in simulations. Sensitivity to material imperfections and electrodynamic parameters of the disk-and-ring (DaR) structure are considered numerically using a single cell model.
	Poster TUPOB40 [1.447 MB]
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TUPOB45	A Model to Simulate the Effect of a Transverse Feedback System on Single Bunch Instability Thresholds	ion, feedback, kicker, damping	596
	G. Bassi, A. Blednykh, V.V. Smaluk BNL, Upton, Long Island, New York, USA Z. Yang Auburn University, Auburn, USA
	Funding: DOE Contract No. DE-AC02-98CH10886 A model to simulate the effect of a transverse feedback system is implemented in SPACE, a parallel, self-consistent code for collective effects. As an application, we discuss single bunch instability thresholds in the NSLS-II storage ring and compare the numerical results with measurements.
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TUPOB51	A NUMERICAL STUDY OF THE MICROWAVE INSTABILITY AT APS	ion, storage-ring, vacuum, experiment	602
	A. Blednykh, G. Bassi, V.V. Smaluk BNL, Upton, Long Island, New York, USA R.R. Lindberg ANL, Argonne, Illinois, USA
	Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886. Two particle tracking codes, ELEGANT and SPACE, have been used to simulate the microwave instability in the APS storage ring. The total longitudinal wakepotential for the APS vacuum components, computed by GdfidL, has been used as the input file for the simulations. The numerical results have been compared with bunch length and the energy spread measurements for different single-bunch intensities.
	Poster TUPOB51 [1.032 MB]
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TUPOB62	Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design	ion, proton, electron, emittance	628
	J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA Y. Hao BNL, Upton, Long Island, New York, USA
	The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB62
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TUPOB63	POSINST Simulation on Fermilab Main Injector and Recycler Ring	ion, electron, dipole, proton	632
	Y. Ji IIT, Chicago, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA R.M. Zwaska Fermilab, Batavia, Illinois, USA
	The Fermilab accelerator complex is currently undergoing an upgrade from 400kW to 700kW. This intensity could push operations into the region where electron cloud (e-cloud) generation could be observed and even cause instabilities. The POSINST simulation code was used to study how in- creasing beam intensities will affect electron cloud genera- tion. Threshold simulations show how the e-cloud density depend on the beam intensity and secondary electron yield (SEY) in the Main Injector (MI) and Recycler Ring (RR).
	Poster TUPOB63 [1.542 MB]
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TUPOB64	Beam Measurements at the PIP-II Injector Test LEBT	ion, solenoid, emittance, ion-source	636
	J.-P. Carneiro, B.M. Hanna, L.R. Prost, V.E. Scarpine, A.V. Shemyakin Fermilab, Batavia, Illinois, USA
	This paper presents the main results obtained during a series of beam measurements performed on the PIP-II Injector Test LEBT from November 2014 to June 2015. The measurements which focus on beam transmission, beam size and emittance at various locations along the beamline are compared with the beam dynamics code TRACK. These studies were aimed at preparing the beam for optimal operation of the RFQ, while evaluating simulation tools with respect to experimental data.
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WEA1IO02	Computation of Electromagnetic Fields Generated by Relativistic Beams in Complicated Structures	ion, electromagnetic-fields, vacuum, wakefield	642
	I. Zagorodnov DESY, Hamburg, Germany
	We discuss recent developments of numerical methods for computation of wakefields excited by short bunches in accelerators. They include a low-dispersive computational algorithm, conformal approximation of the boundaries, surface conductivity, and indirect wake potential integration. The implementation of these methods in the electromagnetic code ECHO for 2D and 3D problems are presented with a special emphasis on a new ECHO2D code for fast calculations of wakefields in rectangular geometries. Several examples of application of the code to calculation of wakefields for the European Free Electron Laser project and in the Linac Coherent Light Source (LCLS) project are considered.
	Slides WEA1IO02 [4.461 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA1IO02
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WEA1CO03	Simulations of Booster Injection Efficiency for the APS-Upgrade	ion, booster, lattice, injection	647
	J.R. Calvey, M. Borland, K.C. Harkay, R.R. Lindberg, C. Yao ANL, Argonne, Illinois, USA
	The APS-Upgrade will require the injector chain to provide high single bunch charge for swap-out injection. One possible limiting factor to achieving this is an observed reduction of injection efficiency into the booster synchrotron at high charge. We have simulated booster injection using the particle tracking code elegant, including a model for the booster impedance and beam loading in the RF cavities. The simulations point to two possible causes for reduced efficiency: energy oscillations leading to losses at high dispersion locations, and a vertical beam size blowup caused by ions in the particle accumulator ring. We also show that the efficiency is much higher in an alternate booster lattice with smaller vertical beta function and zero dispersion in the straight sections.
	Slides WEA1CO03 [0.682 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA1CO03
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WEA1CO04	Hollow Electron Beam Collimation for HL-LHC - Effect on the Beam Core	ion, experiment, emittance, electron	651
	M. Fitterer, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA R. Bruce, S. Papadopoulou, G. Papotti, D. Pellegrini, S. Redaelli, D. Valuch, J.F. Wagner CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.
	Slides WEA1CO04 [1.830 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA1CO04
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WEA1CO05	Microwave Instability Studies in NSLS-II	ion, lattice, wiggler, electron	655
	A. Blednykh, B. Bacha, G. Bassi, Y. Chen-Wiegart, W.X. Cheng, O.V. Chubar, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886. The microwave instability in the NSLS-II has been studied for the current configuration of insertion devices, 9 In-Vacuum Undulators (IVU's), 3EPU's, 3 Damping Wigglers. The energy spread as a function of single bunch current has been measured based on the frequency spectrum of IVU for X-Ray Spectroscopy (SRX) beam line. The results for two lattices, bare lattice with nominal energy spread 0.0005 and a lattice with one DW magnet gap closed (nominal energy spread 0.0007) are compared. In addition we used a Spectrum Analyzer to measure the beam spectrum. The instability thresholds for two different lattices cross-checked numerically using the particle tracking code SPACE and longitudinal impedance.
	Slides WEA1CO05 [2.380 MB]
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WEA2CO03	Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA	ion, electron, dipole, positron	672
	S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538. We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Complementary data with an electron beam were obtained to distinguish EC effects from other sources of tune shifts and emittance growth. High resolution electric field maps are computed with EC buildup simulation codes (ECLOUD) in the small region around the beam as the bunch passes through the cloud. These time-sliced field maps are input to a tracking simulation based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong). Tracking through the full lattice over multiple radiation damping times with electron cloud elements in the dipole and field-free regions predict vertical emittance growth, and tune shifts in agreement with the measurements.
	Slides WEA2CO03 [1.227 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA2CO03
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WEA2CO04	Vlasov Analysis of Microbunching Gain for Magnetized Beams	ion, bunching, electron, radiation	675
	C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA Y.S. Derbenev, D. Douglas, R. Li, C. Tennant JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE- AC05-06OR23177. For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring* for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design. *Ya. Derbenev and Y. Zhang, COOL'09 (FRM2MCCO01)
	Slides WEA2CO04 [4.662 MB]
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WEPOA20	Numerical Simulations of Collimation Efficiency for Beam Collimation System in the Fermilab Booster	ion, proton, booster, collimation	735
	V.V. Kapin, V.A. Lebedev, N.V. Mokhov, S.I. Striganov, I.S. Tropin Fermilab, Batavia, Illinois, USA
