| 摘要 |
Ion source enveloped in a uniform magnetic induction @. The electrons, emitted by a heated filament, are injected into the ionisation chamber and confined in a thin sheet by @. Under the combined action of @ and an electric deflecting field @ perpendicular to the electron sheet, the ions created in the latter describe cycloids in planes perpendicular to @ and emerge sideways from the source. The system ensures both high efficiency of ionisation and almost total extraction of the ions with mass lower than a critical mass, proportional to B<2> DIVIDED EL. The electron sheet coincides with an equipotential surface of the field @ and the ion beam extracted is therefore monoenergetic. The system constitutes an ideal ion source, in mass spectrometry for example, and can be used in isolation for the detection of light ions such as helium. <IMAGE>
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