NAPAC2019 - List of Keywords (storage-ring)

Paper	Title	Other Keywords	Page
MOPLM01	Alternative Injection Schemes to the NSLS-II Using Nonlinear Injection Magnets	injection, kicker, septum, multipole	91
	R.P. Fliller, III, G. Bassi, A. Blednykh, C. Hetzel, V.V. Smaluk, C.J. Spataro, P. Zuhoski BNL, Upton, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy The NSLS-II storage ring uses the standard four bump injection scheme to inject beam off axis. BESSY and MAX IV are now using a pulsed multipole magnet as an injection kicker. The injected beam sees a field off axis for injection while the stored beam experiences no field on the magnet axis. The principle advantage of using a pulsed multipole for injection is that the stored beam motion is greatly reduced since the field on axis is negligible. The number of pulsed magnets is reduced from five in the nominal scheme (septum and four bumps) to two or three thereby reducing the possible failure modes. This also eliminates the need to precisely match the pulse shapes of four dipole magnets to achieve minimal stored beam motion outside of the bump. In this paper we discuss two schemes of injecting into the NSLS-II using a pulsed multipole magnet. The first scheme uses a single pulsed multipole located in one cell downstream of the injection septum as the injection kicker. The second scheme uses two pulsed multipoles in the injection straight to perform the injection. We discuss both methods of injection and compare each method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM01
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLM04	First Attempts at Applying Machine Learning to ALS Storage Ring Stabilization	experiment, quadrupole, emittance, operation	98
	S.C. Leemann, Ph. Amstutz, W.E. Byrne, M.P. Ehrlichman, T. Hellert, A. Hexemer, S. Liu, M. Marcus, C.N. Melton, H. Nishimura, G. Penn, F. Sannibale, D.A. Shapiro, C. Sun, D. Ushizima, M. Venturini LBNL, Berkeley, USA
	Funding: This research is funded by the US Department of Energy (BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231. The ALS storage ring operates multiple feedbacks and feed-forwards during user operations to ensure that various source properties such as beam position, beam angle, and beam size are maintained constant. Without these active corrections, strong perturbations of the electron beam would result from constantly varying ID gaps and phases. An important part of the ID gap/phase compensation requires recording feed-forward tables. While recording such tables takes a lot of time during dedicated machine shifts, the resulting compensation data is imperfect due to machine drift both during and after recording of the table. Since it is impractical to repeat recording feed-forward tables on a more frequent basis, we have decided to employ Machine Learning techniques to improve ID compensation in order to stabilize electron beam properties at the source points.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM04
About •	paper received ※ 26 August 2019 paper accepted ※ 31 August 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, simulation, 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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MOPLM09	High-Power Design of a Cavity Combiner for a 352-MHz Solid State Amplifier System at the Advanced Photon Source	cavity, klystron, interface, network	113
	G.J. Waldschmidt, D.J. Bromberek, A. Goel, D. Horan, A. Nassiri ANL, Lemont, Illinois, USA
	A cavity combiner has been designed as part of a solid state amplifier system at the Advanced Photon Source with a power requirement of up to 200 kW for the full system. Peak field levels and thermal loading have been optimized to enhance the rf and mechanical perfor-mance of the cavity and to augment its reliability. The combiner consists of 16 rotatable input couplers, a re-duced-field output coupler, and static tuning. The power handling capability of the cavity will be evaluated during a back-feed test where an external klystron source will be used to transmit power through the cavity into loads on each of the input couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM09
About •	paper received ※ 28 August 2019 paper accepted ※ 04 December 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	simulation, experiment, 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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MOPLO12	The RF BPM Pickup Electrodes Development for the APS-MBA Upgrade	pick-up, vacuum, simulation, electron	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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TUYBB3	Final Design of the APS-Upgrade Storage Ring Vacuum System	vacuum, photon, extraction, alignment	315
	J.A. Carter, B. Billett, B. Brajuskovic, M.A. Lale, A. McElderry, O.K. Mulvany, J.R. Noonan, M.M. O’Neill, R.R. Swanson, K.J. Wakefield, D.R. Walters, G.E. Wiemerslage, J. Zientek ANL, Lemont, Illinois, USA
	Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357. The Advanced Photon Source Upgrade project is progressing from its final design phase into production for the future 6 GeV, 200 mA upgrade of the existing APS. The storage ring arc vacuum system will include over 2500 custom vacuum chambers ranging from 70 mm to 2.5 meters in length and typically feature a narrow 22 mm inner diameter aperture. The scope of NEG coatings was increased to 40% of the length along the e-beam path to ensure efficient conditioning and low pressure requirements can be met. The final design phase required advancing previous work to a procurement-ready level and to address local and system level challenges. Local challenges include designing thin-walled vacuum chambers with carefully controlled lengths and outer profiles and also mitigating significant radiation heat loads absorbed along vacuum chamber walls. System level challenges include planning for the complex machine assembly, networking components to utilities, managing the quality of upcoming procurements. This presentation will highlight the major design challenges and solutions for the storage ring vacuum system and also plans for production and installation.
