| 摘要 |
PURPOSE:To prevent dielectric breakdown of facing faces of a microchannel plate detector even if the vacuum degree is degraded by installing a bypass element in which a pair of facing electrodes connected with the facing faces of the detector are set so as to have lower dielectric strength than that between the facing faces. CONSTITUTION:Regarding a microchannel plate detector 14 in an analyzer main body 10, a large number of glass tubes C with a small diameter are bundled and put between facing faces A, B to be connected respectively with a high voltage electric power supply 15 and thus a secondary electron multiplying part 16 is formed. A plurality of glass tubes 62 are put between one pair of facing electrodes 21, 22 connected with the facing faces A, B and a bypass element 20 is installed so as to make the dielectric strength between the electrodes lower than that between the facing faces A, B of the secondary electron multiplying part 16. As a result, even if the vacuum degree near the secondary electron multiplying part is lowered, dielectric breakdown of the bypass element 20 occurs before dielectric breakdown occurs between the facing faces A, B and voltage to be applied to the facing faces A, B is short-circuited and thus high voltage application to the facing faces A, B is prevented and dielectric breakdown between the facing faces never occurs.
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