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Journal Articles

Multi-wire profile monitor for J-PARC 3GeV RCS

Hiroki, Seiji; Hayashi, Naoki; Kawase, Masato; Noda, Fumiaki; Saha, P. K.; Sako, Hiroyuki; Takahashi, Hiroki; Ueno, Akira; Arakida, Yoshio*; Lee, S.*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1131 - 1133, 2008/06

A set of six multi-wire profile monitors (MWPMs) has been installed in the injection area of the RCS (Rapid-Cycling Synchrotron), and contributed to the initial commissioning for establishing an optimum injection orbit. The Au coated W wires (0.1 mm dia.) for the H$$^{-}$$ beam are fixed to a ceramic wind frame for two directions (horizontal and vertical with 17.7 deg. tilt, typically 51 wires with 2.9 mm or 9.5 mm distance), and the frame can be scanned for horizontal or vertical direction by using a stepping-motor driven actuator. A combination of the 17.7 deg. tilt wires and the precise scan function provides two step measurements, i.e. a rough profile is obtained only at one shot, and a detailed profile is measured for typically 101 shots (10 mm scan at 0.1 mm interval) thereafter. The beam induced charge signals are amplified, integrated and held by using a signal processing circuit. The signals are sequentially retrieved through multiplexers and digitized for obtaining a beam profile.

Journal Articles

Heating rate of highly space-charge-dominated ion beams in a storage ring

Yuri, Yosuke; Okamoto, Hiromi*

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.3080 - 3082, 2008/06

Journal Articles

Beam uniformization using multipole magnets at the JAEA AVF cyclotron

Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Okumura, Susumu; Ishibori, Ikuo; Miyawaki, Nobumasa; Kurashima, Satoshi; Yoshida, Kenichi; Kashiwagi, Hirotsugu; Agematsu, Takashi; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.3077 - 3079, 2008/06

Journal Articles

Beam instrumentations for the J-PARC RCS commissioning

Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyokawa, Ryoji; Yamamoto, Kazami; Yoshimoto, Masahiro; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; Sato, Kenichiro*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1125 - 1127, 2008/06

A 3-GeV Rapid-Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has been commissioned recently. During its beam commissioning, various beam diagnostic instrumentation has been used. The multi-wire profile monitor (MWPM) is used to establish injection and H0 dump line. The electron catcher confirms that the beam hits a charge exchange carbon foil and the specified current monitor limits the beam current to the H0 dump. Single pass BPMs and ionization profile monitors (IPM) help to check the one pass orbit without circulation of the beam. The beam position monitor (BPM) can measure both COD and turn-by-turn position. Tune monitor system consists of exciter and its own BPM. The exciter shakes the beam and coherent oscillation. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedfoward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning.

Journal Articles

The Beam position monitor system for the J-PARC RCS

Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyokawa, Ryoji*; Yamamoto, Kazami; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; Sato, Kenichiro*; Tejima, Masaki*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1128 - 1130, 2008/06

The Beam Position Monitor (BPM) system of the J-PARC RCS has been fabricated, installed and operated successfully during the beam commissioning. There are 54 BPMs around the ring and most of them are placed inside steering magnets. The BPM is electro static type and it has four electrodes. A pair of electrode gives a linear response with diagonal cut shape and they were calibrated before their installation. The signal processing unit, which is equipped with 14-bit 14MSPS ADC and 600MHz DSP, has been developed for the system. In order to measure small signal, especially during the initial phase of the commissioning, careful design also done for cabling. The paper presents the current performance of the system.

Journal Articles

Commissioning results of the kicker magnet in J-PARC RCS

Kamiya, Junichiro; Kinsho, Michikazu; Kuramochi, Masaya; Takayanagi, Tomohiro; Togashi, Tomohito; Ueno, Tomoaki; Watanabe, Masao; Yoshimoto, Masahiro

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.3590 - 3592, 2008/06

Installation of the kickers in the extraction section of the RCS in J-PARC facility was completed. And they succeeded to extract the proton beams accelerated up to 3 GeV in the first beam test. The operation parameters of the kickers agreed well with the parameters which were estimated from the magnetic field measurement and the current test of the each power supply. In this report, we summarized the results of the excitation test and the commissioning of the kicker magnet. Combining the results of the magnetic field measurements, the relation between the setup charging voltage and the integrated magnetic field was obtained for each kicker. The accelerated beam was successfully extracted at the operation parameters which were obtained from the relationship. The measurements result which was obtained by using the beam is also reported.