	Slides TUYBB3 [10.852 MB]
	Poster TUYBB3 [5.028 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBB3
About •	paper received ※ 27 August 2019 paper accepted ※ 30 August 2019 issue date ※ 08 October 2019
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TUPLM11	Beam-Beam Damping of the Ion Instability	electron, simulation, 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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TUPLM13	Two-Energy Storage-Ring Electron Cooler for Relativistic Ion Beams	cavity, electron, emittance, damping	399
	B. Dhital, J.R. Delayen, G.A. Krafft ODU, Norfolk, Virginia, USA J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA
	An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of equilibrium emittance shows that these models give a bunch length of the order of cm and energy spread of the order of 〖10〗^-5 in the cooling section which are required parameters for the better cooling. Numerical calculations along with elegant simulation are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM13
About •	paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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TUPLM22	Off Axis Dependence of Current Dependent Coherent Tune Shifts in the UMER Ring	experiment, space-charge, electron, dipole	422
	D.F. Sutter, B.L. Beaudoin, L. Dovlatyan UMD, College Park, Maryland, USA
	Funding: Work supported by U. S. Department of Energy grant number DESC00010301 The University of Maryland Electron Ring (UMER) was built to explore space charge effects in the extreme - beyond the space charge limit of most existing storage rings. At the nominal operating kinetic energy of 10 keV, the beam is also non relativistic. We have experimentally verified that the current dependent coherent tune shift obeys the Laslett formula over a wide current range for a cylindrical geometry and non penetrating magnetic fields when the beam is on axis; i.e. the average closed orbit displacement around the ring is essentially zero.* In the current experiment this measurement is extended to the change in current dependent coherent tune shift as the average closed orbit is moved off axis. It can be displaced over approximately ±10 mm of the vacuum pipe diameter of 50 mm without loss of beam. Because the 36 bending magnets in UMER are very short, we treat each of them as a local kick and then increment each by a calculated small amount to achieve the desired, global closed orbit displacement. Experimental results are compared to predictions by Zotter and others. * D. für Sutter, M.Cornacchia, et al, "Current dependent tune shifts in the University of Maryland electron ring", NAPAC 2013.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM22
About •	paper received ※ 29 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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TUPLM25	Connecting Gas-Scattering Lifetime and Ion Instabilities	scattering, experiment, electron, vacuum	430
	B. Podobedov, M. Blaskiewicz BNL, Upton, New York, USA
	Recently there is a renewed interest in fast ion instability (FII) which is of concern for future low-emittance electron storage rings, such as MBA light sources and colliders, i.e. eRHIC. While analytical theories and numerical codes exist to model the effect, due to various assumptions and limitations, accurate experimental verification is often desirable. Unfortunately, one of the most critical parameters for FII (as well as the classical "trapped-ion" instability), the residual ion concentration, is usually the most uncertain. Vacuum gauges and residual gas analyzers (RGAs) provide some useful data, but they are often not accurate enough, and, more importantly, they cannot directly probe the ion concentration along the beam orbit. In this paper we show how one could use gas-scattering lifetime measurements to infer the residual gas concentration suitable for ion instability experiment modelling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM25
About •	paper received ※ 21 September 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLM37	High Energy Beam Transport Along the 68-m LANSCE 1L Beamline to Optimize Neutron Production	target, proton, neutron, beam-transport	446
	P.K. Roy, E.L. Kerstiens, R.J. Macek, C. Pillai, C.E. Taylor LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. An 800 MeV 100 µA proton beam is delivered to the Lujan Center, one of five user facilities at the LANSCE linear accelerator center, to generate an intense beam of pulsed neutrons. The Lujan Center beam transport line, known as 1L beamline, is over 68 meters in length, starting from the ROWS01. The beamline is consisted with bending and focusing elements before it reaches the end of the 1L beam optics system, where the beam spot size is nominally 1.5 cm (RMS). The Mark IV target assembly has been designed to optimize the neutron production for the 1L target in the Lujan center to improve the flux and resolution. As part of the safety review of this design, it becomes necessary to know the beam intensity and size on the new target. Using the new measurements of the beamline, calculated beam sizes using the LANL version of the beam envelope code TRANSPORT and CERN code MAD-X are compared. The input beam parameters for the codes were extracted from ORBIT analysis of the proton storage ring beam. Beam envelope measurements were made at various locations throughout the beamline using wire scanners. The predicted beam envelopes and measured data agree within expected errors. LA-UR-19-22889
