| 摘要 |
A turbo molecular pump comprises a pump body having a vacuum chamber, a gas inlet port and a gas outlet port. A rotor shaft is mounted in the pump body for undergoing rotation. A rotor vane section is disposed in the vacuum chamber and has rotor vanes connected to the rotor shaft for rotation therewith. A stator vane section is disposed in the vacuum chamber and has stator vanes interleaved with the rotor vanes in spaced-apart relation. A distance between at least one of the rotor vanes and an adjacent one of the stator vanes is set to a value in accordance with a mean free path of molecules contained in a gas flowing between the rotor vanes and the stator vanes such that a pressure of the vacuum chamber is not less than 10 mTorr during a normal operation of the turbo molecular pump. Alternatively, the distance between at least one of the rotor vanes and an adjacent one of the stator vanes is set to a value in accordance with a mean free path of molecules contained in a gas flowing between the rotor vanes and the stator vanes such that a discharge throughput of the turbo molecular pump during a normal operation thereof is not less than 1000 SCCM.
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