HIGH-FREQUENCY ELECTRON GUN

PURPOSE:To prevent the deterioration of an electron generating device without damaging it, accelerate and focus electrons from the electron generating device toward an electron beam outgoing port, and improve the stability of an electron beam. CONSTITUTION:The high-frequency accelerating cavity 23 of a high-frequency electron gun 21 is constituted of a cavity body 3 opened at both end sections of the cavity and side walls 5, 22 provided at both end sections of the cavity body 3 respectively. An electron generating device 10 is arranged on the center axis Ax of one side wall 22, and an electron beam outgoing port 11 is formed on the center axis of the other side wall 5. The wall face 22a around the electron generating device 10 is formed with a recessed face 24 having the electron generating device 10 at the bottom section, and electrons going toward a cathode 7 are attracted.