NAPAC2019 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOYBA5	Weak-Strong Simulation of Beam-Beam Effects in Super Proton-Proton Collider	proton, collider, luminosity, resonance	22
	L.J. Wang, J.Y. Tang IHEP, Beijing, People’s Republic of China T. Sen Fermilab, Batavia, Illinois, USA
	A Super Proton-Proton Collider (SPPC) that aims to explore new physics beyond the standard model is planned in China. Here we focus on the impact of beam-beam interactions in the SPPC. Simulations show that with the current optics and nominal tunes, the dynamic aperture (DA) with all the beam-beam interactions is less than 6σ, the dominant cause being the long-range interactions. First, we show the results of a tune scan done to maximize the DA. Next, we discuss the compensation of the long-range interactions by increasing the crossing angle and also by using current carrying wires.
	Slides MOYBA5 [1.004 MB]
	Poster MOYBA5 [0.727 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBA5
About •	paper received ※ 25 August 2019 paper accepted ※ 20 November 2019 issue date ※ 08 October 2019
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MOZBA4	Recent Developments in High Power High Brightness Double Bunch Self-Seeding at LCLS-II	FEL, undulator, photon, electron	67
	A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.A. Lutman, G. Marcus, C. Pellegrini SLAC, Menlo Park, California, USA
	We discuss the power and spectral characteristics of an X-ray FEL, LCLS-II, operating in a double bunch self-seeding scheme (DBFEL). We show that it can reach very high power levels in the photon energy range of 4-8 keV. We discuss the system implementation on LCLS-II, including the design of a four-bounce crystal monochromator, and linac wakefields effects. Finally, we offer multiple applications of the DBFEL for high-field QED, AMO physics and single particle imaging.
	Slides MOZBA4 [3.175 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA4
About •	paper received ※ 02 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOZBA5	Optimized Linear and Second Order Chromaticity Setpoints for the Advanced Photon Source Upgrade	lattice, sextupole, MMI, photon	70
	Y.P. Sun ANL, Lemont, 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 nominal single particle dynamics optimizations of the Advanced Photon Source upgrade (APS-U) lattice are performed with dense numerical simulations of local momentum acceptance and dynamic acceptance. These simulations are quite time consuming, which may take weeks for optimizing one setpoint of linear chromaticity. In this paper, an alternative optimization method is adopted to generate optimized linear and second order chromaticity setpoints for the Advanced Photon Source upgrade lattice. This method is efficient in computing time needed, which is capable to generate a grid of optimized chromaticity setpoints in a relatively short time. The performance of these lattice solutions are verified by simulations with reasonable errors. These lattice solutions with different linear (or second order) chromaticity may be useful for the future APS-U commissioning and operations.
	Slides MOZBA5 [3.350 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA5
About •	paper received ※ 31 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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MOZBA6	The Broad-Band Impedance Budget of the Accumulator Ring in the ALS-U Project	impedance, wakefield, cavity, vacuum	74
	D. Wang, S. De Santis, D. Li, T.H. Luo, M. Venturini LBNL, Berkeley, California, USA K.L.F. Bane SLAC, Menlo Park, California, USA
	Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. It consists of an accumulator and a storage ring. In both rings, coupling-impedance driven instabilities need careful evaluation to ensure meeting the machine high-performance goals. This paper presents the impedance budget of the accumulator ring both longitudinally and transversely. The budget includes the resistive wall impedance as well as the geometric impedance from the main vacuum components. Our calculations primarily rely on electromagnetic simulations with the CST code; when possible validation has been sought against analytical modeling, typically in the low-frequency limit, and good agreement generally found. Collective-instability current thresholds are also discussed.
	Slides MOZBA6 [8.926 MB]
	Poster MOZBA6 [3.542 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA6
About •	paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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MOPLM03	Correlations Between Beta Beating and APS-U Single Particle Dynamics Performance	lattice, focusing, sextupole, quadrupole	95
	Y.P. Sun ANL, Lemont, 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. In the optimizations and evaluations process of the Advanced Photon Source upgrade (APS-U) lattice, it was observed that there are negative correlations between beta beating and APS-U single particle dynamics performance (such as dynamic acceptance and local momentum acceptance). These correlations are not always present due to different reasons. In this paper, a systematic simulation study is performed to understand the correlations between beta beating and APS-U single particle dynamics performance. Relatively high beta beatings are generated to reveal these effects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM03
About •	paper received ※ 31 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLM07	Simulation of Beam Aborts for the Advanced Photon Source to Probe Material-Damage Limits for Future Storage Rings	experiment, storage-ring, emittance, photon	106
	M. Borland, J.C. Dooling, R.R. Lindberg, V. Sajaev, Y.P. Sun ANL, Lemont, 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. Damage to tungsten beam dumps has been observed in the Advanced Photon Source (APS), a 7-GeV, third-generation storage ring light source. This issue is expected to be much more severe in the APS Upgrade, owing to doubling of the stored charge and much lower emittance. An experiment was conducted in the existing APS ring to test several possible dump materials and also assess the accuracy of predictions of beam-induced damage. Prior to the experiments, extensive beam abort simulations were performed with ELEGANT to predict thresholds for material damage, dependence on vertical beam size, and even the size of the trenches expected to be created by the beam. This paper presents the simulation methods, simple models for estimating damage, and results. A companion paper in this conference presents experimental results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM07
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM08	Controlling Transient Collective Instabilities During Swap-Out Injection	lattice, injection, octupole, emittance	110
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 Previous work has shown that collective instabilities at injection may reduce injection efficiency even for on-axis injection as planned for the APS-Upgrade. Stability at injection is governed by a number of factors, including phase-space mismatch between injected and stored bunch, strength of the impedance, degree of nonlinearities, and feedback. We find that the large tune-shift with amplitude of the most recent APS-U lattice largely tames the transient instability via Landau damping, and show that using octupoles to increase the nonlinear tune shift can stabilize the transient instability at injection that plagued a previously unstable lattice. R.R. Lindberg, M. Borland, and A. Blednykh, Proc. of NA-PAC 2016, pp. 901
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM08
About •	paper received ※ 24 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLM10	Simulation Study With Septum Field Map for the APS Upgrade	septum, magnet-design, injection, photon	116
	A. Xiao, M. Abliz, M. Borland ANL, Lemont, 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. One of the biggest challenges faced by the Advanced Photon Source Upgrade injection system design is the septum magnet. Not only does the required leakage field inside the stored beam chamber need to be smaller than for the present ring, the magnet has to be slightly tilted about the z-axis to provide a gentle vertical bend that brings the injected beam trajectory close to y=0 when it passes through the storage ring quadrupole magnets upstream of the straight section. This paper describes the coordinate system transformation necessary to properly model the magnet from field maps. The main field is checked by tracking the injected beam backwards, while leakage fields are included in dynamic aperture simulation and beam lifetime calculation. Simulation results show that the magnet design satisfies the physics requirement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM10
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM12	Progress on the Injection Transport Line Design for the APS Upgrade	injection, septum, extraction, booster	120
	A. Xiao, M. Borland ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. An on-axis vertical injection scheme was adopted for the Advanced Photon Source upgrade multi-bend achromat lattice. As the design of the injection scheme has become more detailed, the booster to storage ring transport line (BTS) has advanced, including effects such as the septum field map and stray fields of storage ring magnets. Various error effects are simulated for setting specifications and predicting expected performance. The beam diagnostic scheme, including emittance measurement, is incorporated into the beamline design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM12
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLM14	Studies of Beam Dumps in Candidate Horizontal Collimator Materials for the Advanced Photon Source Upgrade Storage Ring	experiment, storage-ring, photon, emittance	128
	J.C. Dooling, W. Berg, M. Borland, G. Decker, L. Emery, K.C. Harkay, R.R. Lindberg, A.H. Lumpkin, G. Navrotski, V. Sajaev, Y.P. Sun, K.P. Wootton, A. Xiao ANL, Lemont, 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 We present the results of experiments intended to show the effects of beam dumps on candidate collimator materials for the Advanced Photon Source Upgrade (APS-U) storage ring (SR). Due to small transverse electron beam sizes, whole beam loss events are expected to yield dose levels in excess of 10 MGy in beam-facing components, pushing irradiated regions into a hydrodynamic regime. Whole beam aborts have characteristic time scales ranging from 100s of ps to 10s of microseconds which are either much shorter than or roughly equal to thermal diffusion times. Aluminum and titanium alloy test pieces are each exposed to a series of beam aborts of varying fill pattern and charge. Simulations suggest the high energy/power densities are likely to lead to phase transitions and damage in any material initially encountered by the beam. We describe measurements used to characterize the beam aborts and compare the results with those from the static particle-matter interaction code, MARS; we also plan to explore wakefield effects. Beam dynamics modeling, done with elegant is discussed in a companion paper at this conference. The goal of this work is to guide the design of APS-U SR collimators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM14
About •	paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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MOPLM17	Longitudinal Impedance Modeling of APS Particle Accumulator Ring with CST	impedance, kicker, cavity, vacuum	140
	C. Yao, J. Carvelli, K.C. Harkay, L.H. Morrison ANL, Lemont, Illinois, USA D. Hui University of Arizona, Tucson, Arizona, USA J.S. Wang Dassault Systems Simulia, Waltham, Massachusetts, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The APS-U (APS upgrade) ring plans implement a "swap out" injection scheme, which requires a injected beam of 15.6 nC single-bunch beam. The Particle Accumulator Ring (PAR), originally designed for up to 6 nC charge, must be upgraded to provide 20 nC single bunch beam. Our studies have shown that bunch length of the PAR beam, typically 300 ps at lower charge, increases to 800 ps at high charge due to longitudinal instabilities, which causes low injection efficiency of the downstream Booster ring. We completed beam impedance of all the PAR vacuum components recently with CST wakefield solver. 3D CAD models are directly imported into CST and various techniques were explored to improve and verify the results. The results are also cross-checked with that from GdfidL and Echo simulation. We identified 23 bellow- and 24 non-bellow flanges that contribute to as much as 50% of the total loss factor. We are considering upgrade options to reduce over all beam loading and longitudinal impedance. Beam tracking simulation is in progress that including the longitudinal impedance results from the simulations. We report the results and methods of the CST impedance simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM17
About •	paper received ※ 22 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLM20	Impedance Considerations for the APS Upgrade	impedance, photon, vacuum, cavity	147
	R.R. Lindberg ANL, Lemont, Illinois, USA A. Blednykh BNL, Upton, New York, USA
	Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 The APS-Upgrade is targeting a 42 pm lattice that requires strong magnets and small vacuum chambers. Hence, impedance is of significant concern. We overview recent progress on identifying and modelling vacuum components that are important sources of impedance in the ring, including photon absorbers, BPMs, and flange joints. We also show how these impact collective dynamics in the APS-U lattice.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM20
About •	paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLS08	Error Tolerance Characterization for the HUST MeV Ultrafast Electron Diffraction System	emittance, electron, injection, laser	166
	Y. Song, K. Fan, C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	Ultrafast electron diffraction (UED) is a powerful tool for probing atomic dynamics with a femtosecond resolution. Such a spatiotemporal resolution requires error tolerance for the UED system which includes the RF system, the laser system, the beamline elements, etc. To characterize the error tolerance of the required spatiotemporal resolution for the 1.4-cell MeV UED we are developing, we use ASTRA to simulate the UED model with errors including initial transverse beam centroid offset, RF amplitude jitter and injection phase jitter, etc. By performing simulations with different errors omitted, we can characterize the contribution of each error and thus set the tolerance for each error to obtain the required performance of UED experiment. In the end, we present the error tolerance for 10% emittance growth and 100 fs time of flight variation to maintain the required spatiotemporal resolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLS08
About •	paper received ※ 25 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLH02	Study of Photocathode Surface Damage due to Ion Back-Bombardment in High Current DC Gun	cathode, gun, electron, laser	174
	J.P. Biswas Stony Brook University, Stony Brook, USA O.H. Rahman, E. Wang BNL, Upton, New York, USA
	Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704, with the U.S. DOE In high current DC gun, GaAs photocathode lifetime is limited by the ion back-bombardment. While gun operation ions are generated and accelerate back towards the cathode thus remove the activation layer’s material Cesium from the photocathode surface. We have developed an object-oriented code to simulate the ion generation due to dynamic gas pressure and ion trace in the electromagnetic field. The pressure profile varies from cathode position towards the transfer line behind the anode, which signifies the importance of dynamic simulation for ion back-bombardment study. In our surface damage study, we traced the energy and position of the ions on the photocathode surface and performed the Stopping and Range of Ions in Matter(SRIM) simulation to count the number of Cesium atoms removed from the surface due to single bunch impact. Cesium atom removal is directly related to the photocathode Quantum Efficiency(QE) decay. Our new dynamic simulation code can be used in any DC gun to study ion back-bombardment. We have used this new code to better understand the ion generation in prototype BNL 350 KV DC gun, and we have also estimated the normalized QE decay due to ion back-bombardment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH02
About •	paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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MOPLH19	Beam Dynamics Simulations for a Conduction-Cooled Superconducting RF Electron Source	electron, cathode, emittance, experiment	213
	O. Mohsen, V. Korampally, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia Northern Illinois University, DeKalb, Illinois, USA R. Dhuley, M.G. Geelhoed, J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359 The development of robust and portable high-average power electron sources is key to many societal applications. An approach toward such sources is the use of cryogen-free superconducting radiofrequency cavities. This paper presents beam-dynamics simulations for a proof-of-principle experiment on a cryogen-free SRF electron source being prototyped at Fermilab. The proposed design implement a geometry that enhances the electric field at the cathode surface to simultaneously extract and accelerate electrons. In this paper, we explore the beam dynamics considering both the case of field and photoemission mechanism.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH19
About •	paper received ※ 02 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLH23	An Analysis of Potential Compact Positron Beam Source	positron, plasma, emittance, cavity	220
	R.M. Hessami UCLA, Los Angeles, USA S.J. Gessner CERN, Geneva, Switzerland
	For positron studies in plasma wakefield accelerators such as AWAKE, the development of new, cheaper, and compact positron beam sources is necessary. Using an electrostatic trap with parameters similar to other experiments, this paper explores converting that trapped positron plasma into a usable beam. Bunching is initially accomplished by an electrostatic buncher and the beam is accelerated to 148 keV by pulsed electrostatic accelerators. This is necessary for injection into the beta-matched rf cavities operating at 600 MHz, which bring the positron beam to a transverse emittance of 1.3 pi mrad mm, a longitudinal emittance of 93.3 pi keV mm, stdz of 1.85 mm and an energy of 22 MeV. The beamline used here is far simpler and less expensive than those at many facilities, such as SLAC, allowing for a cheap source of positron beams, potentially opening up positron beam studies to many facilities that could not previously afford such a source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH23
About •	paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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MOPLH26	Design of a Compact Wakefield Accelerator Based on a Corrugated Waveguide	GUI, wakefield, coupling, electron	232
	A.E. Siy UW-Madison/PD, Madison, Wisconsin, USA G.J. Waldschmidt, A. Zholents ANL, Lemont, Illinois, USA
	A compact wakefield accelerator is being developed at the Argonne National Laboratory for a future multiuser x-ray free electron laser facility. A cylindrical structure with a 2 mm internal diameter and fine corrugations on the wall will be used to create Čerenkov radiation. A "drive" bunch producing radiation at 180 GHz will create accelerating gradients on the order of 100 MV/m for the "witness" bunch. The corrugated structure will be approximately half meter long with the entire accelerator spanning a few tens of meters. An ultra-compact transition region between each corrugated structure has been designed to accommodate an output coupler, a notch filter, an integrated offset monitor, bellows, pumping and water cooling ports. The output coupler will extract on the order of a kilowatt of power from the Čerenkov radiation unused by the witness bunch. The integrated offset monitor is a novel diagnostic which will measure the cumulative offset of the electron beam in the corrugated structure upstream of the monitor. The specific details of the rf design will be presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH26
