| 摘要 |
<p>PURPOSE:To obtain a directly heated cathode structure excellent in both heat economy and vibration-proof property, by mounting heating units, which are formed by alternate lamination of conductive materials and insulating materials, on the back of a cathode disc emitting electrons from its top and electrifying these heating units to heat the disc to a desirable temperature. CONSTITUTION:A cathode disc 1 emitting electrons from its top is formed from an impregnated-type disc with BaO/CaO/Al2O3 whose mol ratio is 5/3/2, and its dimensions shall be about 5mm in diameter and about 2mm in thickness. while the central part of the back of the disc 1 is covered with a shielding material which is to be removed later, heating units 2 formed by alternate lamination of a plurality of conductive layers 21 and insulating layers 22a-22d in spraying melted W and AL2O3 alternately by means of a plasma jet gun, are mounted on the back of this disc 1. Successively a lead conductor 5 is connected with the end part of these conductive layers 21 formed in series, and a lead conductor 4 is connected to the back of the disc 1 exposed in an opening 3 made by removal of the shielding material.</p> |
