NAPAC2019 - List of Keywords (injection)

Paper	Title	Other Keywords	Page
MOYBA2	Commissioning of the Phase 2 and Phase 3 SuperKEKB / B-Factory	detector, MMI, luminosity, optics	14
	S. Nakamura KEK, Ibaraki, Japan
	The next generation of B-Factory, the SuperKEKB electron-positron collider at KEK (Japan) has started after two years shutdown from the Phase 1 commissioning in 2016. The first phase for the vacuum scrubbing in 2016 and the second phase focused on the verification of the novel "nano-beam" collision scheme were successfully completed in 2018. The modifications between Phase 1 and Phase 2 follows Phase 3 are installations of the final focus system and the Belle II detector. In order to accomplish the higher luminosity more than the predecessor KEKB , the nano-beam scheme is studied with higher bunch currents to reduce the beam-beam blowup which degrade the luminosity. The new collision scheme is reviewed and the luminosity performance and overall status in the Phase 2 and Phase 3 commissioning are presented.
	Slides MOYBA2 [13.453 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBA2
About •	paper received ※ 30 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLM01	Alternative Injection Schemes to the NSLS-II Using Nonlinear Injection Magnets	kicker, septum, storage-ring, 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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MOPLM08	Controlling Transient Collective Instabilities During Swap-Out Injection	lattice, octupole, emittance, simulation	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, simulation, magnet-design, 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	simulation, 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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MOPLM21	Circuit Model Analysis for High Charge in the APS Particle Accumulator Ring	impedance, booster, synchrotron, photon	151
	K.C. Harkay, J.R. Calvey, J.C. Dooling, L. Emery, R.R. Lindberg, K.P. Wootton, C. Yao ANL, Lemont, Illinois, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) particle accumulator ring (PAR) was designed to accumulate linac pulses into a single bunch with a fundamental rf system, and longitudinally compress the beam with a harmonic rf system prior to injection into the booster. For APS Upgrade, the injectors will need to supply full-current bunch replacement with high single-bunch charge for swap-out in the new storage ring. Significant bunch lengthening, energy spread, and synchrotron sidebands are observed in PAR at high charge. Lower-charge dynamics are dominated by potential well distortion, while higher-charge dynamics appear to be dominated by microwave instability. Before a numerical impedance model was available, a simple circuit model was developed by fitting the measured bunch distributions to the Haissinski equation. Energy scaling was then used to predict the beam energy sufficient to raise the instability threshold to 18-20 nC. With the beam in a linear or nearly linear regime, higher harmonic radio frequency (rf) gap voltage can be used to reduce the bunch length at high charge and better match the booster acceptance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM21
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLS08	Error Tolerance Characterization for the HUST MeV Ultrafast Electron Diffraction System	emittance, electron, laser, simulation	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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MOPLO09	A Pulsed, Current Regulated Magnet Power Supply for Small Magnets	quadrupole, controls, operation, timing	252
	G.D. Wyche, B.L. Beaudoin, L. Dovlatyan, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: Work supported by U. S. Department of Energy grant number DESC00010301 The University of Maryland Electron Ring (UMER) has two pulsed quadrupoles in the injection section that must be current regulated to the same precision as the other DC quadrupoles in the ring, as well as accurately synchro-nized to the ring operating cycle. To meet this need, a practical pulsed current, regulated power supply has been designed and built using a commercial power operational amplifier for output, standard operational amplifiers for feedback control and monitoring, and matched resistor pairs to produce the desired transfer function of 10 Volts to 6 Amperes. For other applications the circuit can be modified to produce a range of transfer functions by varying the appropriate resistor pair ratios. Output pulse width and timing are generated by a standardized TTL pulse from the control system that gates the output of the amplifier. Installed safety circuitry detects the absence of a proper control pulse, an open circuit or shorted output, and measures and returns to the control system the actual operating amplitude of the current pulse. In this paper we present the design, implementation, and operational results of the prototyped pulsed current source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO09
About •	paper received ※ 28 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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MOPLO24	A Novel Technique for Pulsed Operation of Magnetrons without Modulation of Cathode Voltage	controls, cathode, operation, cavity	290
	G.M. Kazakevich, R.P. Johnson Muons, Inc, Illinois, USA T.N. Khabiboulline, V.A. Lebedev, G.V. Romanov, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Modern pulsed superconducting accelerators of megawatt beams require efficient RF sources controllable in phase and power. For each Superconducting RF (SRF) cavity is desirable a separate RF source with power up to hundreds of kW with pulse duration in the millisecond range. The efficiency of the traditional RF sources (klystrons, IOTs, solid-state amplifiers) is lower than that of the magnetrons, while the cost of a unit of RF power is much higher. Therefore the magnetron-based RF sources would significantly reduce the capital and operation costs in comparison with the traditional RF sources. A recently developed an innovative technique makes possible the pulsed generation of magnetrons powered below the self-excitation threshold voltage. This technique does not require pulse modulators to form RF pulses. The magnetron operation in this regime is stable, low noise, controllable in phase and power, and provides higher efficiency than other types of RF power sources. It allows operation in pulsed modes with large duty factor. The developed technique and its experimental verification are considered and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO24
About •	paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLS14	Analyzing Accelerator Operation Data with Neural Networks	operation, storage-ring, 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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TUPLH19	Upgrade and Operation Experience of Solid-State Switching Klystron Modulator in NSLS-II Linac	klystron, linac, operation, high-voltage	519
