| CPC H01J 27/22 (2013.01) [A61N 1/44 (2013.01)] | 20 Claims |

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1. An ion source comprising:
a chamber having a first end, a second end opposite the first end, a first wall extending from the first end to the second end, and a second wall opposite the first wall;
a source filament at the first end of the chamber and configured to emit electrons and a first amount of heat;
a beam aperture at the second wall of the chamber; and
one or more heaters positioned within the chamber and between the second end and the beam aperture and operable to provide a second amount of heat;
wherein the one or more heaters are positioned and operable such that the second amount of heat balances the first amount of heat to reduce or eliminate a temperature gradient in the chamber.
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