About •	paper received ※ 27 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019
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MOPLO12	The RF BPM Pickup Electrodes Development for the APS-MBA Upgrade	pick-up, vacuum, electron, storage-ring	256
	X. Sun, R.M. Lill ANL, Lemont, Illinois, USA
	Beam stability is critical for the Advanced Photon Source (APS) multi-bend achromat (MBA) lattice up-grade and will employ 560 radio frequency (RF) beam position monitors (BPMs). The RF BPMs will provide the primary measurement of the electron beam. Design goals for the BPM assembly include high sensitivity, low wakefield impedance, and ultra-mechanically stability. The design, electromagnetic simulation, manufacturing tolerance and prototype testing will be presented in this paper. *Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO12
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUXBA3	Robust Thermoacoustic Range Verification for Pulsed Ion Beam Therapy	proton, target, radiation, experiment	294
	S.K. Patch UWM, Milwaukee, Wisconsin, USA B.M. Brahim, D. Santiago-Gonzalez ANL, Lemont, Illinois, USA
	Funding: * Supported by the U.S D.O.E., Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. Measurements were performed at ANL’s ATLAS facility, which is a DOE Office of Science User Facility. Lack of online range verification generally limits application of proton therapy to cancers in the brain, spine, and to pediatric patients. Previously, thermoacoustic range verification (TARV) has been demonstrated in weakly scattering media with known sound speed [1]. At ATLAS, we demonstrated the accuracy and robustness of TARV relative to ultrasound (US) images despite acoustic heterogeneity and sound speed errors representing in vivo conditions [2]. 250 ns pulses deposited 0.26 Gy of 16 MeV protons and 2.3 Gy of 60 MeV helium ions into liquid targets. TA signals were detected by an US array that also generated US images. An air gap phantom displaced the Bragg peak by 6.5 mm and the scanner’s propagation speed setting was altered by ±5%. Weak and strong scatterers were placed between the Bragg peak and US array. Estimated Bragg peak locations were translated 6.5 mm by the air gap phantom and agreed with TRIM simulations to within 0.3 mm, even when TA emissions traveled through a strong acoustic scatterer. Soundspeed errors dilated, and acoustic heterogeneities deformed both US images and TA range estimates, confirming that TARV is accurate relative to US images. [1] Hickling, et al, Med Phys, 45(7), 2018. (review article) [2] S. Patch, D. Santiago, & B. Mustapha, Med Phys, 46(1), 2019.
	Slides TUXBA3 [4.449 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUXBA3
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUXBA4	Rapid Radio-Frequency Beam Energy Modulator for Proton Therapy	cavity, proton, GUI, klystron	298
	X. Lu, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, A.V. Sy, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by US Department of Energy (DOE) Contract No. DE-AC02-76SF00515. We present the design for a rapid proton energy modulator with radio-frequency (RF) accelerator cavities. The energy modulator is designed as a multi-cell one-meter long accelerator working at 2.856 GHz. We envision that each individual accelerator cavity is powered by a 400 kW low-voltage klystron to provide an accelerating / decelerating gradient of 30 MV/m. We have performed beam dynamics simulations showing that the modulator can provide ± 30MeV of beam energy change, with an energy spread of 3 MeV for a 7 mm long (full length) proton bunch. A prototype experiment of a single cell is in preparation at the Next Linear Collider Test Accelerator (NLCTA) at SLAC.
	Slides TUXBA4 [3.275 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUXBA4
About •	paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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TUYBA3	Benchmarking the LCLS-II Photoinjector	laser, gun, solenoid, emittance	301
	N.R. Neveu, T.J. Maxwell, C.E. Mayes SLAC, Menlo Park, California, USA
	Funding: DOE Contract No. DE-AC02-76SF00515 Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.
	Slides TUYBA3 [1.320 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3
About •	paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM01	Experimental Studies of Resonance Structure Dynamics With Space Charge	resonance, space-charge, experiment, quadrupole	372
	L. Dovlatyan, T.M. Antonsen, B.L. Beaudoin, S. Bernal, I. Haber, D.F. Sutter, G.D. Wyche UMD, College Park, Maryland, USA
	Funding: Funding for this project is provided by DOE-HEP award #DE-SC0010301 Space charge is one of the fundamental limitations for next generation high intensity circular accelerators. It can lead to halo growth as well as beam loss, and affect resonance structure in ways not completely understood. We employ the University of Maryland Electron Ring (UMER), a circular 10 keV storage machine, to experimentally study the structure of betatron resonances for beams of varying degrees of space charge intensity. Experimental techniques such as tune scans and frequency maps are employed. Results are also compared to computer simulations using the WARP code.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM01
About •	paper received ※ 26 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM03	Adjoint Approach to Accelerator Lattice Design	lattice, focusing, quadrupole, plasma	376
	T.M. Antonsen, B.L. Beaudoin, L. Dovlatyan, I. Haber UMD, College Park, Maryland, USA
	Funding: Supported by USDoE DESC0010301 Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques []. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented. T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM03
About •	paper received ※ 23 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLM09	A Fast Method to Evaluate Transverse Coupled-Bunch Stability at Non-Zero Chromaticity	synchrotron, wakefield, dipole, betatron	387
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 We present a dispersion relation that gives the complex growth rate for coupled-bunch instabilities at arbitrary chromaticity in terms of its value at zero chromaticity. We compare predictions of the theory to elegant tracking simulations, and show that there are two distinct regimes to stability depending upon whether the zero chromaticity growth rate is smaller or larger than the chromatic tune shift over the bunch. We derive an approximate expression that is easily solved numerically, and furthermore indicate how the formalism can be extended to describe arbitrary longitudinal potentials.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM09
About •	paper received ※ 25 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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TUPLM11	Beam-Beam Damping of the Ion Instability	electron, storage-ring, damping, feedback	391
	M. Blaskiewicz BNL, Upton, New York, USA
	Funding: Work Supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Beam-Beam damping of the Ion Instability The electron storage ring of the proposed electron ion collider at BNL has bunch charges as large as 50 nC and bunch spacings as small as 10 ns. For molecules like CO a dangerous buildup of positive ions is possible and a significant fraction of these ions can survive allowable clearing gaps. The instability is thus multi-turn and the weak damping required to stop the ion instabilty with an ideal clearing gap is ineffective here. The beam-beam force is highly nonlinear and a potent source of tune spread. Simulations employing several macro-particles per electron bunch and several ion macroparticles are used to estimate maximum gas densities for some common molecules. A simplified model is introduced and compared with simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM11
About •	paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLM12	Method for a Multiple Square Well Model to Study Transverse Mode Coupling Instability	DTL, collective-effects, space-charge, longitudinal-dynamics	395
	M.A. Balcewicz, Y. Hao FRIB, East Lansing, Michigan, USA M. Blaskiewicz BNL, Upton, New York, USA
	In the high intensity limit it can become difficult to simulate intense beams sufficiently within a short time scale due to collective effects. Semi-Analytic methods such as the Square Well Model/AirBag Square Well* (SWM/ABS) exist to estimate collective effects within a short time scale. SWM/ABS discretizes the longitudinal confining potential into a single square well enforcing linearity for the case of linear transverse optics. A method is proposed here to extend the Square Well Method multiple square wells. This method preserves linearity properties that make it easily solvable within a short time scale as well as including nonlinear effects from the longitudinal potential shape. M. Blaskiewicz PRSTAB 1, 044201. 1998 *A. Burov PRAB 22, 034202. 2019
	Poster TUPLM12 [1.818 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM12
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM16	Double-Horn Suppression in EEX Based Bunch Compression	octupole, controls, emittance, quadrupole	407
	J. Seok, M. Chung UNIST, Ulsan, Republic of Korea M.E. Conde, G. Ha, J.G. Power ANL, Lemont, Illinois, USA
	Nonlinearities on the longitudinal phase space in-duce a double-horn current profile when the bunch is compressed strongly. Since this double-horn can de-grade the performance of FELs due to the CSR it makes, the suppression of the double-horn is one of important beam dynamics issues. Emittance exchange (EEX) can be interesting option for this issue due to its longitudinal controllability. Since EEX exchanges the longitudinal phase space and transverse phase space, higher order magnets such as octupole can control the nonlinearity. In this paper, we present simulation re-sults on the suppression of the double-horn current profile using EEX based bunch compression. We use a double EEX beamline installed at the Argonne Wake-field Accelerator facility for the simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM16
About •	paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM18	Improving Energy Resolution and Compensating Chromatic Aberration With a TM010 Microwave Cavity	cavity, electron, gun, laser	411
	C.J.R. Duncan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA P. Cueva, J.M. Maxson, D.A. Muller Cornell University, Ithaca, New York, USA
	Funding: National Science Foundation under Award OIA-1549132, the Center for Bright Beams The intrinsic energy spread of electron sources limits the achievable resolution of electron microscopes in both spectroscopic and spatially resolved measurements. We propose that the TM010 mode of a single radio frequency (RF) cavity be used to dramatically reduce this energy spread in a pulsed beam. We show with analytic approximations, confirmed in simulations, that the non-linear time-energy correlations that develop in an electron gun can be undone by the RF cavity running near-crest. We derive an expression that gives the required RF field strength as a function of accelerating voltage. We explore multiple applications, including EELS and SEM. By pulsing a photocathode with commercially available, high repetition-rate lasers, our scheme could yield competitive energy spread reduction at higher currents when compared with monochromated continuous-wave sources for electron microscopes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM18
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM20	Generation of High-Charge Magnetized Electron Beams Consistent With JLEIC Electron Cooling Requirements	emittance, electron, cathode, experiment	414
	A.T. Fetterman, P. Piot Northern Illinois University, DeKalb, Illinois, USA S.V. Benson, F.E. Hannon, S. Wang JLab, Newport News, Virginia, USA D.J. Crawford, D.R. Edstrom, P. Piot, J. Ruan 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 contract DE-AC05-06OR23177 and DE-AC02-07CH11359. The proposed Jefferson Lab Electron-Ion Collider (JLEIC), currently under design, relies on electron cooling in order to achieve the desired luminosity. This includes an electron beam with >55 Mev, 3.2 nC bunches that cools hadron beams with energies up to 100 GeV. To enhance the cooling, the electron beam must be magnetized with a specific eigen-emittance partition. This paper explores the use of the Fermilab Accelerator Science and Technology (FAST) facility to demonstrate the generation of an electron beam with parameters consistent with those required in the JLEIC high-energy cooler. We demonstrate via simulations the generation of the required electron-beam parameters and perform a preliminary experiment to validate FAST capabilities to produce such beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM20
About •	paper received ※ 07 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLM33	Optimization of Beam Parameters for UEM with Photo-Emission S-Band RF Gun and Alpha Magnet	electron, gun, emittance, laser	440
	H.R. Lee, P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim University of Science and Technology of Korea (UST), Daejeon, Republic of Korea P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim KAERI, Jeongeup-si, Republic of Korea B.L. Cho KRISS, Daejeon, Republic of Korea M.Y. Han, J.Y. Lee, S.H. Lee Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea H. Suk GIST, Gwangju, Republic of Korea
	Ultrafast Electron Microscopy (UEM) is a powerful tool to observe ultrafast dynamical processes in sample materials at the atomic level. By collaborating with KRISS and GIST, the future accelerator R&D team at KAERI has been developing a UEM facility based on a photo-emission S-band (=2856 MHz) RF gun. Recently, we have added an alpha magnet in the beamline layout of the UEM to improve beam qualities such as emittance, divergence, energy spread, and bunch length. To achieve high spatial and time resolutions, we have been optimizing those beam parameters and other machine parameters by performing numerous ASTRA and ELEGANT code simulations. In this paper, we describe our ASTRA and ELEGANT code optimizations to obtain high-quality beam parameters for the UEM facility with a photo-emission S-band RF gun and an alpha magnet.
	Poster TUPLM33 [0.931 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM33
About •	paper received ※ 30 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLS07	Helical Transmission Line Test Stand for Non-Relativistic BPM Calibration	impedance, network, resonance, linac	463
	C.J. Richard NSCL, East Lansing, Michigan, USA S.M. Lidia FRIB, East Lansing, Michigan, USA
	Measurements of non-relativistic beams by coupling to the fields are affected by the properties of the non-relativistic fields. The authors propose calibrating for these effects with a test stand using a helical line which can propagate pulses at low velocities. Presented are simulations of a helical transmission line for such a test stand which propagates pulses at 0.033c. A description of the helix geometry used to reduce dispersion is given as well as the geometry of the input network.
	Poster TUPLS07 [3.469 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS07
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLH04	Feasibility Study of Fast Polarization Switching Superconducting Undulator	undulator, polarization, coupling, power-supply	497
	I. Kesgin, Y. Ivanyushenkov, M. Kasa ANL, Lemont, Illinois, USA
	Funding: U.S. Department of Energy, Office of Science, under Contract No. DE-ACO₂-O6CH11357. Polarization switching x-ray probes coupled with high-flux provide a unique tool to unraveling the nature of electronic heterogeneity and drive discovery of novel phases of electronic matter. Superconducting Arbitrary Polarization Emitter (SCAPE) is a new concept for a universal undulator, which offers linear or circular polarization states in one device and is ideal for experiments that require polarization switching. Polarization switching relies on modulating the magnetic field in the undulator. This, however, inevitably incurs losses in superconductors, which need to be mitigated. In this study, feasibility of fast switching SCAPE has been investigated through fabricating and testing several short prototype magnets wound with different superconductors and new design concepts. The losses at different frequencies and field amplitudes are measured and details will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH04
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUPLH09	Thermal Effects on Bragg Diffraction of XFEL Optics	FEL, photon, optics, synchrotron	506
	Z. Qu, J. Wu, G. Zhou SLAC, Menlo Park, California, USA Y. Ma, Z. Qu UC Merced, Merced, California, USA B. Yang Western Digital, Milpitas, California, USA
	Funding: The US Department of Energy (DOE) (DE-AC02-76SF00515); The US DOE Office of Science Early Career Research Program grant (FWP-2013-SLAC-100164). Crystal optical devices are widely used in X-ray free electron laser (XFEL) systems, monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, and spectrometers. The absorption of X-ray in these optical devices can cause increase of temperature and consequent thermal deformation, which can dynamic change in optic output. In self-seeding XFEL, the thermal deformation and strain in monochromator could cause significant seed quality degradation: central energy shift, band broadening and reduction in seed power. To quantitatively estimate the impact of thermomechanical effects on seed quality, we conduct thermomechanical simulations combined with diffraction to evaluate the seed quality with residual temperature field in a pump-probe manner. With our results, we show that a critical repetition rate could be determined, once the criteria for deviation of the seed quality are selected. This tool shows great potential for the design of XFEL optics for stable operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH09
About •	paper received ※ 28 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLO04	The Latest Code Development Progress of JSPEC	electron, emittance, collider, operation	539
	H. Zhang, S.V. Benson, Y. Roblin, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. The JLab Simulation Package on Electron Cooling (JSPEC) is an open source software developed at Jefferson Lab for electron cooling and intrabeam scattering (IBS) simulations. IBS is an important factor that leads to the growth of the beam emittance and hence the reduction of the luminosity in a high density ion collider ring. Electron cooling is an effective measure to overcome the IBS effect. Although JSPEC is initiated to fulfill the simulation needs in JLab Electron Ion Collider project, it can be used as a general design tool for other accelerators. JSPEC provides various models of the ion beam and the electron beam and it calculates the expansion rate and simulates the evolution of the ion beam under the IBS and/or electron cooling effect. In this report, we will give a brief introduction of JSPEC and then present the latest code development progress of JSPEC, including new models, algorithms, and the user interface.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO04
About •	paper received ※ 20 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLO06	Weak-Strong Beam-Beam Simulation for eRHIC	proton, cavity, luminosity, electron	545
	Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, C. Montag, V. Ptitsyn, F.J. Willeke BNL, Upton, New York, USA Y. Hao, D. Xu FRIB, East Lansing, Michigan, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the eRHIC, to compensate the geometric luminosity loss due to the crossing angle, crab cavities are to be installed on both sides of the interaction point. When the proton bunch length is comparable to the wavelength of its crab cavities, protons will not be perfectly tilted in the x-z plane. In the article, we employ weak-strong beam-beam interaction model to calculate the proton beam size growth rates and luminosity degradation rate with various machine and time parameters. The goal of these studies is to optimize the the beam-beam related machine and beam parameters of eRHIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO06