	Poster TUPLM37 [5.009 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM37
About •	paper received ※ 23 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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TUPLS02	APS Upgrade Insertion Device Vacuum Chamber Design	vacuum, alignment, photon, distributed	450
	J.E. Lerch, T.J. Bender, O.K. Mulvany, M.E. Szubert ANL, Lemont, Illinois, USA
	A straight section vacuum system (nominally 5.363 meters long) has been designed for the APS upgrade project. This vacuum system will be used in straight sections equipped with hybrid permanent magnet undulators (HPMU). The vacuum system assembly consists of the insertion device vacuum chamber (IDVC), the vacuum chamber distributed support, and the photon absorber. Numerous functional requirements constrained the IDVC design. These constraints included incorporation of the beam aperture transition into the end of the aluminium vacuum chamber extrusion (storage ring aperture to IDVC aperture), thin walls (~600 microns) surrounding the beam aperture to allow for as small a magnetic gap as possible, and complicated weld paths to ensure a continuous beam surface to minimize impedance. Additionally, extensive FEA and raytrace analysis were performed to ensure that the chamber would not fail due to structural or thermal perturbations.
	Poster TUPLS02 [3.816 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS02
About •	paper received ※ 26 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUPLS03	Advanced Photon Source Upgrade	vacuum, photon, operation, undulator	453
	M.E. Szubert, E.R. Anliker, T.J. Bender, J.E. Lerch ANL, Lemont, Illinois, USA
	The Advanced Photon Source Upgrade (APS-U) in-cludes four straight sections equipped with full length Superconducting Undulators (SCUs). These sections require vacuum systems that must span 5.383 meters at nominal length, accommodate the SCU device, and ac-commodate additional magnets for the canted configura-tions. In the direction of the beam, the upstream portion of the vacuum system is a copper chamber doubling as a photon absorber with a design that is manufactured to allow a 13.5 mm canting magnet gap. This portion of the vacuum system operates at room temperature and shad-ows the length of the vacuum chamber that operates within the cryostat at 20K. The vacuum chamber inside the cryostat is a weldment including a machined alumi-num extrusion allowing for an 8mm magnetic gap, stain-less steel thermal insulators, copper shields, and bel-lows/flange assembly. The vacuum system includes an-other room temperature copper chamber and absorber on the downstream end of the straight section. The vacuum system provides Ultra-high Vacuum (UHV) continuity through the straight section, connecting the storage ring vacuum systems.
	Poster TUPLS03 [0.974 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS03
About •	paper received ※ 26 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLS11	NEG-Coated Copper Vacuum Chambers for the APS-Upgrade Storage Ring Vacuum System	vacuum, photon, radiation, operation	477
	O.K. Mulvany, B. Billett, B. Brajuskovic, J.A. Carter, A. McElderry, K.J. Wakefield ANL, Lemont, Illinois, USA
	Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357. The APS-Upgrade (APS-U) storage ring features a diverse group of vacuum chambers including seven distinctive, non-evaporable getter (NEG)-coated copper vacuum chambers per each of the 40 sectors. These chambers feature a 22-millimeter diameter aperture along the electron-beam path, with two vacuum chambers permitting photon extraction through a keyhole-shaped extension to this aperture. The chambers range from 0.3-meters to 1.7-meters in length and fit within the narrow envelope of quadrupole and sextupole magnets. Six of the seven copper vacuum chambers intercept significant heat loads from synchrotron radiation; five of these designs are fabricated entirely from OFS copper extrusions and are equipped with a compact Glidcop® photon absorber. A hybrid vacuum chamber, fabricated from OFS copper extrusion and a copper chromium zirconium (CuCrZr) keyhole transition, also intercepts synchrotron radiation. The seventh vacuum chamber design features a keyhole aperture across its length and is entirely fabricated from CuCrZr. This paper details the careful balance of vacuum chamber functionality, manufacturability, and the overall design process followed to achieve the final designs.
	Poster TUPLS11 [4.941 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS11
About •	paper received ※ 27 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLS12	Final Design of NEG-Coated Aluminum Vacuum Chambers & Stainless Steel Keyhole Vacuum Chambers for the APS-U Storage Ring	vacuum, photon, radiation, quadrupole	480
	A. McElderry, B. Billett, J.A. Carter, K.J. Wakefield ANL, Lemont, Illinois, USA
	Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357. The APS-Upgrade storage ring features a diverse group of vacuum chambers which includes eight NEG (non-evaporable getter) coated aluminum chambers and two copper coated stainless steel keyhole-shaped chambers per sector (40 total). Each chamber contains a 22 mm diameter electron beam aperture; the keyhole chambers also include a photon extraction antechamber. The chambers vary in length of approximately 289 ’ 792 mm and fit within the narrow envelope of quadrupole and sextupole magnets. Each design is a balance of functionality, manufacturability, and installation space. An innovative CAD skeleton model system and ray tracing layout accurately determined synchrotron radiation heat loads on built-in photon absorbers and the internal envelope of the keyhole antechamber. Chamber designs were optimized using thermal-structural FEA for operating and bakeout conditions. The group of chambers require complex manufacturing processes including EDM, explosion-bonded metals, furnace brazing, and welding with minimal space. This paper describes the design process and manufacturing plan for these vacuum chambers including details about FEA, fabrication plans, and cooling/bakeout strategies.
	Poster TUPLS12 [2.581 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS12
About •	paper received ※ 27 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLS14	Analyzing Accelerator Operation Data with Neural Networks	injection, operation, network, booster	487
	F.Y. Wang, X. Huang, Z. Zhang SLAC, Menlo Park, California, USA
	Funding: Work is supported by DOE contract DE-AC02-76SF00515 (SLAC) and DOE contracts 2018-SLAC-100469 and 2018-SLAC-100469ASCR. Accelerator operation history data are used to train neural networks in an attempt to understand the underly-ing causes of performance drifts. In the study, injection efficiency of SPEAR3 [1] over two runs is modelled with a neural network (NN) to map the relationship of the injection efficiency with the injected beam trajectory and environment variables. The NN model can accurately predict the injection performance for the test data. With the model, we discovered that an environment parameter, the ground temperature, has a big impact to the injection performance. The ideal trajectory as a function of the ground temperature can be extracted from the model. The method has the potential for even larger scale application for the discovery of deep connections between machine performance and environment parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS14
About •	paper received ※ 29 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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TUPLH01	Status of the Superconducting Undulator Program at the Advanced Photon Source	undulator, operation, alignment, photon	490
	M. Kasa, E.R. Anliker, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, W.G. Jansma, I. Kesgin, Y. Shiroyanagi ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Since 2013 there has been at least one superconducting undulator (SCU) in operation at the Advanced Photon Source (APS), currently there are two planar SCUs and one helical SCU. The combined operational experience of SCUs at the APS is more than 11 years and counting. Through all these years, APS SCUs operated with the predicted or better than predicted radiation performance and with 99% availability. With this demonstrated reliability and experimentally confirmed spectral performance, the APS upgrade project is planning on leveraging the advantages of SCU technology. The present planar SCUs are comprised of ~1.1-m-long magnets, each operated within a 2-m-long cryostat, while the planar SCUs for the upgrade will have two ~1.8-m-long magnets operating within a 5-m-long cryostat. Progress is also being made in other areas of SCU development with work on an arbitrary polarizing SCU, referred to as SCAPE, and a planar SCU wound with Nb₃Sn superconductor. A Nb₃Sn SCU is being designed with two 1.3-m-long magnets within a 5-m-long cryostat, and installation is planned for 2021. Also under development are the alignment and magnetic measurement systems for use with the 5-m-long cryostat.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH01
About •	paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLH20	Commissioning of the CESR Upgrade for CHESS-U	MMI, HOM, wiggler, impedance	522
	J.P. Shanks, G.W. Codner, M.J. Forster, D.L. Rubin, S. Wang, L. Ying Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Funding for the CHESS-U upgrade provided by New York State Capital Grant #AA737 / CFA #53676 The Cornell Electron Storage Ring (CESR) was upgraded in the second half of 2018 to become a dedicated synchrotron light source, CHESS-U. The upgrade is by far the largest modification to CESR in its 40-year history, replacing one-sixth of the storage ring with six new double-bend achromats, increasing beam energy from 5.3 GeV to 6.0 GeV, and switching from two counter-rotating beams to a single on-axis positron beam. The new achromats include combined-function dipoles, a first in CESR, and reduce the horizontal emittance by a factor of four. Eight compact narrow-gap undulators (4.6mm vacuum chamber aperture) and one high-energy 24-pole wiggler feed a total of six new and five existing x-ray end stations from a single positron beam. Commissioning of CHESS-U took place in the first half of 2019. We report on the methods and results of beam commissioning, including initial beam accumulation, optics correction, characterization, and commissioning of compact permanent-magnet insertion devices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH20
About •	paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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WEPLE06	Linear and Second Order Map Tracking with Artificial Neural Network	network, simulation, framework, software	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, simulation, 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
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THYBA3	Use of Solid Xenon as a Beam Dump Material for 4th-Generation Storage Rings	electron, emittance, simulation, 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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Paper

