| 摘要 |
<p>An electric-discharge tube includes a cathode whose distal end is fixed to a lead rod and an anode opposed to the distal end of the cathode, and an arc discharge occurs between them in a gas-filled enclosure. The distal end of the cathode includes a metal base, comprising either refractory porous metal impregnated with electron-emitting material or refractory metal impregnated with electron-emitting material and then sintered; and a refractory metal coating that covers predetermined surface portions of the metal base to a thickness between 0.02 and 5 microns. The distal end of the metal base is exposed or uncovered and tapered toward the anode.</p> |