	A two-stage beam collimation (2SC) system has been installed in the Fermilab Booster more than 10 years ago. It consists of two primary collimators (horizontal and vertical) and three 1.2m-long secondary collimators. The two-stage collimation has never been used in Booster operations due to uncontrolled beam orbit variations produced by radial cogging (it is required for beam accumulation in Recycler). Instead, only secondary collimators were used in the single-stage collimation (1SC). Recently introduced magnetic cogging resulted in orbit stabilization in the course of almost entire accelerating cycle and created a possibility for the 2SC. In this paper, the 2SC performance is evaluated and compared the 1SC. Several parameters characterizing collimation efficiency are calculated in order to compare both schemes. A combination of the MADX and MARS15 codes is used for proton tracking in the Booster with their scattering in collimators being accounted. The dependence of efficiency on the primary collimators foil thickness is presented. The efficiency dependence on the proton energy is also obtained for the optimal foil. The feasibility of the 2SC scheme for the Booster is discussed.
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WEPOA26	Fermilab Muon Campus as a Potential Probe to Study Neutrino Physics	ion, detector, experiment, target	749
	D. Stratakis, Z. Pavlovic Fermilab, Batavia, Illinois, USA J.M. Grange ANL, Argonne, Illinois, USA S-C. Kim Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA R. Miceli Stony Brook University, Stony Brook, USA J.A. Zennamo Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. In the next decade the Fermilab Muon Campus will host two world class experiments dedicated to the search for signals of new physics. The Muon g-2 experiment will determine with unprecedented precision the anomalous magnetic moment of the muon. The Mu2e experiment will improve by four orders of magnitude the sensitivity on the search for the as-yet unobserved Charged Lepton Flavor Violation process of a neutrinoless conversion of a muon to an electron. In this paper, we will discuss the possibility for extending the Muon Campus capabilities for neutrino research. With the aid of numerical simulations, we estimate the number of produced neutrinos at various locations along the beamlines as well along the Small Baseline Neutrino Detector which faces one of the straight sections of the delivery ring. Finally, we discuss diagnostics required for realistic implementation of the experiment.
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WEPOA30	High-Performance Modeling of Plasma-Based Acceleration and Laser-Plasma Interactions.	ion, plasma, laser, GPU	758
	J.-L. Vay, G. Blaclard, R. Lehé, M. Lobet, H. Vincenti LBNL, Berkeley, California, USA B.B. Godfrey UMD, College Park, Maryland, USA M. Kirchen University of Hamburg, Hamburg, Germany P. Lee CNRS LPGP Univ Paris Sud, Orsay, France
	Funding: Work supported by US-DOE Contracts DE-AC02-05CH11231 and by the European Commission through the Marie Slowdoska-Curie actions. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231. Large-scale numerical simulations are essential to the design of plasma-based accelerators and laser-plasma interations for ultra-high intensity (UHI) physics. The electromagnetic Particle-In-Cell (PIC) approach is the method of choice for self-consistent simulations, as it is based on first principles, and captures all kinetic effects, and also scales easily (for uniform plasmas) to many cores on supercomputers. The standard PIC algorithm relies on second-order finite-difference discretizations of the Maxwell and Newton-Lorentz equations. We present here novel PIC formulations, based on the use of very high-order pseudo-spectral Maxwell solvers, which enable near-total elimination of the numerical Cherenkov instability and increased accuracy over the standard PIC method. We also discuss the latest implementations in the PIC modules Warp-PICSAR and FBPIC on the Intel Xeon Phi and GPU architectures. Examples of applications are summarized on the simulation of laser-plasma accelerators and high-harmonic generation with plasma mirrors.
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WEPOA34	Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices	ion, plasma, emittance, scattering	765
	J.S. Ellison IIT, Chicago, Illinois, USA P. Snopok Fermilab, Batavia, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: Work supported by the U.S. Department of Energy. New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA34
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WEPOA35	Wedge Absorbers for Muon Cooling with a Test Beam at MICE	ion, emittance, collider, experiment	768
	D.V. Neuffer Fermilab, Batavia, Illinois, USA J.G. Acosta, D.J. Summers UMiss, University, Mississippi, USA T.A. Mohayai IIT, Chicago, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented.
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WEPOA37	Hybrid Methods for Simulation of Muon Ionization Cooling Channels	ion, scattering, collider, experiment	775
	J.D. Kunz, P. Snopok IIT, Chicago, Illinois, USA M. Berz MSU, East Lansing, Michigan, USA J.D. Kunz Anderson University, Anderson, USA P. Snopok Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy COSY Infinity is an arbitrary-order beam dynamics simulation and analysis code. It uses high-order transfer maps of combinations of particle optical elements of arbitrary field configurations. New features have been developed and implemented in COSY to follow charged particles through matter. To study in detail the properties of muons passing through a material, the transfer map approach alone is not sufficient. The interplay of beam optics and atomic processes must be studied by a hybrid transfer map–Monte Carlo approach in which transfer map methods describe the average behavior of the particles including energy loss, and Monte Carlo methods are used to provide small corrections to the predictions of the transfer map, accounting for the stochastic nature of scattering and straggling of particles. This way the vast majority of the dynamics is represented by fast application of the high-order transfer map of an entire element and accumulated stochastic effects. The gains in speed simplify the optimization of muon cooling channels which are usually very computationally demanding. Progress on the development of the required algorithms is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA37
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WEPOA42	RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source	ion, cathode, gun, electron	789
	N. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA42
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WEPOA43	Simulations of High Current Magnetic Horn Striplines at Fermilab	ion, site, experiment, proton	792
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA J. Hylen, R.M. Zwaska Fermilab, Batavia, Illinois, USA
	Both the NuMI (Neutrinos and the Main Injector) beam line, that has been providing intense neutrino beams for several Fermilab experiments (MINOS, MINERVA, NOVA), and the newly proposed LBNF (Long Baseline Neutrino Facility) beam line, which plans to produce the highest power neutrino beam in the world for DUNE (the Deep Underground Neutrino Experiment), need pulsed magnetic horns to focus the mesons that decay to produce the neutrinos. The high-current horn and stripline design has been evolving as NuMI reconfigures for higher beam power and to meet the needs of the future LBNF program. We evaluated the two existing high-current striplines for NuMI and NOvA at Fermilab by producing Electromagnetic simulations of the magnetic horns and the required high-current striplines. In this paper, we present the comparison of these two designs using the ANSYS Electric and ANSYS Maxwell 3D codes with special attention on the critical stress points. These results are being used to support the development of evolving horn stripline designs to handle increased electrical current and higher beam power for NuMI upgrades and for the LBNF experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA43
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WEPOA46	The Muon Injection Simulation Study for the Muon g-2 Experiment at Fermilab	ion, kicker, storage-ring, injection	803
	S-C. Kim Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA N.S. Froemming University of Washington, CENPA, Seattle, USA D. L. Rubin Cornell University, Ithaca, New York, USA D. Stratakis Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. The new experiment, under construction at Fermilab, to measure the muon magnetic moment anomaly, aims to reduce measurement uncertainty by a factor of four to 140 ppb. The required statistics depend on efficient production and delivery of the highly polarized muon beams from production target into the g-2 storage ring at the design "magic"-momentum of 3.094 GeV/c, with minimal pion and proton contamination. We have developed the simulation tools for the muon transport based on G4Beamline and BMAD, from the target station, through the pion decay line and delivery ring and into the storage ring, ending with detection of decay positrons. These simulation tools are being used for the optimization of the various beam line guide field parameters related to the muon capture efficiency, and the evaluation of systematic measurement uncertainties. We describe the details of the model and some key findings of the study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA46
