Gas discharge ion source III. Modified Berkeley multifilament ion source

Total ion current, ion energy, mass and current density distributions, and the impurity content of the ion beams produced by a modified Berkeley multifilament ion source (MFIS) were measured as a function of source configuration, gas pressure, and operating conditions: the ’’best’’ configuration produced beams of 200 mA or more at pressures between 0.40 and 2.0 Pa. In comparison with earlier studies of duoplasmatron and duopigatron sources, the MFIS beams contained less D+, only ca. 33%, but the beams had much narrower energy distributions and flatter current density distributions. The beams contained 1%–2% impurities which consisted mainly of masses 18, 20, and 22.