低溫超導多極增頻磁鐵原型真空腔之開發

本文主要描述，國家同步輻射研究中心（Synchrotron Radiation Research Center, NSRRC）低溫超導多極增頻磁鐵上橢圓狀真空腔之開發。此橢圓真空腔採無縫不銹鋼SUS304L管，經特殊之冷抽製程（Cold drawing）加工成型。在設計上並利用ANSYS軟體，分析真空結構上所承受之應力及真空變形。在本實驗中測量了腔體之表面釋氣率，並利用殘留氣體分析儀測量殘留氣體成份。此外，為了增加影像電流之電導性，此根真空腔，以磁控濺鍍方式於腔體內壁鍍金並曾安裝於NSRRC之19B1光束線，以瞭解受光激發釋氣PSD（Photon Simulated Desorption）之影響。

A prototype cryogenic vacuum chamber for the super-conducting multipole wiggler has been developed. The elliptical shape vacuum chamber is made of 304L stainless steel. It is manufactured by a special cold drawing system to form the shape of the cross section from circular to elliptical. A program of ANSYS is used to analyze the stress and the deformation of the tube, 1 mm in thickness, at a pressure difference of 1 atm and a temperature change from 4 K to 423 K. The thermal outgassing rate was measured by a throughput method. The residual gas was measured by a pressure build up method. In addition, in order to increase the electrical conductivity on the inner surface, an interior coating of gold by magnetron sputtering coating process was preformed. The photon stimulated desorption (PSD) for this chamber has been measured at a 19B1 beam line of Taiwan Light Source (TLS).