TURBO-MOLECULAR PUMP

PURPOSE:To maintain a clean vacuum by constituting so that a magnetic field is applied to an air passage formed by a rotor and a stator and capturing gases scattered from the lubricating oil after ionizing them by a spatter ion pump effect in the air passage under the magnetic field. CONSTITUTION:A projection body 8 fixed to the upper end of a stationary casing 3 is inserted into a recess 1a section of a rotor 1 so as to maintain a gap from the rotor 1. A magnet 9 made of ferrite, etc. is fixed to the outer periphery of the projection body 8, and a magnet 10 is also fixed to the inner periphery of the stationary casing 3 facing the magnet 9, then both of them are magnetized in opposite directions. Therefore, a magnetic field is applied to the passage formed by rotary blades 2 and stationary blades 4, and electrons introduced into the passage under the magnetic field are captured in the passage after gases scattered from the lubricating oil, for instance, are ionized by a spatter ion pump effect. Thereby, pollution of high vacuum side due to the lubricating oil can be prevented and a clean vacuum can be maintained.