Title

Other Keywords

Page

MOPLM01

Alternative Injection Schemes to the NSLS-II Using Nonlinear Injection Magnets

injection, kicker, septum, multipole

91

R.P. Fliller, III, G. Bassi, A. Blednykh, C. Hetzel, V.V. Smaluk, C.J. Spataro, P. Zuhoski
BNL, Upton, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The NSLS-II storage ring uses the standard four bump injection scheme to inject beam off axis. BESSY and MAX IV are now using a pulsed multipole magnet as an injection kicker. The injected beam sees a field off axis for injection while the stored beam experiences no field on the magnet axis. The principle advantage of using a pulsed multipole for injection is that the stored beam motion is greatly reduced since the field on axis is negligible. The number of pulsed magnets is reduced from five in the nominal scheme (septum and four bumps) to two or three thereby reducing the possible failure modes. This also eliminates the need to precisely match the pulse shapes of four dipole magnets to achieve minimal stored beam motion outside of the bump. In this paper we discuss two schemes of injecting into the NSLS-II using a pulsed multipole magnet. The first scheme uses a single pulsed multipole located in one cell downstream of the injection septum as the injection kicker. The second scheme uses two pulsed multipoles in the injection straight to perform the injection. We discuss both methods of injection and compare each method.

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MOPLM04

First Attempts at Applying Machine Learning to ALS Storage Ring Stabilization

experiment, quadrupole, emittance, operation

98

S.C. Leemann, Ph. Amstutz, W.E. Byrne, M.P. Ehrlichman, T. Hellert, A. Hexemer, S. Liu, M. Marcus, C.N. Melton, H. Nishimura, G. Penn, F. Sannibale, D.A. Shapiro, C. Sun, D. Ushizima, M. Venturini
LBNL, Berkeley, USA

Funding: This research is funded by the US Department of Energy (BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231.
The ALS storage ring operates multiple feedbacks and feed-forwards during user operations to ensure that various source properties such as beam position, beam angle, and beam size are maintained constant. Without these active corrections, strong perturbations of the electron beam would result from constantly varying ID gaps and phases. An important part of the ID gap/phase compensation requires recording feed-forward tables. While recording such tables takes a lot of time during dedicated machine shifts, the resulting compensation data is imperfect due to machine drift both during and after recording of the table. Since it is impractical to repeat recording feed-forward tables on a more frequent basis, we have decided to employ Machine Learning techniques to improve ID compensation in order to stabilize electron beam properties at the source points.

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paper received ※ 26 August 2019 paper accepted ※ 31 August 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, simulation, 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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MOPLM09

High-Power Design of a Cavity Combiner for a 352-MHz Solid State Amplifier System at the Advanced Photon Source

cavity, klystron, interface, network

113

G.J. Waldschmidt, D.J. Bromberek, A. Goel, D. Horan, A. Nassiri
ANL, Lemont, Illinois, USA

A cavity combiner has been designed as part of a solid state amplifier system at the Advanced Photon Source with a power requirement of up to 200 kW for the full system. Peak field levels and thermal loading have been optimized to enhance the rf and mechanical perfor-mance of the cavity and to augment its reliability. The combiner consists of 16 rotatable input couplers, a re-duced-field output coupler, and static tuning. The power handling capability of the cavity will be evaluated during a back-feed test where an external klystron source will be used to transmit power through the cavity into loads on each of the input couplers.

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paper received ※ 28 August 2019 paper accepted ※ 04 December 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

simulation, experiment, 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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MOPLO12

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

pick-up, vacuum, simulation, electron

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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TUYBB3

Final Design of the APS-Upgrade Storage Ring Vacuum System

vacuum, photon, extraction, alignment

315

J.A. Carter, B. Billett, B. Brajuskovic, M.A. Lale, A. McElderry, O.K. Mulvany, J.R. Noonan, M.M. O’Neill, R.R. Swanson, K.J. Wakefield, D.R. Walters, G.E. Wiemerslage, J. Zientek
ANL, Lemont, Illinois, USA

Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357.
The Advanced Photon Source Upgrade project is progressing from its final design phase into production for the future 6 GeV, 200 mA upgrade of the existing APS. The storage ring arc vacuum system will include over 2500 custom vacuum chambers ranging from 70 mm to 2.5 meters in length and typically feature a narrow 22 mm inner diameter aperture. The scope of NEG coatings was increased to 40% of the length along the e-beam path to ensure efficient conditioning and low pressure requirements can be met. The final design phase required advancing previous work to a procurement-ready level and to address local and system level challenges. Local challenges include designing thin-walled vacuum chambers with carefully controlled lengths and outer profiles and also mitigating significant radiation heat loads absorbed along vacuum chamber walls. System level challenges include planning for the complex machine assembly, networking components to utilities, managing the quality of upcoming procurements. This presentation will highlight the major design challenges and solutions for the storage ring vacuum system and also plans for production and installation.

