Bellows with a new RF shield made of metal braid for high intensity proton accelerators

金属編組体製RFシールドを備えた大強度陽子加速器用ベローズの開発

荻原 徳男; 神谷 潤一郎   ; 菖蒲田 義博   ; 金正 倫計  ; 小泉 欧児*

Ogiwara, Norio; Kamiya, Junichiro; Shobuda, Yoshihiro; Kinsho, Michikazu; Koizumi, Oji*

In the 3 GeV-RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Accelerator Research Complex) project, large-scale hydro-formed bellows were developed to adjust the gap between the ceramic ducts and/or between the ceramic ducts and the transport ducts. They have been equipped with a newly developed RF shield, because the usual beryllium-copper spring finger contacts were found to be very hard (roughly 1000 N/mm) owing to the large size. The newly developed RF shield is made of metal braid, which consists of wires with a diameter of 0.3-0.5 mm. Because of the spring effect, the contact can change shape easily. In addition, the shield can easily connect the different cross sections in a smooth fashion. Furthermore, this structure is almost free from the dust generation, which is one of the most troublesome problems for the usual spring finger contacts.