@techreport{oai:nifs-repository.repo.nii.ac.jp:00010183,
 author = {"Sasao,  M. and Yamaoka,  H. and Wada,  M. and Fujita,  J."},
 month = {Jul},
 note = {Negative sodium ions (Na^-) were extracted from a small multi-cusp ion source. A steady state sodium plasma was produced by primary electrons in a sodium gas evaporating from a metal sample placed in the discharge chamber. The Na^- current density of I.5 muA/cm^2 was obtained from a single aperture of 1.5 mm diameter at relatively low discharge power of about 0.4 W and filament power of 50 W. Extraction characteristics were studied by changing the plasma electrode bias. The extracted Na^- current showed dependence on the bias voltage similar to that of H^- or Li^- volume production.},
 title = {Direct Extraction of a Na- Beam from a Sodium Plasma},
 year = {1990}
}