PURPOSE: To manufacture an emitter having a large top end radius.
CONSTITUTION: The gap between the top end of an emitter having a top end radius of 0.2μm-0.8μm and a discharge plate 7 is set to about 0.5mm. A negative low voltage is applied between the emitter 1 and the discharge plate 7. The emitter 1 is gradually approached to the discharge plate 7. When the gap is less than 1.0μm, a minute discharge is generated between the emitter 1 and the discharge plate 7, a discharge current is carried between the both to weld the top end of the emitter by the Joule heat, and recrystallized into a sphere having an emitter top end radius of about 1.0μm or more. A low voltage power source 13 is cut off, and a vacuum vessel 8 is laid in high vacuum state. The gap between the emitter 1 and the discharge electrode is returned to the original gap of about 0.5mm. An emission circuit 16 is operated to emit a thermoelectric field emitting electron from the top end of the emitter 1, 100 crystal orientation is grown on the top end of the emitter, and a parallel part 1H' and a facet 1F' having a large diameter are formed.
TANAKA SHUNJI
SHIBUKI YOICHI
