| 摘要 |
PROBLEM TO BE SOLVED: To increase the time before replacing the main electrode, by controlling the auxiliary ionizing positions in the width wise direction of the main electrodes in the discharging space by an auxiliary ionizing means. SOLUTION: When the main discharging process is repeated in the width directional one end of main electrodes 2, 3, the width directional one end on the surfaces of the electrodes 2, 3 are worn out, thereby changing the beam shape and output of output laser beams comparing with the initial state thereof. In such a case, an X ray emitter 13 is shifted to the width directional other end of the main electrodes 2, 3 using the screw 18 of an auxiliary ionizing position controller 15. That is, the region wherein the discharging is arcked in a discharging space 6 is initially positioned on the width directional one end side of the main electrodes 2, 3 to be shifted to the other end when the surface shape of the one end is worn out, thereby extending the life time of the electrode. |