About •	paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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TUPLO07	Calculation of Action Diffusion With Crabbed Collision in eRHIC	proton, cavity, electron, luminosity	549
	Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, C. Montag, V. Ptitsyn, F.J. Willeke BNL, Upton, New York, USA Y. Hao, D. Xu FRIB, East Lansing, Michigan, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the eRHIC, to compensate the geometric luminosity loss due to the crossing angle, crab cavities are to be installed on both sides of the interaction point. When the proton bunch length is comparable to the wavelength of its crab cavities, protons will not be perfectly tilted in the x-z plane. In the article, we develop a simulation code to calculate the transverse action diffusion rate as function of the initial proton longitudinal action. The goal of this study is to identify the contributions from various protons to the overall emittance growth. Tune scan is also performed to locate optimum working points which yield less proton emittance growth.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO07
About •	paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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TUPLO09	Electron-Ion Collider Performance Studies With Beam Synchronization via Gear-Change	luminosity, electron, collider, beam-beam-effects	553
	I. Neththikumara, G.A. Krafft, B. Terzić ODU, Norfolk, Virginia, USA G.A. Krafft, Y. Roblin JLab, Newport News, Virginia, USA
	Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as "gear-change", whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and Bassetti-Erskine approach for beam-beam interactions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO09
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLE16	RFA Measurement of E-Cloud Generation Process at Fermilab Main Injector	electron, acceleration, ECR, proton	595
	Y. Ji IIT, Chicago, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA R.M. Zwaska Fermilab, Batavia, Illinois, USA
	Fermilab aims to provide greater beam power for the neutrino physics program. As the beam power increases, the unwanted production of secondary electrons in the beam pipe, known as ‘electron cloud’ or ‘E-cloud’ may become disruptive to high intensity operation. Instrumentation has been deployed in the Fermilab Main Injector (MI) to study E-cloud. One of these is a Retard Field Analyzer (RFA) that can be used to directly measure E-cloud generation at the location of the instrument. Studies of the dependence of E-cloud on beam intensity and bunch length have been carried out. The experimental results are compared to POSINST simulations. These simulations are guided by measurements from a Secondary Electron Yield (SEY) test stand installed in the MI to measure the SEY of materials such as the beam pipe stainless steel. The SEY has a strong influence on the E-cloud density. Results of these comprehensive studies comparing the RFA data with realistic MI simulations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE16
About •	paper received ※ 28 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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WEXBA3	CSR Phase Space Dilution in CBETA	linac, lattice, radiation, shielding	605
	W. Lou, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C.E. Mayes SLAC, Menlo Park, California, USA
	CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated.
	Slides WEXBA3 [6.121 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBA3
About •	paper received ※ 28 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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WEYBA6	A High-Precision Emission Computational Model for Ultracold Electron Sources	electron, cathode, framework, multipole	622
	A.J. Tencate, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work is supported by NSF award #1535401. The high-intensity, high-brightness and precision frontiers for charged particle beams are an increasingly important focus for study. Ultimately for electron beam applications, including FELs and microscopy, the quality of the source is the limiting factor in the final quality of the beam. It is imperative to understand and develop a new generation of sub-Kelvin electron sources, and the current state of PIC codes are not precise enough to adequately treat this ultracold regime. Our novel computational framework is capable of modelling electron field emission from nanoscale structures on a substrate, with the precision to handle the ultracold regime. This is accomplished by integrating a newly developed Poisson integral solver capable of treating highly curved surfaces and an innovative collisional N-body integrator to propagate the emitted electron with prescribed accuracy. The electrons are generated from a distribution that accounts for quantum confinement and material properties and propagated to the cathode surface. We will discuss the novel techniques that we have developed and implemented, and show emission characteristics for several cathode designs.
	Slides WEYBA6 [4.215 MB]
	Poster WEYBA6 [5.758 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA6
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLM01	Studies in Applying Machine Learning to Resonance Control in Superconducting RF Cavities	controls, cavity, LLRF, resonance	659
	J.A. Diaz Cruz, S. Biedron, M. Martinez-Ramon, R. Pirayesh, S.I. Sosa Guitron University of New Mexico, Albuquerque, USA J.A. Diaz Cruz SLAC, Menlo Park, California, USA
	Traditional PID, active resonance and feed-forward controllers are dominant strategies for cavity resonance control, but performance may be limited for systems with tight detuning requirements, as low as 10 Hz peak detuning (few nanometers change in cavity length), that are affected by microphonics and Lorentz Force Detuning. Microphonic sources depend on cavity and cryomodule mechanical couplings with their environment and come from several systems: cryoplant, RF sources, tuners, etc. A promising avenue to overcome the limitations of traditional resonance control techniques is machine learning due to recent theoretical and practical advances in these fields, and in particular Neural Networks (NN), which are known for their high performance in complex and nonlinear systems with large number of parameters and have been applied successfully in other areas of science and technology. In this paper we introduce NN to resonance control and compare initial performance results with traditional control techniques. An LCLS-II superconducting cavity type system is simulated in an FPGA, using the Cryomodule-on-Chip model developed by LBNL, and is used to evaluate machine learning algorithms.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM01
About •	paper received ※ 05 September 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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WEPLM06	NuMI Beam Muon Monitor Data Analysis and Simulation for Improved Beam Monitoring	target, proton, diagnostics, experiment	677
	P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA A. Bashyal Oregon State University, Corvallis, USA T.J. Rehak Drexel University, Philadelphia, Pennsylvania, USA D.A. Wickremasinghe, K. Yonehara Fermilab, Batavia, Illinois, USA Y. Yu IIT, Chicago, Illinois, USA
	Funding: Work supported by US DOE grants DE-SC0019264 and DE-SC0017815 and Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359. The NuMI muon monitors (MMs) are a very important diagnostic tool for monitoring the stability of the neutrino beam used by the NOvA experiment at Fermilab. The goal of our study is to maintain the quality of the MM signal and to establish the correlations between the neutrino and muon beam profile. This study could also inform the LBNF decision on the beam diagnostic tools. We report on the progress of beam scan data analysis (beam position, spot size, and magnetic horn current scan) and comparison with the simulation outcomes.
	Poster WEPLM06 [6.150 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM06
About •	paper received ※ 30 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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WEPLM11	Closed Loop Modeling of the APS-U Orbit Feedback System	controls, feedback, power-supply, vacuum	683
	P.S. Kallakuri, A.R. Brill, J. Carwardine, N. Sereno ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO₂-O6CH11357. Orbit stabilization to 10% of the expected small beam sizes for Advanced Photon Source Upgrade (APS-U) requires pushing the state of the art in fast orbit feedback (FOFB) control, both in the spatial domain and in dynamical performance. We are building a Matlab/Simulink fast orbit feedback system model to guide decisions about APS-U fast orbit feedback system implementation and to provide a test bench for optimal-control methodologies and orbit correction algorithms applicable to the APS-U. A transfer function model was built from open-loop frequency-response and step-response measurements of the present APS and subsequently validated against closed-loop measurements. A corresponding model for APS-U fast orbit feedback was generated by substituting measured responses of APS-U prototype corrector magnets and power supplies into this same model. Stabilizing PID gains are designed using model, and simulated dynamic performance of the new controller is validated through experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM11
About •	paper received ※ 27 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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WEPLM13	Multipactor Electron Cloud Analysis in a 17 GHz Standing Wave Accelerator Cavity	electron, multipactoring, cavity, experiment	687
	H. Xu, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA
	Funding: US Department of Energy High Energy Physics Theoretical predictions of single-surface one-point multipactor modes have been confirmed in experiments with a 17 GHz standing wave single cell disk-loaded waveguide accelerator structure operated in gradient range of 45-90 MV/m. A dc-biased probe placed outside of a slit in the side wall of the structure was used to measure the internal dark current electron energy distribution. The results indicated that the electrons had kinetic energy up to about 50 eV, in agreement with our CST particle-in-cell (PIC) simulations. Further theoretical calculations were performed to calculate the frequency detuning introduced by the multipactor electron cloud on the cell side wall for different electron cloud thicknesses and densities. We found that the detuning (Δf/f) due to the electron cloud was small, about two orders of magnitude smaller than the reciprocal of the cavity loaded quality factor. This detuning is sufficiently small that it does not cause significant power reflection. Similar calculations were carried out for high gradient operation of accelerator structures at frequencies of 2.856 GHz and 110.0 GHz, showing similar small detuning by multipactor discharges.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM13
About •	paper received ※ 19 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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WEPLM50	Beam Driven Bimodal Cavity Structure for High Gradient Acceleration	cavity, bunching, acceleration, site	707
	X. Chang, Y. Jiang, S.V. Shchelkunov Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA J.L. Hirshfield Omega-P, Inc., New Haven, Connecticut, USA
	Funding: Supported by USA National Science Foundation, Award #1632588 Abstract: Research aiming to increase the RF breakdown threshold in electron/positron accelerators is being conducted at the Yale University Beam Physics Laboratory. Our two-beam accelerator approach employs a beam driven bimodal cavity structure. This cavity includes (i) two modes excited by the drive beam, with the higher mode frequency three times that of the fundamental TM010 mode; (ii) a low-current accelerated beam and high-current drive beam traversing the same cavity structure. This approach has the potential advantages of (a) operating at higher acceleration gradient with lower breakdown and pulsed heating rates than that of a single-mode cavity structure at the same acceleration gradient, due to the spatiotemporal field distribution properties in the bimodal cavities; and (b) obtaining high accelerating gradient with a low energy drive beam. Recent progress in simulations and work towards an experimental test stand is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM50
About •	paper received ※ 23 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLM51	Ka-Band High Power Harmonic Amplifier for Bunch Phase-Space Linearization	cavity, klystron, linac, bunching	710
	X. Chang, Y. Jiang, S.V. Shchelkunov Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA J.L. Hirshfield Omega-P, Inc., New Haven, Connecticut, USA
	Funding: Supported by USA National Science Foundation, Award #1632588 Abstract: A future European light source CompactLight is being proposed to extend FEL operation further into the x-ray region than other light sources by using a linac operating at X-band (12 GHz) with a short Ka-band (36 GHz) section for linearizing bunch phase space. The Ka-band system requires a high-power RF amplifier, synchronized with the main X-band source. We report here on design of a third-harmonic klystron amplifier for this application. Our design employs a four-cavity system with a multi-cell extended interaction output cavity. Initial simulation results indicate that more than 10 MW of 36-GHz power can be obtained with an efficiency exceeding 20%, and with 12-GHz drive power of 30 W. A preliminary design for a proof-of-principal experimental test of this concept is described
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM51
About •	paper received ※ 23 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLM68	Design of a Dielectric-Loaded Accelerator for Short Pulse High Gradient Research	acceleration, wakefield, accelerating-gradient, experiment	751
	M.M. Peng, J. Shi TUB, Beijing, People’s Republic of China M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	The short-pulse two-beam acceleration approach is a promising candidate to meet the cost and luminosity requirements for future linear colliders. Dielectric-loaded structure has been intensely investigated for this approach because of its low fabrication cost, low RF loss, and potential to withstand GV/m gradient. An X-band 11.7~GHz dielectric-loaded accelerator (DLA) has been designed for high power test with short RF pulses (3~ns) generated from a power extractor driven by high charge bunches at Argonne Wakefield Accelerator (AWA) facility. The gradient is expected to be over 100~MV/m with the maximum input power of 400~MW.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM68
About •	paper received ※ 05 September 2019 paper accepted ※ 27 November 2019 issue date ※ 08 October 2019
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WEPLS02	Simulation of a Klystron Input Cavity using a Steady-State Full-Wave Solver	experiment, klystron, cavity, electron	768
	A.R. Gold, S.G. Tantawi SLAC, Menlo Park, California, USA
	The simulation of vacuum electronic radio-frequency (RF) power sources is generally done through semi-analytical modeling approaches. These techniques are computationally efficient as they make assumptions on the source topology, such as the requirement that the electron beam travel longitudinally and interact with cylindrical modes. To simulate more general interactions, transient particle-in-cell (PIC) codes are currently required. We present here simulation results of a 5045 klystron using a newly developed steady state code which does not make assumptions on the beam configuration or geometry of the structure and resonant modes. As we solve directly for the steady-state system dynamics, this approach is computationally efficient yet, as demonstrated through comparison with experimental results, provides similar accuracy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS02
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLS03	Analytical Expression for a N-Turn Trajectory in the Presence of Quadrupole Magnetic Errors	quadrupole, betatron, experiment, lattice	772
	Y. Rodriguez Garcia, J.F. Cardona UNAL, Bogota D.C, Colombia Y. Rodriguez Garcia UAN, Bogotá D.C., Colombia
	The action and phase jump method is a technique, based on the use of turn-by-turn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS03
About •	paper received ※ 26 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLS05	Simulation Analysis of the LCLS-II Injector using ACE3P and IMPACT	cavity, emittance, booster, lattice	779
	D.A. Bizzozero, J. Qiang LBNL, Berkeley, California, USA L. Ge, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA
	Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DEAC02-05CH11231 and DE-AC02-76-SF00515. The LCLS-II beam injector system consists of a 186 MHz normal-conducting RF gun, a two-cell 1.3 GHz normal-conducting buncher cavity, two transverse focusing solenoids, and eight 1.3 GHz 9-cell Tesla-like super-conducting booster cavities. With a coordinated effort between LBNL and SLAC, we have developed a simulation workflow combining the electromagnetic field solvers from ACE3P with the beam dynamics modeling code IMPACT. This workflow will be used to improve performance and minimize beam emittance for given accelerator structures through iterative optimization. In our current study, we use this workflow to compare beam quality parameters between using 2D axisymmetric field profiles and fully 3D non-axisymmetric fields caused by geometrical asymmetries (e.g. RF coupler ports).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS05
About •	paper received ※ 20 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLS12	A Semi-Analytical Approach to Six-Dimensional Path-Dependent Transport Matrices With Application to High-Brightness Charged-Particle Beam Transport	solenoid, emittance, cavity, electron	792
	C.-Y. Tsai HUST, Wuhan, People’s Republic of China K. Fan Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
	Funding: This work was supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049. Efficient and accurate estimate of high-brightness electron beam dynamics is an important step to the overall performance evaluation in modern particle accelerators. Utilizing the moment description to study multi-particle beam dynamics, it is necessary to develop a path-dependent transport matrix, together with application of the drift-kick algorithm. In this paper we will construct semi-analytical models for three typical beam transport elements, solenoid with fringe fields, transverse deflecting cavity, and a beam slit. To construct the semi-analytical models for these elements, we begin by formulating the simplified single-particle equations of motion, and apply typical numerical techniques to solve the corresponding six-by-six transport matrix as a function of the path coordinate. The developed semi-analytical models are demonstrated with three practical examples, where our numerical results are discussed, compared with and validated by particle tracking simulations. These path-dependent transport matrix models can be incorporated to the analysis based on beam matrix method for the application to high-brightness charged-particle beam transport. C.-Y. Tsai et al., Nuclear Inst. And Methods in Physics Research, A 937 (2019) 1-20
	Poster WEPLS12 [3.099 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS12
About •	paper received ※ 20 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLS14	A C++ TPSA/DA Library With Python Wrapper	multipole, operation, framework, collective-effects	796
