Beam commissioning and operation of the Japan Proton Accelerator Research Complex 3-GeV rapid cycling synchrotron

The 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) is now in the final beam commissioning phase, aiming for a design output beam power of 1 MW. With a series of injector linac upgrades in 2013 and 2014, RCS developed a high-intensity beam test, and launched 1-MW beam tuning in October 2014. The most important issues in realizing such a high-power continuous beam operation are to control and minimize beam loss for maintaining machine activations within permissible levels. In RCS, numerical simulation was successfully utilized along with experimental approaches to isolate the mechanism of beam loss and find its solution. By iteratively performing actual beam experiments and numerical simulations, and also by several hardware improvements, we have recently established a 1-MW beam operation with very low fractional beam loss of a couple of 10 −3 . In this paper, our recent efforts toward realizing such a low-loss high-intensity beam acceleration are presented as a follow-up of our previous article, H. Hotchi et al. Phys. Rev. ST Accel. Beams 12, 040402 (2009), in which the initial beam commissioning status of RCS has been reported.

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“…Our numerical simulation includes all lattice imperfections, that have been identified so far [3,11];…”

Section: Outline Of Numerical Simulationmentioning

confidence: 99%

“…Figure 2 shows the history of the RCS output beam power. RCS was beam commissioned in October 2007 and made available for the user program in December 2008 with an output beam power of 4 kW [2,3]. Since then, the RCS beam power ramp-up has steadily proceeded as per progressions in beam tuning and hardware improvements.…”

Section: Introductionmentioning

confidence: 99%

Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Hotchi

Harada

Hayashi

et al. 2017

Phys. Rev. Accel. Beams

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“…Switching painting area MLF to MR By using PSTR magnets we first carried out an experimental test for switching MLF painting area of 150 mm mrad to the MR painting area of 100 mm mrad. It is important to mention that at present a maximum painting area within an acceptable beam loss is unfortunately limited up to about 150 mm mrad due to mainly a large vertical beta beating (as much as more than 30% around the ring) caused by the edge effect of the chicane bump magnets during beam injection and also for some other lattice imperfections [13,15]. These lead to a significant reduction of the dynamic aperture of the ring but at present there exist no knobs for compensating these effects.…”

Section: Experimental Results and Comparison With Numerical Simumentioning

confidence: 99%

“…The latest tune diagram of the RCS obtained for a single particle dynamic aperture calculation has been reported in Ref. [13]. The betatron tunes are changed by changing focusing strength of the ring quadrupoles and thus Twiss parameters of the circulating beam at the stripper foil is changed.…”

Section: Principles and Design Specifications Of The Pstr Magnetsmentioning

confidence: 99%

“…At present there exists a limitation on expanding a transverse injection painting area larger than 150 mm mrad. This is mainly because of a large vertical beta beating around the ring (as much as more than 30%) caused by the edge effect of the chicane bump magnets during beam injection and also for some other lattice imperfections [13,15]. The dynamic aperture of the RCS is then greatly reduced and consequently leads to an unacceptable beam loss but there exist no knobs for compensating these effects at present.…”

Section: Measurement Of the Extracted Beam Profiles For The Mlf Anmentioning

confidence: 99%

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Beam emittance control by changing injection painting area in a pulse-to-pulse mode in the 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex

Saha

Harada

Hayashi

et al. 2013

Phys. Rev. ST Accel. Beams

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The 3-GeV rapid cycling synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) simultaneously delivers high intensity beam to the Material and Life Science Experimental Facility (MLF) as well as to the main ring (MR) at a repetition rate of 25 Hz. The RCS is designed for a beam power of 1 MW. RCS has to meet not only the need of power upgrade but also the specific requirement of each downstream facility. One of the issues, especially for high intensity operation, is to maintain two different transverse sizes of the extracted beam for MLF and MR; namely, a wider beam for MLF in order to reduce damage on the neutron production target but reversely a narrower one for the MR in order to ensure a permissible beam loss in the beam transport line of 3-GeV to MR and also in the MR. We proposed pulseto-pulse direct control of the transverse painting area during the RCS beam injection process in order to get an extracted beam profile as desired. In addition to two existing dc septum magnets used for fixing injected beam trajectory for MLF beam, two additional dipoles named pulse steering magnets are designed for that purpose in order to control injected beam trajectory for a smaller painting area for the MR. The magnets are already installed in the injection beam transport line and successfully commissioned well in advance before they will be put in normal operation in 2014 for the 400 MeV injected beam energy upgraded from that of the present 181 MeV. Their parameters are found to be consistent to those expected in the corresponding numerical simulations. A trial one cycle user operation run for a painting area of 100 mm mrad for the MR switching from the MLF painting area of 150 mm mrad has also been successfully carried out. The extracted beam profile for the MR is measured to be sufficiently narrower as compared to that for the MLF, consistent with numerical simulation successfully demonstrating validity of the present principle.

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Experimental Consideration on Influence of Magnetic After Effect on Gap Magnetic Field and Applicability of Conventional Hysteresis Models for Particle Accelerator Electromagnets

Hane

Urata

Onchi

et al. 2022

IEEJ Transactions Elec Engng

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To further improve the control accuracy of the magnetic field generated by particle accelerator electromagnets, it is necessary to model not only the magnetic hysteresis behavior but also the magnetic after effect, which has never been studied in the previous literature. In this paper, the gap magnetic field of an accelerator magnet was measured under various excitation conditions to acquire the experimental data required for modeling. Consequently, it was clarified that the magnetic after effect may influence the magnetic hysteresis behavior. Moreover, it was accordingly indicated that a novel modeling technique is required in addition to the conventional hysteresis models developed in the electric machine field. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

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Beam commissioning and operation of the Japan Proton Accelerator Research Complex 3-GeV rapid cycling synchrotron

Cited by 26 publications

References 10 publications

Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Beam emittance control by changing injection painting area in a pulse-to-pulse mode in the 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex

Experimental Consideration on Influence of Magnetic After Effect on Gap Magnetic Field and Applicability of Conventional Hysteresis Models for Particle Accelerator Electromagnets

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