One-dimensional simulations of Langmuir collapse in a radiation-driven plasma

Abstract

Langmuir collapse in a radiation-driven plasma is simulated in one dimension using both the hybrid Vlasov model and the modified Zakharov model. In the hybrid model, the electrons are described by the Vlasov equation and the ions are described by the fluid equations. Two numerical runs with different parameters are performed: (a) a weakly driven case, and (b) a strongly driven case. The comparisons of the results between the two models for each case are carried out in detail. It is found that the dynamic behavior of the plasma can be changed dramatically by varying the external driving field. The electron temperature increases only ∼10% in the weakly driven case, while it increases ∼200% in the strongly driven case during a single Langmuir collapse. The two models agree with each other during the first collapse after the saturation of modulational instability. Dynamic differences appear after the first collapse, caused by the electron heating in the hybrid model, which is not accounted for in the standard isothermal Zakharov model.