	H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Truncated power series algebra (TPSA) or differential algebra (DA) is often used by accelerator physicists to generate a transfer map of a dynamic system. The map then can be used in dynamic analysis of the system or in particle tracking study. TPSA/DA can also be used in some fast algorithms, eg. the fast multipole method, for collective effect simulation. This paper reports a new TPSA/DA library written in C++. This library is developed based on Dr. Lingyun Yang’s TPSA code, which has been used in MAD-X and PTC. Compared with the original code, the updated version has the following changes: (1) The memory management has been revised to improve the efficiency; (2) A new data type of DA vector is defined and supported by most frequently used operators; (3) Support of inverse trigonometric functions and hyperbolic functions for the DA vector has been added; (4) function composition is revised for better efficiency; (5) a python wrapper is provided. The code is hosted at github and available to the public.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS14
About •	paper received ※ 20 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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WEPLH03	Redesign of ReA3 4-Rod RFQ	rfq, MMI, operation, linac	807
	A.S. Plastun, P.N. Ostroumov, A.C.C. Villari, Q. Zhao FRIB, East Lansing, Michigan, USA A.C.C. Villari, Q. Zhao NSCL, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. DoE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University. The present RFQ of ReA3 reaccelerator at Michigan State University (MSU) has been commissioned in 2010. This 4-rod RFQ was designed to accelerate the prebunched 80.5 MHz beams with the lowest Q/A = 1/5. However, the lack of proper cooling limited the RFQ performance to the pulsed operation with the lowest Q/A = 1/4. The design voltage for Q/A = 1/5 has never been reached even in a pulsed mode due to the sparking. In 2016 we initiated the upgrade of ReA3 RFQ to support high duty cycle (up to CW) operation with Q/A = 1/5 beams. The upgrade included the new rods with trapezoidal modulation, and new stems with improved cooling. The redesigned 80.5 MHz RFQ will consume only 65% rf power of the present RFQ for Q/A = 1/5 beam. It will provide the transmission up to 78% for 16.1 MHz beams and 89% for 80.5 MHz beams. High reliability and efficiency of the RFQ are very important for the going-on reaccelerator upgrade to ReA6 and for future operation as a part of FRIB. The electrodes have been manufactured and are being installed. The RF and beam tests are scheduled to summer 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH03
About •	paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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WEPLO02	Progress on Muon Ionization Cooling Demonstration with MICE	emittance, experiment, detector, instrumentation	852
	P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: STFC, NSF, DOE, INFN, CHIPP andd more The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory has collected extensive data to study the ionization cooling of muons. Several million individual particle tracks have been recorded passing through a series of focusing magnets in a number of different configurations and a liquid hydrogen or lithium hydride absorber. Measurement of the tracks upstream and downstream of the absorber has shown the expected effects of the 4D emittance reduction. Further studies are providing more and deeper insight.
	Poster WEPLO02 [0.477 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO02
About •	paper received ※ 30 August 2019 paper accepted ※ 17 November 2020 issue date ※ 08 October 2019
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WEPLO05	Developing Criteria for Laser Transverse Instability in LWFA Simulations	laser, plasma, wakefield, electron	855
	Y. Yan, L.D. Amorim, P. Iapozzuto, V. Litvinenko, N. Vafaei-Najafabadi Stony Brook University, Stony Brook, USA M. Babzien, M.G. Fedurin, Y.C. Jing, K. Kusche, M.A. Palmer, I. Pogorelsky, M.N. Polyanskiy BNL, Upton, New York, USA M. Downer, J.R. Welch, R. Zgadzaj The University of Texas at Austin, Austin, Texas, USA C. Joshi, W.B. Mori UCLA, Los Angeles, California, USA P. Kumar, V. Samulyak SBU, Stony Brook, USA
	Funding: We acknowledge resources of NERSC facility, operated under Contract No. DE-AC02-5CH11231, and of SEAWULF at Stony Brook University as well as funding from SBU-BNL Seed Grants. Laser-driven plasma wakefield acceleration (LWFA) is considered as a potential technology for future colliders and light sources. To make the best use of a laser’s power, the laser is expected to maintain a stable propagation. A transverse instability is observed in our previous simulations when a long, intense CO₂ laser propagates inside a plasma. This unstable motion is accompanied by strong transverse diffraction of the laser power and results in the disruption of the ion channel typically used for radiation generation. We investigated the hosing-like instability using the Particle-in-Cell code OSIRIS** by modeling the laser portion where this instability is seeded and then evolves. In this proceeding, a criteria will be described that allows for the characterization of the temporal and spatial evolution of this instability. J. Yan, et al. , AAC, IEEE, 2018. * L. Nemos et al., PPCF, 58(3), 2016. ***R. A. Fonseca et al., Lecture Notes Computation Science (2331) 342, 2002.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO05
About •	paper received ※ 16 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019
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WEPLO06	Start-to-End Simulation of the Drive-Beam Longitudinal Dynamics for Beam-Driven Wakefield Acceleration	laser, electron, wakefield, linac	858
	W.H. Tan, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA A. Zholents, A. Zholents ANL, Lemont, Illinois, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science under contracts No. DE-AC02-06CH11357 (via a laboratory- directed R&D program at ANL) and No. DE-SC0018656 at NIU. Collinear beam-driven wakefield acceleration (WFA) relies on shaped driver beam to provide higher accelerating gradient at a smaller cost and physical footprint. This acceleration scheme is currently envisioned to accelerate electron beams capable of driving free-electron laser . Start-to-end simulation of drive-bunch beam dynamics is crucial for the evaluation of the design of accelerators built upon WFA. We report the start-to-end longitudinal beam dynamics simulations of an accelerator beamline capable of producing high charge drive beam. The generated wakefield when it passes through a corrugated waveguide results in a transformer ratio of 5. This paper especially discusses the challenges and criteria associated with the generation of temporally-shaped driver beam, including the beam formation in the photoinjector, and the influence of energy chirp control on beam transport stability. A. Zholents et al., "A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility"*
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO06
About •	paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLO18	Numerical Study of Coherent Radiation from Induced Plasma Dipole Oscillation by Detuned Laser Pulses	plasma, laser, radiation, dipole	874
	P.C. Castillo, S.D. Rodriguez, D.A. Wan SUNY Farmingdale State College, State University of New York, Farmingdale, New York, USA B. Gross City College of The City University of New York, New York, USA M.S. Hur, S. Kylychbekov, H.S. Song UNIST, Ulsan, Republic of Korea D.G. Lee SBU, Stony Brook, New York, USA K. Yu BNL, Upton, New York, USA
	The study of intense laser-plasma interactions is a growing field of both theoretical and applied research. This research focuses on simulating the cross/self-interactions between high-intense short laser pulses and an initial target for preliminary ionization. Unlike our previous studies of laser-matter interaction over preformed plasma, we will explore the injection of laser pulses to induce background plasma driven by the self-guided laser wakefield mechanism, which is used to perturb the plasma for induced dipole oscillations followed by radiation. Inducing a cylindrical spatial plasma column within the laser beam radius regime, it is expected that a stable spatially localized plasma channel will result and the emitted radiation from the plasma dipole oscillation (PDO) will not be affected by surrounding absorption, resulting in effective radiation. We will depict the injection of laser pulses accounting for parameters such as field intensity, profile and phase difference defining the coordinated pulses to assess the potential of enhancing the efficiency and spectral properties of the transverse emitted radiation due to the counter-propagating pulses interaction in plasma.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO18
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLO20	High Gradient High Efficiency C-Band Accelerator Structure Research at LANL	operation, experiment, cavity, electron	882
	E.I. Simakov, A.W. Garmon, T.C. Germann, M.F. Kirshner, F.L. Krawczyk, J.W. Lewellen, D. Perez, G. Wang LANL, Los Alamos, New Mexico, USA A. Fukasawa, J.B. Rosenzweig UCLA, Los Angeles, California, USA
	Funding: Los Alamos National Laboratory LDRD Program This poster will report on the status of the new high gradient C-band accelerator project at LANL. Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. Our goal is to use a multi-disciplinary approach that includes accelerator design, molecular dynamics simulations, and advanced manufacturing to develop high gradient, high efficiency RF structures for both compact and facility-size accelerator systems. We considered common operation frequencies for accelerators and identified C-band as the optimal frequency band for high gradient operations based on achievable gradients and means to control wakefields. We are putting together a high gradient C-band test facility that includes a 50 MW Toshiba klystron and cryo-coolers for operating copper NCRF accelerator cavities at long pulse duration. We plan to conduct high gradient testing of the optimized RF structures made of copper and novel copper alloys. LANL modeling capabilities will be used to systematically study the formation of breakdown precursors at high fields to develop basic theoretical understanding of the breakdown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO20
About •	paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLE02	Integrated Accelerator Simulation with Electromagnetics and Beam Physics Codes	cavity, plasma, electron, emittance	885
	L. Ge, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA D.A. Bizzozero, J. Qiang, J.-L. Vay LBNL, Berkeley, California, USA D.P. Grote LLNL, Livermore, California, USA
	Funding: Work supported by US Department of Energy under contracts AC02-76SF00515, DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of the National Energy Research Scientific Computing Center. This paper presents an integrated simulation capability for accelerators including electromagnetic field and beam dynamics effects. The integrated codes include the parallel finite-element code suite ACE3P for electromagnetic field calculation of beamline components, the parallel particle-in-cell (PIC) code IMPACT for beamline particle tracking with space-charge effects, and the parallel self-consistent PIC code Warp for beam and plasma simulations. The common data format OpenPMD has been adopted for efficient field and particle I/O data transfer between codes. One application is to employ ACE3P and IMPACT for studying beam qualities in accelerator beamlines. Another is to combine ACE3P and Warp for investigating plasma processing for operational performance of RF cavities. A module for mapping the CAD geometry used in ACE3P to Warp Cartesian grid representation has been developed. Furthermore, a workflow has been implemented that enables the execution of integrated simulation on HPC systems. Examples for simulation of the LCLS-II injector using ACE3P-IMPACT and plasma ignition in SRF cavities using ACE3P-Warp will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE02
About •	paper received ※ 20 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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WEPLE04	Recent Developments and Applications of Parallel Multi-Physics Accelerator Modeling Suite ACE3P	cavity, cryomodule, dipole, GUI	888
	Z. Li, L. Ge, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA
	Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515. SLAC’s ACE3P code suite is developed to harness the power of massively parallel computers to tackle large complex problems with increased memory and solve them at greater speed. ACE3P parallel multi-physics codes are based on higher-order finite elements for superior geometry fidelity and better solution accuracy. ACE3P consists of an integrated set of electromagnetic, thermal and mechanical solvers for accelerator modeling and virtual prototyping. The use of ACE3P has contributed to the design and optimization of existing and future accelerator projects around the world. Multi-physics analysis on high performance computing (HPC) platform enables thermal-mechanical simulations of largescale systems such as the LCLS-II cryomodule. Recently, new capabilities have been added to ACE3P including a nonlinear eigenvalue solver for calculating mode damping, a moving window for pulse propagation in the time domain to reduce computational cost, thin layer coating representation using a surface impedance model, and improved boundary conditions using perfectly matched layers (PML) to terminate wave propagation. These new developments are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE04
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLE05	Tracking With Space Harmonics in ELEGANT Code	cavity, electromagnetic-fields, electron, photon	892
	Y.P. Sun, C. Yao ANL, Lemont, 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 elegant code has the capability of simulating particle motion in accelerating or deflecting RF cavities, with a simplified (or ideal) model of the electromagnetic fields. To improve the accuracy of RF cavity simulations, the ability to track with space harmonics has been added to the elegant code. The sum of all the space harmonics will mimic the real electromagnetic fields in the RF cavity. These space harmonics will be derived from electromagnetic fields simulation of the RF cavity. This method should be general, which can be applied to any RF cavity structure, including accelerating and deflecting cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE05
About •	paper received ※ 31 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLE06	Linear and Second Order Map Tracking with Artificial Neural Network	network, framework, software, storage-ring	895
	Y.P. Sun ANL, Lemont, 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. In particle accelerators, the tracking simulation is usually performed with symplectic integration, or linear/nonlinear transfer maps. In this paper, it is shown that the linear/nonlinear transfer maps may be represented by an artificial neural network. To solve this multivariate regression problem, both random datasets and structured datasets are explored to train the neural networks. The achieved accuracy will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE06
About •	paper received ※ 30 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLE08	Parallel Tracking-Based Modeling of Gas Scattering and Loss Distributions in Electron Storage Rings	scattering, lattice, storage-ring, electron	901
	M. Borland ANL, Lemont, 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. Estimation of gas scattering lifetimes in storage rings is typically done using a simple approach that can readily be performed by hand. A more sophisticated approach uses linear mapping of the angular dynamic acceptance around the ring and allows including variation of gas pressure and composition. However, neither approach is appropriate for highly nonlinear lattices, in which the angular acceptance does not map according to the linear optics. Further, these approaches provide no detailed information about the location of losses. To address these limitations, a tracking-based approach was implemented in the program Pelegant. We describe the implementation and performance of this method, as well as several applications to the Advanced Photon Source Upgrade. M. Borland, J. Carter, H. Cease, and B. Stillwell, Proc. IPAC 2015, 546. ** Y. Wang and M. Borland, AIP Conf. Proc. 877, 241 (2006).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE08
About •	paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLE10	Simulating Space Charge Dominated Beam Dynamics Using FMM	space-charge, emittance, cathode, multipole	909
	S.A. Schmid, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany M. Dohlus DESY, Hamburg, Germany
	Funding: This work is supported by the DFG in the framework of GRK 2128. In this contribution, we simulate the beam generation in the high brilliance photoinjector of the European XFEL developed at DESY-PITZ. The investigation addresses the influence of space charge on the emittance of bunches with up to 1.0 nC bunch charge. For the simulations, we implemented a mesh-less fast multipole method (FMM) in the 3D tracking code REPTIL. We present numerical convergence and performance studies as well as a validation with commonly used simulation tools ASTRA and KRACK3. Furthermore, we provide a machine parameter study to minimize the beam emittance in the injector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE10
About •	paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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THYBA3	Use of Solid Xenon as a Beam Dump Material for 4th-Generation Storage Rings	electron, emittance, storage-ring, vacuum	927
	M. Borland, H. Cease, J.C. Dooling ANL, Lemont, 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 Damage to tungsten beam dumps has been observed in the Advanced Photon Source due to the high charge (368 nC/store), high energy (7 GeV), and short loss time (about 15 microseconds). Owing to the higher charge (736 nC/store) and much lower emittance (42 pm vs 2.5 nm), this issue is expected to be much more severe in the APS Upgrade. This strongly suggests that such dumps are necessary in 4th-generation electron storage rings to prevent catastrophic damage to vacuum systems when, for example, rf systems trip. However, it also implies that the dump will be damaged by each strike and will thus need to be "refreshed," perhaps by moving the dump surface vertically to expose undamaged material. Xenon, a gas that solidifies at 161K, is an intriguing possibility for a beam dump material. Calculations suggest that as the beam spirals in toward a dump in a high-dispersion area the tails of the electron beam would vaporize sufficient xenon to rapidly diffuse the beam and render it harmless. The dump surface could be periodically reformed without breaking vacuum. Issues with the concept include the need to protect the frozen xenon from wakefield heating.
	Slides THYBA3 [2.451 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBA3
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THZBA4	Characterization and Modeling of High-Intensity Evolution in the SNS Beam Test Facility	emittance, diagnostics, lattice, controls	954
	K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA Z.L. Zhang ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. Partial support by NSF Accelerator Science grant 1535312 Modern high-power accelerators are charged with delivering reliable beam with low losses. Resolving the complex dynamics arising from space charge and nonlinear forces requires detailed models of the accelerator and particle-in-cell simulation. There has historically been discrepancy between simulated and measured beam distributions, particularly at the low-density halo level. The Beam Test Facility (BTF) at the Spallation Neutron Source is outfitted to study beam evolution in a high-power linear accelerator MEBT. This includes capability for high-dimensional measurements of the post-RFQ beam distribution, including interplane correlations that may be the key to accurate simulation. Beam is transported through a 4.6 m FODO channel (9.5 cells) to a second distribution measurement stage. Plans for validating simulations against BTF measurements of beam evolution in the FODO channel are discussed.
	Slides THZBA4 [8.316 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA4
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOYBA5

