Patent ID: 8664853
Filing Date: 2014-03-04
Classification: H01J

Abstract:
1. A photoelectric cathode having: a heater element; a work function lowering material thermally coupled to said heater element; a low diffusion layer formed by a material having a plurality of passageways which reduce the diffusion rate of said work function lowering material; a uniform porosity layer providing a greater diffusion rate than said low diffusion layer and also providing a plurality of apertures which are uniformly separated in space; said uniform porosity layer having an outward facing photoelectric interaction surface; an enclosure surrounding said work function lowering material, said low diffusion layer, and said uniform porosity layer, said low diffusion layer and said uniform porosity layer separated by a free space layer; whereby said heater element causes said work function lowering material to pass through said low diffusion layer and into said free space layer, thereafter through said uniform porosity layer to said photoelectric interaction surface.