| 摘要 |
PURPOSE:To remove effectively contamination on an electron beam path by providing discharge electrodes in parallel to the inside wall of a conductive pipe member, introducing a clean gas to an inside space, and discharging the contamination through application of a high voltage on the discharge electrodes. CONSTITUTION:Discharge electrodes 22, 22' are provided in the vicinity of the electron beam path wall of an electron lens 7, i.e. the inside wall of a pipe 15, and the electron beam path wall of an electron lens 7', i.e. the inside wall of a protecting pipe 20. The electrodes 22, 22' are electrically insulated from the body by electrode supports 23, 23', and connected to a high voltage source 26 to be supplied with a high voltage through hermetic seals 24, 24' passing through the equipment wall and a switch 25. A leak valve 27 to introduce a clean gas to the inside of the equipment and a needle valve 27 to control the quantity of leak are provided. Thus the pass of the electron beam can be cleaned easily without need for high skill. |
