A turbomolecular pump, a vacuum pumping system and a method of evacuating a vacuum chamber

Abstract

A turbomolecular pump, vacuum pumping system and method of evacuating a vacuum chamber is disclosed. The turbomolecular pump comprises: a rotor comprising a plurality of rotor blade rows, a stator comprising a plurality of stator blade rows and an outer casing, the rotor being rotatably mounted within the stator; wherein at least a portion of a surface of at least one of the rotor and the stator comprise a non-evaporable getter material.

1 . A turbomolecular pump comprising:
 a rotor comprising a plurality of rotor blade rows, a stator comprising a plurality of stator blade rows and an outer casing, said rotor being rotatably mounted within said stator; wherein   at least a portion of a surface of at least one of said rotor and said stator comprises a non-evaporable getter material; said turbomolecular pump further comprising:   a pressure sensor for sensing pressure;   a heater configured to heat said at least a portion of said turbomolecular pump such that said non-evaporable getter material is heated to above its activation temperature; and   control circuitry for controlling operation of said turbomolecular pump said control circuitry being configured in response to a signal from said pressure sensor indicating a pressure to have fallen below a first predetermined value to activate said heater.   
     
     
         2 . The turbomolecular pump according to  claim 1 , wherein said control circuitry is further configured to activate rotation of a rotor of said pump in response to a signal from said pressure sensor indicating a pressure to have fallen below an initial predetermined value, said first pressure being lower than said initial pressure. 
     
     
         3 . The turbomolecular pump according to  claim 1 , wherein said control circuitry is further configured to deactivate said heater in response to one of:
 a predetermined time and a temperature sensor indicating a temperature in said turbomolecular pump being at or above a predetermined value.   
     
     
         4 . The turbomolecular pump according to  claim 1 , wherein said control circuitry is configured in response to detecting said pressure reaching a second predetermined level, to generate a rotor deactivation signal for deactivating rotation of said rotor. 
     
     
         5 . The turbomolecular pump according to  claim 1 , wherein said at least a portion comprises at least one of a subset of said rotor blade rows and an inner surface of said outer casing. 
     
     
         6 . The turbomolecular pump according to  claim 1 , further comprising an exhaust conduit for exhausting gas output from said turbomolecular pump, at least a portion of an internal surface of said exhaust conduit being coated with said non-evaporable getter material. 
     
     
         7 . The turbomolecular pump according to  claim 6 , wherein said at least a portion of said exhaust conduit is detachably mounted to said turbomolecular pump. 
     
     
         8 . A turbomolecular pump comprising:
 a rotor comprising a plurality of rotor blade rows, a stator comprising a plurality of stator blade rows and an outer casing, said rotor being rotatably mounted within said stator; wherein   at least a portion of at least one of said stator and said outer casing comprises a gas capture structure for capturing gas, said gas capture structure comprising a skeletal framework comprising a non-evaporable getter material, said skeletal framework being formed from an aerogel.   
     
     
         9 . The turbomolecular pump according to  claim 8 , wherein said at least a portion comprises a static portion of said turbomolecular pump close to an inlet of said pump. 
     
     
         10 . A vacuum pumping system comprising a turbomolecular pump according to  claim 1 , and comprising at least one further pump downstream and in series with said turbomolecular pump. 
     
     
         11 . The vacuum pumping system according to  claim 10 , wherein said at least one further pump comprises a further turbomolecular pump. 
     
     
         12 . The vacuum pumping system according to  claim 10 , wherein said at least one further pump comprises a primary pump. 
     
     
         13 . A method of evacuating a chamber comprising:
 attaching a vacuum pumping system according to  claim 12  to said chamber;   
       evacuating said chamber to a first pressure using said primary pump;
 rotating the rotor of the turbmolecular pump; 
 activating a heater to heat said turbomolecular pump to activate said non-evaporable getter material; 
 deactivating said heater. 
 
     
     
         14 . The method according to  claim 13 , comprising a further step of stopping rotation of said turbomolecular pump and continuing to provide a pumping process using capture by said non-evaporable getter material. 
     
     
         15 . The method according to  claim 13 , wherein said heating step is part of a bakeout process during which the vacuum chamber and turbomolecular pump are heated to encourage outgassing.