New insights into the decay of ion waves to turbulence, ion heating, and soliton generation

The decay of a single-frequency, propagating ion acoustic wave (IAW) via two-ion wave decay to a continuum of IAW modes is found to result in a highly turbulent plasma, ion soliton production, and rapid ion heating. Instability growth rates, thresholds, and sensitivities to plasma conditions are studied via fully kinetic Vlasov simulations. The decay rate of IAWs is found to scale linearly with the fundamental IAW potential amplitude phi(1) for ZT(e)/T-i less than or similar to 20, beyond which the instability is shown to scale with a higher power of phi(1), where Z is the ion charge number and T-e (T-i) is the electron (ion) thermal temperature. The threshold for instability is found to be smaller by an order of magnitude than linear theory estimates. Achieving a better understanding of the saturation of stimulated Brillouin scatter levels observed in laser-plasma interaction experiments is part of the motivation for this study. (C) 2014 AIP Publishing LLC.