Development of a turbo-molecular pump with a magnetic shield function

磁気シールド機能付ターボ分子ポンプの開発

荻原 徳男; 柳橋 亨; 引地 裕輔; 西川 雅章; 神谷 潤一郎   ; 和田 薫*

Ogiwara, Norio; Yanagibashi, Toru; Hikichi, Yusuke; Nishikawa, Masaaki; Kamiya, Junichiro; Wada, Kaoru*

In order to safely use turbo-molecular pumps (TMPs) in a magnetic field, it is necessary to reduce the eddy current induced on the rotating rotor. Usually, a magnetic shield facility is added to a normal TMP available in the market. In this study, we have developed a TMP with a magnetic shield function by replacing the housing materials with a ferromagnetic substrate, SUS430. Before and after machining, SUS430 was vacuum-fired at 700C for 10 h in order to have good vacuum quality and to recover high magnetic permeability. The magnetic shield efficiency of a housing made of SUS430 was examined. When the vertical magnetic field of 0.009 T was applied, the field inside of the TMP was reduced to less than 0.0003 T. We then confirmed that the developed TMP shows a good performance in achieving an ultrahigh vacuum in magnetic fields of up to 0.009 T.