| 摘要 |
PURPOSE:To facilitate a treatment over a wider region by scanning once by a method wherein an electron beam is deflected by a voltage which is obtained by superposing an AC wave upon a specified step-shape potential with a frequency equivalent to or lower than the frequency of the AC wave. CONSTITUTION:A deflecting voltage is applied to deflecting electrode 6 and the waveform is created by superposing a sine wave with the total amplitude of Vh and a period of Th upon a rectangular wave with a positive and negative voltage of amplitude V and period Ts. The amplitude V of the rectangular wave is 50V and the period Ts is 2musec and the total amplitude Vh of the sine wave is 100V and the period Th is 0.9musec. In other words, two different potentials are applied periodically to a pair of the static deflecting electrodes 6 and the AC wave is superposed upon those two potentials to form a quasi linear beam at respective positions. At that time, the width of the quasi linear beam can be controlled by changing the amplitude of the AC wave. With this constitution, even if the width of the zone to be heated by a point source cathode 1 is wide, the treatment can be performed without degrading uniformity in the treated zone.
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