Effect of argon additive on H − density and temperature in volume negative ion source Rev. Sci. Instrum. 75, 1747 (2004); 10.1063/1.1695618Effect of cesium and xenon seeding in negative hydrogen ion sources Rev.

No abstract

A broad mixed ion beam containing positive ions of gallium (Ga) was produced with a plasma sputter-type ion source. Liquid Ga was suspended on a tungsten reservoir to be sputtered and postionized in argon (Ar) plasma excited by a radio frequency (rf) power at 13.56 MHz. Optical emission spectra from the plasma near the Ga sputtering target had indicated that the release of Ga into plasma increased with increasing negative bias to the sputtering target. The ratio of Ga(+) current to Ar(+) current was measured to be about 1% with a quadrupole mass analyzer at 100 V extraction voltage for incident rf power as low as 30 W. Ions in the plasma were extracted through a pair of multiaperture electrodes. The homogeneity of Ga flux was examined by making a Ga deposition pattern on a glass substrate located behind the extractor electrodes.

A molybdenum plasma grid was installed in a 30-cm-long 16-cm-diam 16-pole magnetic multicusp ion source to simulate the effect of a plasma electrode bias of a negative ion source. Effects caused by the bias voltage applied to the electrode upon the plasma parameters, the density of negative hydrogen ions (H−), and the drift velocity of plasma perturbed by the photodetachment of H− were investigated with the direct current laser photodetachment method. The electron density at the distance of 0.5 cm from the plasma grid decreased from 8×1010 to 4×1010cm−3 by increasing the grid bias from 0 to +4V, while the H− density increased from 8×108 to 4.5×109cm−3. The drift velocity of plasma perturbation was changed by a factor of 3 corresponding with the gradient of the plasma potential near the electrode.

No abstract