Patent ID: 8878148
Filing Date: 2014-11-04
Classification: H01J

Abstract:
1. A method of pre-treating an ultra high vacuum electron gun chamber by ion stimulated desorption, wherein the electron gun chamber includes an electron emitter for generating an electron beam, the method comprising: generating a plasma in a plasma region containing the electron emitter by direct current discharge or by high frequency discharge of a discharge electrode to provide a plasma ion source in the plasma region in the electron gun chamber near the electron emitter; and applying a negative potential to at least one surface in the gun chamber, wherein the negative potential extracts an ion flux from the plasma ion source in the plasma region located near or around the electron emitter to the at least one surface for desorbing contamination particles from the at least one surface by the ion flux impinging on the at least one surface, wherein the electron emitter is not biased during pre-treating the vacuum electron gun chamber, and the ion flux has substantially the same origin as the electron beam generated by the electron emitter during operation.