Multicharged ion source with several electron cyclotron resonance zones

Claim 1

A multicharged ion source comprising a sealed enclosure containing a gas for forming a plasma confined within said enclosure, means for producing within said enclosure a high frequency electromagnetic field, means for producing within said enclosure a group of axial and radial, local magnetic fields defining equimagnetic surfaces for confining said plasma produced by electron cyclotron resonance whereof the condition has been satisfied on one of them, said group having an axis of symmetry, means for extracting said ions through an orifice made on the wall of said enclosure and located on said axis of symmetry, said means for producing said local fields comprising first and second alternated magnetic bars arranged symmetrically around said enclosure and formed by several elementary magnets, the magnets of said first bars having polarities opposed to the polarities of the magnets of said second bars except that the terminal elementary magnets situated at the extraction orifice have the same polarity in order to reduce outside the volume occupied by the confined plasma, the amplitude of the local axial magnetic fields located in the vicinity of the extraction orifice, slightly upstream and downstream of said orifice, in n small zones located outside the axis of symmetry.