Low work function electron beam filament assembly

A filament assembly comprising:

• a button having a planar emitter region with one or more apertures extending from an emission surface of the planar emitter region to an internal surface opposite of the emission surface;
• an inlet electrical lead coupled to the button at a first side;
• an outlet electrical lead coupled to the button at a second side opposite of the first side;
• a low work function object positioned adjacent to the internal surface of the planar emitter region and retained to the button;
• and
• a cylindrical tantalum foil associated with the button.

A method of emitting electrons from a filament assembly, the method comprising:

• providing a filament assembly comprising:
• a button having a planar emitter region with one or more apertures extending from an emission surface of the planar emitter region to an internal surface opposite of the emission surface;
• an inlet electrical lead coupled to the button at a first side;
• an outlet electrical lead coupled to the button at a second side opposite of the first side;
• and
• a low work function object positioned adjacent to the internal surface of the planar emitter region and retained to the button;
• passing current from the inlet electrical lead through the filament assembly to the outlet electrical lead;
• heating the filament assembly until electrons are emitted from the planar emitter region of the button;
• decontaminating the button by flash heating the button to a first temperature that vaporizes one or more contaminants such that the low work function object is at a second temperature that is lower than the first temperature so that barium is not evolved therefrom;
• cooling the button to an operational temperature;
• and
• heating the low work function object to the operational temperature.