IPAC2015 - List of Keywords (beam-loading)

Paper	Title	Other Keywords	Page
MOPWA022	Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR	synchrotron, damping, simulation, cavity	141
	M. Ruprecht, P. Goslawski, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld HZB, Berlin, Germany T. Weis DELTA, Dortmund, Germany
	BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed . The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron frequency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi-bunch oscillations for the projected setup of BESSY VSR. G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA022
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MOPMA026	Proposed Cavity for Reduced Slip-Stacking Loss	cavity, booster, injection, emittance	600
	J.S. Eldred Indiana University, Bloomington, Indiana, USA J.S. Eldred, R.M. Zwaska Fermilab, Batavia, Illinois, USA
	This paper employs a novel dynamical mechanism to improve the performance of slip-stacking. Slip-stacking in an accumulation technique used at Fermilab since 2004 which nearly double the proton intensity. During slip-stacking, the Recycler or the Main Injector stores two particles beams that spatially overlap but have different momenta. The two particle beams are longitudinally focused by two 53 MHz 100 kV RF cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV RF cavity, with a frequency at the double the average of the upper and lower main RF frequencies. In simulation, we find the proposed RF cavity significantly enhances the stable bucket area and reduces slip-stacking losses under reasonable injection scenarios. We quantify and map the stability of the parameter space for any accelerator implementing slip-stacking with the addition of a harmonic RF cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA026
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MOPHA010	RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities	cavity, feedback, synchrotron, operation	798
	A. Neumann, P. Echevarria, P. Goslawski, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld HZB, Berlin, Germany
	For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring's RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zero-crossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and low power consumption at a loaded Q of 5·10⁷. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated. * G. Wüstefeld et al., IPAC 11, San Sebastiàn, Spain, p. 2936.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA010
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MOPHA056	Status of LLRF Control System for SuperKEKB Commissioning	controls, cavity, LLRF, klystron	924
	T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri KEK, Ibaraki, Japan H. Deguchi, K. Hayashi, T. Iwaki, M. Ryoshi Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan
	Beam commissioning of the SuperKEKB will be started in JFY2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed for high current beam operation of the SuperKEKB. The mass production and installation of the new systems has been completed as scheduled. The new LLRF control systems are applied to nine RF stations (klystron driving units) among existing thirty stations. As a new function, klystron phase lock loop was digitally implemented within the cavity FB control loop in the FPGA, and in the high power test it worked successfully to compensate for the klystron phase change. Beam loading was also simulated in the high power test by using an ARES cavity simulator, and then good performance in the cavity-voltage feedback control and the cavity tuning control was demonstrated to compensate the large beam loading for the SuperKEKB parameters. Fabrication of another new LLRF control system for damping ring which is required for low-emittance positron injection is scheduled in JFY2015.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA056
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MOPTY042	ALBA LLRF Upgrades to Improve Beam Availability	cavity, LLRF, operation, synchrotron	1022
	A. Salom, B. Bravo, J. Marcos, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a 3GeV synchrotron light source located in Barcelona and operating with users since May 2012. The RF system of the SR is composed of six cavities, each one powered by combining the power of two 80 kW IOTs through a Cavity Combiner (CaCo). At present, there are several RF interlocks per week. The redundancy given by the six cavities makes possible the survival of the beam after one of these trips. In these cases, the cavity has to be recovered with the circulating beam. An autorecovery process has been implemented in the digital LLRF system in order to recover the faulty RF plant after a trip. But these trips also create perturbations to the beam stability. In order to minimize the beam perturbations induced by these RF interlock, an additional feed-forward loop is being implemented. The functionally, main parameters and test results of these new algorithms will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY042
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WEPWA017	An Optimization of ILC Positron Source for Electron-Driven Scheme	positron, electron, target, linac	2529
