摘要 |
The present invention provides a highly reliable charged beam gun designed in consideration for environmental protection, which prevents faulty insulation in a high-voltage connection. An insulating liquid is present in a gap formed between a connecting bushing and a receiving-side flange placed in a vacuum container, and the connecting bushing includes first piping and valve that provide communication between the gap and atmospheric air, and second piping and valve that provide communication between the gap and the atmospheric air, whereby the gap is cut off from the atmospheric air.
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