Suppression of the e(sup (minus)) coextracted from a Penning surface-plasma H(sup (minus)) source

摘要

The ratio of electrons to negative ions extracted from Penning surface-plasma sources (SPS) such as the 8X source is low even before any steps are taken to suppress the electrons. For the 8X source the e(sup (minus))/H(sup (minus)) ratio is typically four or five to one for H(sup (minus)) operation and nine to one for D(sup (minus)) operation. Because the coextracted e(sup (minus)) present a power-loading problem to the 8X source extraction system, methods to dissipate and/or reduce the power in the e(sup (minus)) beam must be developed before extracting a dc H(sup (minus)) or D(sup (minus)) beam. Thus, an experiment was run to see if a collar installed in the near extraction region of the 8X source suppresses the electrons extracted from that source.