| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an impregnated cathode where a stable electron emission characteristic can be obtained. SOLUTION: A cathode substrate 1 has a porous tungsten sheet 2 being made by compressing tungsten powder 3-8μm in average grain diameter. First and second ruhenium.molybdenum mixed fused layers 3 and 4 are made of ruthenium and molybdenum powder 9-10μm and 5μm or under, respectively, in average grain diameter and are stacked on the rear. A cathode substrate 1 is inserted into a high fusing metal cup 5 so that the second ruthenium.molybdenum mixed fused layer 4 may be positioned at the bottom, and is accommodated and supported within the high fusing point metal cup 5. The high fusing point metal cup 5 is inserted into the top at one end of a cylindrical sleeve 7 having a heater 6 within. The first ruthenium.molybdenum mixed fused layer 3 prevents the penetration and diffusion of ruthenium.molybdenum into the cavity of the porous tungsten sheet 2, and the second ruthenium.molybdenum mixed fused layer 4 increases the contact area with the high fusing point metal cup 5, thus stable electron emission can be obtained.</p> |
