Patent ID: 6060718
Filing Date: 2000-05-09
Classification: H01J

Abstract:
An attenuator (90) for an ion source (26), the ion source comprising a plasma chamber (76) in which a gas is ionized by an exciter (78) to create a plasma which is extractable through at least one aperture (64) in an aperture plate (50) of said chamber to form an ion beam, said attenuator (90) comprising:a member (90) positioned within said chamber (76) intermediate said exciter (78) and said at least one aperture (64), said member providing at least one first opening (97) corresponding said at least one aperture (64), said member being moveable between first and second positions with respect to said at least one aperture, wherein said member and said aperture plate form a generally closed region (102) therebetween when said member is in said first position, and wherein said aperture (64) is in direct communication with said chamber (76) when said member is in said second position, such that in said first position plasma within said chamber (76) diffuses through said region (102) and is extracted through said aperture and in said second position plasma within said chamber is extracted directly through said aperture.