Patent ID: 8159118

Claim:
An electron gun, comprising: a primary thermionic electron source ( 44 ), a secondary thermionic electron source ( 58 ) and a focusing electrode ( 62 ) disposed within a first housing ( 12 ) comprising a first platform ( 15 ); an accelerating anode ( 78 ) and one or more focusing coils ( 86 A, 86 B) disposed within a second housing ( 14 ), said second housing adjustably connected to said first platform by one or more insulating members ( 11 ); and one or more deflection coils ( 104 A), ( 104 B) disposed within a third housing ( 16 ), said third housing connected to said second housing and said third housing being located opposite said first housing, wherein said first housing comprises a thermionic electron source assembly comprising: a false trap holder ( 20 ) comprising a body having a circumferentially disposed lip and an aperture capable of receiving a false trap ( 18 ); an insulator ( 26 ) comprising two halves connected together to form an aperture receiving said false trap holder, said insulator ( 26 ) disposed about a filament holder ( 32 ), wherein said false trap holder is secured within said insulator by first means for adjusting ( 28 ) through one or more first channels ( 30 ) and said filament holder is secured to said insulator ( 26 ) by second means for adjusting ( 34 ) through one or more second channels ( 36 ); a clamp ( 40 ) disposed about said filament holder ( 32 ) to form a first cavity receiving said primary thermionic electron source, wherein said filament holder is secured to said clamp by third means ( 36 ) for adjusting through one or more third channels ( 48 ); a first thermal shield ( 54 ) comprising a plurality of shield plates, said shield plates having apertures, said primary thermionic electron source ( 44 ) being inserted through the apertures of the shield plates therethrough; and a second thermal shield ( 56 ) having an aperture and disposed below said first thermal shield, said primary thermionic electron source being inserted through the aperture of the second thermal shield; and wherein said false trap holder, said insulator and said filament holder combine to form a gun chamber.