Ion source cathode with monolithic radiation shields

An indirectly heated cathode for an ion source, the indirectly heated cathode comprising:

• a filament defining a filament plane having an axis perpendicular thereto;
• and
• a monolithic cathode body extending from a closed end to an open end thereof along the axis, the monolithic cathode body comprising:
• a solid rod extending from the closed end toward the open end;
• a tubular portion defining a cavity extending from the open end toward the solid rod, wherein the tubular portion is continuous with the solid rod, and wherein the solid rod defines a closed end wall of the cavity, wherein the filament plane of the filament is spaced a first predetermined distance from the closed end wall;
• and
• one or more thermal shields configured to limit a transfer of thermal radiation from the filament to one or more regions external to the monolithic cathode body, wherein the one or more thermal shields comprise at least one disk disposed within the cavity, wherein the filament is disposed between the at least one disk and the closed end wall, and wherein the at least one disk is axially spaced a second predetermined distance from the filament plane of the filament, wherein the second predetermined distance is greater than the first predetermined distance.

A method for forming an indirectly heated cathode, the method comprising:

• forming a tubular member, wherein the tubular member comprises an annular sidewall defining an open end of a monolithic cathode body;
• forming at least one disk, wherein the at least one disk comprises one or more apertures defined therethrough;
• integrally coupling the at least one disk to an internal surface of the annular sidewall;
• inserting one or more filament support leads through the one or more apertures, whereby a filament is coupled to the filament support leads;
• forming a solid rod having a closed end wall;
• and
• integrally coupling the closed end wall to the tubular portion to define a cavity between within the annular sidewall, the closed end wall of the solid rod, and the open end of the tubular member, whereby the tubular member, the at least one disk, and the solid rod define the monolithic cathode body, and wherein the filament is positioned between the at least one disk and the closed end wall of the solid rod within the cavity, whereby the filament support leads extend out of the cavity from the open end of the monolithic cathode body.