Patent ID: 6777686
Filing Date: 2004-08-17
Classification: H01J

Abstract:
An indirectly heated cathode ion source comprising:an arc chamber housing defining an arc chamber having an extraction aperture; an extraction electrode positioned outside of the arc chamber in front of the extraction aperture; an indirectly heated cathode positioned within the arc chamber; a filament for heating the cathode; a filament power supply for providing current for heating the filament; a bias power supply coupled between the filament and the cathode; an arc power supply coupled between the cathode and the arc chamber housing; an extraction power supply, coupled between the arc chamber housing and the extraction electrode, for extracting from the arc chamber an ion beam having a beam current; and an ion source controller for controlling the beam current extracted from the arc chamber at or near a reference extraction current, said ion source controller comprises a feedback controller for controlling a bias current supplied by said bias power supply or a filament current supplied by said filament power supply in response to an error value based on the difference between a sensed beam curren and the reference extraction current.