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WEPOA52	Modeling and Simulation of RFQs for Analysis of Fields and Frequency Deviations with Respect to Internal Dimensional Errors	ion, rfq, resonance, operation	810
	Y.W. Kang, S.W. Lee ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE. Performance of radio frequency quadrupole (RFQ) is sensitive to the errors in internal dimensions which shift resonance frequency and distort field distribution on the beam axis along the structure. The SNS RFQ has been retuned three times to compensate the deviations in frequency and field flatness with suspected dimensional changes since the start of the project for continuous operation with H⁻ ion beams. SNS now has a new RFQ as a spare that is installed in beam test facility (BTF), a low energy test accelerator. In order to understand and predict the performance deviation, full 3D modeling and simulation were performed for the SNS RFQs. Field and frequency errors from hypothetical transverse vane perturbations, and vane erosion (and metal deposition such as Cesium introduced by the ion source operation) at the low energy ends are discussed.
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WEPOA54	Simulation of a Skew Parametric Resonance Ionization Cooling Channel	ion, resonance, cavity, collider	813
	Y. Bao UCR, Riverside, California, USA A. Afanasev GWU, Washington, USA Y.S. Derbenev, V.S. Morozov, A.V. Sy JLab, Newport News, Virginia, USA R.P. Johnson Muons, Inc, Illinois, USA
	Skew Parametric-resonance Ionization Cooling (Skew-PIC) is designed for the final 6D cooling of a high-luminosity muon collider. Tracking of muons in such a channel has been modeled in MAD-X in previous studies. However, the ionization cooling process has to be simulated with a code that can handle matter dominated beam lines. In this paper we present the simulation of a Skew-PIC channel using G4beamline. We implemented the required magnetic field components into G4beamline and compare the tracking of muons by the two different codes. We optimize the cooling channel and present the muon cooling effect in the Skew-PIC channel for the first time.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA54
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WEPOA55	Modulator Simulations for Coherent Electron Cooling	ion, electron, quadrupole, plasma	816
	J. Ma, X. Wang SBU, Stony Brook, New York, USA V. Litvinenko, V. Samulyak, G. Wang, K. Yu BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA V. Samulyak SUNY SB, Stony Brook, New York, USA
	Highly resolved numerical simulations of the modulator, the first section of the proposed coherent electron cooling (CEC) device, have been performed using the code SPACE. The beam parameters for simulations are relevant to the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Numerical convergence has been studied using various numbers of macro-particles and mesh refinements of computational domain. A good agreement of theory and simulations has been obtained for the case of stationary and moving ions in uniform electron clouds with realistic distribution of thermal velocities. The main result of the paper is the prediction of modulation processes for ions with reference and off-reference coordinates in realistic Gaussian electron bunches with quadrupole field.
	Poster WEPOA55 [1.510 MB]
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WEA3IO01	Emittance Growth from Modulated Focusing in Bunched Beam Cooling	ion, emittance, electron, betatron	833
	M. Blaskiewicz BNL, Upton, Long Island, New York, USA
	The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This is the primary source of heating when the cooling is well tuned. An analytic theory of this process is presented and compared with simulations.
	Slides WEA3IO01 [4.160 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3IO01
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WEB3CO03	650 MHz Elliptical Superconducting RF Cavities for PIP-II Project	cavity, ion, SRF, linac	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB3CO03
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WEB4CO03	RF Calibration of CEBAF Linac Cavities Through Phase Shifts	ion, cavity, linac, optics	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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WEPOB02	Simulation of Swap-Out Reliability for the Advance Photon Source Upgrade	ion, operation, injection, lattice	881
	M. Borland ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The proposed upgrade of the Advanced Photon Source (APS) to a multibend achromat lattice relies on the use of swap-out injection to accommodate the small dynamic acceptance, allow use of unusual insertion devices, and minimize collective effects at high single-bunch charge. This, combined with the short beam lifetime, will make injector reliability even more important than it is for top-up operation. We used historical data for the APS injector complex to obtain probability distributions for injector up-time and down-time durations. Using these distributions, we simulated several years of swap-out operation for the upgraded lattice for several operating modes. The results indicate that obtaining very high availability of beam in the storage ring will require improvements to injector reliability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB02
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WEPOB05	Operational Experience With Beam Abort System for Superconducting Undulator Quench Mitigation	ion, kicker, beam-losses, operation	890
	K.C. Harkay, J.C. Dooling, V. Sajaev, J. Wang ANL, Argonne, Illinois, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance of the abort system–kick amplitudes and loss distributions of all bunches–was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss diagnostics described elsewhere [1]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described. [1] J. Dooling et al., these proceedings.
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WEPOB12	Multi-Objective Online Optimization of Beam Lifetime at APS	ion, sextupole, lattice, storage-ring	913
	Y.P. Sun ANL, Argonne, Illinois, USA
	In this paper, online optimization of beam lifetime at the APS (Advanced Photon Source) storage ring is presented. A general genetic algorithm (GA) is developed and employed for some online optimizations in the APS storage ring. Sextupole magnets in 40 sectors of the APS storage ring are employed as variables for the online nonlinear beam dynamics optimization. The algorithm employs several optimization objectives and is designed to run with topup mode or beam current decay mode. Up to 50\% improvement of beam lifetime is demonstrated, without affecting the transverse beam sizes and other relevant parameters. In some cases, the top-up injection efficiency is also improved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB12
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WEPOB16	Simulation Studies of a Prototype Stripline Kicker for the APS-MBA Upgrade	kicker, ion, impedance, high-voltage	928
	X. Sun, C. Yao ANL, Argonne, Illinois, USA
	Funding: *Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A prototype dual-blade stripline kicker for the APS multi-bend achromat (MBA) upgrade has been designed and developed. It was optimized with 3D CST Micro-wave Studio. The high voltage (HV) feedthrough and air-side connector were designed and optimized. The elec-tromagnetic fields along the beam path, deflecting angle and high electric fields with their locations were calculat-ed with 15 kV differential pulse voltage applied to the kicker blades through the feedthroughs. The beam im-pedance and power dissipation on different parts of the kicker and external loads were studied for a 48-bunch fill pattern. Our simulation results show that the prototype kicker with its HV feedthroughs meets the specified re-quirements. The results of TDR (time-domain reflectome-ter) test, high voltage pulse test and beam test of the pro-totype kicker assembly agreed with the simulations.
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WEPOB20	Multiple Scattering Effects on a Short Pulse Electron Beam Travelling Through Thin Beryllium Foils	ion, experiment, scattering, vacuum	937
