MULTICUSP ION-SOURCE FOR PRODUCTION OF NEGATIVE LITHIUM IONS

A beam of negative lithium ions (Li-) with a current density as high as 3 x 10(-5) A/cm2 was extracted from a 5 cm diam, 7 cm long multicusp ion source. The extracted Li- current was correlated to the plasma temperature and density measured with Langmuir probes heated to avoid Li condensation. The neutral lithium flux from the ion source was measured with a Langmuir-Taylor detector, and it showed a linear correlation with the extracted Li- current. Further increase in efficiency to produce Li- current is expected by improving the plasma confinement of the ion source.