	H. Ma, J. Rose BNL, Upton, New York, USA
	Funding: US DOE The NSLS-II synchrotron light-source at BNL uses three S-band, 45MW klystrons in its injector LINAC. At the core of the klystron station design is the novel solid-state switching modulators (or SSM). Compared to the conventional PFN klystron modulators, the main advantages of the SSM include the compact size requiring a smaller footprint in the LINAC, and a very flat top in the produced klystron HV pulses. The flatness of the HV pulses is very important for NSLS-II LINAC that runs multi-bunch beams to keep the beam energy dispersion within the tolerance. The principle of the SSM is fairly simple. It uses a large number of relatively low-voltage switched charging capacitor cells (or SU’s) in parallel. A specially designed, high step-up ratio, pulse transformer in the oil-tank with the same number of primary windings (as SU’s) combines the power from all the SU’s, and steps up to the required ~300kV klystron beam voltage. The operation experience at NSLS-II has proven the performance and reliability of the SSM’s. The BNL Model K2 SSM’s are currently being upgraded to Model K300 to run more powerful, and more cost-effective Canon’s E37302A klystrons.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH19
About •	paper received ※ 27 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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TUPLO12	Off-Momentum Optics Correction in RHIC	optics, lattice, closed-orbit, experiment	556
	G. Robert-Demolaize, A. Marusic, V. Ptitsyn 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. Future operations of the electron-ion collider eRHIC call for beams circulating off of the magnetic center of all arc elements. In order to ensure that both stable beam conditions and the desired circumference change can be achieved, dedicated experiments were conducted during RHIC Run18, which included the first off-momentum linear optics correction. This article reviews the experimental setup as well as the dedicated algorithm for optics correction, and presents the measured radial excursion and residual off-momentum beta-beat.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO12
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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TUPLE06	Skimmer-Nozzle Configuration Measurements for a Gas Sheet Beam Profile Monitor	detector, vacuum, cathode, background	573
	S. Szustkowski, S. Chattopadhyay, B.T. Freemire Northern Illinois University, DeKalb, Illinois, USA S. Chattopadhyay, D.J. Crawford, B.T. Freemire Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program Understanding the characteristics of the gas sheet being produced and optimal configuration of the gas injection system is essential to the the performance of a gas sheet beam profile monitor. A gas injection system test stand has been built at Fermilab to test various nozzle and slit configurations. The distance between the nozzle and slit can be changed to find an optimal configuration. Using a moveable cold cathode gauge the gas profile is measured.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE06
About •	paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEYBB3	Foil Scattering Model for Fermilab Booster	scattering, booster, proton, operation	632
	C.M. Bhat, S. Chaurize, J.S. Eldred, V.A. Lebedev, S. Nagaitsev, K. Seiya, C.-Y. Tan, R. Tesarek Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. At the Fermilab Booster, and many other proton facilities, an intense proton beam is accumulated by injection an H⁻ beam through a stripping foil. The circulating beam scatters off the injection beam and large-angle Coulomb scattering leads to uncontrolled losses concentrated in the first betatron period. We measure the foil scattering rate in the Booster as a function of linac current, number of injection-turns, and time on injection foil. We find that current Booster operations has a 1% foil scattering loss rate and we make projections for the Proton Improvement Plan II (PIP-II) injector upgrade. We find that accurate modeling of the foil scattering loss must account for beam emittance in conjunction with the scattering rate and ring acceptance. Estimate of beam emittance at injection are discussed.
	Slides WEYBB3 [5.690 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB3
About •	paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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WEYBB5	A Crab-Crossing Scheme for Laser-Ion Beam Applications	laser, experiment, linac, cavity	639
	A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, Y. Liu, A. Rakhman, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Lasers have recently been used in many applications to H⁻ beams, including laser charge exchange, laser wire scanners, and laser temporal pulse patterning. The H⁻ beam in these applications has wide variation ofμpulse length width dependence on focusing of the RF cavities, energy spread of the beam, and space charge forces. Achieving the required laser pulse length for complete overlap with the H⁻ can be challenging in some scenarios when available laser power constrained. The scheme proposed here utilizes a crab-crossing concept between the laser and the ion beam to achieve overlap of a short laser pulse with an arbitrarily long H⁻ beam pulse. An experiment to test the hypothesis in the context of H⁻ charge exchange is described.
	Slides WEYBB5 [5.201 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB5
About •	paper received ※ 30 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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WEPLO16	Energy Spread Measurements for 400 MeV LINAC Beam at Fermilab Booster using a LASER Notcher System	booster, linac, laser, experiment	868
	C.M. Bhat, D.E. Johnson Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. To mitigate 8 GeV beam losses at extraction in the Fermilab Booster synchrotron, a LASER notcher system for multi-turn injection that produces notches at 720 keV is used. These notches synchronize with the revolution period of the beam [ref. HB2018, page 416] at injection in the Booster. Recently, a dedicated notching pattern that keeps a single 201 MHz LINAC bunch untouched in the middle of a notch is developed to measure the beam energy spread by studying the time evolution of this bunch in the Booster. A complementary to this method, recently, it has been realized that one can also measure energy spread of the LINAC beam by injecting <2 Booster turn beam and studying the time evolution of the multiple 201 MHz LINAC bunches. In this paper we present the general principle of the method and results from our measurements.
	Poster WEPLO16 [0.193 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO16
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOYBA2

