Harmonic effects on ion-bulk waves and simulation of stimulated ion-bulk-wave scattering in CH plasmas

Ion-bulk (IBk) wave, a novel branch with a phase velocity close to the ion's thermal velocity, discovered by Valentini et al (2011 Plasma Phys. Control. Fusion 53 105017), is recently considered as an important electrostatic activity in solar wind, and thus of great interest to space physics and also inertial confinement fusion. The harmonic effects on IBk waves has been researched by Vlasov simulation for the first time. The condition of excitation of the large-amplitude IBk waves is given. The nature of nonlinear IBk waves in the condition of k < k(lor)/2 (k(lor) is the wave number at loss-of-resonance point) is undamped Bernstein-Greene-Kruskal-like waves with harmonic superposition. Only when the wave number k of IBk waves satisfies k(lor)/2 less than or similar to k <= k(lor), can a large-amplitude and mono-frequency IBk wave be excited. A novel stimulated scattering from IBk modes called stimulated ion-bulk-wave scattering (SIBS) or stimulated Feng scattering (SFS) has been proposed and also verified by Vlasov-Maxwell code. In CH plasmas, in addition to the stimulated Brillouin scattering from multi ion-acoustic waves, there exists SIBS simultaneously. This research gives an insight into the SIBS in the field of laser plasma interaction.National Natural Science Foundation of China [11375032, 11575035, 11475030, 11435011]; National Basic Research Program of China [2013CB834101]; Science Challenge Project [TZ2016005]SCI(E)ARTICLE85