Weak-Strong Simulation of Beam-Beam Effects in Super Proton-Proton Collider

proton, collider, luminosity, resonance

22

L.J. Wang, J.Y. Tang
IHEP, Beijing, People’s Republic of China
T. Sen
Fermilab, Batavia, Illinois, USA

A Super Proton-Proton Collider (SPPC) that aims to explore new physics beyond the standard model is planned in China. Here we focus on the impact of beam-beam interactions in the SPPC. Simulations show that with the current optics and nominal tunes, the dynamic aperture (DA) with all the beam-beam interactions is less than 6σ, the dominant cause being the long-range interactions. First, we show the results of a tune scan done to maximize the DA. Next, we discuss the compensation of the long-range interactions by increasing the crossing angle and also by using current carrying wires.

Slides MOYBA5 [1.004 MB]

Poster MOYBA5 [0.727 MB]

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MOZBA4

Recent Developments in High Power High Brightness Double Bunch Self-Seeding at LCLS-II

FEL, undulator, photon, electron

67

A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.A. Lutman, G. Marcus, C. Pellegrini
SLAC, Menlo Park, California, USA

We discuss the power and spectral characteristics of an X-ray FEL, LCLS-II, operating in a double bunch self-seeding scheme (DBFEL). We show that it can reach very high power levels in the photon energy range of 4-8 keV. We discuss the system implementation on LCLS-II, including the design of a four-bounce crystal monochromator, and linac wakefields effects. Finally, we offer multiple applications of the DBFEL for high-field QED, AMO physics and single particle imaging.

Slides MOZBA4 [3.175 MB]

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MOZBA5

Optimized Linear and Second Order Chromaticity Setpoints for the Advanced Photon Source Upgrade

lattice, sextupole, MMI, photon

70

Y.P. Sun
ANL, Lemont, 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 nominal single particle dynamics optimizations of the Advanced Photon Source upgrade (APS-U) lattice are performed with dense numerical simulations of local momentum acceptance and dynamic acceptance. These simulations are quite time consuming, which may take weeks for optimizing one setpoint of linear chromaticity. In this paper, an alternative optimization method is adopted to generate optimized linear and second order chromaticity setpoints for the Advanced Photon Source upgrade lattice. This method is efficient in computing time needed, which is capable to generate a grid of optimized chromaticity setpoints in a relatively short time. The performance of these lattice solutions are verified by simulations with reasonable errors. These lattice solutions with different linear (or second order) chromaticity may be useful for the future APS-U commissioning and operations.

Slides MOZBA5 [3.350 MB]

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MOZBA6

The Broad-Band Impedance Budget of the Accumulator Ring in the ALS-U Project

impedance, wakefield, cavity, vacuum

74

D. Wang, S. De Santis, D. Li, T.H. Luo, M. Venturini
LBNL, Berkeley, California, USA
K.L.F. Bane
SLAC, Menlo Park, California, USA

Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. It consists of an accumulator and a storage ring. In both rings, coupling-impedance driven instabilities need careful evaluation to ensure meeting the machine high-performance goals. This paper presents the impedance budget of the accumulator ring both longitudinally and transversely. The budget includes the resistive wall impedance as well as the geometric impedance from the main vacuum components. Our calculations primarily rely on electromagnetic simulations with the CST code; when possible validation has been sought against analytical modeling, typically in the low-frequency limit, and good agreement generally found. Collective-instability current thresholds are also discussed.

Slides MOZBA6 [8.926 MB]

Poster MOZBA6 [3.542 MB]

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MOPLM03

Correlations Between Beta Beating and APS-U Single Particle Dynamics Performance

lattice, focusing, sextupole, quadrupole

95

Y.P. Sun
ANL, Lemont, 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.
In the optimizations and evaluations process of the Advanced Photon Source upgrade (APS-U) lattice, it was observed that there are negative correlations between beta beating and APS-U single particle dynamics performance (such as dynamic acceptance and local momentum acceptance). These correlations are not always present due to different reasons. In this paper, a systematic simulation study is performed to understand the correlations between beta beating and APS-U single particle dynamics performance. Relatively high beta beatings are generated to reveal these effects.

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paper received ※ 31 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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MOPLM07

Simulation of Beam Aborts for the Advanced Photon Source to Probe Material-Damage Limits for Future Storage Rings

experiment, storage-ring, emittance, photon

106

M. Borland, J.C. Dooling, R.R. Lindberg, V. Sajaev, Y.P. Sun
ANL, Lemont, 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.
Damage to tungsten beam dumps has been observed in the Advanced Photon Source (APS), a 7-GeV, third-generation storage ring light source. This issue is expected to be much more severe in the APS Upgrade, owing to doubling of the stored charge and much lower emittance. An experiment was conducted in the existing APS ring to test several possible dump materials and also assess the accuracy of predictions of beam-induced damage. Prior to the experiments, extensive beam abort simulations were performed with ELEGANT to predict thresholds for material damage, dependence on vertical beam size, and even the size of the trenches expected to be created by the beam. This paper presents the simulation methods, simple models for estimating damage, and results. A companion paper in this conference presents experimental results.

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MOPLM08

Controlling Transient Collective Instabilities During Swap-Out Injection

lattice, injection, octupole, emittance

110

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Previous work has shown that collective instabilities at injection may reduce injection efficiency even for on-axis injection as planned for the APS-Upgrade*. Stability at injection is governed by a number of factors, including phase-space mismatch between injected and stored bunch, strength of the impedance, degree of nonlinearities, and feedback. We find that the large tune-shift with amplitude of the most recent APS-U lattice largely tames the transient instability via Landau damping, and show that using octupoles to increase the nonlinear tune shift can stabilize the transient instability at injection that plagued a previously unstable lattice.
* R.R. Lindberg, M. Borland, and A. Blednykh, Proc. of NA-PAC 2016, pp. 901

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paper received ※ 24 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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MOPLM10

Simulation Study With Septum Field Map for the APS Upgrade

septum, magnet-design, injection, photon

116

A. Xiao, M. Abliz, M. Borland
ANL, Lemont, 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.
One of the biggest challenges faced by the Advanced Photon Source Upgrade injection system design is the septum magnet. Not only does the required leakage field inside the stored beam chamber need to be smaller than for the present ring, the magnet has to be slightly tilted about the z-axis to provide a gentle vertical bend that brings the injected beam trajectory close to y=0 when it passes through the storage ring quadrupole magnets upstream of the straight section. This paper describes the coordinate system transformation necessary to properly model the magnet from field maps. The main field is checked by tracking the injected beam backwards, while leakage fields are included in dynamic aperture simulation and beam lifetime calculation. Simulation results show that the magnet design satisfies the physics requirement.

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paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLM12

Progress on the Injection Transport Line Design for the APS Upgrade

injection, septum, extraction, booster

120

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

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An on-axis vertical injection scheme was adopted for the Advanced Photon Source upgrade multi-bend achromat lattice. As the design of the injection scheme has become more detailed, the booster to storage ring transport line (BTS) has advanced, including effects such as the septum field map and stray fields of storage ring magnets. Various error effects are simulated for setting specifications and predicting expected performance. The beam diagnostic scheme, including emittance measurement, is incorporated into the beamline design.

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MOPLM14

Studies of Beam Dumps in Candidate Horizontal Collimator Materials for the Advanced Photon Source Upgrade Storage Ring

experiment, storage-ring, photon, emittance

128

J.C. Dooling, W. Berg, M. Borland, G. Decker, L. Emery, K.C. Harkay, R.R. Lindberg, A.H. Lumpkin, G. Navrotski, V. Sajaev, Y.P. Sun, K.P. Wootton, A. Xiao
ANL, Lemont, 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
We present the results of experiments intended to show the effects of beam dumps on candidate collimator materials for the Advanced Photon Source Upgrade (APS-U) storage ring (SR). Due to small transverse electron beam sizes, whole beam loss events are expected to yield dose levels in excess of 10 MGy in beam-facing components, pushing irradiated regions into a hydrodynamic regime. Whole beam aborts have characteristic time scales ranging from 100s of ps to 10s of microseconds which are either much shorter than or roughly equal to thermal diffusion times. Aluminum and titanium alloy test pieces are each exposed to a series of beam aborts of varying fill pattern and charge. Simulations suggest the high energy/power densities are likely to lead to phase transitions and damage in any material initially encountered by the beam. We describe measurements used to characterize the beam aborts and compare the results with those from the static particle-matter interaction code, MARS; we also plan to explore wakefield effects. Beam dynamics modeling, done with elegant is discussed in a companion paper at this conference. The goal of this work is to guide the design of APS-U SR collimators.

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MOPLM17

Longitudinal Impedance Modeling of APS Particle Accumulator Ring with CST

impedance, kicker, cavity, vacuum

140

C. Yao, J. Carvelli, K.C. Harkay, L.H. Morrison
ANL, Lemont, Illinois, USA
D. Hui
University of Arizona, Tucson, Arizona, USA
J.S. Wang
Dassault Systems Simulia, Waltham, Massachusetts, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS-U (APS upgrade) ring plans implement a "swap out" injection scheme, which requires a injected beam of 15.6 nC single-bunch beam. The Particle Accumulator Ring (PAR), originally designed for up to 6 nC charge, must be upgraded to provide 20 nC single bunch beam. Our studies have shown that bunch length of the PAR beam, typically 300 ps at lower charge, increases to 800 ps at high charge due to longitudinal instabilities, which causes low injection efficiency of the downstream Booster ring. We completed beam impedance of all the PAR vacuum components recently with CST wakefield solver. 3D CAD models are directly imported into CST and various techniques were explored to improve and verify the results. The results are also cross-checked with that from GdfidL and Echo simulation. We identified 23 bellow- and 24 non-bellow flanges that contribute to as much as 50% of the total loss factor. We are considering upgrade options to reduce over all beam loading and longitudinal impedance. Beam tracking simulation is in progress that including the longitudinal impedance results from the simulations. We report the results and methods of the CST impedance simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM17

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paper received ※ 22 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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MOPLM20

Impedance Considerations for the APS Upgrade

impedance, photon, vacuum, cavity

147

R.R. Lindberg
ANL, Lemont, Illinois, USA
A. Blednykh
BNL, Upton, New York, USA

Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
The APS-Upgrade is targeting a 42 pm lattice that requires strong magnets and small vacuum chambers. Hence, impedance is of significant concern. We overview recent progress on identifying and modelling vacuum components that are important sources of impedance in the ring, including photon absorbers, BPMs, and flange joints. We also show how these impact collective dynamics in the APS-U lattice.

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MOPLS08

Error Tolerance Characterization for the HUST MeV Ultrafast Electron Diffraction System

emittance, electron, injection, laser

166

Y. Song, K. Fan, C.-Y. Tsai
HUST, Wuhan, People’s Republic of China

Ultrafast electron diffraction (UED) is a powerful tool for probing atomic dynamics with a femtosecond resolution. Such a spatiotemporal resolution requires error tolerance for the UED system which includes the RF system, the laser system, the beamline elements, etc. To characterize the error tolerance of the required spatiotemporal resolution for the 1.4-cell MeV UED we are developing, we use ASTRA to simulate the UED model with errors including initial transverse beam centroid offset, RF amplitude jitter and injection phase jitter, etc. By performing simulations with different errors omitted, we can characterize the contribution of each error and thus set the tolerance for each error to obtain the required performance of UED experiment. In the end, we present the error tolerance for 10% emittance growth and 100 fs time of flight variation to maintain the required spatiotemporal resolution.

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MOPLH02

Study of Photocathode Surface Damage due to Ion Back-Bombardment in High Current DC Gun

cathode, gun, electron, laser

174

J.P. Biswas
Stony Brook University, Stony Brook, USA
O.H. Rahman, E. Wang
BNL, Upton, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704, with the U.S. DOE
In high current DC gun, GaAs photocathode lifetime is limited by the ion back-bombardment. While gun operation ions are generated and accelerate back towards the cathode thus remove the activation layer’s material Cesium from the photocathode surface. We have developed an object-oriented code to simulate the ion generation due to dynamic gas pressure and ion trace in the electromagnetic field. The pressure profile varies from cathode position towards the transfer line behind the anode, which signifies the importance of dynamic simulation for ion back-bombardment study. In our surface damage study, we traced the energy and position of the ions on the photocathode surface and performed the Stopping and Range of Ions in Matter(SRIM) simulation to count the number of Cesium atoms removed from the surface due to single bunch impact. Cesium atom removal is directly related to the photocathode Quantum Efficiency(QE) decay. Our new dynamic simulation code can be used in any DC gun to study ion back-bombardment. We have used this new code to better understand the ion generation in prototype BNL 350 KV DC gun, and we have also estimated the normalized QE decay due to ion back-bombardment.

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MOPLH19

Beam Dynamics Simulations for a Conduction-Cooled Superconducting RF Electron Source

electron, cathode, emittance, experiment

213

O. Mohsen, V. Korampally, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia
Northern Illinois University, DeKalb, Illinois, USA
R. Dhuley, M.G. Geelhoed, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359
The development of robust and portable high-average power electron sources is key to many societal applications. An approach toward such sources is the use of cryogen-free superconducting radiofrequency cavities. This paper presents beam-dynamics simulations for a proof-of-principle experiment on a cryogen-free SRF electron source being prototyped at Fermilab. The proposed design implement a geometry that enhances the electric field at the cathode surface to simultaneously extract and accelerate electrons. In this paper, we explore the beam dynamics considering both the case of field and photoemission mechanism.

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paper received ※ 02 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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MOPLH23

An Analysis of Potential Compact Positron Beam Source

positron, plasma, emittance, cavity

220

R.M. Hessami
UCLA, Los Angeles, USA
S.J. Gessner
CERN, Geneva, Switzerland

For positron studies in plasma wakefield accelerators such as AWAKE, the development of new, cheaper, and compact positron beam sources is necessary. Using an electrostatic trap with parameters similar to other experiments, this paper explores converting that trapped positron plasma into a usable beam. Bunching is initially accomplished by an electrostatic buncher and the beam is accelerated to 148 keV by pulsed electrostatic accelerators. This is necessary for injection into the beta-matched rf cavities operating at 600 MHz, which bring the positron beam to a transverse emittance of 1.3 pi mrad mm, a longitudinal emittance of 93.3 pi keV mm, stdz of 1.85 mm and an energy of 22 MeV. The beamline used here is far simpler and less expensive than those at many facilities, such as SLAC, allowing for a cheap source of positron beams, potentially opening up positron beam studies to many facilities that could not previously afford such a source.

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MOPLH26

Design of a Compact Wakefield Accelerator Based on a Corrugated Waveguide

GUI, wakefield, coupling, electron

232

A.E. Siy
UW-Madison/PD, Madison, Wisconsin, USA
G.J. Waldschmidt, A. Zholents
ANL, Lemont, Illinois, USA

A compact wakefield accelerator is being developed at the Argonne National Laboratory for a future multiuser x-ray free electron laser facility. A cylindrical structure with a 2 mm internal diameter and fine corrugations on the wall will be used to create Čerenkov radiation. A "drive" bunch producing radiation at 180 GHz will create accelerating gradients on the order of 100 MV/m for the "witness" bunch. The corrugated structure will be approximately half meter long with the entire accelerator spanning a few tens of meters. An ultra-compact transition region between each corrugated structure has been designed to accommodate an output coupler, a notch filter, an integrated offset monitor, bellows, pumping and water cooling ports. The output coupler will extract on the order of a kilowatt of power from the Čerenkov radiation unused by the witness bunch. The integrated offset monitor is a novel diagnostic which will measure the cumulative offset of the electron beam in the corrugated structure upstream of the monitor. The specific details of the rf design will be presented here.

