CPC H01J 49/147 (2013.01) [H01J 27/205 (2013.01); H01J 49/068 (2013.01); H01J 49/24 (2013.01); H01J 49/025 (2013.01); H01J 49/26 (2013.01)] | 11 Claims |
1. An ionization device, comprising:
an ionization space formed in a chamber,
an inlet system for supplying a gas to be ionized to the ionization space,
an electron source having at least one filament for supply of an electron beam to the ionization space, and
an outlet system for letting the ionized gas out of the ionization space,
characterized in that
an electron optics comprising at least two electrodes is installed between the filament and the ionization space wherein the electron optics are configured to use one of the at least two electrodes to measure an emission current of the filament.
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