Abstract A high power electron beam machine for operating on a workpiece is disclosed in which the beam focus is automatically maintained constant without the necessity of lens current variation regardless of changes in beam current. The electron gun assembly for the machine consists of a Rogowski gun having a square ribbon filament recessed from an enlarged filament aperture, and a pin type anode with a reduced height and an increased gap from the bias electrode. The electron gun produces a stationary image or apparent source of electrons even though the beam current or the high voltage operating level of the electron gun is varied. Increased life of the ribbon filament is obtained by using a ribbon filament consisting of tungsten with 3 percent rhenium added thereto.
AN IMPROVED LONG-LIFE FILAMENT FOR A HIGH POWER ELECTRON BEAM MACHINE COMPRISING A CONTINOUS THIN RIBBON OF TUNGSTEN RHENIUM ALLOY CONTAINING ABOUT 3% RHENIUM BY WEIGHT AND FORMED TO HAVE A FLAT EMITTING FACE WITH THE PORTION OF SAID RIBBON ON OPPOSITE SIDES OF SAID EMITTING FACE BEING BENT TO FORM FIRST AND SECOND LEG PORTIONS EXTENDING FROM AND CONTINOUS WITH SAID EMITTING FACE.
Claim 2
Dependent Claim
64 words
AN IMPROVED LONG-LIFE FILAMENT FOR A HIGH POWER ELECTRON BEAM MACHINE COMPRISING A CONTINOUS THIN RIBBON OF TUNGSTEN RHENIUM ALLOY CONTAINING ABOUT 3% RHENIUM BY WEIGHT AND FORMED TO HAVE A FLAT EMITTING FACE WITH THE PORTION OF SAID RIBBON ON OPPOSITE SIDES OF SAID EMITTING FACE BEING BENT TO FORM FIRST AND SECOND LEG PORTIONS EXTENDING FROM AND CONTINOUS WITH SAID EMITTING FACE.
Claim 3
Dependent Claim
25 words
Apparatus as in claim 1 in which said first and second leg portions form an angle of between 45* and 90* with said emitting face.
Claim 4
Dependent Claim
33 words
Apparatus as in claim 1 in which the junction between each of said first and second leg portions and said flat emitting face is a bend with a maximum radius of 0.015 inch.
Claim 5
Dependent Claim
55 words
Apparatus as in claim 3 and including third and fourth leg portions continuous with and extending respectively from said first and second leg portions approximately at right angles with said flat emitting face, the junction between said first and third leg portions and the junction between said second and fourth leg portions being a bend.
Claim 6
Dependent Claim
14 words
Apparatus as in claim 1 in which said flat emitting face is substantially rectangular.
Claim 7
Dependent Claim
22 words
Apparatus as in claim 1 in which said emitting face is square with the length of the sides being approximately 0.055 inch.
Claim 8
Dependent Claim
17 words
Apparatus as in claim 1 in which said thin ribbon has a thickness of about 0.007 inch.
Claim 9
Dependent Claim
18 words
Apparatus as in claim 1 in which said thin ribbon has a constant width of about 0.055 inch.