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MOPLO12

The RF BPM Pickup Electrodes Development for the APS-MBA Upgrade

pick-up, vacuum, electron, storage-ring

256

X. Sun, R.M. Lill
ANL, Lemont, Illinois, USA

Beam stability is critical for the Advanced Photon Source (APS) multi-bend achromat (MBA) lattice up-grade and will employ 560 radio frequency (RF) beam position monitors (BPMs). The RF BPMs will provide the primary measurement of the electron beam. Design goals for the BPM assembly include high sensitivity, low wakefield impedance, and ultra-mechanically stability. The design, electromagnetic simulation, manufacturing tolerance and prototype testing will be presented in this paper.
*Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO12

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUXBA3

Robust Thermoacoustic Range Verification for Pulsed Ion Beam Therapy

proton, target, radiation, experiment

294

S.K. Patch
UWM, Milwaukee, Wisconsin, USA
B.M. Brahim, D. Santiago-Gonzalez
ANL, Lemont, Illinois, USA

Funding: * Supported by the U.S D.O.E., Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. Measurements were performed at ANL’s ATLAS facility, which is a DOE Office of Science User Facility.
Lack of online range verification generally limits application of proton therapy to cancers in the brain, spine, and to pediatric patients. Previously, thermoacoustic range verification (TARV) has been demonstrated in weakly scattering media with known sound speed [1]. At ATLAS, we demonstrated the accuracy and robustness of TARV relative to ultrasound (US) images despite acoustic heterogeneity and sound speed errors representing in vivo conditions [2]. 250 ns pulses deposited 0.26 Gy of 16 MeV protons and 2.3 Gy of 60 MeV helium ions into liquid targets. TA signals were detected by an US array that also generated US images. An air gap phantom displaced the Bragg peak by 6.5 mm and the scanner’s propagation speed setting was altered by ±5%. Weak and strong scatterers were placed between the Bragg peak and US array. Estimated Bragg peak locations were translated 6.5 mm by the air gap phantom and agreed with TRIM simulations to within 0.3 mm, even when TA emissions traveled through a strong acoustic scatterer. Soundspeed errors dilated, and acoustic heterogeneities deformed both US images and TA range estimates, confirming that TARV is accurate relative to US images.
[1] Hickling, et al, Med Phys, 45(7), 2018. (review article)
[2] S. Patch, D. Santiago, & B. Mustapha, Med Phys, 46(1), 2019.

Slides TUXBA3 [4.449 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUXBA3

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUXBA4

Rapid Radio-Frequency Beam Energy Modulator for Proton Therapy

cavity, proton, GUI, klystron

298

X. Lu, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, A.V. Sy, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by US Department of Energy (DOE) Contract No. DE-AC02-76SF00515.
We present the design for a rapid proton energy modulator with radio-frequency (RF) accelerator cavities. The energy modulator is designed as a multi-cell one-meter long accelerator working at 2.856 GHz. We envision that each individual accelerator cavity is powered by a 400 kW low-voltage klystron to provide an accelerating / decelerating gradient of 30 MV/m. We have performed beam dynamics simulations showing that the modulator can provide ± 30MeV of beam energy change, with an energy spread of 3 MeV for a 7 mm long (full length) proton bunch. A prototype experiment of a single cell is in preparation at the Next Linear Collider Test Accelerator (NLCTA) at SLAC.

Slides TUXBA4 [3.275 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUXBA4

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paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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TUYBA3

Benchmarking the LCLS-II Photoinjector

laser, gun, solenoid, emittance

301

N.R. Neveu, T.J. Maxwell, C.E. Mayes
SLAC, Menlo Park, California, USA

Funding: DOE Contract No. DE-AC02-76SF00515
Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.

Slides TUYBA3 [1.320 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3

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paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM01

Experimental Studies of Resonance Structure Dynamics With Space Charge

resonance, space-charge, experiment, quadrupole

372

L. Dovlatyan, T.M. Antonsen, B.L. Beaudoin, S. Bernal, I. Haber, D.F. Sutter, G.D. Wyche
UMD, College Park, Maryland, USA

Funding: Funding for this project is provided by DOE-HEP award #DE-SC0010301
Space charge is one of the fundamental limitations for next generation high intensity circular accelerators. It can lead to halo growth as well as beam loss, and affect resonance structure in ways not completely understood. We employ the University of Maryland Electron Ring (UMER), a circular 10 keV storage machine, to experimentally study the structure of betatron resonances for beams of varying degrees of space charge intensity. Experimental techniques such as tune scans and frequency maps are employed. Results are also compared to computer simulations using the WARP code.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM01

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paper received ※ 26 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM03

Adjoint Approach to Accelerator Lattice Design

lattice, focusing, quadrupole, plasma

376

T.M. Antonsen, B.L. Beaudoin, L. Dovlatyan, I. Haber
UMD, College Park, Maryland, USA

Funding: Supported by USDoE DESC0010301
Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques [*]. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented.
* T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM03

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paper received ※ 23 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019

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TUPLM09

A Fast Method to Evaluate Transverse Coupled-Bunch Stability at Non-Zero Chromaticity

synchrotron, wakefield, dipole, betatron

387

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
We present a dispersion relation that gives the complex growth rate for coupled-bunch instabilities at arbitrary chromaticity in terms of its value at zero chromaticity. We compare predictions of the theory to elegant tracking simulations, and show that there are two distinct regimes to stability depending upon whether the zero chromaticity growth rate is smaller or larger than the chromatic tune shift over the bunch. We derive an approximate expression that is easily solved numerically, and furthermore indicate how the formalism can be extended to describe arbitrary longitudinal potentials.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM09

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paper received ※ 25 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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TUPLM11

Beam-Beam Damping of the Ion Instability

electron, storage-ring, damping, feedback

391

M. Blaskiewicz
BNL, Upton, New York, USA

Funding: Work Supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Beam-Beam damping of the Ion Instability The electron storage ring of the proposed electron ion collider at BNL has bunch charges as large as 50 nC and bunch spacings as small as 10 ns. For molecules like CO a dangerous buildup of positive ions is possible and a significant fraction of these ions can survive allowable clearing gaps. The instability is thus multi-turn and the weak damping required to stop the ion instabilty with an ideal clearing gap is ineffective here. The beam-beam force is highly nonlinear and a potent source of tune spread. Simulations employing several macro-particles per electron bunch and several ion macroparticles are used to estimate maximum gas densities for some common molecules. A simplified model is introduced and compared with simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM11

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paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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TUPLM12

Method for a Multiple Square Well Model to Study Transverse Mode Coupling Instability

DTL, collective-effects, space-charge, longitudinal-dynamics

395

M.A. Balcewicz, Y. Hao
FRIB, East Lansing, Michigan, USA
M. Blaskiewicz
BNL, Upton, New York, USA

In the high intensity limit it can become difficult to simulate intense beams sufficiently within a short time scale due to collective effects. Semi-Analytic methods such as the Square Well Model*/AirBag Square Well** (SWM/ABS) exist to estimate collective effects within a short time scale. SWM/ABS discretizes the longitudinal confining potential into a single square well enforcing linearity for the case of linear transverse optics. A method is proposed here to extend the Square Well Method multiple square wells. This method preserves linearity properties that make it easily solvable within a short time scale as well as including nonlinear effects from the longitudinal potential shape.
*M. Blaskiewicz PRSTAB 1, 044201. 1998
**A. Burov PRAB 22, 034202. 2019

Poster TUPLM12 [1.818 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM12

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM16

Double-Horn Suppression in EEX Based Bunch Compression

octupole, controls, emittance, quadrupole

407

J. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
M.E. Conde, G. Ha, J.G. Power
ANL, Lemont, Illinois, USA

Nonlinearities on the longitudinal phase space in-duce a double-horn current profile when the bunch is compressed strongly. Since this double-horn can de-grade the performance of FELs due to the CSR it makes, the suppression of the double-horn is one of important beam dynamics issues. Emittance exchange (EEX) can be interesting option for this issue due to its longitudinal controllability. Since EEX exchanges the longitudinal phase space and transverse phase space, higher order magnets such as octupole can control the nonlinearity. In this paper, we present simulation re-sults on the suppression of the double-horn current profile using EEX based bunch compression. We use a double EEX beamline installed at the Argonne Wake-field Accelerator facility for the simulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM16

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paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM18

Improving Energy Resolution and Compensating Chromatic Aberration With a TM010 Microwave Cavity

cavity, electron, gun, laser

411

C.J.R. Duncan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
P. Cueva, J.M. Maxson, D.A. Muller
Cornell University, Ithaca, New York, USA

Funding: National Science Foundation under Award OIA-1549132, the Center for Bright Beams
The intrinsic energy spread of electron sources limits the achievable resolution of electron microscopes in both spectroscopic and spatially resolved measurements. We propose that the TM010 mode of a single radio frequency (RF) cavity be used to dramatically reduce this energy spread in a pulsed beam. We show with analytic approximations, confirmed in simulations, that the non-linear time-energy correlations that develop in an electron gun can be undone by the RF cavity running near-crest. We derive an expression that gives the required RF field strength as a function of accelerating voltage. We explore multiple applications, including EELS and SEM. By pulsing a photocathode with commercially available, high repetition-rate lasers, our scheme could yield competitive energy spread reduction at higher currents when compared with monochromated continuous-wave sources for electron microscopes.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM18

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLM20

Generation of High-Charge Magnetized Electron Beams Consistent With JLEIC Electron Cooling Requirements

emittance, electron, cathode, experiment

414

A.T. Fetterman, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S.V. Benson, F.E. Hannon, S. Wang
JLab, Newport News, Virginia, USA
D.J. Crawford, D.R. Edstrom, P. Piot, J. Ruan
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 contract DE-AC05-06OR23177 and DE-AC02-07CH11359.
The proposed Jefferson Lab Electron-Ion Collider (JLEIC), currently under design, relies on electron cooling in order to achieve the desired luminosity. This includes an electron beam with >55 Mev, 3.2 nC bunches that cools hadron beams with energies up to 100 GeV. To enhance the cooling, the electron beam must be magnetized with a specific eigen-emittance partition. This paper explores the use of the Fermilab Accelerator Science and Technology (FAST) facility to demonstrate the generation of an electron beam with parameters consistent with those required in the JLEIC high-energy cooler. We demonstrate via simulations the generation of the required electron-beam parameters and perform a preliminary experiment to validate FAST capabilities to produce such beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM20

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paper received ※ 07 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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TUPLM33

Optimization of Beam Parameters for UEM with Photo-Emission S-Band RF Gun and Alpha Magnet

electron, gun, emittance, laser

440

H.R. Lee, P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
KAERI, Jeongeup-si, Republic of Korea
B.L. Cho
KRISS, Daejeon, Republic of Korea
M.Y. Han, J.Y. Lee, S.H. Lee
Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
H. Suk
GIST, Gwangju, Republic of Korea

Ultrafast Electron Microscopy (UEM) is a powerful tool to observe ultrafast dynamical processes in sample materials at the atomic level. By collaborating with KRISS and GIST, the future accelerator R&D team at KAERI has been developing a UEM facility based on a photo-emission S-band (=2856 MHz) RF gun. Recently, we have added an alpha magnet in the beamline layout of the UEM to improve beam qualities such as emittance, divergence, energy spread, and bunch length. To achieve high spatial and time resolutions, we have been optimizing those beam parameters and other machine parameters by performing numerous ASTRA and ELEGANT code simulations. In this paper, we describe our ASTRA and ELEGANT code optimizations to obtain high-quality beam parameters for the UEM facility with a photo-emission S-band RF gun and an alpha magnet.

Poster TUPLM33 [0.931 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM33

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paper received ※ 30 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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TUPLS07

Helical Transmission Line Test Stand for Non-Relativistic BPM Calibration

impedance, network, resonance, linac

463

C.J. Richard
NSCL, East Lansing, Michigan, USA
S.M. Lidia
FRIB, East Lansing, Michigan, USA

Measurements of non-relativistic beams by coupling to the fields are affected by the properties of the non-relativistic fields. The authors propose calibrating for these effects with a test stand using a helical line which can propagate pulses at low velocities. Presented are simulations of a helical transmission line for such a test stand which propagates pulses at 0.033c. A description of the helix geometry used to reduce dispersion is given as well as the geometry of the input network.

Poster TUPLS07 [3.469 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS07

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLH04

Feasibility Study of Fast Polarization Switching Superconducting Undulator

undulator, polarization, coupling, power-supply

497

I. Kesgin, Y. Ivanyushenkov, M. Kasa
ANL, Lemont, Illinois, USA

Funding: U.S. Department of Energy, Office of Science, under Contract No. DE-ACO₂-O6CH11357.
Polarization switching x-ray probes coupled with high-flux provide a unique tool to unraveling the nature of electronic heterogeneity and drive discovery of novel phases of electronic matter. Superconducting Arbitrary Polarization Emitter (SCAPE) is a new concept for a universal undulator, which offers linear or circular polarization states in one device and is ideal for experiments that require polarization switching. Polarization switching relies on modulating the magnetic field in the undulator. This, however, inevitably incurs losses in superconductors, which need to be mitigated. In this study, feasibility of fast switching SCAPE has been investigated through fabricating and testing several short prototype magnets wound with different superconductors and new design concepts. The losses at different frequencies and field amplitudes are measured and details will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH04

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUPLH09

Thermal Effects on Bragg Diffraction of XFEL Optics

FEL, photon, optics, synchrotron

506

Z. Qu, J. Wu, G. Zhou
SLAC, Menlo Park, California, USA
Y. Ma, Z. Qu
UC Merced, Merced, California, USA
B. Yang
Western Digital, Milpitas, California, USA

Funding: The US Department of Energy (DOE) (DE-AC02-76SF00515); The US DOE Office of Science Early Career Research Program grant (FWP-2013-SLAC-100164).
Crystal optical devices are widely used in X-ray free electron laser (XFEL) systems, monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, and spectrometers. The absorption of X-ray in these optical devices can cause increase of temperature and consequent thermal deformation, which can dynamic change in optic output. In self-seeding XFEL, the thermal deformation and strain in monochromator could cause significant seed quality degradation: central energy shift, band broadening and reduction in seed power. To quantitatively estimate the impact of thermomechanical effects on seed quality, we conduct thermomechanical simulations combined with diffraction to evaluate the seed quality with residual temperature field in a pump-probe manner. With our results, we show that a critical repetition rate could be determined, once the criteria for deviation of the seed quality are selected. This tool shows great potential for the design of XFEL optics for stable operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH09

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paper received ※ 28 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019

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TUPLO04

The Latest Code Development Progress of JSPEC

electron, emittance, collider, operation

539

H. Zhang, S.V. Benson, Y. Roblin, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The JLab Simulation Package on Electron Cooling (JSPEC) is an open source software developed at Jefferson Lab for electron cooling and intrabeam scattering (IBS) simulations. IBS is an important factor that leads to the growth of the beam emittance and hence the reduction of the luminosity in a high density ion collider ring. Electron cooling is an effective measure to overcome the IBS effect. Although JSPEC is initiated to fulfill the simulation needs in JLab Electron Ion Collider project, it can be used as a general design tool for other accelerators. JSPEC provides various models of the ion beam and the electron beam and it calculates the expansion rate and simulates the evolution of the ion beam under the IBS and/or electron cooling effect. In this report, we will give a brief introduction of JSPEC and then present the latest code development progress of JSPEC, including new models, algorithms, and the user interface.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO04

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paper received ※ 20 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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TUPLO06