Journal Articles

Acceleration voltage pattern for J-PARC RCS

Yamamoto, Masanobu; Hasegawa, Katsushi; Nomura, Masahiro; Schnase, A.; Tamura, Fumihiko; Anami, Shozo*; Ezura, Eiji*; Hara, Keigo*; Omori, Chihiro*; Takagi, Akira*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.379 - 381, 2008/06

The calculation code for the acceleration voltage pattern is usually based on the differential equation of the longitudinal synchrotron motion. We have developed the code based on the forward-difference equation which satisfies the synchronization with the bending magnetic field ramping accurately. This is very useful especially at the rapid cycling synchrotron where the ramping rate is high.

Journal Articles

Radiation level in the J-PARC Rapid Cycling Synchrotron after first study

Yamamoto, Kazami; Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyama, Takeshi*; Teshima, Masaki*; Sato, Kenichiro*

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.382 - 384, 2008/06

Journal Articles

Results of vertical tests for the KEK-ERL single cell superconducting cavities

Umemori, Kensei*; Furuya, Takaaki*; Takahashi, Takeshi*; Sakai, Hiroshi*; Shinoe, Kenji*; Sawamura, Masaru

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.925 - 927, 2008/06

We have been developing L-band superconducting cavities for energy recovery linacs. In order to verify our design, we have fabricated two types of single cell cavities. One is a rather simple center-cell type cavity and another is an end-cell type single cell cavity which has complicated structures. After applying a series of surface treatment procedures, cavity performances were evaluated by way of vertical tests at 2K. A rotating mapping system with temperature and X-ray sensors were mounted on the cavities to make a diagnosis of the cavity behaviours. Results of vertical tests are described below. Both cavities satisfied the requirements against ERL cavities.

Journal Articles

Grounding and induced voltage issues of the injection bump magnet system of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Ueno, Tomoaki; Kinsho, Michikazu; Yoshimoto, Masahiro; Kamiya, Junichiro; Watanabe, Masao; Irie, Yoshiro*

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1461 - 1463, 2008/06

IGBT choppers with multiple-connection are applied as the switching power supply for large current and high precision pulse current. However, when the number of switching device increases, the damage with noise of the high frequency is given to the system. In that case, the problem is improved by reinforcing the ground-line system. Furthermore, the induced voltage of the RF shield that is dependent on the magnetic field and the current pattern has been confirmed.

Journal Articles

Beam acceleration with full-digital LLRF control system in the J-PARC RCS

Tamura, Fumihiko; Schnase, A.; Nomura, Masahiro; Yamamoto, Masanobu; Hasegawa, Katsushi; Haga, Koichi; Yoshii, Masahito*; Omori, Chihiro*; Toda, Makoto*; Hara, Keigo*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.364 - 366, 2008/06

In the J-PARC RCS (Rapid Cycling Synchrotron) we employ a full-digital LLRF control system to accelerate an ultra-high intensity proton beam. The key feature is the multi-harmonic RF signal generation by using direct digital synthesis (DDS) technology. By employing a full-digital system, highly accurate, stable and reproductive RF voltages are generated in the wide-band RF cavities loaded by magneticalloy (MA) cores. The beam commissioning of the J-PARC RCS has been started in October 2007. The accelerators, the linac and the RCS, show good stability. The beam orbit and the longitudinal beam shape and phase are reproductive from cycle to cycle especially thanks to the stability of the linac energy, the RCS bending field and the frequency and voltage of the RCS RF. This reproductivity makes the beam commissioning efficient. We present the examples of the orbit signals and the longitudinal currentsignals. Also, we discuss the longitudinal beam control performance and future plans.

Journal Articles

Cavity diagnostics using rotating mapping system for L-band ERL superconducting cavity

Sakai, Hiroshi*; Shinoe, Kenji*; Furuya, Takaaki*; Takahashi, Takeshi*; Umemori, Kensei*; Sawamura, Masaru

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.907 - 909, 2008/06

We are developing the superconducting (SC) cavity for Energy Recovery Linac (ERL) in Japan. In order to survey the electron emission and the heating spot of the cavity inner surface in detail, cavity diagnostics with the rotating mapping system was applied. Two types of sensors, one of which is the carbon resistor and the other is the Si PIN photo diode, were set to detect the temperature rise and electron emission. By rotating the sensor arrays around the cavity axis, a lot of information is obtained all over the cavity surface in detail. This paper reports the results of vertical tests by using this rotating mapping system with Nb single cell ERL-shape cavities.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06

Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.

Journal Articles

J-PARC RCS non-linear frequency sweep analysis

Schnase, A.; Anami, Shozo*; Ezura, Eiji*; Haga, Kaiichi*; Hara, Keigo*; Hasegawa, Katsushi; Nomura, Masahiro; Omori, Chihiro*; Takagi, Akira*; Tamura, Fumihiko; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.346 - 348, 2008/06

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