| 摘要 |
Apparatus for generating negative ions, specifically He- ions. Positive ions at a predetermined energy level from a conventional ion source are directed to a permanent magnet channel that utilizes two, spaced permanent magnet assemblies to analyze the ions and, with double focusing, to direct them to a focal point located in a lithium vapor canal. As the positive ion beam passes through a lithium vapor of constant density in a predetermined volume at the central region of the canal, electrons transfer to the ions and produce He- ions. The canal is constructed to efficiently condense and collect lithium vapor as it escapes the predetermined volume. The beam of negative ions then passes to another permanent magnet assembly that corrects any astigmatism in the emerging beam and that directs the beam, with appropriate optical properties, onto an injection axis for another accelerating structure.
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