| 摘要 |
An annular electron gun adapted to produce a conical electron beam capable of vaporizing a source material situated at the apex of the beam. The gun comprises an annular filament, a truncated conical electrode disposed coaxially just below the beam, and an annular wire ring electrode suspended just above the beam in coaxial spaced relation with the conical electrode. The filament is maintained at a high negative potential, the electrodes at the same positive potential. Vaporized atoms of source material are ionized by the annular electrodes, and accumulate into an ion cloud within the cone of, but separated from, the electron beam.
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