Spectroscopic study of theta discharges in hydrogen and helium

A well-diagnosed theta discharge was investigated using a variety of spectroscopic techniques. In helium, a method for measuring high frequency plasma turbulence was demonstrated. The method consisted of using a tunable dye laser to resonantly enhance satellite features in the emission spectrum of neutral helium caused by electron plasma waves. The position and strength of the satellites determined the frequency and amplitude of the waves. In a nonturbulent Hydrogen plasma, the ion-dynamical contributions to the broadening of H/sub β/ and H/sub Gamma/ were measured. The profile of H/sub Gamma/ was found to be well predicted by standard Stark broadening calculations with no additional effects due to ion-dynamical corrections. H/sub β/ was found to show clear evidence of additional ion-dynamical broadening, with the additional broadening in rough agreement with predictions originally developed for hydrogenic Lyman series lines