ANALYZER USING CHARGED PARTICLE

PURPOSE:To make it possible to maintain the inside of a sample chamber in a clean vacuum condition by providing a purge gas supply means for supplying a small amount of purge gas during the process of exhausting the inside of the sample chamber to a pressure to be attained on the upstream side of an oil rotary pump. CONSTITUTION:A purge gas supply means 40 is provided at the part of a suction pipe 32 located between a suction port of an oil rotary pump 30 and a leak valve 38. During the process of exhausting a sample introduction chamber 10 of an analyzer using charged particles to a pressure attainable by means of the oil rotary pump 30, a minimum amount of purge gas necessary and enough for suppressing a reverse flow of oil used in the oil rotary pump to the suction port side is blown by means of the purge gas supply means 40. The amount of the purge gas at this time is about one tenth of the conventional process. As a result, almost no influence is exerted on the attainable pressure in the vacuum line, clean vacuum is obtained, and the oil is prevented from being contaminated with the line to be exhausted.