| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely emit electrons corresponding to an exactly designed quantity, so as to emit a beam according to a designed orbit by forming an electron emission part and an electron non-emission part at the same time, without a generation of a gap between them on an electron emission surface of an impregnated negative electrode which is composed of a base metal having tungsten and at least BaO impregnated as an impregnant. SOLUTION: It is desirable that one containing one or both of CaO and Al2 O3 , or one containing Sc2 O3 mixed therein or a mixture of W powder and BaO and Sc2 O3 is used as an impregnant. Electrons are emitted by forming a mono-atomic layer of barium on an electron emission surface 4. An impregnated negative electrode 1 integrally has an electron emission part 9 and an electron non-emission part 10 on the electron emission surface 4. The electron non-emission part 10 is formed according to the addition of a prescribed patterned groove or an adhesion of moisture of a surface of the impregnated negative electrode 1 in order to cut off a barium dispersion path based on heating.</p> |
