| 摘要 |
PURPOSE:To enable a life of an electrode to be extended by relaxing concentration of electric field to a tip portion of the electrode and prevent crack of a ceramic tube which is generated at the tip portion of the electrode. CONSTITUTION:A groove 10 is provided on an inner surface of a ceramic tube 2 and a tip portion of an electrode 1 is not in contact with an inner surface of the ceramic tube 2. A life of an electrode can be extended, a crack of the ceramic tube can be prevented, and reduction in laser output due to contamination of a window can be prevented. |