Commissioning of the Phase 2 and Phase 3 SuperKEKB / B-Factory

detector, MMI, luminosity, optics

14

S. Nakamura
KEK, Ibaraki, Japan

The next generation of B-Factory, the SuperKEKB electron-positron collider at KEK (Japan) has started after two years shutdown from the Phase 1 commissioning in 2016. The first phase for the vacuum scrubbing in 2016 and the second phase focused on the verification of the novel "nano-beam" collision scheme were successfully completed in 2018. The modifications between Phase 1 and Phase 2 follows Phase 3 are installations of the final focus system and the Belle II detector. In order to accomplish the higher luminosity more than the predecessor KEKB , the nano-beam scheme is studied with higher bunch currents to reduce the beam-beam blowup which degrade the luminosity. The new collision scheme is reviewed and the luminosity performance and overall status in the Phase 2 and Phase 3 commissioning are presented.

Slides MOYBA2 [13.453 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBA2

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paper received ※ 30 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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MOPLM01

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

kicker, septum, storage-ring, 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

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

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MOPLM08

Controlling Transient Collective Instabilities During Swap-Out Injection

lattice, octupole, emittance, simulation

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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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM08

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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, simulation, magnet-design, 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

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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

simulation, 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

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

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MOPLM21

Circuit Model Analysis for High Charge in the APS Particle Accumulator Ring

impedance, booster, synchrotron, photon

151

K.C. Harkay, J.R. Calvey, J.C. Dooling, L. Emery, R.R. Lindberg, K.P. Wootton, C. Yao
ANL, Lemont, Illinois, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) particle accumulator ring (PAR) was designed to accumulate linac pulses into a single bunch with a fundamental rf system, and longitudinally compress the beam with a harmonic rf system prior to injection into the booster. For APS Upgrade, the injectors will need to supply full-current bunch replacement with high single-bunch charge for swap-out in the new storage ring. Significant bunch lengthening, energy spread, and synchrotron sidebands are observed in PAR at high charge. Lower-charge dynamics are dominated by potential well distortion, while higher-charge dynamics appear to be dominated by microwave instability. Before a numerical impedance model was available, a simple circuit model was developed by fitting the measured bunch distributions to the Haissinski equation. Energy scaling was then used to predict the beam energy sufficient to raise the instability threshold to 18-20 nC. With the beam in a linear or nearly linear regime, higher harmonic radio frequency (rf) gap voltage can be used to reduce the bunch length at high charge and better match the booster acceptance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM21

