Thermoelectron generating source and ion beam radiating apparatus with the same

摘要

A thermoelectron generating source including a facial main cathode for emitting thermoelectrons by being heated from behind, a filament for heating the main cathode from behind to emit the thermoelectrons, an extraction electrode for extracting the thermoelectrons emitted from the main cathode under an electric field, the extraction electrode being provided near the front of the main cathode, and two deflecting electrodes and disposed on the left and right sides near the front of the extraction electrode to carry the extraction electrode. The potentials of the two deflecting electrodes are kept in a relation V_LV_R≧0, where the potential of one deflecting electrode is V_L and the potential of the other deflecting electrode is V_R.