Slides TUYBB3 [10.852 MB]

Poster TUYBB3 [5.028 MB]

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TUPLM11

Beam-Beam Damping of the Ion Instability

electron, simulation, 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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TUPLM13

Two-Energy Storage-Ring Electron Cooler for Relativistic Ion Beams

cavity, electron, emittance, damping

399

B. Dhital, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of equilibrium emittance shows that these models give a bunch length of the order of cm and energy spread of the order of 〖10〗^-5 in the cooling section which are required parameters for the better cooling. Numerical calculations along with elegant simulation are presented.

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TUPLM22

Off Axis Dependence of Current Dependent Coherent Tune Shifts in the UMER Ring

experiment, space-charge, electron, dipole

422

D.F. Sutter, B.L. Beaudoin, L. Dovlatyan
UMD, College Park, Maryland, USA

Funding: Work supported by U. S. Department of Energy grant number DESC00010301
The University of Maryland Electron Ring (UMER) was built to explore space charge effects in the extreme - beyond the space charge limit of most existing storage rings. At the nominal operating kinetic energy of 10 keV, the beam is also non relativistic. We have experimentally verified that the current dependent coherent tune shift obeys the Laslett formula over a wide current range for a cylindrical geometry and non penetrating magnetic fields when the beam is on axis; i.e. the average closed orbit displacement around the ring is essentially zero.* In the current experiment this measurement is extended to the change in current dependent coherent tune shift as the average closed orbit is moved off axis. It can be displaced over approximately ±10 mm of the vacuum pipe diameter of 50 mm without loss of beam. Because the 36 bending magnets in UMER are very short, we treat each of them as a local kick and then increment each by a calculated small amount to achieve the desired, global closed orbit displacement. Experimental results are compared to predictions by Zotter and others.
* D. für Sutter, M.Cornacchia, et al, "Current dependent tune shifts in the University of Maryland electron ring", NAPAC 2013.

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TUPLM25

Connecting Gas-Scattering Lifetime and Ion Instabilities

scattering, experiment, electron, vacuum

430

B. Podobedov, M. Blaskiewicz
BNL, Upton, New York, USA

Recently there is a renewed interest in fast ion instability (FII) which is of concern for future low-emittance electron storage rings, such as MBA light sources and colliders, i.e. eRHIC. While analytical theories and numerical codes exist to model the effect, due to various assumptions and limitations, accurate experimental verification is often desirable. Unfortunately, one of the most critical parameters for FII (as well as the classical "trapped-ion" instability), the residual ion concentration, is usually the most uncertain. Vacuum gauges and residual gas analyzers (RGAs) provide some useful data, but they are often not accurate enough, and, more importantly, they cannot directly probe the ion concentration along the beam orbit. In this paper we show how one could use gas-scattering lifetime measurements to infer the residual gas concentration suitable for ion instability experiment modelling.

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TUPLM37

High Energy Beam Transport Along the 68-m LANSCE 1L Beamline to Optimize Neutron Production

target, proton, neutron, beam-transport

446

P.K. Roy, E.L. Kerstiens, R.J. Macek, C. Pillai, C.E. Taylor
LANL, Los Alamos, New Mexico, USA

Funding: *Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
An 800 MeV 100 µA proton beam is delivered to the Lujan Center, one of five user facilities at the LANSCE linear accelerator center, to generate an intense beam of pulsed neutrons. The Lujan Center beam transport line, known as 1L beamline, is over 68 meters in length, starting from the ROWS01. The beamline is consisted with bending and focusing elements before it reaches the end of the 1L beam optics system, where the beam spot size is nominally 1.5 cm (RMS). The Mark IV target assembly has been designed to optimize the neutron production for the 1L target in the Lujan center to improve the flux and resolution. As part of the safety review of this design, it becomes necessary to know the beam intensity and size on the new target. Using the new measurements of the beamline, calculated beam sizes using the LANL version of the beam envelope code TRANSPORT and CERN code MAD-X are compared. The input beam parameters for the codes were extracted from ORBIT analysis of the proton storage ring beam. Beam envelope measurements were made at various locations throughout the beamline using wire scanners. The predicted beam envelopes and measured data agree within expected errors.
*LA-UR-19-22889