	E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford ANL, Argonne, Illinois, USA S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA Q. Gao TUB, Beijing, People's Republic of China G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The Argonne Wakefield Accelerator beamlines have stringent vacuum requirements (100 picotorr) necessitated by the Cesium telluride photoinjector. In direct conflict with this, the structures-based wakefield accelerator research program sometimes includes worthy but complex experimental installations with components or structures unable to meet the vacuum standards. A proposed chamber to sequester such experiments safely behind a thin beryllium (Be) window is described and the results of a study of beam-quality issues due to the multiple scattering of the beam through the window are presented and compared to GEANT4 simulations via G4beamline. Three thicknesses of Be foil were used: 30, 75 and 127 micron, probed by electron beams of three different energies: 25, 45, and 65 MeV. Multiple scattering effects were evaluated by comparing the measured transverse rms beam size for the scattered vs. unscattered beam. The experimental results are presented and compared to simulations. Results are discussed along with the implications and suggestions for the future sequestered vacuum chamber design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB20
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WEPOB22	Beam Loss Simulation and Collimator System Configurations for the Advanced Photon Source Upgrade	ion, beam-losses, shielding, injection	943
	A. Xiao, M. Borland ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The proposed multi-bend achromat lattice for the Advanced Photon Source upgrade (APS-U) has a design emittance of less than 70 pm. The Touschek loss rate is high: compared with the current APS ring, which has an average beam lifetime ∼ 10 h, the simulated beam lifetime for APS-U is only ~2 h when operated in the high flux mode (I=200 mA in 48 bunches). An additional consequence of the short lifetime is that injection must be more frequent, which provides another potential source of particle loss. In order to provide information for the radiation shielding system evaluation and to avoid particle loss in sensitive locations around the ring (for example, insertion device straight sections), simulations of the detailed beam loss distribution have been performed. Several possible collimation configurations have been simulated and compared.
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WEPOB24	Preliminary Test Results of a Prototype Fast Kicker for APS MBA Upgrade	kicker, ion, high-voltage, impedance	950
	C. Yao, A. Barcikowski, A.R. Brill, J. Carwardine, T.K. Clute, Z.A. Conway, A.R. Cours, G. Decker, R.T. Keane, F. Lenkszus, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The APS multi-bend achromatic (MBA) upgrade storage ring plans to support two bunch fill patterns: a 48-bunch and a 324-bunch. A "swap out" injection scheme is required. In order provide the required kick to injected beam, to minimize the beam loss and residual oscillation of injected beam, and to minimize the perturbation to stored beam during injection, the rise, fall, and flat-top parts of the kicker pulse must be within a 16.9-ns interval. Stripling-type kickers are chosen for both injection and extraction. We developed a prototype kicker that supports a ±15kV differential pulse voltage. We performed high voltage discharge, TDR measurement, high voltage pulse test and beam test of the kicker. We report the design of the fast kicker and the test results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB24
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WEPOB25	Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns	ion, gun, cathode, electron	953
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.
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WEPOB30	Simulation of the Shot-Noise Driven Microbunching Instability Experiment at the LCLS	ion, laser, electron, bunching	967
	J. Qiang LBNL, Berkeley, California, USA Y. Ding, P. Emma, Z. Huang, D.F. Ratner, T.O. Raubenheimer, F. Zhou SLAC, Menlo Park, California, USA
	The shot-noise driven microbunching instability can significantly degrade electron beam quality in next generation light sources. Experiments were carried out at the Linac Coherent Light Source (LCLS) to study this instability. In this paper, we will present start-to-end simulation of the shot-noise driven microbunching instability experiment at the LCLS.
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WEPOB31	Dark Current Study of a Standing Wave Disk-Loaded Waveguide Structure at 17 GHz	ion, electron, experiment, multipactoring	971
	H. Xu, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA
	Funding: US DoE, Office of High Energy Physics We present calculations of the dark current in a high gradient accelerator with the intent of understanding its role in breakdown. The initial source of the dark current is the field emission of electrons. For a 17 GHz single-cell standing wave disk-loaded waveguide structure, the 3D particle-in-cell simulation shows that only a small portion of the charge emitted reaches the current monitors at the ends of the structure, while most of the current collides on the structure surfaces, causing secondary electron emission. In the simulation, a two-point multipactor process is observed on the side wall of the cell due to the low electric field on the surface. The multipactor approaches a steady state within nanoseconds when the electric field is suppressed by the electron cloud formed so that the average secondary electron yield is reduced. This multipactor current can cause the ionization of the metal material and surface outgassing, leading to breakdown. We report first results from an experiment designed to extract dark current directly from an accelerator cell from the side through two slits. First results show that the dark current behavior deviates from the field emission theory.
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WEPOB32	Performance of a Combined System Using an X-Ray FEL Oscillator and a High-Gain FEL Amplifier	ion, FEL, radiation, laser	974
	L. Gupta University of Chicago, Chicago, Illinois, USA K.-J. Kim, R.R. Lindberg ANL, Argonne, Illinois, USA
	Funding: [5] R. R. Lindberg, K.-J. Kim, "Intense, coherent x-rays at 40 keV or higher by combining an XFELO and a high-gain harmonic generation," (in prep) US DOE contract DE-AC02-06CH11357 & NSF PHY-1535639 The LCLS-II at SLAC will feature a 4 GeV CW superconducting (SC) RF linac [1] that can potentially drive a 5th harmonic X-Ray FEL Oscillator to produce fully coherent, 1 MW photon pulses with a 5 meV bandwidth at 14.4 keV [2]. The XFELO output can serve as the input seed signal for a high-gain FEL amplifier employing fs electron beams from the normal conducting SLAC linac, thereby generating coherent, fs x-ray pulses with ~TW peak powers using a tapered undulator after saturation [3]. Coherent, intense output at several tens of keV will also be feasible if one considers a harmonic generation scheme. Thus, one can potentially reach the 42 keV photon energy required for the MaRIE project [4] by beginning with an XFELO operating at the 5th harmonic to produce 8.4 keV photons using a 3.1 GeV SCRF linac, and then subsequently using the high-gain harmonic generation scheme to generate and amplify the 5th harmonic at 42 keV [5]. We report extensive GINGER simulations that determine an optimized parameter set for the combined system. [1] "Linac Coherent Light Source-II Conceptual Design Report," SLAC-R-978 (2011) [2] T. J. Maxwell, et al., "Feasibility Study for an X-Ray FEL Oscillator at the LCLS-II," IPAC, Richmond, VA (May, 2015) [3] K.-J. Kim, et al., IPAC 2016 [4] http://www.lanl.gov
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB32
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WEPOB35	LLNL Laser-Compton X-Ray Characterization	ion, electron, laser, scattering	977
	Y. Hwang, T. Tajima UCI, Irvine, California, USA G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344 30 keV Compton-scattered X-rays have been produced at LLNL. The flux, bandwidth, and X-ray source focal spot size have been characterized using an X-ray ICCD camera and results agree very well with modeling predictions. The RMS source size inferred from direct electron beam spot size measurement is 17 um , while imaging of the penumbra yields an upper bound of 42 um. The accuracy of the latter method is limited by the spatial resolution of the imaging system, which has been characterized as well, and is expected to improve after the upgrade of the X-ray camera later this year.
	Poster WEPOB35 [37.648 MB]
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WEPOB39	Photo-Injector Optimization and Validation Study with the OPAL Beam Simulation Code	ion, emittance, booster, FEL	984
	L.D. Duffy, K. Bishofberger, J.W. Lewellen, S.J. Russell, D.Y. Shchegolkov LANL, Los Alamos, New Mexico, USA
	A 42 keV x-ray free electron laser (XFEL) is a plausible technology alternative for the Matter Radiation Interactions in Extremes (MaRIE) experimental project, a concept developed by Los Alamos National Laboratory. An early pre-conceptual design for such an XFEL calls for 100 pC electron bunches with very low emittance and energy spread. High fidelity simulations that capture all beamline physics will be required to ensure a successful design. We expect to use the beam simulation code OPAL as one of the tools in this process. In this study, we validate OPAL as a photo-injector design tool by comparing its performance with published PITZ experimental data and simulations.
