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Saha, P. K.; Harada, Hiroyuki; Hotchi, Hideaki; Takayanagi, Tomohiro
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.394 - 398, 2015/03
Yamamoto, Kazami; Hayashi, Naoki; Okabe, Kota; Harada, Hiroyuki; Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Hashimoto, Yoshinori*; Toyama, Takeshi*
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.278 - 282, 2015/03
Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Complex (J-PARC) is providing more than 300 kW of proton beam to Material and Life science Facility (MLF) and Main Ring (MR). Last summer shutdown, a new ion source was installed to increase output power to 1 MW. In order to achieve reliable operation of 1 MW, we need to reduce beam loss as well. Beam quality of such higher output power is also important for users. Therefore we developed new monitors that can measure the halo with higher accuracy. We present beam monitor systems for these purposes.
Shobuda, Yoshihiro; Toyama, Takeshi*; Chin, Y. H.*; Takata, Koji*
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.74 - 78, 2015/03
Shobuda, Yoshihiro; Saha, P. K.; Toyama, Takeshi*; Yamamoto, Masanobu; Chin, Y. H.*; Irie, Yoshiro*
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.369 - 373, 2015/03
Hotchi, Hideaki
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.6 - 11, 2015/03
The J-PARC 3-GeV Rapid Cycling Synchrotron (RCS) is the world's highest class of high-power pulsed proton driver aiming at 1-MW output beam power. In the last summer shutdown of 2013, the injection energy from the linac was upgraded from 181 MeV to the design value of 400 MeV. In addition, in this summer shutdown of 2014, the maximum peak current of the injection beam was increased from 30 mA to the design value of 50 mA. In October 2014 after completing these series of the injector linac upgrades, we have started the final stage of beam tuning toward the design output beam power of 1 MW. The most important issues in realizing such a high power 1 MW beam operation are control and minimization of beam loss. This talk will present our approaches to beam loss issues that we faced on the process of the beam power ramp-up.
Harada, Hiroyuki; Saha, P. K.; Tamura, Fumihiko; Meigo, Shinichiro; Hotchi, Hideaki
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.389 - 393, 2015/03
The 3-GeV Rapid Cycling Synchrotron (RCS) of J-PARC is designed for a high-intensity output beam power of 1MW. The RCS is extracted 2 bunches by using 8 pulsed kicker and 3 septum magnets with 25Hz repetition. The extracted beam is simultaneously delivered to the Material and Life science Facility (MLF) as well as the 50-GeV synchrotron. The kicker magnets have the ringing of flat-top field and the ringing causes the position displacement. The displacement is big issue because it directly causes an emittance growth of the extracted beam. In the beam tuning, we performed a timing scan of each kicker magnet by using a shorter pulse beam and understood the characteristics of ringing field. We then carefully optimized timing of each kicker for the ringing cancellation. The displacement was reduced to be less than 1mm as compared to that of 15mm with no ringing correction. The present correction method and experimental results will be reported.
Yoshimoto, Masahiro; Harada, Hiroyuki; Okabe, Kota; Kinsho, Michikazu
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.143 - 147, 2015/03
Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. In the beam profile, there are the beam core which is a high density area, the beam tail which is a low density area around the beam core, and the beam halo which is the area outside of the beam tail and in which few particles are straggling. Generally, the beam halo intensity is less than 1/100000 
1/1000000 of the beam core. Therefore, the dynamic range of the beam halo is required typically an order of 10
, but it is difficult to achieve this ultra wide dynamic range by any one diagnostics. Then, new beam halo monitor, which is combined a wire type beam scraper and some beam loss monitors, are developed and installed in the extraction beam transport line. Each beam loss monitor has not more than 10
order of the dynamic range. However, to use some beam loss monitors with a plurality of different sensitivity range, its ultra wide dynamic range can be achieved and beam profile including both of the beam core, beam tail, and beam halo can be obtained.
