ECR and cesium ionizer systems for the Triangle Universities Nuclear Laboratory atomic beam polarized ion source

Abstract

A plasma ionizer in which the electrons are heated via electron-cyclotron resonance is used to produce beams of polarized H + (or D +) ions from spin-polarized H 0 (or D 0) beams. The plasma is confined axially via a magnetic mirror field and radially by a sextupole field created by permanent magnets. Plasma heating is accomplished via 75 to 100 W of rf power fed radially into the region between the mirror coils either from a variable frequency, 2.8 or 4.8 GHz traveling wave tube amplifier or from a 2.45 GHz magnetron source. The operation of the system is simple, stable, and reproducible. The extracted positive polarized beam can be converted to negative by adding electrons in a cesium vapor charge-exchange canal; the effective conversion efficiency ranges between 15 and 20%. The extracted polarized beam has an energy spread < 15 eV.