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WEPOB47	Development of a Short Period Cryogenic Undulator at RadiaBeam	ion, undulator, cryogenics, electron	995
	F.H. O'Shea, R.B. Agustsson, Y.C. Chen, A.J. Palmowski, E. Spranza RadiaBeam, Santa Monica, California, USA
	Funding: Work supported by DOE under contracts DE-SC0006288 and NNSA SSAA DE-NA0001979. RadiaBeam Technologies has developed a 7-mm period length cryogenic undulator prototype to test fabrications techniques in cryogenic undulator production. We present here our first prototype, the production techniques used to fabricate it, its magnetic performance at room temperature and the temperature uniformity after cool down.
	Poster WEPOB47 [2.725 MB]
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WEPOB53	Computation of Synchrotron Radiation	ion, undulator, radiation, synchrotron	1005
	D.A. Hidas BNL, Upton, Long Island, New York, USA
	This presentation introduces a new open-source software development for the computation of radiation from charged particles and beams in magnetic and electric fields. The computations are valid in the near-field regime for both relativistic and non-relativistic scenarios. This project is being developed, and is currently in use, at Brookhaven National Laboratory's National Synchrotron Light Source II. Primary applications include, but are not limited to, the computation of spectra, photon flux densities, and power density distributions from undulators, wigglers, and bending magnets on arbitrary shaped surfaces in 3D making possible detailed study of sensitive accelerator and beam-line equipment. Application interfaces are available in Python, Mathematica, and C. Practical use cases are demonstrated and benchmarked. Additionally, future upgrades will be elaborated on.
	Poster WEPOB53 [27.003 MB]
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WEPOB61	Magnetic Shielding of LEReC Cooling Section	ion, shielding, solenoid, electron	1030
	S. Seletskiy, A.V. Fedotov, D.M. Gassner, D. Kayran, G.J. Mahler, W. Meng BNL, Upton, Long Island, New York, USA
	The transverse angle of the electron beam trajectory in the low energy RHIC Electron Cooling (LEReC) accelerator cooling section (CS) must be much smaller than 100 urad. This requirement sets 2.3 mG limit on the ambient transverse magnetic field. The maximum ambient field in the RHIC tunnel along the cooling section was measured to be 0.52 G. In this paper we discuss the design of the proposed LEReC CS magnetic shielding, which is capable of providing required attenuation.
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WEPOB62	Absolute Energy Measurement of the LEReC Electron Beam	ion, dipole, electron, HOM	1033
	S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, T.A. Miller, P. Thieberger BNL, Upton, Long Island, New York, USA
	The goal of future operation of the low energy RHIC Electron Cooling (LEReC) accelerator is to cool the RHIC ion beams. To provide successful cooling, the velocities of the RHIC ion beam and the LEReC electron beam must be matched with 10^-4 accuracy. While the energy of ions will be known with the required accuracy, the e-beam energy can have an initial offset as large as 5%. The final setting of the e-beam energy will be performed by observing either the Schottky spectrum of debunched ions co-traveling with the e-beam or the recombination signal. Yet, to start observing such signals one has to set the absolute energy of the electron beam with an accuracy better than 10^-2, preferably better than 5·10^-3. In this paper we discuss how such accuracy can be reached by utilizing the LEReC 180 degree bend as a spectrometer.
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WEPOB68	DESIGN AND SIMULATION OF EMITTANCE MEASUREMENT WITH MULTI-SLIT FOR LEREC	ion, emittance, electron, space-charge	1045
	C. Liu, A.V. Fedotov, J. Kewisch, M.G. Minty BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. To improve the luminosity of beam energy scan of low energy Au-Au collision, a electron machine is under con- struction to cool ion beams in both RHIC rings with pulsed electron beam. Over the course of the project, a multi- slit device is needed to characterize the transverse beam emittance of three energies, 0.4, 1.6 and 2.6 MeV. This re- port shows the optimization and compromise of the design, which include the slit width, slit spacing, and drift space from the multi-slit to the downstream profile monitor.
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WEPOB69	Impedance Simulation for LEReC Booster Cavity Transformed from ERL Gun Cavity	ion, impedance, cavity, 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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THA2CO04	Bench Measurements of a Multi-Frequency Prototype Cavity for the Fast Kicker in the JLEIC Circulator Cooler Ring	ion, cavity, 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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THPOA07	Probablistic Estimation of Low Energy Electron Trapping in Quadrupoles	ion, electron, quadrupole, storage-ring	1112
	K.G. Sonnad KEK, Ibaraki, Japan J.A. Crittenden, K.G. Sonnad Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Electron cloud formation in quadrupoles is important for storage rings because they have the potential of being trapped for a time period that exceeds the revolution period of the beam. This can result in a turn by turn build up of cloud, that could potentially interfere with beam motion. The mechanism of electron trapping can be understood based on dynamics associated with the motion of an isolated charged particle in a magnetic field. In such a system, energy is conserved and so is the magnetic moment of the gyrating electron which is an adiabatic invariant. This leads to determination of a so called loss cone in velocity space. Using these principles we describe a method to estimate the probability distribution of trapping across the cross-section of a quadrupole for a given field gradient and electron energy. Such an estimate can serve as a precursor to more detailed numerical studies of electron cloud build and trapping in quadrupoles.
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THPOA14	Ion Effects in the APS Particle Accumulator Ring	ion, vacuum, emittance, coherent-effects	1123
	J.R. Calvey, K.C. Harkay, C. Yao ANL, Argonne, Illinois, USA
	Trapped ions in the APS Particle Accumulator Ring (PAR) lead to a positive coherent tune shift in both planes, which increases along the PAR cycle as more ions accumulate. This effect has been studied using an ion simulation code developed at SLAC. After modifying the code to include a realistic vacuum profile, multiple ionization, and the effect of shaking the beam to measure the tune, the simulation agrees well with our measurements. This code has also been used to evaluate the possibility of ion instabilities at the high bunch charge needed for the APS-Upgrade.
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THPOA15	Adaptive Space Charge Calculations in MADX-SC	ion, emittance, optics, resonance	1126
	Y.I. Alexahin, V.V. Kapin, A. Valishev Fermilab, Batavia, Illinois, USA F. Schmidt, R. Wasef CERN, Geneva, Switzerland
	Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE Since a few years MAD-X allows to simulate beam dynamics with frozen space charge à la Basseti-Erskine. The limitation of simulation with a fixed distribution is somewhat overcome by an adaptive approach that consists of updating the emittances once per turn and by recalculating the Twiss parameters after certain intervals, typically every 1,000 turns to avoid an excessive slowdown of the simulations. The technique has been benchmarked for the PS machines over 800, 000 turns. MADX-SC code developments are being discussed that include the re-introduction of acceleration into MAD-X and more advanced beam σ calculations that will avoid code interruptions for the Twiss parameters calculation.
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THPOA17	Computing Eigen-Emittances from Tracking Data	ion, emittance, optics, controls	1132
	Y.I. Alexahin Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE In a strongly nonlinear system the particle distribution in the phase space may develop long tails which contribution to the covariance (σ) matrix should be suppressed for a correct estimate of the beam emittance. A method is offered based on Gaussian approximation of the original particle distribution in the phase space (Klimontovich distribution) which leads to an equation for the σ matrix which provides efficient suppression of the tails and cannot be obtained by introducing weights. This equation is easily solved by iterations in the multi-dimensional case. It is also shown how the eigen-emittances and coupled optics functions can be retrieved from the σ matrix in a strongly coupled system.
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THPOA18	Simulating Batch-on-Batch Slip-Stacking in the Fermilab Recycler Using a New Multiple Interacting Bunch Capability in Synergia	ion, space-charge, collective-effects, wakefield	1135

