Ion pump having emission containment
View Patent ↗An ion pump having emissions containment. The ion pump includes an anode constructed from a plurality of tubes and a cathode constructed from plates positioned on opposite sides of the anode and positioned apart from the anode. The anode and cathode are positioned within a gastight housing having a gas inlet. A blocking shield assembly is provided within the line of sight between the gas inlet and the cathode. The blocking shield assembly is also provided within the line of sight between the gas inlet and any surface within the ion pump that itself is within the line of sight of the cathode. The blocking shield assembly prevents photons and neutral particles from being emitted from the ion pump.
1. An ion pump comprising:
a gastight housing defining a gas inlet, wherein the housing is configured for attachment to a vacuum chamber;
an anode comprising a plurality of electrically-bonded, open tubes within the housing;
a cathode comprising a first plate positioned on one side of the anode and spaced apart from the anode and a second plate positioned on an opposite side of the anode and spaced apart from the anode;
one or more magnets for creating a magnetic field at the anode;
a source for providing an electrical potential to the anode; and
a blocking shield assembly within the housing between the cathode and the gas inlet configured to block particles generated at the cathode from direct line-of-sight transmission through the gas inlet, wherein the blocking shield assembly is further configured to block particles from transmission through the gas inlet that are generated at or reflected from surfaces within the housing that have line-of-sight to the cathode.
2. The ion pump of claim 1 , wherein the blocking shield assembly further comprises:
a first cathode blocking shield oriented at an angled relationship with respect to the first cathode plate, wherein the first cathode blocking shield defines an angle of at least 10 degrees and not more than 80 degrees with respect to a plane parallel to the first cathode plate, wherein the first cathode blocking shield extends along one edge of the first cathode plate.
3. The ion pump of claim 2 , wherein the blocking shield assembly further comprises:
a second cathode blocking shield oriented at an angled relationship with respect to the second cathode plate, wherein the second cathode blocking shield defines an angle of at least 10 degrees and not more than 80 degrees with respect to a plane parallel to the second cathode plate, wherein the second cathode blocking shield extends along one edge of the second cathode plate.
4. The ion pump of claim 1 , wherein the blocking shield assembly further comprises:
at least one inlet blocking shield positioned immediately adjacent to the gas inlet,
wherein the inlet blocking shield is configured to block particles from transmission through the gas inlet from surfaces within the housing that have a line-of-sight path to the cathode,
wherein the inlet blocking shield does not block particles generated at the cathode from line-of-sight transmission through the gas inlet.
5. The ion pump of claim 4 , wherein the inlet blocking shield includes at least one portion that is angled at least 10 degrees and not more than 170 degrees with respect to a plane that is perpendicular to the direction of flow through the gas inlet.
6. The ion pump of claim 4 , wherein the inlet blocking shield comprises one or more portions spaced surrounding the gas inlet.
7. The ion pump of claim 1 , wherein the blocking shield assembly defines an opening allowing line-of-sight transmission from at least a portion of the gas inlet to at least a portion of the anode.
8. The ion pump of claim 1 , wherein the blocking shields are electrically grounded.
9. An ion pump comprising:
a housing containing an anode and cathode; and
a blocking shield assembly within the housing configured to block particles generated at the cathode from line-of-sight transmission out of the housing and further configured to block line-of-sight transmission out of the housing of particles generated at or reflected from surfaces within the ion pump that have a line-of-sight path to the cathode.
10. The ion pump of claim 9 , wherein the cathode comprises a first plate positioned on one side of the anode and spaced apart from the anode and a second plate positioned on an opposite side of the anode and spaced apart from the anode and wherein the blocking shield assembly further comprises:
a first cathode blocking shield oriented at an angled relationship with respect to the first cathode plate, wherein the first cathode blocking shield defines an angle of at least 10 degrees and not more than 80 degrees with respect to a plane parallel to the first cathode plate, wherein the first cathode blocking shield extends along one edge of the first cathode plate.
11. The ion pump of claim 10 , wherein the blocking shield assembly further comprises:
a second cathode blocking shield oriented at an angled relationship with respect to the second cathode plate, wherein the second cathode blocking shield defines an angle of at least 10 degrees and not more than 80 degrees with respect to a plane parallel to the second cathode plate, wherein the second cathode blocking shield extends along one edge of the second cathode plate.
12. The ion pump of claim 9 , wherein the blocking shield assembly further comprises:
at least one inlet blocking shield positioned immediately adjacent to the gas inlet,
wherein the inlet blocking shield is configured to block particles from transmission through the gas inlet from surfaces within the housing that have a line-of-sight path to the cathode,
wherein the inlet blocking shield does not block particles generated at the cathode from line-of-sight transmission through the gas inlet.
13. The ion pump of claim 12 , wherein the inlet blocking shield includes at least one portion that is angled at least 10 degrees and not more than 170 degrees with respect to a plane that is perpendicular to the direction of flow through the gas inlet.
14. The ion pump of claim 12 , wherein the inlet blocking shield comprises one or more portions spaced surrounding the gas inlet.
15. The ion pump of claim 9 , wherein the blocking shield assembly defines an opening allowing line-of-sight transmission from at least a portion of the gas inlet to at least a portion of the anode.
16. The ion pump of claim 9 , wherein the blocking shields are electrically grounded.