Weak-Strong Beam-Beam Simulation for eRHIC

proton, cavity, luminosity, electron

545

Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, C. Montag, V. Ptitsyn, F.J. Willeke
BNL, Upton, New York, USA
Y. Hao, D. Xu
FRIB, East Lansing, Michigan, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the eRHIC, to compensate the geometric luminosity loss due to the crossing angle, crab cavities are to be installed on both sides of the interaction point. When the proton bunch length is comparable to the wavelength of its crab cavities, protons will not be perfectly tilted in the x-z plane. In the article, we employ weak-strong beam-beam interaction model to calculate the proton beam size growth rates and luminosity degradation rate with various machine and time parameters. The goal of these studies is to optimize the the beam-beam related machine and beam parameters of eRHIC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO06

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paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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TUPLO07

Calculation of Action Diffusion With Crabbed Collision in eRHIC

proton, cavity, electron, luminosity

549

Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, C. Montag, V. Ptitsyn, F.J. Willeke
BNL, Upton, New York, USA
Y. Hao, D. Xu
FRIB, East Lansing, Michigan, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the eRHIC, to compensate the geometric luminosity loss due to the crossing angle, crab cavities are to be installed on both sides of the interaction point. When the proton bunch length is comparable to the wavelength of its crab cavities, protons will not be perfectly tilted in the x-z plane. In the article, we develop a simulation code to calculate the transverse action diffusion rate as function of the initial proton longitudinal action. The goal of this study is to identify the contributions from various protons to the overall emittance growth. Tune scan is also performed to locate optimum working points which yield less proton emittance growth.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO07

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paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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TUPLO09

Electron-Ion Collider Performance Studies With Beam Synchronization via Gear-Change

luminosity, electron, collider, beam-beam-effects

553

I. Neththikumara, G.A. Krafft, B. Terzić
ODU, Norfolk, Virginia, USA
G.A. Krafft, Y. Roblin
JLab, Newport News, Virginia, USA

Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as "gear-change", whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and Bassetti-Erskine approach for beam-beam interactions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO09

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paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUPLE16

RFA Measurement of E-Cloud Generation Process at Fermilab Main Injector

electron, acceleration, ECR, proton

595

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

Fermilab aims to provide greater beam power for the neutrino physics program. As the beam power increases, the unwanted production of secondary electrons in the beam pipe, known as ‘electron cloud’ or ‘E-cloud’ may become disruptive to high intensity operation. Instrumentation has been deployed in the Fermilab Main Injector (MI) to study E-cloud. One of these is a Retard Field Analyzer (RFA) that can be used to directly measure E-cloud generation at the location of the instrument. Studies of the dependence of E-cloud on beam intensity and bunch length have been carried out. The experimental results are compared to POSINST simulations. These simulations are guided by measurements from a Secondary Electron Yield (SEY) test stand installed in the MI to measure the SEY of materials such as the beam pipe stainless steel. The SEY has a strong influence on the E-cloud density. Results of these comprehensive studies comparing the RFA data with realistic MI simulations will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE16

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paper received ※ 28 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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WEXBA3

CSR Phase Space Dilution in CBETA

linac, lattice, radiation, shielding

605

W. Lou, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.E. Mayes
SLAC, Menlo Park, California, USA

CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated.

Slides WEXBA3 [6.121 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBA3

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paper received ※ 28 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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WEYBA6

A High-Precision Emission Computational Model for Ultracold Electron Sources

electron, cathode, framework, multipole

622

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

Funding: This work is supported by NSF award #1535401.
The high-intensity, high-brightness and precision frontiers for charged particle beams are an increasingly important focus for study. Ultimately for electron beam applications, including FELs and microscopy, the quality of the source is the limiting factor in the final quality of the beam. It is imperative to understand and develop a new generation of sub-Kelvin electron sources, and the current state of PIC codes are not precise enough to adequately treat this ultracold regime. Our novel computational framework is capable of modelling electron field emission from nanoscale structures on a substrate, with the precision to handle the ultracold regime. This is accomplished by integrating a newly developed Poisson integral solver capable of treating highly curved surfaces and an innovative collisional N-body integrator to propagate the emitted electron with prescribed accuracy. The electrons are generated from a distribution that accounts for quantum confinement and material properties and propagated to the cathode surface. We will discuss the novel techniques that we have developed and implemented, and show emission characteristics for several cathode designs.

Slides WEYBA6 [4.215 MB]

Poster WEYBA6 [5.758 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA6

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLM01

Studies in Applying Machine Learning to Resonance Control in Superconducting RF Cavities

controls, cavity, LLRF, resonance

659

J.A. Diaz Cruz, S. Biedron, M. Martinez-Ramon, R. Pirayesh, S.I. Sosa Guitron
University of New Mexico, Albuquerque, USA
J.A. Diaz Cruz
SLAC, Menlo Park, California, USA

Traditional PID, active resonance and feed-forward controllers are dominant strategies for cavity resonance control, but performance may be limited for systems with tight detuning requirements, as low as 10 Hz peak detuning (few nanometers change in cavity length), that are affected by microphonics and Lorentz Force Detuning. Microphonic sources depend on cavity and cryomodule mechanical couplings with their environment and come from several systems: cryoplant, RF sources, tuners, etc. A promising avenue to overcome the limitations of traditional resonance control techniques is machine learning due to recent theoretical and practical advances in these fields, and in particular Neural Networks (NN), which are known for their high performance in complex and nonlinear systems with large number of parameters and have been applied successfully in other areas of science and technology. In this paper we introduce NN to resonance control and compare initial performance results with traditional control techniques. An LCLS-II superconducting cavity type system is simulated in an FPGA, using the Cryomodule-on-Chip model developed by LBNL, and is used to evaluate machine learning algorithms.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM01

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paper received ※ 05 September 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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WEPLM06

NuMI Beam Muon Monitor Data Analysis and Simulation for Improved Beam Monitoring

target, proton, diagnostics, experiment

677

P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA
A. Bashyal
Oregon State University, Corvallis, USA
T.J. Rehak
Drexel University, Philadelphia, Pennsylvania, USA
D.A. Wickremasinghe, K. Yonehara
Fermilab, Batavia, Illinois, USA
Y. Yu
IIT, Chicago, Illinois, USA

Funding: Work supported by US DOE grants DE-SC0019264 and DE-SC0017815 and Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359.
The NuMI muon monitors (MMs) are a very important diagnostic tool for monitoring the stability of the neutrino beam used by the NOvA experiment at Fermilab. The goal of our study is to maintain the quality of the MM signal and to establish the correlations between the neutrino and muon beam profile. This study could also inform the LBNF decision on the beam diagnostic tools. We report on the progress of beam scan data analysis (beam position, spot size, and magnetic horn current scan) and comparison with the simulation outcomes.

Poster WEPLM06 [6.150 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM06

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paper received ※ 30 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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WEPLM11

Closed Loop Modeling of the APS-U Orbit Feedback System

controls, feedback, power-supply, vacuum

683

P.S. Kallakuri, A.R. Brill, J. Carwardine, N. Sereno
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO₂-O6CH11357.
Orbit stabilization to 10% of the expected small beam sizes for Advanced Photon Source Upgrade (APS-U) requires pushing the state of the art in fast orbit feedback (FOFB) control, both in the spatial domain and in dynamical performance. We are building a Matlab/Simulink fast orbit feedback system model to guide decisions about APS-U fast orbit feedback system implementation and to provide a test bench for optimal-control methodologies and orbit correction algorithms applicable to the APS-U. A transfer function model was built from open-loop frequency-response and step-response measurements of the present APS and subsequently validated against closed-loop measurements. A corresponding model for APS-U fast orbit feedback was generated by substituting measured responses of APS-U prototype corrector magnets and power supplies into this same model. Stabilizing PID gains are designed using model, and simulated dynamic performance of the new controller is validated through experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM11

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paper received ※ 27 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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WEPLM13

Multipactor Electron Cloud Analysis in a 17 GHz Standing Wave Accelerator Cavity

electron, multipactoring, cavity, experiment

687

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

Funding: US Department of Energy High Energy Physics
Theoretical predictions of single-surface one-point multipactor modes have been confirmed in experiments with a 17 GHz standing wave single cell disk-loaded waveguide accelerator structure operated in gradient range of 45-90 MV/m. A dc-biased probe placed outside of a slit in the side wall of the structure was used to measure the internal dark current electron energy distribution. The results indicated that the electrons had kinetic energy up to about 50 eV, in agreement with our CST particle-in-cell (PIC) simulations. Further theoretical calculations were performed to calculate the frequency detuning introduced by the multipactor electron cloud on the cell side wall for different electron cloud thicknesses and densities. We found that the detuning (Δf/f) due to the electron cloud was small, about two orders of magnitude smaller than the reciprocal of the cavity loaded quality factor. This detuning is sufficiently small that it does not cause significant power reflection. Similar calculations were carried out for high gradient operation of accelerator structures at frequencies of 2.856 GHz and 110.0 GHz, showing similar small detuning by multipactor discharges.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM13

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paper received ※ 19 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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WEPLM50

Beam Driven Bimodal Cavity Structure for High Gradient Acceleration

cavity, bunching, acceleration, site

707

X. Chang, Y. Jiang, S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield
Omega-P, Inc., New Haven, Connecticut, USA

Funding: Supported by USA National Science Foundation, Award #1632588
Abstract: Research aiming to increase the RF breakdown threshold in electron/positron accelerators is being conducted at the Yale University Beam Physics Laboratory. Our two-beam accelerator approach employs a beam driven bimodal cavity structure. This cavity includes (i) two modes excited by the drive beam, with the higher mode frequency three times that of the fundamental TM010 mode; (ii) a low-current accelerated beam and high-current drive beam traversing the same cavity structure. This approach has the potential advantages of (a) operating at higher acceleration gradient with lower breakdown and pulsed heating rates than that of a single-mode cavity structure at the same acceleration gradient, due to the spatiotemporal field distribution properties in the bimodal cavities; and (b) obtaining high accelerating gradient with a low energy drive beam. Recent progress in simulations and work towards an experimental test stand is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM50

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paper received ※ 23 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLM51

Ka-Band High Power Harmonic Amplifier for Bunch Phase-Space Linearization

cavity, klystron, linac, bunching

710

X. Chang, Y. Jiang, S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield
Omega-P, Inc., New Haven, Connecticut, USA

Funding: Supported by USA National Science Foundation, Award #1632588
Abstract: A future European light source CompactLight is being proposed to extend FEL operation further into the x-ray region than other light sources by using a linac operating at X-band (12 GHz) with a short Ka-band (36 GHz) section for linearizing bunch phase space. The Ka-band system requires a high-power RF amplifier, synchronized with the main X-band source. We report here on design of a third-harmonic klystron amplifier for this application. Our design employs a four-cavity system with a multi-cell extended interaction output cavity. Initial simulation results indicate that more than 10 MW of 36-GHz power can be obtained with an efficiency exceeding 20%, and with 12-GHz drive power of 30 W. A preliminary design for a proof-of-principal experimental test of this concept is described

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM51

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paper received ※ 23 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLM68

Design of a Dielectric-Loaded Accelerator for Short Pulse High Gradient Research

acceleration, wakefield, accelerating-gradient, experiment

751

M.M. Peng, J. Shi
TUB, Beijing, People’s Republic of China
M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

The short-pulse two-beam acceleration approach is a promising candidate to meet the cost and luminosity requirements for future linear colliders. Dielectric-loaded structure has been intensely investigated for this approach because of its low fabrication cost, low RF loss, and potential to withstand GV/m gradient. An X-band 11.7~GHz dielectric-loaded accelerator (DLA) has been designed for high power test with short RF pulses (3~ns) generated from a power extractor driven by high charge bunches at Argonne Wakefield Accelerator (AWA) facility. The gradient is expected to be over 100~MV/m with the maximum input power of 400~MW.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM68

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paper received ※ 05 September 2019 paper accepted ※ 27 November 2019 issue date ※ 08 October 2019

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WEPLS02

Simulation of a Klystron Input Cavity using a Steady-State Full-Wave Solver

experiment, klystron, cavity, electron

768

A.R. Gold, S.G. Tantawi
SLAC, Menlo Park, California, USA

The simulation of vacuum electronic radio-frequency (RF) power sources is generally done through semi-analytical modeling approaches. These techniques are computationally efficient as they make assumptions on the source topology, such as the requirement that the electron beam travel longitudinally and interact with cylindrical modes. To simulate more general interactions, transient particle-in-cell (PIC) codes are currently required. We present here simulation results of a 5045 klystron using a newly developed steady state code which does not make assumptions on the beam configuration or geometry of the structure and resonant modes. As we solve directly for the steady-state system dynamics, this approach is computationally efficient yet, as demonstrated through comparison with experimental results, provides similar accuracy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS02

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paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLS03

Analytical Expression for a N-Turn Trajectory in the Presence of Quadrupole Magnetic Errors

quadrupole, betatron, experiment, lattice

772

Y. Rodriguez Garcia, J.F. Cardona
UNAL, Bogota D.C, Colombia
Y. Rodriguez Garcia
UAN, Bogotá D.C., Colombia

The action and phase jump method is a technique, based on the use of turn-by-turn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS03

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paper received ※ 26 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLS05

Simulation Analysis of the LCLS-II Injector using ACE3P and IMPACT

cavity, emittance, booster, lattice

779

D.A. Bizzozero, J. Qiang
LBNL, Berkeley, California, USA
L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DEAC02-05CH11231 and DE-AC02-76-SF00515.
The LCLS-II beam injector system consists of a 186 MHz normal-conducting RF gun, a two-cell 1.3 GHz normal-conducting buncher cavity, two transverse focusing solenoids, and eight 1.3 GHz 9-cell Tesla-like super-conducting booster cavities. With a coordinated effort between LBNL and SLAC, we have developed a simulation workflow combining the electromagnetic field solvers from ACE3P with the beam dynamics modeling code IMPACT. This workflow will be used to improve performance and minimize beam emittance for given accelerator structures through iterative optimization. In our current study, we use this workflow to compare beam quality parameters between using 2D axisymmetric field profiles and fully 3D non-axisymmetric fields caused by geometrical asymmetries (e.g. RF coupler ports).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS05

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paper received ※ 20 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLS12

A Semi-Analytical Approach to Six-Dimensional Path-Dependent Transport Matrices With Application to High-Brightness Charged-Particle Beam Transport

solenoid, emittance, cavity, electron

792

C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
K. Fan
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China

Funding: This work was supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049.
Efficient and accurate estimate of high-brightness electron beam dynamics is an important step to the overall performance evaluation in modern particle accelerators. Utilizing the moment description to study multi-particle beam dynamics, it is necessary to develop a path-dependent transport matrix, together with application of the drift-kick algorithm*. In this paper we will construct semi-analytical models for three typical beam transport elements, solenoid with fringe fields, transverse deflecting cavity, and a beam slit. To construct the semi-analytical models for these elements, we begin by formulating the simplified single-particle equations of motion, and apply typical numerical techniques to solve the corresponding six-by-six transport matrix as a function of the path coordinate. The developed semi-analytical models are demonstrated with three practical examples, where our numerical results are discussed, compared with and validated by particle tracking simulations. These path-dependent transport matrix models can be incorporated to the analysis based on beam matrix method for the application to high-brightness charged-particle beam transport.
* C.-Y. Tsai et al., Nuclear Inst. And Methods in Physics Research, A 937 (2019) 1-20

Poster WEPLS12 [3.099 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS12

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paper received ※ 20 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLS14

A C++ TPSA/DA Library With Python Wrapper

multipole, operation, framework, collective-effects

796

H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Truncated power series algebra (TPSA) or differential algebra (DA) is often used by accelerator physicists to generate a transfer map of a dynamic system. The map then can be used in dynamic analysis of the system or in particle tracking study. TPSA/DA can also be used in some fast algorithms, eg. the fast multipole method, for collective effect simulation. This paper reports a new TPSA/DA library written in C++. This library is developed based on Dr. Lingyun Yang’s TPSA code, which has been used in MAD-X and PTC. Compared with the original code, the updated version has the following changes: (1) The memory management has been revised to improve the efficiency; (2) A new data type of DA vector is defined and supported by most frequently used operators; (3) Support of inverse trigonometric functions and hyperbolic functions for the DA vector has been added; (4) function composition is revised for better efficiency; (5) a python wrapper is provided. The code is hosted at github and available to the public.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS14