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

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MOPLS08

Error Tolerance Characterization for the HUST MeV Ultrafast Electron Diffraction System

emittance, electron, laser, simulation

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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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLS08

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paper received ※ 25 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLO09

A Pulsed, Current Regulated Magnet Power Supply for Small Magnets

quadrupole, controls, operation, timing

252

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

Funding: Work supported by U. S. Department of Energy grant number DESC00010301
The University of Maryland Electron Ring (UMER) has two pulsed quadrupoles in the injection section that must be current regulated to the same precision as the other DC quadrupoles in the ring, as well as accurately synchro-nized to the ring operating cycle. To meet this need, a practical pulsed current, regulated power supply has been designed and built using a commercial power operational amplifier for output, standard operational amplifiers for feedback control and monitoring, and matched resistor pairs to produce the desired transfer function of 10 Volts to 6 Amperes. For other applications the circuit can be modified to produce a range of transfer functions by varying the appropriate resistor pair ratios. Output pulse width and timing are generated by a standardized TTL pulse from the control system that gates the output of the amplifier. Installed safety circuitry detects the absence of a proper control pulse, an open circuit or shorted output, and measures and returns to the control system the actual operating amplitude of the current pulse. In this paper we present the design, implementation, and operational results of the prototyped pulsed current source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO09

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paper received ※ 28 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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MOPLO24

A Novel Technique for Pulsed Operation of Magnetrons without Modulation of Cathode Voltage

controls, cathode, operation, cavity

290

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
T.N. Khabiboulline, V.A. Lebedev, G.V. Romanov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Modern pulsed superconducting accelerators of megawatt beams require efficient RF sources controllable in phase and power. For each Superconducting RF (SRF) cavity is desirable a separate RF source with power up to hundreds of kW with pulse duration in the millisecond range. The efficiency of the traditional RF sources (klystrons, IOTs, solid-state amplifiers) is lower than that of the magnetrons, while the cost of a unit of RF power is much higher. Therefore the magnetron-based RF sources would significantly reduce the capital and operation costs in comparison with the traditional RF sources. A recently developed an innovative technique makes possible the pulsed generation of magnetrons powered below the self-excitation threshold voltage. This technique does not require pulse modulators to form RF pulses. The magnetron operation in this regime is stable, low noise, controllable in phase and power, and provides higher efficiency than other types of RF power sources. It allows operation in pulsed modes with large duty factor. The developed technique and its experimental verification are considered and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO24

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

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TUPLS14

Analyzing Accelerator Operation Data with Neural Networks

operation, storage-ring, 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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TUPLH19

Upgrade and Operation Experience of Solid-State Switching Klystron Modulator in NSLS-II Linac

klystron, linac, operation, high-voltage

519

H. Ma, J. Rose
BNL, Upton, New York, USA

Funding: US DOE
The NSLS-II synchrotron light-source at BNL uses three S-band, 45MW klystrons in its injector LINAC. At the core of the klystron station design is the novel solid-state switching modulators (or SSM). Compared to the conventional PFN klystron modulators, the main advantages of the SSM include the compact size requiring a smaller footprint in the LINAC, and a very flat top in the produced klystron HV pulses. The flatness of the HV pulses is very important for NSLS-II LINAC that runs multi-bunch beams to keep the beam energy dispersion within the tolerance. The principle of the SSM is fairly simple. It uses a large number of relatively low-voltage switched charging capacitor cells (or SU’s) in parallel. A specially designed, high step-up ratio, pulse transformer in the oil-tank with the same number of primary windings (as SU’s) combines the power from all the SU’s, and steps up to the required ~300kV klystron beam voltage. The operation experience at NSLS-II has proven the performance and reliability of the SSM’s. The BNL Model K2 SSM’s are currently being upgraded to Model K300 to run more powerful, and more cost-effective Canon’s E37302A klystrons.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH19