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MOA2CO04

MICE Operation and Demonstration of Muon Ionization Cooling

ion, emittance, optics, cavity

10

A. Liu
Fermilab, Batavia, Illinois, USA

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

Slides MOA2CO04 [10.025 MB]

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MOB2CO04

Multiphysics Analysis of Crab Cavities for High Luminosity LHC Upgrade

ion, cavity, luminosity, 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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MOPOB28

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

ion, cavity, booster, 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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MOPOB53

Simulation of Ping-Pong Multipactor with Continuous Electron Seeding

ion, electron, multipactoring, resonance

181

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

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

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MOPOB56

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

ion, cavity, GUI, 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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MOPOB69

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

ion, cavity, experiment, cryomodule

225

H. Wang
JLab, Newport News, Virginia, USA

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

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MOPOB71

Consideration on Determination of Coupling Factors of Waveguide Iris Couplers

cavity, ion, DTL, coupling

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, cavity, electron, SRF

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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TUB2CO03

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

ion, damping, impedance, synchrotron

290

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

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

Slides TUB2CO03 [1.717 MB]

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TUPOA36

Computed Tomography of Transverse Phase Space

ion, quadrupole, instrumentation, optics

358

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

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

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TUPOA52

Updates to the Low-Level RF Architecture for Fermilab

ion, controls, LLRF, hardware

394

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

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

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TUPOA57

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

ion, electron, positron, dipole

399

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

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

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TUPOA58

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

ion, emittance, storage-ring, lattice

402

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

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

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TUPOA68

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

ion, linac, electron, beam-loading

421

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

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

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TUB3CO03

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

ion, electron, experiment, FEL

450

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

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

Slides TUB3CO03 [10.423 MB]

Poster TUB3CO03 [3.275 MB]

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TUA4CO03

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

ion, plasma, proton, wakefield

457

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

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

Slides TUA4CO03 [3.103 MB]

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TUPOB02

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

ion, cavity, GUI, 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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TUPOB09

Solid-State Pulsed Power System for a Stripline Kicker

ion, kicker, ISOL, operation

500

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

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

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TUPOB13

Simulations of Space Charge Neutralization in a Magnetized Electron Cooler

ion, electron, collider, experiment

511

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

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

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TUPOB14

An Accurate and Efficient Numerical Integrator for Pair-Wise Interaction

ion, proton, software, operation

514

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

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

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TUPOB15

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

ion, multipole, controls, lattice

518

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

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

Poster TUPOB15 [1.727 MB]

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TUPOB17

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

ion, experiment, emittance, optics

525

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

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

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TUPOB18

Beam Test of Masked-Chicane Micro-Buncher

ion, electron, bunching, controls

528

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

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

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TUPOB21

MuSim, A Graphical User Interface for Multiple Simulation Codes

ion, interface, resonance, proton

535

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

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

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TUPOB36

Simulation Study on JLEIC High Energy Bunched Electron Cooling

ion, electron, emittance, collider

568

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

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

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TUPOB37

Diffusion Measurement From Transverse Echoes

ion, quadrupole, dipole, octupole

572

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

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

Poster TUPOB37 [2.109 MB]

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TUPOB38

Implementation of MAD-X into MuSim

ion, interface, detector, resonance

575

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

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

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TUPOB39

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

ion, vacuum, alignment, optics

578

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

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

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TUPOB40

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

ion, linac, impedance, coupling

582

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

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

Poster TUPOB40 [1.447 MB]

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TUPOB45

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

ion, feedback, kicker, damping

596

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

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

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TUPOB51

A NUMERICAL STUDY OF THE MICROWAVE INSTABILITY AT APS

ion, storage-ring, vacuum, experiment

602

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

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

Poster TUPOB51 [1.032 MB]

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TUPOB62

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

ion, proton, electron, emittance

628

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

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

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TUPOB63

POSINST Simulation on Fermilab Main Injector and Recycler Ring

ion, electron, dipole, proton

632

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

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

Poster TUPOB63 [1.542 MB]

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TUPOB64

Beam Measurements at the PIP-II Injector Test LEBT

ion, solenoid, emittance, ion-source

636

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

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

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WEA1IO02

Computation of Electromagnetic Fields Generated by Relativistic Beams in Complicated Structures

ion, electromagnetic-fields, vacuum, wakefield

642

I. Zagorodnov
DESY, Hamburg, Germany

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

Slides WEA1IO02 [4.461 MB]

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WEA1CO03

Simulations of Booster Injection Efficiency for the APS-Upgrade

ion, booster, lattice, injection

647

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

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

Slides WEA1CO03 [0.682 MB]

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WEA1CO04

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

ion, experiment, emittance, electron

651

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

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

Slides WEA1CO04 [1.830 MB]

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WEA1CO05

Microwave Instability Studies in NSLS-II

ion, lattice, wiggler, electron

655

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

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

Slides WEA1CO05 [2.380 MB]

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WEA2CO03

Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA

ion, electron, dipole, positron

672

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

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

Slides WEA2CO03 [1.227 MB]

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WEA2CO04

Vlasov Analysis of Microbunching Gain for Magnetized Beams

ion, bunching, electron, radiation

675

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

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

Slides WEA2CO04 [4.662 MB]

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WEPOA20

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

ion, proton, booster, collimation

735

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

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

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WEPOA26

Fermilab Muon Campus as a Potential Probe to Study Neutrino Physics

ion, detector, experiment, target

749

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

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

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WEPOA30

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

ion, plasma, laser, GPU

758

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

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

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WEPOA34

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

ion, plasma, emittance, scattering

765

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

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

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WEPOA35

Wedge Absorbers for Muon Cooling with a Test Beam at MICE

ion, emittance, collider, experiment

768

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

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

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WEPOA37

Hybrid Methods for Simulation of Muon Ionization Cooling Channels

ion, scattering, collider, experiment

775

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

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

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WEPOA42

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

ion, cathode, gun, electron

789

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

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

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WEPOA43

Simulations of High Current Magnetic Horn Striplines at Fermilab

ion, site, experiment, proton

792

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

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

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WEPOA46

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

ion, kicker, storage-ring, injection

803

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

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

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WEPOA52

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

ion, rfq, resonance, operation

810

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

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

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WEPOA54

Simulation of a Skew Parametric Resonance Ionization Cooling Channel

ion, resonance, cavity, collider

813

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

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

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WEPOA55

Modulator Simulations for Coherent Electron Cooling

ion, electron, quadrupole, plasma

816

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

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

Poster WEPOA55 [1.510 MB]

