| 摘要 |
PURPOSE:To prevent arc discharge caused in a vacuum by highfrequency waves as well as to prevent increase in temperature due to induction heating by magnetic fields, by providing a copper cap covering the end of a ceramic member of a shield section in a vacuum chamber, and feeding coil cooling water through hollow parts of the shield section and of a core arranged coaxially therewith. CONSTITUTION:Coil cooling water is fed through a hollow copper pipe 8 disposed within a ceramic tube 3 and exhausted from an external copper pipe 9. Electric current is supplied through the copper pipe 8 and finally grounded from the copper pipe 9. A copper cap 1 prevents arc discharge which would otherwise be often caused at the ends of the ceramic tube 2 and copper pipe 9 within a vacuum chamber. Further, by using such coaxial cable, two magnetic fields created by the coaxial circles are oriented to the directions opposite to each other and they are cancelled each other. Thus, production of current is also prevented. In this manner, it is possible to prevent increase in temperature caused by induction heating by magnetic fields created at the chamber wall from which power is introduced into the chamber, without producing arc discharge in vacuum by high-frequency waves. Further, a high-frequency coil disposed within vacuum can be supplied with electric power as well as cooling water.
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