摘要
By using the physical characteristic of the titanium when it is subliming, fourteen titanium balls are fixed in the vacuum chamber to improve the background of the wall of the vacuum chamber of HL-2A. When the filaments of the balls have 40- 50 A current,temperatures of the balls is up to 1200 centigrade and the balls begin to sublime. Therefore in order to get better parameters of plasma, we fabricate fourteen power supplies to heat the balls.