油拡散ポンプ

(oil) diffusion pump

[目次：真空系]

油を高温に加熱し、油蒸気をノズルから高速で吹き出させ、その噴流の勢いにのせて気体分子を輸送するポンプ。ポンプのバック側は油回転ポンプなどで引かれる。機構が簡単で安価。10^-1Paの真空度から使用でき、しかも排気速度が大きいので、透過電子顕微鏡では排気容積が大きく放出ガスが多いカメラ室の排気に用いられる。使用圧力範囲は10^-1～10^-8Pa。オイルフリーの高度な真空を要求する場合には使用できない。水の排気は不得意。

The (oil) diffusion pump heats the oil to a high temperature. The oil vapor is sprayed out at a high speed from the nozzle. The residual gas molecules are carried with the aid of the jet flow of the vapor. The back side of the pump is evacuated with a rotary pump. The pump mechanism is simple and its price is low. Since the diffusion pump operates from 10^-1 Pa and its evacuation speed is high, the pump is used for evacuation of the TEM camera chamber with a large evacuation volume and large gas emission. The working pressure is from 10^-1 to 10^-8 Pa. When oil-free, high vacuum is required, the pump cannot be used. The pump is not suitable for pumping H₂O.