| 摘要 |
PURPOSE:To gassify the conductive composite compound on a ceramic plate by oxidation reaction and automatically recover the electrical insulation between electrodes by introducing air into an electron gun section several minutes after cutting off a cathode heating power supply, etc. CONSTITUTION:When the insulation resistance on a ceramic plate 4 is deteriorated due to the thermal decomposition of oil, an increase of the primary side current value is detected by a bias current detector 17 as the secondary side current value of a bias power supply 9 is increased. When such a bias current value is attained as to give an influence on an electron gun section 30 and the generation of an electron beam 6, a power supply switch 16 is opened by a signal from an overcurrent detecting circuit, and the heating of a cathode is stopped and the generation of the electron beam 6 is also stopped. Three minutes later after that time, for example, a leak value 21 is opened by a signal generated by a delay circuit 19, and air flows into the electron gun section 30, thus performing flushing. Then, the leak valve 21 is closed, an auxiliary power supply switch is closed by the vacuum discharge completion signal of the electron gun section 30 and the cathode is heated again. |