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WEA3IO01

Emittance Growth from Modulated Focusing in Bunched Beam Cooling

ion, emittance, electron, betatron

833

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

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

Slides WEA3IO01 [4.160 MB]

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WEB3CO03

650 MHz Elliptical Superconducting RF Cavities for PIP-II Project

cavity, ion, SRF, linac

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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WEB4CO03

RF Calibration of CEBAF Linac Cavities Through Phase Shifts

ion, cavity, linac, optics

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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WEPOB02

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

ion, operation, injection, lattice

881

M. Borland
ANL, Argonne, Illinois, USA

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

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WEPOB05

Operational Experience With Beam Abort System for Superconducting Undulator Quench Mitigation

ion, kicker, beam-losses, operation

890

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

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

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WEPOB12

Multi-Objective Online Optimization of Beam Lifetime at APS

ion, sextupole, lattice, storage-ring

913

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

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

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WEPOB16

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

kicker, ion, impedance, high-voltage

928

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

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

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WEPOB20

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

ion, experiment, scattering, vacuum

937

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

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

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WEPOB22

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

ion, beam-losses, shielding, injection

943

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

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

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WEPOB24

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

kicker, ion, high-voltage, impedance

950

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

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

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WEPOB25

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

ion, gun, cathode, electron

953

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

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

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WEPOB30

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

ion, laser, electron, bunching

967

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

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

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WEPOB31

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

ion, electron, experiment, multipactoring

971

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

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

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WEPOB32

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

ion, FEL, radiation, laser

974

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

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

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WEPOB35

LLNL Laser-Compton X-Ray Characterization

ion, electron, laser, scattering

977

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

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

Poster WEPOB35 [37.648 MB]

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WEPOB39

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

ion, emittance, booster, FEL

984

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

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

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WEPOB47

Development of a Short Period Cryogenic Undulator at RadiaBeam

ion, undulator, cryogenics, electron

995

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

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

Poster WEPOB47 [2.725 MB]

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WEPOB53

Computation of Synchrotron Radiation

ion, undulator, radiation, synchrotron

1005

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

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

Poster WEPOB53 [27.003 MB]

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WEPOB61

Magnetic Shielding of LEReC Cooling Section

ion, shielding, solenoid, electron

1030

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

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

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WEPOB62

Absolute Energy Measurement of the LEReC Electron Beam

ion, dipole, electron, HOM

1033

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

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

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WEPOB68

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

ion, emittance, electron, space-charge

1045

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

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

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WEPOB69

Impedance Simulation for LEReC Booster Cavity Transformed from ERL Gun Cavity

ion, impedance, cavity, 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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THA2CO04

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

ion, cavity, 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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THPOA07

Probablistic Estimation of Low Energy Electron Trapping in Quadrupoles

ion, electron, quadrupole, storage-ring

1112

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

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

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THPOA14

Ion Effects in the APS Particle Accumulator Ring

ion, vacuum, emittance, coherent-effects

1123

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

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

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THPOA15

Adaptive Space Charge Calculations in MADX-SC

ion, emittance, optics, resonance

1126

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

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

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THPOA17

Computing Eigen-Emittances from Tracking Data

ion, emittance, optics, controls

1132

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

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

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THPOA18

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

ion, space-charge, collective-effects, wakefield

1135

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

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

Poster THPOA18 [2.144 MB]

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THPOA20

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

ion, space-charge, multipactoring, cavity

1142

G.V. Romanov
Fermilab, Batavia, Illinois, USA

The central element of the Proton Improvement Plan -II at Fermilab is a new 800 MeV superconducting linac, injecting into the existing Booster. Multipacting affects superconducting RF cavities in the entire range from high energy elliptical cavities to coaxial resonators for low-beta part of the linac. The extensive simulations of multipacting in the cavities with updated material properties and comparison of the results with experimental data are routinely performed during electromagnetic design at Fermilab. This work is focused on multipacting study in the low-beta and high-beta 650 MHz elliptical cavities. The new advanced computing capabilities made it possible to take the space charge effect into account in this study. The results of the simulations and new features of multipacting due to the space charge effect are discussed.

Poster THPOA20 [3.572 MB]

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THPOA33

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

ion, impedance, cavity, vacuum

1174

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang
LBNL, Berkeley, California, USA

The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.

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THPOA35

Analysis of Microbunching Structures in Transverse and Longitudinal Phase Spaces

ion, bunching, electron, lattice

1177

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
R. Li
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Microbunching instability (MBI) has been a challenging issue in high-brightness electron beam transport for modern accelerators. The existing Vlasov analysis of MBI is based on single-pass configuration*. For multi-pass recirculation or a long beamline, the intuitive argument of quantifying MBI, by successive multiplication of MBI gains, was found to underestimate the effect**. More thorough analyses based on concatenation of gain matrices aimed to combine both density and energy modulations for a general beamline**. Yet, quantification still focuses on characterizing longitudinal phase space; microbunching residing in (x,z) or (x',z) was observed in particle tracking simulation. Inclusion of such cross-plane microbunching structures in Vlasov analysis shall be a crucial step to systematically characterize MBI for a beamline complex in terms of concatenating individual beamline segments. We derived a semi-analytical formulation to include the microbunching structures in longitudinal and transverse phase spaces. Having numerically implemented the generalized formulae, an example lattice*** is studied and reasonable agreement achieved when compared with particle tracking simulation.
* Heifets et al., PRSTAB 5, 064401 (2002), Huang and Kim, PRSTAB 5, 074401 (2002), and Vneturini, PRSTAB 10, 104401 (2007)
** Tsai et al., IPAC'16 (TUPOR020)
*** Di Mitri, PRSTAB 17, 074401 (2014)

Poster THPOA35 [4.710 MB]

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THPOA37

Study of 2D CSR Effects in a Compression Chicane

ion, dipole, electron, FEL

1181

C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

The study of coherent synchrotron radiation (CSR) has been an area of great interest because of its negative impact on FEL performance. The modeling of CSR is frequently performed using a 1D approximation*, as 2D and 3D models can become extremely computational intensive. While experimental evidence is lacking in this area most studies show reasonable agreement between 1D and 2D CSR models for beam parameters in existing accelerators. In this work we focus on 2D modeling of CSR in a four-dipole chicane lattice based on the Jefferson Lab FEL. Comparison is shown between several models and measurement for energy loss due to CSR in the chicane. While good agreement is generally observed we also present investigation of several key differences observed in simulation. In particular, showing how the 1D and 2D CSR models deviate in regards to CSR and beam interaction within the drift spaces of the chicane and the downstream drift at the chicane end.
*E. Saldin, E. Schneidmiller, and M. Yurkov, Nucl. Instr. Meth. A398, 373 (1997).

