| 摘要 |
PURPOSE: An apparatus for measuring a degree of a vacuum is provided to prevent an external factor from intervening in a vacuum measuring process of a certain device, thereby exactly measuring a degree of vacuum of the device. CONSTITUTION: The device comprises an electron emitting portion(42); a collector(44) disposed to be opposite to the electron emitting portion to collect positive ion; a grid(46) disposed between the electron emitting portion and the collector to be aligned in parallel with the collector while enclosing the collector; and an electromagnetic shielding portion(48) enclosing the electron emitting portion, the collector and the grid. In the apparatus, the electron emitting portion is a filament from which thermal electron is emitted. The filament and the collector are vertically arranged in parallel. The grid is comprised of a plurality of annular rings enclosing the collector. The electromagnetic shielding portion is a suppression electrode formed of a conductive material having an electric resistance of 0.0001 ohm meter.
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