Increasing the space-charge limit and other effects of cesium seeding in hydrogen negative ion sources

The role of cesium seeding in increasing the negative ion current in volume sources is described. By a reduction in the local plasma potential the current of extracted electrons is vastly reduced. As a result, cesium increases the fraction of the transverse space-charge limit available to the ions b...

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Bibliographic Details
Published in:Review of Scientific Instruments 2000-02, Vol.71 (2), p.872-874
Main Authors: Whealton, J. H., Bacal, M., Bruneteau, J., Raridon, R. J.
Format: Article
Language:English
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Summary:The role of cesium seeding in increasing the negative ion current in volume sources is described. By a reduction in the local plasma potential the current of extracted electrons is vastly reduced. As a result, cesium increases the fraction of the transverse space-charge limit available to the ions by as much as a factor of 3. In addition, cesium can increase the total space-charge limit by injection of Cs + into the presheath—a newly recognized phenomenon consistent with experimental measurements and determined from application of a Double–Vlasov model for negative ion extraction.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1150317