	Y. Seimiya, M. Kuriki, M. Urano HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, School of Science, Sendai, Japan T. Okugi, T. Omori, M. Satoh, J. Urakawa KEK, Ibaraki, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	International Linear Collider is a future accelerator to find new physics behind the electroweak symmetry breaking by precise measurements of Higgs sector, Top quark, and so on. ILC has capacities to reveal new phenomena beyond Standard model, such as Supersymmetry particles and dark matters. In current design of positron source, undulator scheme is adapted as a baseline. In the scheme, positrons are generated from gamma rays through pair-creation process in Ti-alloy target. Generations of the gamma rays by the undulator radiation requires more than 130 GeV electrons. Therefore, a system demonstration of the scheme is practically difficult prior to the real construction. Consequently, it is desirable to prepare a technical backup of this undulator scheme. We study an optimization of positron source based on the conventional electron-driven scheme for ILC. In this scheme, positron beam is generated by several GeV electron beam impinging on W-Re target. Although heavy heat load and destruction of the target is a potential problem, it can be relaxed by stretching the effective pulse length to 60 ms instead of 1 ms, by a dedicated electron linac for the positron production. In this report, a start-to-end simulation of the electron-driven ILC positron source is performed. Beam-loading effect caused by multi-bunch acceleration in the standing wave RF cavity is also considered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA017
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WEPWA026	Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch	plasma, electron, proton, simulation	2551
	V.K.B. Olsen, E. Adli University of Oslo, Oslo, Norway L.D. Amorim IST, Lisboa, Portugal P. Muggli MPI, Muenchen, Germany J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026
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WEPWA048	Design Studies and Commissioning Plans for PARS Experimental Program	plasma, acceleration, wakefield, electron	2612
	Ö. Mete, K. Hanahoe, J. Wright, G.X. Xia UMAN, Manchester, United Kingdom M. Dover, M. Wigram, J. Zhang University of Manchester, Manchester, United Kingdom J.D.A. Smith Tech-X, Boulder, Colorado, USA
	Funding: Science and Technology Facilities Council and Cockcroft Institute Core Grant PARS (Plasma Acceleration Research Station) is an electron beam driven plasma wakefield acceleration test stand proposed for VELA/CLARA facility in Daresbury Laboratory. In order to optimise various operational configurations, 2D numerical studies were performed by using VSIM for a range of parameters such as bunch length, radius, plasma density and positioning of the bunches with respect to each other for the two-beam acceleration scheme. In this paper, some of these numerical studies and considered measurement methods are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA048
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WEPMA054	A Disturbance-Observer-based Controller for LLRF Systems	controls, LLRF, cavity, experiment	2895
	F. Qiu, D.A. Arakawa, Y. Honda, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Obina KEK, Ibaraki, Japan S.B. Wibowo Sokendai, Ibaraki, Japan
	Digital low-level radio frequency (LLRFs) systems have been developed and evaluated in the compact energy recovery linac (cERL) at KEK. The required RF stabilities are 0.1% rms in amplitude and 0.1° rms in phase. These requirements are satisfied by applying digital LLRF systems. To further enhance the control system and make it robust to disturbances such as large power supply (PS) ripples and high-intensity beams, we have designed and developed a disturbance observer (DOB)-based control method. This method utilizes the RF system model, which can be acquired using modern system identification methods. Experiments show that the proposed DOB-based controller is more effective in the presence of high disturbances compared with the conventional proportional and integral (PI) controller. In this paper, we present the preliminary results based on the experiments with DOB-based controller.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA054
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WEPTY044	Phase Transients in the Higher-Harmonic RF Systems For the ALS-U Proposal	simulation, experiment, impedance, synchrotron	3372
	J.M. Byrd, S. De Santis, T.H. Luo, C. Steier LBNL, Berkeley, California, USA
	Funding: This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231. The ALS upgrade proposal (ALS-U) requires lengthening the bunch by a factor of at least four in order to increase the beam lifetime to acceptable values. Due to the presence of gaps in the fill pattern, required by the injection/extraction kicker system, the beam-induced voltage in the passive, normal-conducting, cavities which we plan to use is not constant over the length of a bunch train. We present our result on the optimal tuning of the harmonic cavities to obtain the best lifetime increase, including the effects of strongly non-gaussian bunch shapes and wakefield distortions of the potential well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY044
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THPF140	Unique Accelerator Integration Features of the Heavy Ion CW Driver Linac at FRIB	linac, proton, solenoid, focusing	4051
	Y. Yamazaki, N.K. Bultman, A. Facco, M. Ikegami, F. Marti, G. Pozdeyev, J. Wei, Y. Zhang, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The FRIB driver linac is a front runner for the future high power hadron linacs, making a full use of CW, superconducting acceleration from very low β. Accelerator Driven Nuclear Waste Transmutation System (ADS), International Fusion Material Irradiation Facility (IFMIF), Project-X type proton accelerators for high energy physics and others may utilize the technologies developed for the design, construction, commissioning and power ramp up of the FRIB linac. Although each technology has been already well developed individually (except for charge stripper), their integration is another challenge. In addition, extremely high Bragg peak of uranium beams (several thousand times as high as that of proton beams) gives rise to one of the biggest challenges in many aspects. This report summarizes these challenges and their mitigations, emphasizing the commonly overlooked features.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF140
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Paper

