Anti-Langmuir decay instability in Langmuir decay instability cascade

Abstract

Backward stimulated Raman scattering (BSRS) with Langmuir decay instability (LDI) and anti-Langmuir decay instability (ALDI or anti-LDI) has been researched by Vlasov simulation. The decay productions of anti-LDI in LDI cascade and their evolution with time are demonstrated for the first time. The BSRS reflectivity will be decreased largely through LDI cascade and ALDI in the small wave-number region. Different mechanisms to saturate BSRS in CH (or H) and C plasmas have been demonstrated. The dominant saturation mechanism of BSRS in CH (or H) plasmas is LDI cascade and ALDI. However, in C plasmas, due to very weak Landau damping of ion acoustic waves, LDI cascade will promote stimulated Brillouin scattering (SBS) excitation, then SBS will compete with BSRS and saturate BSRS in the later stage. The proportion of the hot electrons is decreased largely through LDI cascade and ALDI. These results give an effective mechanism to suppress BSRS and hot electron generation in the small wave-number region, which are of important significance in the inertial confinement fusion.