Poster TUPLM37 [5.009 MB]

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TUPLS02

APS Upgrade Insertion Device Vacuum Chamber Design

vacuum, alignment, photon, distributed

450

J.E. Lerch, T.J. Bender, O.K. Mulvany, M.E. Szubert
ANL, Lemont, Illinois, USA

A straight section vacuum system (nominally 5.363 meters long) has been designed for the APS upgrade project. This vacuum system will be used in straight sections equipped with hybrid permanent magnet undulators (HPMU). The vacuum system assembly consists of the insertion device vacuum chamber (IDVC), the vacuum chamber distributed support, and the photon absorber. Numerous functional requirements constrained the IDVC design. These constraints included incorporation of the beam aperture transition into the end of the aluminium vacuum chamber extrusion (storage ring aperture to IDVC aperture), thin walls (~600 microns) surrounding the beam aperture to allow for as small a magnetic gap as possible, and complicated weld paths to ensure a continuous beam surface to minimize impedance. Additionally, extensive FEA and raytrace analysis were performed to ensure that the chamber would not fail due to structural or thermal perturbations.

Poster TUPLS02 [3.816 MB]

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TUPLS03

Advanced Photon Source Upgrade

vacuum, photon, operation, undulator

453

M.E. Szubert, E.R. Anliker, T.J. Bender, J.E. Lerch
ANL, Lemont, Illinois, USA

The Advanced Photon Source Upgrade (APS-U) in-cludes four straight sections equipped with full length Superconducting Undulators (SCUs). These sections require vacuum systems that must span 5.383 meters at nominal length, accommodate the SCU device, and ac-commodate additional magnets for the canted configura-tions. In the direction of the beam, the upstream portion of the vacuum system is a copper chamber doubling as a photon absorber with a design that is manufactured to allow a 13.5 mm canting magnet gap. This portion of the vacuum system operates at room temperature and shad-ows the length of the vacuum chamber that operates within the cryostat at 20K. The vacuum chamber inside the cryostat is a weldment including a machined alumi-num extrusion allowing for an 8mm magnetic gap, stain-less steel thermal insulators, copper shields, and bel-lows/flange assembly. The vacuum system includes an-other room temperature copper chamber and absorber on the downstream end of the straight section. The vacuum system provides Ultra-high Vacuum (UHV) continuity through the straight section, connecting the storage ring vacuum systems.

Poster TUPLS03 [0.974 MB]

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TUPLS11

NEG-Coated Copper Vacuum Chambers for the APS-Upgrade Storage Ring Vacuum System

vacuum, photon, radiation, operation

477

O.K. Mulvany, B. Billett, B. Brajuskovic, J.A. Carter, A. McElderry, K.J. Wakefield
ANL, Lemont, Illinois, USA

Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357.
The APS-Upgrade (APS-U) storage ring features a diverse group of vacuum chambers including seven distinctive, non-evaporable getter (NEG)-coated copper vacuum chambers per each of the 40 sectors. These chambers feature a 22-millimeter diameter aperture along the electron-beam path, with two vacuum chambers permitting photon extraction through a keyhole-shaped extension to this aperture. The chambers range from 0.3-meters to 1.7-meters in length and fit within the narrow envelope of quadrupole and sextupole magnets. Six of the seven copper vacuum chambers intercept significant heat loads from synchrotron radiation; five of these designs are fabricated entirely from OFS copper extrusions and are equipped with a compact Glidcop® photon absorber. A hybrid vacuum chamber, fabricated from OFS copper extrusion and a copper chromium zirconium (CuCrZr) keyhole transition, also intercepts synchrotron radiation. The seventh vacuum chamber design features a keyhole aperture across its length and is entirely fabricated from CuCrZr. This paper details the careful balance of vacuum chamber functionality, manufacturability, and the overall design process followed to achieve the final designs.

