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Nakamura, Yoshiteru; Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Tamura, Hiroyuki; Kurashima, Satoshi; Yokota, Wataru; Okumura, Susumu; Fukuda, Mitsuhiro; Arakawa, Kazuo
AIP Conference Proceedings 600, p.129 - 132, 2001/00
The AVF cyclotron system at JAERI Takasaki has been smoothly operated without serious troubles since the first beam extraction of 50 MeV 4He2+ in March 1991. A yearly operation time is about 3200 hours on an average for past several years. In last three years, we performed some improvements and developments as followings: stabilization of the cyclotron beam, renewal of the control computers and basic programs, installation of a new ECR ion source and reconstruction of the rotary shutter. Furthermore, cocktail beams of series M/Q=4 and M/Q=2 have been developed continuously. Now we are modifying the RF cavity for the flat-top acceleration by the addition of 5th harmonic frequency.
Kurashima, Satoshi; Fukuda, Mitsuhiro; Nakamura, Yoshiteru; Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Tamura, Hiroyuki; Yokota, Wataru; Okumura, Susumu; Arakawa, Kazuo; et al.
AIP Conference Proceedings 600, p.303 - 305, 2001/00
A flat-top acceleration system for the JAERI AVF cyclotron has been designed. The fifth harmonic of the fundamental frequency is used to obtain uniform energy gain. To determine optimum parameters of the flat-top system, a cold model test was carried out and flat-top waveforms of the voltages were observed successfully in the whole range of the fundamental frequency. An rf power required for generating a flat-top dee voltage of 30 kV was estimated to be about 1 kW. The design of the flat-top cavity is being modified using the MAFIA code.
Okumura, Susumu; Arakawa, Kazuo; Fukuda, Mitsuhiro; Nakamura, Yoshiteru; Yokota, Wataru; Ishimoto, Takayuki*; Kurashima, Satoshi; Ishibori, Ikuo; Nara, Takayuki; Agematsu, Takashi; et al.
AIP Conference Proceedings 600, p.330 - 332, 2001/00
Frequent corrections of the magnetic field of the JAERI AVF cyclotron were required for keeping a beam current constant during long time operation. We observed correlation between the magnetic field and the temperature of the cyclotron magnet yoke by measuring the magnetic field with an NMR probe and the temperature with platinum resistance thermometers. The unstable phenomenon of a cyclotron beam was induced by temperature change in the magnet yoke caused mainly by thermal conduction from the main coil. To restrain the thermal conduction to the yoke, we have inserted temperature controlled copper plates between the yoke and the main coil. In addition, a temperature control system of the cooling water of the trim coils has been installed independent of the total cooling system for controlling the pole tip temperature. An optimum condition of the temperature control systems for stabilizing the magnetic field has been investigated.
Fukuda, Mitsuhiro; Arakawa, Kazuo; Yokota, Wataru; Okumura, Susumu; Agematsu, Takashi; Kamiya, Tomihiro; Mizuhashi, Kiyoshi; Nara, Takayuki; Saito, Yuichi; Ishii, Yasuyuki; et al.
AIP Conference Proceedings 600, p.189 - 191, 2001/00
A new project aiming for a breakthrough in biotechnology and materials science has been proposed at TIARA(Takasaki Ion Accelerators for Advanced Radiation Application) facilities of JAERI. Heavy ion beams with an energy of more than a hundred MeV/n will contribute to remarkable progress in breeding of plants and development of new materials. We have started designing a new superconducting AVF cyclotron with a bending limit of 900 and a focusing limit of 300. The cyclotron magnet is being designed to cope with acceleration of both the heavy ions and 300 MeV protons.