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paper received ※ 20 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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WEPLH03

Redesign of ReA3 4-Rod RFQ

rfq, MMI, operation, linac

807

A.S. Plastun, P.N. Ostroumov, A.C.C. Villari, Q. Zhao
FRIB, East Lansing, Michigan, USA
A.C.C. Villari, Q. Zhao
NSCL, East Lansing, Michigan, USA

Funding: Work supported by the U.S. DoE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University.
The present RFQ of ReA3 reaccelerator at Michigan State University (MSU) has been commissioned in 2010. This 4-rod RFQ was designed to accelerate the prebunched 80.5 MHz beams with the lowest Q/A = 1/5. However, the lack of proper cooling limited the RFQ performance to the pulsed operation with the lowest Q/A = 1/4. The design voltage for Q/A = 1/5 has never been reached even in a pulsed mode due to the sparking. In 2016 we initiated the upgrade of ReA3 RFQ to support high duty cycle (up to CW) operation with Q/A = 1/5 beams. The upgrade included the new rods with trapezoidal modulation, and new stems with improved cooling. The redesigned 80.5 MHz RFQ will consume only 65% rf power of the present RFQ for Q/A = 1/5 beam. It will provide the transmission up to 78% for 16.1 MHz beams and 89% for 80.5 MHz beams. High reliability and efficiency of the RFQ are very important for the going-on reaccelerator upgrade to ReA6 and for future operation as a part of FRIB. The electrodes have been manufactured and are being installed. The RF and beam tests are scheduled to summer 2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH03

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paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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WEPLO02

Progress on Muon Ionization Cooling Demonstration with MICE

emittance, experiment, detector, instrumentation

852

P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: STFC, NSF, DOE, INFN, CHIPP andd more
The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory has collected extensive data to study the ionization cooling of muons. Several million individual particle tracks have been recorded passing through a series of focusing magnets in a number of different configurations and a liquid hydrogen or lithium hydride absorber. Measurement of the tracks upstream and downstream of the absorber has shown the expected effects of the 4D emittance reduction. Further studies are providing more and deeper insight.

Poster WEPLO02 [0.477 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO02

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paper received ※ 30 August 2019 paper accepted ※ 17 November 2020 issue date ※ 08 October 2019

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WEPLO05

Developing Criteria for Laser Transverse Instability in LWFA Simulations

laser, plasma, wakefield, electron

855

Y. Yan, L.D. Amorim, P. Iapozzuto, V. Litvinenko, N. Vafaei-Najafabadi
Stony Brook University, Stony Brook, USA
M. Babzien, M.G. Fedurin, Y.C. Jing, K. Kusche, M.A. Palmer, I. Pogorelsky, M.N. Polyanskiy
BNL, Upton, New York, USA
M. Downer, J.R. Welch, R. Zgadzaj
The University of Texas at Austin, Austin, Texas, USA
C. Joshi, W.B. Mori
UCLA, Los Angeles, California, USA
P. Kumar, V. Samulyak
SBU, Stony Brook, USA

Funding: We acknowledge resources of NERSC facility, operated under Contract No. DE-AC02-5CH11231, and of SEAWULF at Stony Brook University as well as funding from SBU-BNL Seed Grants.
Laser-driven plasma wakefield acceleration (LWFA) is considered as a potential technology for future colliders and light sources. To make the best use of a laser’s power, the laser is expected to maintain a stable propagation. A transverse instability is observed in our previous simulations when a long, intense CO₂ laser propagates inside a plasma*. This unstable motion is accompanied by strong transverse diffraction of the laser power and results in the disruption of the ion channel typically used for radiation generation**. We investigated the hosing-like instability using the Particle-in-Cell code OSIRIS*** by modeling the laser portion where this instability is seeded and then evolves. In this proceeding, a criteria will be described that allows for the characterization of the temporal and spatial evolution of this instability.
*J. Yan, et al. , AAC, IEEE, 2018.
** L. Nemos et al., PPCF, 58(3), 2016.
***R. A. Fonseca et al., Lecture Notes Computation Science (2331) 342, 2002.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO05

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paper received ※ 16 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019

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WEPLO06

Start-to-End Simulation of the Drive-Beam Longitudinal Dynamics for Beam-Driven Wakefield Acceleration

laser, electron, wakefield, linac

858

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
A. Zholents, A. Zholents
ANL, Lemont, Illinois, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science under contracts No. DE-AC02-06CH11357 (via a laboratory- directed R&D program at ANL) and No. DE-SC0018656 at NIU.
Collinear beam-driven wakefield acceleration (WFA) relies on shaped driver beam to provide higher accelerating gradient at a smaller cost and physical footprint. This acceleration scheme is currently envisioned to accelerate electron beams capable of driving free-electron laser *. Start-to-end simulation of drive-bunch beam dynamics is crucial for the evaluation of the design of accelerators built upon WFA. We report the start-to-end longitudinal beam dynamics simulations of an accelerator beamline capable of producing high charge drive beam. The generated wakefield when it passes through a corrugated waveguide results in a transformer ratio of 5. This paper especially discusses the challenges and criteria associated with the generation of temporally-shaped driver beam, including the beam formation in the photoinjector, and the influence of energy chirp control on beam transport stability.
A. Zholents et al., "A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility"

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO06

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paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLO18

Numerical Study of Coherent Radiation from Induced Plasma Dipole Oscillation by Detuned Laser Pulses

plasma, laser, radiation, dipole

874

P.C. Castillo, S.D. Rodriguez, D.A. Wan
SUNY Farmingdale State College, State University of New York, Farmingdale, New York, USA
B. Gross
City College of The City University of New York, New York, USA
M.S. Hur, S. Kylychbekov, H.S. Song
UNIST, Ulsan, Republic of Korea
D.G. Lee
SBU, Stony Brook, New York, USA
K. Yu
BNL, Upton, New York, USA

The study of intense laser-plasma interactions is a growing field of both theoretical and applied research. This research focuses on simulating the cross/self-interactions between high-intense short laser pulses and an initial target for preliminary ionization. Unlike our previous studies of laser-matter interaction over preformed plasma, we will explore the injection of laser pulses to induce background plasma driven by the self-guided laser wakefield mechanism, which is used to perturb the plasma for induced dipole oscillations followed by radiation. Inducing a cylindrical spatial plasma column within the laser beam radius regime, it is expected that a stable spatially localized plasma channel will result and the emitted radiation from the plasma dipole oscillation (PDO) will not be affected by surrounding absorption, resulting in effective radiation. We will depict the injection of laser pulses accounting for parameters such as field intensity, profile and phase difference defining the coordinated pulses to assess the potential of enhancing the efficiency and spectral properties of the transverse emitted radiation due to the counter-propagating pulses interaction in plasma.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO18

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLO20

High Gradient High Efficiency C-Band Accelerator Structure Research at LANL

operation, experiment, cavity, electron

882

E.I. Simakov, A.W. Garmon, T.C. Germann, M.F. Kirshner, F.L. Krawczyk, J.W. Lewellen, D. Perez, G. Wang
LANL, Los Alamos, New Mexico, USA
A. Fukasawa, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: Los Alamos National Laboratory LDRD Program
This poster will report on the status of the new high gradient C-band accelerator project at LANL. Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. Our goal is to use a multi-disciplinary approach that includes accelerator design, molecular dynamics simulations, and advanced manufacturing to develop high gradient, high efficiency RF structures for both compact and facility-size accelerator systems. We considered common operation frequencies for accelerators and identified C-band as the optimal frequency band for high gradient operations based on achievable gradients and means to control wakefields. We are putting together a high gradient C-band test facility that includes a 50 MW Toshiba klystron and cryo-coolers for operating copper NCRF accelerator cavities at long pulse duration. We plan to conduct high gradient testing of the optimized RF structures made of copper and novel copper alloys. LANL modeling capabilities will be used to systematically study the formation of breakdown precursors at high fields to develop basic theoretical understanding of the breakdown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO20

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paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLE02

Integrated Accelerator Simulation with Electromagnetics and Beam Physics Codes

cavity, plasma, electron, emittance

885

L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA
D.A. Bizzozero, J. Qiang, J.-L. Vay
LBNL, Berkeley, California, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: Work supported by US Department of Energy under contracts AC02-76SF00515, DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of the National Energy Research Scientific Computing Center.
This paper presents an integrated simulation capability for accelerators including electromagnetic field and beam dynamics effects. The integrated codes include the parallel finite-element code suite ACE3P for electromagnetic field calculation of beamline components, the parallel particle-in-cell (PIC) code IMPACT for beamline particle tracking with space-charge effects, and the parallel self-consistent PIC code Warp for beam and plasma simulations. The common data format OpenPMD has been adopted for efficient field and particle I/O data transfer between codes. One application is to employ ACE3P and IMPACT for studying beam qualities in accelerator beamlines. Another is to combine ACE3P and Warp for investigating plasma processing for operational performance of RF cavities. A module for mapping the CAD geometry used in ACE3P to Warp Cartesian grid representation has been developed. Furthermore, a workflow has been implemented that enables the execution of integrated simulation on HPC systems. Examples for simulation of the LCLS-II injector using ACE3P-IMPACT and plasma ignition in SRF cavities using ACE3P-Warp will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE02

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paper received ※ 20 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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WEPLE04

Recent Developments and Applications of Parallel Multi-Physics Accelerator Modeling Suite ACE3P

cavity, cryomodule, dipole, GUI

888

Z. Li, L. Ge, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515.
SLAC’s ACE3P code suite is developed to harness the power of massively parallel computers to tackle large complex problems with increased memory and solve them at greater speed. ACE3P parallel multi-physics codes are based on higher-order finite elements for superior geometry fidelity and better solution accuracy. ACE3P consists of an integrated set of electromagnetic, thermal and mechanical solvers for accelerator modeling and virtual prototyping. The use of ACE3P has contributed to the design and optimization of existing and future accelerator projects around the world. Multi-physics analysis on high performance computing (HPC) platform enables thermal-mechanical simulations of largescale systems such as the LCLS-II cryomodule. Recently, new capabilities have been added to ACE3P including a nonlinear eigenvalue solver for calculating mode damping, a moving window for pulse propagation in the time domain to reduce computational cost, thin layer coating representation using a surface impedance model, and improved boundary conditions using perfectly matched layers (PML) to terminate wave propagation. These new developments are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE04

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paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLE05

Tracking With Space Harmonics in ELEGANT Code

cavity, electromagnetic-fields, electron, photon

892

Y.P. Sun, C. Yao
ANL, Lemont, 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 elegant code has the capability of simulating particle motion in accelerating or deflecting RF cavities, with a simplified (or ideal) model of the electromagnetic fields. To improve the accuracy of RF cavity simulations, the ability to track with space harmonics has been added to the elegant code. The sum of all the space harmonics will mimic the real electromagnetic fields in the RF cavity. These space harmonics will be derived from electromagnetic fields simulation of the RF cavity. This method should be general, which can be applied to any RF cavity structure, including accelerating and deflecting cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE05

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paper received ※ 31 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLE06

Linear and Second Order Map Tracking with Artificial Neural Network

network, framework, software, storage-ring

895

Y.P. Sun
ANL, Lemont, 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.
In particle accelerators, the tracking simulation is usually performed with symplectic integration, or linear/nonlinear transfer maps. In this paper, it is shown that the linear/nonlinear transfer maps may be represented by an artificial neural network. To solve this multivariate regression problem, both random datasets and structured datasets are explored to train the neural networks. The achieved accuracy will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE06

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paper received ※ 30 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLE08

Parallel Tracking-Based Modeling of Gas Scattering and Loss Distributions in Electron Storage Rings

scattering, lattice, storage-ring, electron

901

M. Borland
ANL, Lemont, 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.
Estimation of gas scattering lifetimes in storage rings is typically done using a simple approach that can readily be performed by hand. A more sophisticated approach uses linear mapping of the angular dynamic acceptance around the ring and allows including variation of gas pressure and composition*. However, neither approach is appropriate for highly nonlinear lattices, in which the angular acceptance does not map according to the linear optics. Further, these approaches provide no detailed information about the location of losses. To address these limitations, a tracking-based approach was implemented in the program Pelegant**. We describe the implementation and performance of this method, as well as several applications to the Advanced Photon Source Upgrade.
* M. Borland, J. Carter, H. Cease, and B. Stillwell, Proc. IPAC 2015, 546.
** Y. Wang and M. Borland, AIP Conf. Proc. 877, 241 (2006).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE08

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paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLE10

Simulating Space Charge Dominated Beam Dynamics Using FMM

space-charge, emittance, cathode, multipole

909

S.A. Schmid, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany
M. Dohlus
DESY, Hamburg, Germany

Funding: This work is supported by the DFG in the framework of GRK 2128.
In this contribution, we simulate the beam generation in the high brilliance photoinjector of the European XFEL developed at DESY-PITZ. The investigation addresses the influence of space charge on the emittance of bunches with up to 1.0 nC bunch charge. For the simulations, we implemented a mesh-less fast multipole method (FMM) in the 3D tracking code REPTIL. We present numerical convergence and performance studies as well as a validation with commonly used simulation tools ASTRA and KRACK3. Furthermore, we provide a machine parameter study to minimize the beam emittance in the injector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE10

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paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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THYBA3

Use of Solid Xenon as a Beam Dump Material for 4th-Generation Storage Rings

electron, emittance, storage-ring, vacuum

927

M. Borland, H. Cease, J.C. Dooling
ANL, Lemont, 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
Damage to tungsten beam dumps has been observed in the Advanced Photon Source due to the high charge (368 nC/store), high energy (7 GeV), and short loss time (about 15 microseconds). Owing to the higher charge (736 nC/store) and much lower emittance (42 pm vs 2.5 nm), this issue is expected to be much more severe in the APS Upgrade. This strongly suggests that such dumps are necessary in 4th-generation electron storage rings to prevent catastrophic damage to vacuum systems when, for example, rf systems trip. However, it also implies that the dump will be damaged by each strike and will thus need to be "refreshed," perhaps by moving the dump surface vertically to expose undamaged material. Xenon, a gas that solidifies at 161K, is an intriguing possibility for a beam dump material. Calculations suggest that as the beam spirals in toward a dump in a high-dispersion area the tails of the electron beam would vaporize sufficient xenon to rapidly diffuse the beam and render it harmless. The dump surface could be periodically reformed without breaking vacuum. Issues with the concept include the need to protect the frozen xenon from wakefield heating.

Slides THYBA3 [2.451 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBA3

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paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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THZBA4

Characterization and Modeling of High-Intensity Evolution in the SNS Beam Test Facility

emittance, diagnostics, lattice, controls

954

K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA
Z.L. Zhang
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. Partial support by NSF Accelerator Science grant 1535312
Modern high-power accelerators are charged with delivering reliable beam with low losses. Resolving the complex dynamics arising from space charge and nonlinear forces requires detailed models of the accelerator and particle-in-cell simulation. There has historically been discrepancy between simulated and measured beam distributions, particularly at the low-density halo level. The Beam Test Facility (BTF) at the Spallation Neutron Source is outfitted to study beam evolution in a high-power linear accelerator MEBT. This includes capability for high-dimensional measurements of the post-RFQ beam distribution, including interplane correlations that may be the key to accurate simulation. Beam is transported through a 4.6 m FODO channel (9.5 cells) to a second distribution measurement stage. Plans for validating simulations against BTF measurements of beam evolution in the FODO channel are discussed.

Slides THZBA4 [8.316 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA4

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paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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