Title

Other Keywords

Page

MOPWA022

Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR

synchrotron, damping, simulation, cavity

141

M. Ruprecht, P. Goslawski, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
T. Weis
DELTA, Dortmund, Germany

BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed *. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron frequency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi-bunch oscillations for the projected setup of BESSY VSR.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA022

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MOPMA026

Proposed Cavity for Reduced Slip-Stacking Loss

cavity, booster, injection, emittance

600

J.S. Eldred
Indiana University, Bloomington, Indiana, USA
J.S. Eldred, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

This paper employs a novel dynamical mechanism to improve the performance of slip-stacking. Slip-stacking in an accumulation technique used at Fermilab since 2004 which nearly double the proton intensity. During slip-stacking, the Recycler or the Main Injector stores two particles beams that spatially overlap but have different momenta. The two particle beams are longitudinally focused by two 53 MHz 100 kV RF cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV RF cavity, with a frequency at the double the average of the upper and lower main RF frequencies. In simulation, we find the proposed RF cavity significantly enhances the stable bucket area and reduces slip-stacking losses under reasonable injection scenarios. We quantify and map the stability of the parameter space for any accelerator implementing slip-stacking with the addition of a harmonic RF cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA026

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MOPHA010

RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities

cavity, feedback, synchrotron, operation

798

A. Neumann, P. Echevarria, P. Goslawski, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld
HZB, Berlin, Germany

For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring's RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zero-crossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and low power consumption at a loaded Q of 5·10⁷. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated.
* G. Wüstefeld et al., IPAC 11, San Sebastiàn, Spain, p. 2936.

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MOPHA056

Status of LLRF Control System for SuperKEKB Commissioning

controls, cavity, LLRF, klystron

924

T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
KEK, Ibaraki, Japan
H. Deguchi, K. Hayashi, T. Iwaki, M. Ryoshi
Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan

Beam commissioning of the SuperKEKB will be started in JFY2015. A new LLRF control system, which is an FPGA-based digital RF feedback control system on the MicroTCA platform, has been developed for high current beam operation of the SuperKEKB. The mass production and installation of the new systems has been completed as scheduled. The new LLRF control systems are applied to nine RF stations (klystron driving units) among existing thirty stations. As a new function, klystron phase lock loop was digitally implemented within the cavity FB control loop in the FPGA, and in the high power test it worked successfully to compensate for the klystron phase change. Beam loading was also simulated in the high power test by using an ARES cavity simulator, and then good performance in the cavity-voltage feedback control and the cavity tuning control was demonstrated to compensate the large beam loading for the SuperKEKB parameters. Fabrication of another new LLRF control system for damping ring which is required for low-emittance positron injection is scheduled in JFY2015.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA056

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MOPTY042

ALBA LLRF Upgrades to Improve Beam Availability

cavity, LLRF, operation, synchrotron

1022

A. Salom, B. Bravo, J. Marcos, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3GeV synchrotron light source located in Barcelona and operating with users since May 2012. The RF system of the SR is composed of six cavities, each one powered by combining the power of two 80 kW IOTs through a Cavity Combiner (CaCo). At present, there are several RF interlocks per week. The redundancy given by the six cavities makes possible the survival of the beam after one of these trips. In these cases, the cavity has to be recovered with the circulating beam. An autorecovery process has been implemented in the digital LLRF system in order to recover the faulty RF plant after a trip. But these trips also create perturbations to the beam stability. In order to minimize the beam perturbations induced by these RF interlock, an additional feed-forward loop is being implemented. The functionally, main parameters and test results of these new algorithms will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY042

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WEPWA017

An Optimization of ILC Positron Source for Electron-Driven Scheme

positron, electron, target, linac

2529

Y. Seimiya, M. Kuriki, M. Urano
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, School of Science, Sendai, Japan
T. Okugi, T. Omori, M. Satoh, J. Urakawa
KEK, Ibaraki, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

International Linear Collider is a future accelerator to find new physics behind the electroweak symmetry breaking by precise measurements of Higgs sector, Top quark, and so on. ILC has capacities to reveal new phenomena beyond Standard model, such as Supersymmetry particles and dark matters. In current design of positron source, undulator scheme is adapted as a baseline. In the scheme, positrons are generated from gamma rays through pair-creation process in Ti-alloy target. Generations of the gamma rays by the undulator radiation requires more than 130 GeV electrons. Therefore, a system demonstration of the scheme is practically difficult prior to the real construction. Consequently, it is desirable to prepare a technical backup of this undulator scheme. We study an optimization of positron source based on the conventional electron-driven scheme for ILC. In this scheme, positron beam is generated by several GeV electron beam impinging on W-Re target. Although heavy heat load and destruction of the target is a potential problem, it can be relaxed by stretching the effective pulse length to 60 ms instead of 1 ms, by a dedicated electron linac for the positron production. In this report, a start-to-end simulation of the electron-driven ILC positron source is performed. Beam-loading effect caused by multi-bunch acceleration in the standing wave RF cavity is also considered.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA017

