Patent ID: 7049605

Claim:
A detector using microchannel plates, comprising: a microchannel plate assembly having a secondary electron emissive surface and a particle incident surface; a disk-like anode placed opposite to the secondary electron emissive surface of the microchannel plate assembly and placed at an electrical potential; a dielectric body having a central portion to which the anode is mounted; a disk-like electrode placed opposite to the anode such that the dielectric body is sandwiched between the disk-like electrode and the anode to form a capacitor; first and second annular electrodes placed outside the anode and outside the disk-like electrode, said dielectric body being sandwiched between said first and second annular electrodes to form a second capacitor; a power supply for applying a high voltage to the particle incident surface of the microchannel plate assembly; and a second power supply for developing a potential gradient between the particle incident surface and the secondary electron emissive surface of the microchannel plate assembly, wherein said first annular electrode is placed at an electrical potential sufficiently close to the electrical potential of the anode to prevent discharging around the anode.