Multi-ampere duopigatron ion source

Claim 1

A high current duopigatron ion source comprising a heated filament cathode; an intermediate electrode provided with an apertured, tapered lower end portion, said intermediate electrode enclosing said filament cathode and adapted to receive a feed gas thereinto; a source coil encompassing the upper portion of said intermediate electrode; a source magnet supply connected to said coil; a copper anode insulatingly spaced from said intermediate electrode, said anode being provided with a centrally disposed aperture and a hollow elongated tail portion contingent with said aperture and extending longitudinally away from said intermediate electrode; a target cathode assembly defining an elongated ion beam drift space and including a first, centrally apertured electrode insulatingly spaced from said anode and encompassing a portion of said anode tail portion, a first tubular elongated member affixed to said first electrode, an annular auxiliary, field shaping coil affixed to said first member, a second tubular member affixed to said auxiliary coil, a third tubular member affixed to said second tubular member, a cylindrical target cathode support member affixed to said third tubular member, a fourth elongated tubular member affixed to said cathode support member and to the housing of said ion source, and a multiapertured target cathode supported by said cathode support member; means for cooling said intermediate electrode, anode, and first electrode, a source of arc supply connected between said filament cathode and said anode; a multi-apertured acceleration electrode mounted beyond and closely spaced from said apertured target cathode; a source of negative acceleration voltage connected to said acceleration electrode; a source of high voltage connected to said target cathode; means for cooling said acceleration electrode; a multi-apertured deceleration electrode connected to ground and mounted beyond and in close proximity to said apertured acceleration electrode; and means for cooling said deceleration electrode, said anode and target cathode assembly providing a long mean free path for the electrons produced by the ion source discharge with the combined effect of shaping the electric and magnetic fields to produce a large uniform density plasma surface at the surface of said apertured target cathode thereby permitting the extraction of a high density and high temperature ion beam through said apertured electrodes.