| 摘要 |
1,060,309. Ion or electron sources. SIEMENS-SCHUCKERTWERKE A.G. Nov. 20, 1963 [Nov. 20, 1962], No. 45884/63. Heading HID. An ion or electron source is based upon the principle of the duoplasmatron and comprises at least two sources arranged in cascade so that the electrons emitted by one source serve as a virtual cathode for the succeeding source, the discharge currents of the sources increasing from stage to stage with utilization of volume ionization. As shown, each stage of a twostage source is generally similar to the duoplasmatron source described in the German Specification 1,059,581. A low-pressure discharge between cathode 10 and anode '13 is fed from a 200 to 300 V source 19 through a stabilizing resistance 20. No ballast resistance is provided in the external circuit of the second and any succeeding stages, wherein the pulling voltage is adjusted to maintain a discharge with positive current-voltage characteristic without cathode drop. The intermediate electrode 16 is initially connected to anode 13 through resistance 22 to set up an intense ionization between electrodes 16 and 13, the plasma being constricted by a magnetic field, and is then made more negative through resistance 23 so that electrons are accelerated and emitted through the anode aperture to the second stage. With the exception of the last stage tne emission aperture may be larger than the plasma cross-section. The wall of the intermediate electrode aperture may be provided with a metal layer 31, thermally insulated by layer 32, and which emits electrons upon heating by ion bombardment. The source may be used in high-vacuum, electron beam, melting furnaces or for ion propulsion in space travel. |
