Spectroscopic observations of turbulence in a fast theta pinch

The spectrum of fluctuating fields in a collisionless magnetized plasma produced in a high voltage theta pinch is studied using satellite line techniques. Differences in the turbulent spectrum exist depending on whether the initial magnetic field is parallel or antiparallel to the driving magnetic field with the possible identification of electron cyclotron modes in the antiparallel case and electron plasma oscillations in the parallel case. By including quadratic Stark shifts, difficulties in interpretation of an earlier satellite experiment are explained. Predictions of various instability theories are tested experimentally with the aid of additional diagnostic methods.