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THPOA41

Simulations of Hole Injection in Diamond Detectors

ion, electron, detector, injection

1184

G.I. Bell, D.A. Dimitrov, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, M. Gaowei, T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller
SBU, Stony Brook, New York, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences, under grant DE-SC0007577.
We present simulations of a semiconductor beam detector using the code VSIM. The 3D simulations involve the movement and scattering of electrons and holes in the semiconductor, voltages which may be applied to external contacts, and self-consistent electrostatic fields inside the device. Electrons may experience a Schottky barrier when attempting to move from the semiconductor into a metal contact. The strong field near the contact, due to trapped electrons, can result in hole injection into the semiconductor due to transmission of electrons from the valence band of the semiconductor into the metal contact. Injected holes are transported in the applied field leading to current through the detector. We compare our simulation results with experimental results from a prototype diamond X-ray detector.

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THPOA42

3D Modeling and Simulations of Electron Emission From Photocathodes With Controlled Rough Surfaces

ion, electron, cathode, scattering

1187

D.A. Dimitrov, G.I. Bell, D.N. Smithe, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J. Smedley
BNL, Upton, Long Island, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Developments in materials design and synthesis have resulted in photocathodes that can have a high quantum efficiency (QE), operate at visible wavelengths, and are robust enough to operate in high electric field gradient photoguns, for application to free electron lasers and in dynamic electron microscopy and diffraction. However, synthesis often results in roughness, ranging from the nano to the microscale. The effect of this roughness in a high gradient accelerator is to produce a small transverse accelerating gradient, which therefore results in emittance growth. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking, and our work aims to bridge this gap. We report results on electron emission modeling and 3D simulations from photocathodes with controlled surface roughness similar to grated surfaces that have been fabricated by nanolithography. The simulations include both charge carrier dynamics in the photocathode material and a general electron emission modeling that includes field enhancement effects at rough surfaces. The models are being implemented in the VSim code.

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THPOA46

Benchmark of RF Photoinjector and Dipole Using ASTRA, GPT, and OPAL

ion, gun, emittance, dipole

1194

N.R. Neveu
IIT, Chicago, Illinois, USA
A. Adelmann
PSI, Villigen PSI, Switzerland
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
C.J. Metzger-Kraus
HZB, Berlin, Germany
N.R. Neveu, J.G. Power
ANL, Argonne, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S.J. Russell
LANL, Los Alamos, New Mexico, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Grant no. DE-SC0015479, and contract No. DE-AC02-06CH11357.
With the rapid improvement in computing resources and codes in recent years, accelerator facilities can now achieve and rely on accurate beam dynamics simulations. These simulations include single particle effects (e.g. particle tracking in a magnetic field) as well as collective effects such as space charge (SC), and coherent synchrotron radiation (CSR). Using portions of the Argonne Wakefield Accelerator (AWA) as the benchmark model, we simulated beam dynamics with three particle tracking codes. The AWA rf photoinjector was benchmarked, primarily to study SC, in ASTRA, GPT, and OPAL-T using a 1 nC beam. A 20° dipole magnet was used to benchmark CSR effects in GPT and OPAL-T by bending a 1nC beam at energies between 2 MeV and 100 MeV. In this paper we present the results, and discuss the similarities and differences between the codes.

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THPOA48

Model of Electron Cloud Instability in Fermilab Recycler

ion, electron, proton, dipole

1197

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
A.V. Burov, S. Nagaitsev
Fermilab, Batavia, Illinois, USA

An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future in-tensity upgrades.

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THPOA52

A Simulation for Bright THz Light Source from Wiggler Radiation at KEK LUCX

ion, wiggler, radiation, experiment

1210

Y. Sumitomo, S. Araki, A. Aryshev, M.K. Fukuda, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A. Deshpande
SAMEER, Mumbai, India
N. Terunuma
Sokendai, Ibaraki, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We study a bright THz light source generated by a wiggler radiation at KEK LUCX THz experiment, where an injected four pre-micro-bunched electron beam with few hundreds femto-seconds separation plays a crucial role. The energy of pre-bunched beam reaches few MeV at an S-band 3.6 cell RF Gun, and hence the space-charge effect is not negligible. We simulate the beam optics by ASTRA code, a charged beam optics simulator with space-charge effect, and then the resultant particle distribution is passed to GENESIS, a FEL simulator to deal with the wiggler radiation. We also present an experimental result at KEK LUCX. The major advantage of this system is a compactness of total setup that is expected to generate a MW class peak power THz beam by the coherent radiation.

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THPOA68

The First Particle-Based Proof of Principle Numerical Simulation of Electron Cooling

ion, electron, proton, emittance

1241

S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Envisioned particle accelerators such as JLEIC demand unprecedented luminosities of 10³⁴ cm -2 s -1 and small emittances are key to achieve them. Electron cooling, where a 'cold' electron beam and the 'hot' proton or ion beam co-propagate in the cooling section of the accelerator, can be used to reduce the emittance growth. It is required to precisely calculate the cooling force among particles to estimate accurately the cooling time. There are different methods to simulate electron cooling. We have developed a novel code, Particles' High-order Adaptive Dynamics (PHAD), for electron cooling. This code differs from other established methods since it is the first particle-based simulation method employing full particle nonlinear dynamics. In this paper we present the first results obtained that establish electron cooling of heavy ions.

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FRA1CO04

6D Phase Space Measurement of Low Energy, High Intensity Hadron Beam

ion, electron, emittance, quadrupole

1271

B.L. Cathey
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The work has been partially supported by NSF grant 1535312
The goal of this project is to demonstrate a method for measuring the full 6D phase space of an low energy, high intensity hadron beam. This is done by combining 4D emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and phase space components. The measurement will be performed on new Beam Testing Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end.

Slides FRA1CO04 [8.295 MB]

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FRB2IO03

GEM*STAR Accelerator-Driven Subcritical System for Improved Safety, Waste Management, and Plutonium Disposition

ion, neutron, proton, target

1300

M.A. Cummings, R.J. Abrams, R.P. Johnson, T.J. Roberts
Muons, Inc, Illinois, USA

Operation of high-power SRF particle accelerators at two US national laboratories allows us to consider a less-expensive nuclear reactor that operates without the need for a critical core, fuel enrichment, or reprocessing. A multipurpose reactor design that takes advantage of this new accelerator capability includes an internal spallation neutron target and high-temperature molten-salt fuel with continuous purging of volatile radioactive fission products. The reactor contains less than a critical mass and almost a million times fewer volatile radioactive fission products than conventional reactors like those at Fukushima. We describe GEMSTAR , a reactor that without redesign will burn spent nuclear fuel, natural uranium, thorium, or surplus weapons material. A first application is to burn 34 tonnes of excess weapons grade plutonium as an important step in nuclear disarmament under the 2000 Plutonium Management and Disposition Agreement **. The process heat generated by this W-Pu can be used for the Fischer-Tropsch conversion of natural gas and renewable carbon into 42 billion gallons of low-CO2-footprint, drop-in, synthetic diesel fuel for the DOD.

Slides FRB2IO03 [8.681 MB]

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