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

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TUPLO12

Off-Momentum Optics Correction in RHIC

optics, lattice, closed-orbit, experiment

556

G. Robert-Demolaize, A. Marusic, V. Ptitsyn
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.
Future operations of the electron-ion collider eRHIC call for beams circulating off of the magnetic center of all arc elements. In order to ensure that both stable beam conditions and the desired circumference change can be achieved, dedicated experiments were conducted during RHIC Run18, which included the first off-momentum linear optics correction. This article reviews the experimental setup as well as the dedicated algorithm for optics correction, and presents the measured radial excursion and residual off-momentum beta-beat.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO12

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

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TUPLE06

Skimmer-Nozzle Configuration Measurements for a Gas Sheet Beam Profile Monitor

detector, vacuum, cathode, background

573

S. Szustkowski, S. Chattopadhyay, B.T. Freemire
Northern Illinois University, DeKalb, Illinois, USA
S. Chattopadhyay, D.J. Crawford, B.T. Freemire
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program
Understanding the characteristics of the gas sheet being produced and optimal configuration of the gas injection system is essential to the the performance of a gas sheet beam profile monitor. A gas injection system test stand has been built at Fermilab to test various nozzle and slit configurations. The distance between the nozzle and slit can be changed to find an optimal configuration. Using a moveable cold cathode gauge the gas profile is measured.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE06

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paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEYBB3

Foil Scattering Model for Fermilab Booster

scattering, booster, proton, operation

632

C.M. Bhat, S. Chaurize, J.S. Eldred, V.A. Lebedev, S. Nagaitsev, K. Seiya, C.-Y. Tan, R. Tesarek
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
At the Fermilab Booster, and many other proton facilities, an intense proton beam is accumulated by injection an H⁻ beam through a stripping foil. The circulating beam scatters off the injection beam and large-angle Coulomb scattering leads to uncontrolled losses concentrated in the first betatron period. We measure the foil scattering rate in the Booster as a function of linac current, number of injection-turns, and time on injection foil. We find that current Booster operations has a 1% foil scattering loss rate and we make projections for the Proton Improvement Plan II (PIP-II) injector upgrade. We find that accurate modeling of the foil scattering loss must account for beam emittance in conjunction with the scattering rate and ring acceptance. Estimate of beam emittance at injection are discussed.

Slides WEYBB3 [5.690 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB3

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paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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WEYBB5

A Crab-Crossing Scheme for Laser-Ion Beam Applications

laser, experiment, linac, cavity

639

A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, Y. Liu, A. Rakhman, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Lasers have recently been used in many applications to H⁻ beams, including laser charge exchange, laser wire scanners, and laser temporal pulse patterning. The H⁻ beam in these applications has wide variation ofμpulse length width dependence on focusing of the RF cavities, energy spread of the beam, and space charge forces. Achieving the required laser pulse length for complete overlap with the H⁻ can be challenging in some scenarios when available laser power constrained. The scheme proposed here utilizes a crab-crossing concept between the laser and the ion beam to achieve overlap of a short laser pulse with an arbitrarily long H⁻ beam pulse. An experiment to test the hypothesis in the context of H⁻ charge exchange is described.

Slides WEYBB5 [5.201 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB5

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

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WEPLO16

Energy Spread Measurements for 400 MeV LINAC Beam at Fermilab Booster using a LASER Notcher System

booster, linac, laser, experiment

868

C.M. Bhat, D.E. Johnson
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
To mitigate 8 GeV beam losses at extraction in the Fermilab Booster synchrotron, a LASER notcher system for multi-turn injection that produces notches at 720 keV is used. These notches synchronize with the revolution period of the beam [ref. HB2018, page 416] at injection in the Booster. Recently, a dedicated notching pattern that keeps a single 201 MHz LINAC bunch untouched in the middle of a notch is developed to measure the beam energy spread by studying the time evolution of this bunch in the Booster. A complementary to this method, recently, it has been realized that one can also measure energy spread of the LINAC beam by injecting <2 Booster turn beam and studying the time evolution of the multiple 201 MHz LINAC bunches. In this paper we present the general principle of the method and results from our measurements.

Poster WEPLO16 [0.193 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO16

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

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