| 摘要 |
PROBLEM TO BE SOLVED: To enhance cooling efficiency so as to prevent demagnetization by fitting an outer cylinder onto an inner cylinder for forming a plasma generating space, and forming a double-start thread-shaped shallow and wide grooves connected in the tip side on at least one of the outside surface of the inner cylinder and the inside surface of the outer cylinder for feeding and discharging cooling water to and from the groove. SOLUTION: A plasma chamber 50 is formed of a thin cylindrical inner cylinder 52 for forming a plasma generating space and a thin cylindrical outer cylinder 54 to be fitted onto the inner cylinder. A double-start tread-shaped wide and shallow groove 52G, cut on the outside surface of the inner cylinder 52 and connected at the tip side and a cooling water passage 56H for feeding cooling water to the groove 52G and discharging it, are formed through the use of a radially formed flange 56. The outer cylinder 54 is put on the inner cylinder 52 so as to lid the groove 52G of the inner cylinder 52, and fixed along the protruding part between the grooves 52G by electron beam welding. The flange 56 is fixed to the inner cylinder 52, so that the cooling water passage 56H of the flange is fitted to the groove 52G. |
