| 摘要 |
PURPOSE:To heighten the degree of vacuum attainable by a molecular turbopump, by providing an attraction-type magnetic bearing comprising permanent magnets made of a rare-earth-element material, at the high vacuum side of the rotor of the pump. CONSTITUTION:A rotor 6 with moving vanes 5 is supported by a permanent magnet unit 9 comprising an annular permanent magnet 9A provided on the rotor 6 in an annular space S and another annular permanent magnet 9B located in the annular space and facing the former magnet. These permanent magnets 9A, 9B are made of a rare-earth-element material of high Curie point, whose magnetic characteristics do not deteriorate in a process of baking at 300 deg.C. Therefore, the baking can be effected at a high temperature to heighten the attainable degree of vacuum. |