Poster TUPLS11 [4.941 MB]

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TUPLS12

Final Design of NEG-Coated Aluminum Vacuum Chambers & Stainless Steel Keyhole Vacuum Chambers for the APS-U Storage Ring

vacuum, photon, radiation, quadrupole

480

A. McElderry, B. Billett, J.A. Carter, K.J. Wakefield
ANL, Lemont, Illinois, USA

Funding: Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357.
The APS-Upgrade storage ring features a diverse group of vacuum chambers which includes eight NEG (non-evaporable getter) coated aluminum chambers and two copper coated stainless steel keyhole-shaped chambers per sector (40 total). Each chamber contains a 22 mm diameter electron beam aperture; the keyhole chambers also include a photon extraction antechamber. The chambers vary in length of approximately 289 ’ 792 mm and fit within the narrow envelope of quadrupole and sextupole magnets. Each design is a balance of functionality, manufacturability, and installation space. An innovative CAD skeleton model system and ray tracing layout accurately determined synchrotron radiation heat loads on built-in photon absorbers and the internal envelope of the keyhole antechamber. Chamber designs were optimized using thermal-structural FEA for operating and bakeout conditions. The group of chambers require complex manufacturing processes including EDM, explosion-bonded metals, furnace brazing, and welding with minimal space. This paper describes the design process and manufacturing plan for these vacuum chambers including details about FEA, fabrication plans, and cooling/bakeout strategies.

Poster TUPLS12 [2.581 MB]

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TUPLS14

Analyzing Accelerator Operation Data with Neural Networks

injection, operation, network, booster

487

F.Y. Wang, X. Huang, Z. Zhang
SLAC, Menlo Park, California, USA

Funding: Work is supported by DOE contract DE-AC02-76SF00515 (SLAC) and DOE contracts 2018-SLAC-100469 and 2018-SLAC-100469ASCR.
Accelerator operation history data are used to train neural networks in an attempt to understand the underly-ing causes of performance drifts. In the study, injection efficiency of SPEAR3 [1] over two runs is modelled with a neural network (NN) to map the relationship of the injection efficiency with the injected beam trajectory and environment variables. The NN model can accurately predict the injection performance for the test data. With the model, we discovered that an environment parameter, the ground temperature, has a big impact to the injection performance. The ideal trajectory as a function of the ground temperature can be extracted from the model. The method has the potential for even larger scale application for the discovery of deep connections between machine performance and environment parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLS14

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paper received ※ 29 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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TUPLH01

Status of the Superconducting Undulator Program at the Advanced Photon Source

undulator, operation, alignment, photon

490

M. Kasa, E.R. Anliker, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, W.G. Jansma, I. Kesgin, Y. Shiroyanagi
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Since 2013 there has been at least one superconducting undulator (SCU) in operation at the Advanced Photon Source (APS), currently there are two planar SCUs and one helical SCU. The combined operational experience of SCUs at the APS is more than 11 years and counting. Through all these years, APS SCUs operated with the predicted or better than predicted radiation performance and with 99% availability. With this demonstrated reliability and experimentally confirmed spectral performance, the APS upgrade project is planning on leveraging the advantages of SCU technology. The present planar SCUs are comprised of ~1.1-m-long magnets, each operated within a 2-m-long cryostat, while the planar SCUs for the upgrade will have two ~1.8-m-long magnets operating within a 5-m-long cryostat. Progress is also being made in other areas of SCU development with work on an arbitrary polarizing SCU, referred to as SCAPE, and a planar SCU wound with Nb₃Sn superconductor. A Nb₃Sn SCU is being designed with two 1.3-m-long magnets within a 5-m-long cryostat, and installation is planned for 2021. Also under development are the alignment and magnetic measurement systems for use with the 5-m-long cryostat.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH01

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

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TUPLH20

Commissioning of the CESR Upgrade for CHESS-U

MMI, HOM, wiggler, impedance

522

J.P. Shanks, G.W. Codner, M.J. Forster, D.L. Rubin, S. Wang, L. Ying
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Funding for the CHESS-U upgrade provided by New York State Capital Grant #AA737 / CFA #53676
The Cornell Electron Storage Ring (CESR) was upgraded in the second half of 2018 to become a dedicated synchrotron light source, CHESS-U. The upgrade is by far the largest modification to CESR in its 40-year history, replacing one-sixth of the storage ring with six new double-bend achromats, increasing beam energy from 5.3 GeV to 6.0 GeV, and switching from two counter-rotating beams to a single on-axis positron beam. The new achromats include combined-function dipoles, a first in CESR, and reduce the horizontal emittance by a factor of four. Eight compact narrow-gap undulators (4.6mm vacuum chamber aperture) and one high-energy 24-pole wiggler feed a total of six new and five existing x-ray end stations from a single positron beam. Commissioning of CHESS-U took place in the first half of 2019. We report on the methods and results of beam commissioning, including initial beam accumulation, optics correction, characterization, and commissioning of compact permanent-magnet insertion devices.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH20

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

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WEPLE06

Linear and Second Order Map Tracking with Artificial Neural Network

network, simulation, framework, software

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, simulation, 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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THYBA3

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

electron, emittance, simulation, 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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