PROTECTIVE DEVICE FOR MICROCHANNEL PLATE DETECTOR

摘要

PURPOSE:To prevent dielectric break down by creeping discharge between opposing surfaces in a secondary electron multiplying section by providing a bypass element consisting of a pair of opposing electrodes which are opposingly disposed to be of lower dielectric strength than that between the opposing surfaces in the secondary electron multiplying section and each electrode is connected to each opposing surface of the secondary electron multiplying section. CONSTITUTION:A bypass element 20 is connected to a high voltage source 15 for supplying a high voltage to a secondary electron multiplying section 16 and has lower dielectric strength than that of the secondary electron multiplying section 16. When the degree of vacuum around the secondary electron multiplying section 16 is lowered a dielectric break down occurs in the bypass element 20 before a dielectric break down occurs between opposed surfaces A and B, which short-circuits the voltage to be applied between opposed surfaces A and B. This prevents the opposed surfaces A and B from being impressed with a high voltage. Thus the dielectric break down between the opposed surfaces A and B is avoided and the function of the secondary electron multiplying section is prevented from damage and maintained in good order.