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    • 1. 发明授权
    • Devices for ionizing residual gases in vacuum systems
    • 真空系统中残留气体的离子化装置
    • US3796917A
    • 1974-03-12
    • US3796917D
    • 1972-08-21
    • NAT ELECTROSTATICS CORP
    • HILLER D
    • H01J41/06H01J41/16H01J19/70H01J41/00
    • H01J41/16H01J41/06
    • The disclosed ionizers are of the orbitron type utilizing a high voltage anode in the form of a wire or rod extending axially within an outer generally cylindrical electrode which may be in the form of a cylindrical conductive screen connected to the negative terminal of the power supply. One or more of the ionizers are mounted within a vacuum space containing residual gas molecules to be ionized. The resulting ions may be propelled by electrostatic field forces to the cylindrical screen and also to the walls of the vacuum chamber where the ions may be absorbed or gettered by freshly deposited titanium or some other gettering material. By this mechanism of ion getter pumping, gas molecules are effectively removed from the vacuum space so as to improve the vacuum. In accordance with the present invention, electrons are injected into the space between the axial anode and the outer cylindrical electrode by an electron-emitting electrode which is typically in the form of a generally circular loop or ring encircling the axial anode and spaced inwardly from the cylindrical outer electrode in the radial electric field beween the inner and outer electrodes. The electron-emitting electrode is preferably energized with a direct current which causes heating of the electron-emitting electrode so that electrons are emitted thermionically therefrom. The current also produces an axial magnetic field in the space between the electron-emitting electrode and the anode. The combination of the radial electric field and the axial magnetic field causes a high percentage of the emitted electrons to go into orbits around the anode so that the electrons have extremely long mean-free paths before finally being attracted to the anode. In this way, the orbiting electrons produce a high degree of ionization of the residual gas molecules in the vacuum space. The axial magnetic field may be enhanced by an electromagnet or a permanent magnet disposed near the circular electron-emitting electrode and preferably aligned axially therewith. The electromagnet may take the form of a loop having one or more turns disposed near the electron-emitting electrode or a coil having a multiplicity of turns and preferably having a core of magnetic material. The permanent magnet may be generally cylindrical in shape and disposed axially. The ionizer may also be used to provide an ion gage in which the ion current to the cylindrical electrode is measured.