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倉島 俊; 田口 光正; 石堀 郁夫; 奈良 孝幸; 横田 渉
Proceedings of 19th International Conference on Cyclotrons and their Applications (CYCLOTRONS 2010), p.247 - 249, 2011/12
The intervals of beam pulses from a cyclotron are generally tens of ns and they are too short for pulse radiolysis experiments which require beam pulses at intervals ranging from 1 s to 1 ms (single-pulse beam). A chopping system, consisting of two types of high voltage kickers, is used at the JAEA AVF cyclotron to form single-pulse beam. The first kicker installed in the injection line generates beam pulses with repetition period of 1 s to 1 ms. The pulse width is about a cycle length of the acceleration frequency. The other kicker in the transport line thins out needless beam pulses caused by multi-turn extraction. We could not provide single-pulse beam stably over 30 min since the magnetic field of the cyclotron gradually decreased by 0.01% and the number of multi-turn extraction increased. The magnetic field was stabilized within 0.001% by keeping temperature of the cyclotron magnet constant. In addition, a new technique to measure and control an acceleration phase has enabled us to reduce the number of multi-turn extraction easier than before. We have succeeded to provide single-pulse beam of a 320 MeV C without retuning of the cyclotron over 4 h, as a result.
湯山 貴裕; 百合 庸介; 石坂 知久; 倉島 俊; 石堀 郁夫; 奥村 進; 吉田 健一; 宮脇 信正; 柏木 啓次; 奈良 孝幸; et al.
Proceedings of 19th International Conference on Cyclotrons and their Applications (CYCLOTRONS 2010), p.90 - 92, 2011/12
The JAEA AVF cyclotron provides various ion beams mainly for research in materials science and biotechnology such as estimation of radiation hardness of space-use devices and plant breeding by ion beams. The cyclotron is operated day and night usually from Monday morning to Friday evening, and the yearly operation time amounted to 3148.3 hours. The number of switchover of ion species, energy and beam course was 547 times. For higher stabilization of ion beam, we have improved the power supplies of the magnet coils by using the new feedback circuits with Peltier device to keep temperature of the circuit at 27 1 C. In addition, a high stability ECR ion source of an all-permanent-magnet type, techniques of quick change of ion species or energy of microbeam by cocktail beam acceleration and large-area uniform beam formation using multipole magnets are being developed.