Turbomolecular pump

A turbomolecular pump for evacuating a space, the turbomolecular pump comprising:

• a casing;
• a rotor in said casing extending axially thereof;
• a stator in said casing located in face-to-face relation to said rotor;
• a plurality of rotor grooves on an outer peripheral surface of said rotor, extending equidistantly in a spaced-apart relation to each other and tilting at a predetermined angle with respect to the axis of the rotor;
• a plurality of stator grooves on a surface of said stator facing the rotor which extend equidistantly in a spaced-apart relationship to each other and tilt at the same angle as said rotor grooves but are oriented in an opposite direction to the rotor grooves, said rotor grooves and stator grooves are located alternately axially of the rotor, and said rotor grooves and stator grooves overlap in part as viewed axially of the rotor;
• and
• wherein a channel for a molecular flow constituted by each of said rotor groove and stator groove has a cross-sectional area thereof reduced successively in going axially of the rotor toward the discharge side.

A turbomolecular pump for evacuating a space, the turbomolecular pump comprising:

• a casing;
• a rotor in said casing extending axially thereof;
• a stator in said casing located in face-to-face relation to said rotor;
• a plurality of rotor grooves on an outer peripheral surface of said rotor, extending equidistantly in a spaced-apart relation to each other and tilting at a predetermined angle with respect to the axis of the rotor;
• a plurality of stator grooves on a surface of said stator facing the rotor which extend equidistantly in a spaced-apart relationship to each other and tilt at the same angle as said rotor grooves but are oriented in an opposite direction to the rotor grooves, said rotor grooves and stator groove overlapping in part as viewed axially of the rotor;
• an axial flow turbine group comprising a plurality of rotor blades and a plurality of stator blades located alternately, said axial flow turbine group being located on a suction side of the group of turbine grooves comprising rotor grooves on the rotor, and stator grooves on the stator extending annularly in face-to-face relation to the rotor.