| 摘要 |
PURPOSE:To eliminate the labor hour for manufacturing a discharge tube by a method wherein the minimum magnetic field is formed in the vicinity of the anode part of the discharge tube to control the noise of the discharge tube. CONSTITUTION:Magnet rows, which respectively consist of 3 pieces of rectangular parallelepiped ferrite magnets M arranging their magnetic poles in the same direction, are formed on the outer peripheral part of a discharge tube T and 4 pieces of these magnet rows are arranged in such a way that the polarities of the magnetic poles opposing to each other become the same one, that is, a fellow S or a fellow N and the polarities of the magnetic poles of the adjacent magnet rows are made to differ from each other to form 4 poles. The magnetic field which is formed by such the magnet groups is 0 in the central axis and the absolute value is increased as the magnetic field heads for the radial direction and the configuration of the minimum magnetic field is formed. Accordingly, the fluctuations of an electron density, an electron temperature and an energy distribution, which are a plasma parameter, are suppressed in the vicinity of an anode A and the noise of the discharge tube is inhibited. Thereby, an existing discharge tube can be used and the labor hour for manufacturing a new discharge tube can be omitted. |
