| 摘要 |
PURPOSE:To eliminate any difficulty caused by the deterioration of a gas laser medium by providing a cover member for surrounding a pin electrode and covering the back surface side of a main electric discharge electrode, and exhaust means for exhausting gas contained. in a back surface side space covered with the cover member. CONSTITUTION:A cover member 20 is provided along the back surface of a main electric discharge electrode 3, which member 20 is to surround a pin electrode 8 for restricting it on the back surface side of the electrode 3. 4n exhaust pipe 21 is connected to the cover member 20 to again return into the pipe 1 a gas laser medium entering the electrode 3 from a through-hole part 7 through a dust-proof filter 22 and a reflux blower 23. More specifically, the gas laser medium is circulated in the pipe 1 by a fan 4, and any product from preionization arc discharge by an electrode 8 and any gaseous matter produced on the inner surface of an electrode surface part 7 of the through-hole part 7 are sent toward the filter 22. A very low flow rate compared with the flow rate in the pipe 1 flows through the pipe 21, and hence the filter 22 can be designed to be very fine compared with that of a filter in the pipe 1. Thus, a high speed gas flow can be maintained to permit stable output characteristics to be ensured. |
