X-ray cathode focusing element

A cathode for an X-ray imaging system, comprising:

• a base assembly;
• a plurality of focusing features on a focusing element;
• a weld coupling;
• wherein the focusing element is coupled to the base assembly by the weld coupling,
• wherein the base assembly is comprised of a lower extender brazed to a first face of an insulator using a filler metal, and an upper extender brazed to a second, opposite face of the insulator using the filler metal, and
• wherein the lower extender has a stepped architecture, and wherein a second level of the stepped architecture extends vertically from a portion of a first level of the stepped architecture such that a height of the second level is at least partially circumferentially surrounded by the insulator;
• a first lateral gap between a second level and the insulator having a first width around a circumference of the second level;
• and
• a second lateral gap between the second level and the upper extender with a second width equal to the first width of the first lateral gap.

A method for manufacturing a cathode, comprising:

• fabricating a base assembly, including:
• brazing a first face of an upper extender to a first face of an insulator using filler metal;
• brazing a lower extender to a second face of the insulator, opposite the first face of the insulator, using filler metal;
• machining weld features on each of a first edge, a second edge, a third edge, and a fourth edge of a second face of the upper extender, opposite the first face of the upper extender, with a curved space between each of the weld features, using electrical discharge machining;
• and
• machining datums on the base assembly;
• cleaning the base assembly by grit blasting the base assembly;
• machining a focusing element with a plurality of focusing features and at least one channel;
• electro-polishing the focusing element;
• positioning a thermionic filament in each of the at least one channel;
• welding a first face of the focusing element to the second face of the upper extender at each of the weld features along the first edge, the second edge, the third edge, and the fourth edge;
• and
• halting welding at each of a first curved space between the first edge and the second edge, a second curved space between the second edge and the third edge, a third curved space between the third edge and the fourth edge, and a fourth curved space between the fourth edge and the first edge.