Whole peripheral limiter in a plasma generator

Object: To enable measuring an image current generated by plasma and easily taking it out of linear of a vacuum container. Structure: A lower plate is mounted on the outer surface of liner, that is, on the surface close to the wall of vacuum container by means of a first bolt inserted into an insulating member made of an electric insulating material such as alumina, and a portion between the liner and the lower plate is electrically insulated by a first spacer made of alumina or the like. Into an opening made in the liner is inserted a second spacer, one end of which is in contact with the lower plate whereas the other end having a doubling plate insulated from the liner. A whole peripheral limiter is secured to the surface of the doubling plate on the interior side of the vacuum container. Therefore, by connecting a suitable lead wire to the lower plate, the image current generated in the whole peripheral limiter by the plasma may easily be taken out of the vacuum container for measurement. (Kamimura, M.)