Self-focusing electron beam apparatus

Claim 1

AN ELECTRON BEAM GENERATING APPARATUS COMPRISING: A HOUSING, MEANS FOR DEFINING A PLURALITY OF ELECTRODES WITHIN SAID HOUSING, AND A HOLLOW CATHODE STRUCTURE HAVING A SURFACE CHARACTERIZED BY A NUMBER OF SMALL OPENINGS THERETHROUGH, SAID CATHODE DISPOSED WITHIN A FIRST OF SAID ENCLOSURES, MEANS FOR INTRODUCING A LOW PRESSURE IONIZABLE GASEOUS MEDIUM WITHIN SAID FIRST ENCLOSURE, MEASNS FOR OPERATING SAID CATHODE AT A HIGH NEGATIVE POTENTIAL RELATIVE TO THE HOUSING SUFFICIENT TO PRODUCE A PLASMA WITHIN SAID CATHODE, SAID CATHODE AND SAID ENCLOSURE DEFINING MEANS EACH HAVING AN APERTURE, THE APERTURES ALIGNED WITH RESPECT TO EACH OTHER WHEREBY AN ELECTRON BEAM ISSUING FROM THE PLASMA PASSES THROUGH SAID APERTURES INTO ANOTHER OF SAID ENCLOSURES, SAID OTHER ENCLOSURE ADAPTED TO UTILIZE SAID BEAM WHICH UTILIZATION MAY GENERATE AN UNDESIRED GASEOUS MEDIUM, THE APERTURE IN SAID ENCLOSURE DEFINING MEANS BEING OF SIZE SUFFICIENT FOR PASSAGE OF THE ELECTRON BEAM AND INSUFFICIENT FOR PASSAGE OF OBJECTIONABLE AMOUNTS OF THE UNDESIRED GASEOUS MEDIUM INTO SAID FIRST ENCLOSURE.