Measurements of the ion acoustic decay instability and the resultant enhanced laser absorption and enhanced bremsstrahlung in laser-plasma interaction experiments

We have studied the impact of the Ion Acoustic Decay Instability on Laser Fusion. This project was supported by the US Department of Energy and performed at the National Laser Users Facility at Laboratory for Laser Energetics. It is shown below that the Ion Acoustic Decay Instability (IADI) is potentially important in laser fusion. The IADI threshold is reduced to the homogeneous collisional plasma values in a large scale plasma. The threshold was as low as IλL2 = 5 x 1012 W/cm2-μm2. Our estimate shows that the electron plasma wave excited by the IADI can significantly heat the hot electrons. We have also shown that Bremsstrahlung radiation due to electron scattering with ion acoustic turbulence is typically small. 2 refs., 7 figs