| 摘要 |
<p>PURPOSE:To stably generate an electron beam with high current density by forming three edges or more on the anode opposed surface of a cathode and arranging the intersection of these edges in matching condition with an anode small opening. CONSTITUTION:Three edges 14 or more are formed on a surface, opposed to the anode 21, of a cathode 13 and the intersection 15 of these edges and the small opening 22 of the anode are installed on the same axis. Since the cathode with a number of edges is used, even if the intersection of these edges is slightly deviated from the small opening of the anode, a stable operation is obtained without generating a great change in the quantity of current that can pass through the small opening.</p> |
