Ion-density fluctuations in laser-heated plasma

Ion turbulence generated in a CO2 laser-heated gas target plasma has been studied using ruby laser Thomson scattering. Considerable enhancement of the ion fluctuations over the thermal level was observed for two high-density plasma regimes (short and long density scale lengths). In the short scale length regime the magnitude of density fluctuations, together with temporal and spectral features of the scattered ruby light, indicate that ion-turbulence levels are sufficient to account for anomalous absorption of CO2 laser energy. In the long scale length regime, measurements of the ion-fluctuation wavenumber spectrum induced in the plane of the CO2 laser electric field, together with high-speed streak camera measurements of the Thomson scattered ruby laser light, were performed to determine general features of strong ion fluctuations in laser heated plasma. Possible mechanisms for generating the observed ion turbulence are discussed