ELECTRON GUN AND ELECTRON BEAM GENERATING DEVICE

PROBLEM TO BE SOLVED: To provide an electron gun and an electron beam generating device having a long life of a filament. SOLUTION: The electron gun 1 includes: the filament 40 for emitting electrons by being heated by the flow of current; a cover 14 that is an opening 16 housing the filament and through which electrons pass have been formed, that is arranged on the opening side of the filament and that covers the filament; a cathode 10 with a protrusion 20 formed directed to the opening at a position separated from the filament; and an anode 30 for accelerating electrons that have passed through the opening of the cathode. This is the electron beam generating device which is provided with the electron gun and an electric source for supplying voltage to the electron gun. COPYRIGHT: (C)2007,JPO&INPIT