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WEPWA026

Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch

plasma, electron, proton, simulation

2551

V.K.B. Olsen, E. Adli
University of Oslo, Oslo, Norway
L.D. Amorim
IST, Lisboa, Portugal
P. Muggli
MPI, Muenchen, Germany
J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026

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WEPWA048

Design Studies and Commissioning Plans for PARS Experimental Program

plasma, acceleration, wakefield, electron

2612

Ö. Mete, K. Hanahoe, J. Wright, G.X. Xia
UMAN, Manchester, United Kingdom
M. Dover, M. Wigram, J. Zhang
University of Manchester, Manchester, United Kingdom
J.D.A. Smith
Tech-X, Boulder, Colorado, USA

Funding: Science and Technology Facilities Council and Cockcroft Institute Core Grant
PARS (Plasma Acceleration Research Station) is an electron beam driven plasma wakefield acceleration test stand proposed for VELA/CLARA facility in Daresbury Laboratory. In order to optimise various operational configurations, 2D numerical studies were performed by using VSIM for a range of parameters such as bunch length, radius, plasma density and positioning of the bunches with respect to each other for the two-beam acceleration scheme. In this paper, some of these numerical studies and considered measurement methods are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA048

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WEPMA054

A Disturbance-Observer-based Controller for LLRF Systems

controls, LLRF, cavity, experiment

2895

F. Qiu, D.A. Arakawa, Y. Honda, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Obina
KEK, Ibaraki, Japan
S.B. Wibowo
Sokendai, Ibaraki, Japan

Digital low-level radio frequency (LLRFs) systems have been developed and evaluated in the compact energy recovery linac (cERL) at KEK. The required RF stabilities are 0.1% rms in amplitude and 0.1° rms in phase. These requirements are satisfied by applying digital LLRF systems. To further enhance the control system and make it robust to disturbances such as large power supply (PS) ripples and high-intensity beams, we have designed and developed a disturbance observer (DOB)-based control method. This method utilizes the RF system model, which can be acquired using modern system identification methods. Experiments show that the proposed DOB-based controller is more effective in the presence of high disturbances compared with the conventional proportional and integral (PI) controller. In this paper, we present the preliminary results based on the experiments with DOB-based controller.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA054

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WEPTY044

Phase Transients in the Higher-Harmonic RF Systems For the ALS-U Proposal

simulation, experiment, impedance, synchrotron

3372

J.M. Byrd, S. De Santis, T.H. Luo, C. Steier
LBNL, Berkeley, California, USA

Funding: This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231.
The ALS upgrade proposal (ALS-U) requires lengthening the bunch by a factor of at least four in order to increase the beam lifetime to acceptable values. Due to the presence of gaps in the fill pattern, required by the injection/extraction kicker system, the beam-induced voltage in the passive, normal-conducting, cavities which we plan to use is not constant over the length of a bunch train. We present our result on the optimal tuning of the harmonic cavities to obtain the best lifetime increase, including the effects of strongly non-gaussian bunch shapes and wakefield distortions of the potential well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY044

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THPF140

Unique Accelerator Integration Features of the Heavy Ion CW Driver Linac at FRIB

linac, proton, solenoid, focusing

4051

Y. Yamazaki, N.K. Bultman, A. Facco, M. Ikegami, F. Marti, G. Pozdeyev, J. Wei, Y. Zhang, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The FRIB driver linac is a front runner for the future high power hadron linacs, making a full use of CW, superconducting acceleration from very low β. Accelerator Driven Nuclear Waste Transmutation System (ADS), International Fusion Material Irradiation Facility (IFMIF), Project-X type proton accelerators for high energy physics and others may utilize the technologies developed for the design, construction, commissioning and power ramp up of the FRIB linac. Although each technology has been already well developed individually (except for charge stripper), their integration is another challenge. In addition, extremely high Bragg peak of uranium beams (several thousand times as high as that of proton beams) gives rise to one of the biggest challenges in many aspects. This report summarizes these challenges and their mitigations, emphasizing the commonly overlooked features.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF140

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