Title: Point Cathode Electron Gun Using Electron Bombardment for Cathode Tip Heating
Abstract: A new type of point cathode electron gun has been developed. In this gun, a straightened thin tungsten wire is used as the cathode and only the tip part is locally heated by a bombarding electron beam (5 keV, ≦1 mA) from a heater assembly set inside the Wehnelt electrode. Experiments showed that (1) the temperature of the cathode tip is raised to 3,100 K at a bombarding power of 3 W and to the melting point (3,650 K) at 5 W, (2) although secondary and backscattered electrons are produced by the electron bombardment and mixed with the thermally emitted electrons, the amount could be suppressed to a practically negligible level, (3) the gun gives a stable operation at a brightness as high as 6.4 × 106 A/cm2sr at an accelerating voltage of 50 kV, and (4) the local heating greatly improves the cathode life and attains the continuous operation at least over 1 hour at the above brightness level. Design features and experimental results are described.
Publication Year: 1988
Publication Date: 1988-02-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 4
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