FABRY-PEROT LINE-SHAPE ANALYSIS ON AN EXPANDING CASCADED ARC PLASMA IN ARGON

Fabry-Perot line profile measurements have been used to obtain heavy particle temperatures and electron densities for an expanding cascaded arc plasma in argon. This was done for the argon 415.9 and 696.5 nm neutral lines as a function of the distance from the onset of the expansion. Temperatures in the range of 2000-12 000 K were obtained. The electron density in the beginning of the expansion appeared to be 5.6 X 10(21) m-3. The 696.5 nm line profiles appeared to be asymmetric because of self-absorption by cool metastables around the plasma. The density and temperature of these metastables could be determined by fitting the measurements to a theoretical model, and appeared to be around 10(-17) m-3 and around 3000 K, respectively.