Generation of Strongly Ionized Aluminum Plasma in a Low-Temperature Tokamak Discharge

Abstract

A new technique to produce a strongly ionized plasma from aluminum metal is achieved by use of the plasma-assisted arc in a tokamak discharge with low temperature (\lesssim10 eV), high electron density (\gtrsim1012 cm-3), and low gas pressure (10-5∼10-4 Torr). On arcing, the spectral lines of AlI, AlII and AlIII have been observed. Using the comparison spectroscopic method with no need of absolute measurement of spectral line intensity, we obtained the result that doubly ionized aluminum ions are dominant, and the density is estimated to be about 1011 cm-3. The aluminum plasma thus produced is useful and has potential for plasma processing, such as thin-film formation of AlN.