baking method for degassing of a kicker magnet in accelerator beam line

加速器ビームラインにおけるキッカー電磁石の脱ガス方法の開発

神谷 潤一郎   ; 荻原 徳男; 柳橋 亨*; 金正 倫計  ; 安田 裕一*

Kamiya, Junichiro; Ogiwara, Norio; Yanagibashi, Toru*; Kinsho, Michikazu; Yasuda, Yuichi*

J-PARC RCSビーム出射用キッカー電磁石の脱ガスを加速器のビームライン上で、すなわちで行うため手法を開発した。その手法とはヒーターと熱輻射遮蔽板をキッカー電磁石と真空容器間に設置し、熱束の多くをキッカー電磁石へ向けることで、真空容器の熱膨張を発生させずにキッカー電磁石を昇温、脱ガスする手法である。フェライトを120C以上へ昇温すること、及び真空容器の温度上昇を30C以下へ抑えることを目標としてヒーター導入式の脱ガス手法の開発を行った。まず、原理実験を行い、本手法で真空内のキッカー電磁石を昇温できることを確認した。その後、実機への適応を見据え、ヒーターの選択、昇温試験を行い良好な結果を得た。

In this study, we propose a new degassing method by which only kicker magnets in the accelerator beam line are baked out without raising the temperature of the vacuum chamber to prevent unwanted heat expansion of the chamber. The bake-out system comprises the heater and thermal radiation shield plates, which are installed between the kicker magnet and the chamber wall. The result of the verification test showed that each part of the kicker magnet was heated to above the target temperature with a small rise in the vacuum chamber temperature. A graphite heater was selected in this application to bake-out the kicker magnet in the beam line to ensure reliability and easy maintainability of the heater. The vacuum characteristics of graphite were suitable for heater operation in the beam line. A preliminary heat-up test conducted in the accelerator beam line also showed that each part of the kicker magnet was successfully heated and that heat expansion of the chamber was negligibly small.