| 摘要 |
<p>An electron gun with a flat cathode has a hole for electron passage in the first anode which is greater than that in the modulator electrode whose thickness is smaller in the hole area. The area of reduced thickness is produced by a cup-shaped recess in the modulator electrode surface facing the cathode. The diameter of this recess if greater than that of the cathode emission surface placed inside the recess. The reduced modulator electrode thickness is between 0.01 and 0.2 mm, preferably 0.02 and 0.12 mm, or more particularly 0.03 and 0.08 mm.</p> |
