Ion acoustic decay instabilities in laser pellet interactions

Microwave experiments and computer simulations have shown that the ion acoustic parametric decay instability (IADI) can produce a significant number of hot electrons in a large-scale plasma. These hot electrons are a concern in proposed inertial confinement fusion (ICF) studies because they preheat the target and degrade compression. The ion wave turbulence excited by IADI will also be the source of anomalous resistivity, so that thermal electrons are strongly heated due to anomalous Joule heating. The authors have extensively studied the IADI in laser-pellet interactions. They have shown that the IADI threshold is quite low, so that IADI is potentially important in laser-driven fusion pellets. They have also shown that the ionic charge state Z can be measured using the Stokes signal. IADI is also a useful tool for plasma diagnostics at the critical surface. The experimental procedure is briefly described.<>