J-PARCリニアックで の 972-MHzサーキュレータ放電とその対策 DISCHARGE OF THE 972-MHz CIRCULAR AT J-PARC LINAC 二ツ川健 太 A),相澤修 一 C),奥山恒 幸 C),川村真 人 A),小林鉄 也 A),佐藤文 明 B),

In the J-PARC linac, the injection energy to the next ring was upgraded from 181MeV to 400MeV by installing Annular Coupled Structure (ACS) cavities which has the resonant frequency of 972 MHz. Therefore, the 972-MHz RF system had been developed and the twenty-five systems were installed and operated from 2013. The cavity conditioning was stated from Nov. 2013, but the discharged problem of some 972-MHz circulars happened. The source was the imperfect RF contact between the body and the metric spring with the problem of the manufacturing accuracy. Ten circulars with the discharge problem were recalled at Dec. 2013 and Jan. 2014 and the others will be improved at this summer. We would like to report the discharged problem of 972-MHz circulators. 1. はじめ