Determination of velocity distribution of metallic atoms in plasma devices with a rapid-frequency-scan dye laser

Abstract

A rapid-frequency-scan dye laser was developed for the measurement of the velocity-distribution functions of impurity atoms sputtered due to the high-temperature plasma-surface interaction. In order to confirm the effectiveness of this rapid-scan technique, measurements of the Doppler profiles of Fe atoms sputtered by Ar ion-beam bombardment with energy 3 keV were performed. A scanning range of more than 40 pm at λ ≈300 nm was obtained with a spectral bandwidth of 1.5 ∼2 pm and good linearity. Doppler profiles were determined in various scattering conditions, and excellent performance of this technique was demonstrated. The distortion error caused by line saturation was analytically discussed, and it is shown that the effect of this error is not so serious (less than 10%) even for highly saturated excitation.