METHOD OF CONTROLLING EMISSION CURRENT OF ELECTRONIC SOURCE AND ELECTRONIC SOURCE IN WHICH EMISSION CURRENT IS CONTROLLED

摘要

PROBLEM TO BE SOLVED: To provide a simple and reliable method to control emission current of an electron source. SOLUTION: A parallel circuit comprising a resistor 6 and a field-effect transistor 7 is installed in high voltage circuit side between a cathode 1 and a control electrode 2 and the supply voltage to the field-effect transistor 7 is generated by dividing the voltage lowered through the resistor 6. The emission current is measured at a low voltage potential and a control single obtained from the measured signal is optically transmitted to a control circuit in the high voltage circuit side through an optical fiber or an optical waveguide.