ONE-DIMENSIONAL SIMULATIONS OF LANGMUIR COLLAPSE IN A RADIATION-DRIVEN PLASMA

Langmuir collapse in a radiation-driven plasma is simulated in one dim ension using both the hybrid Vlasov model and the modified Zakharov mo del. In the hybrid model, the electrons are described by the Vlasov eq uation and the ions are described by the fluid equations. Two numerica l runs with different parameters are performed: (a) a weakly driven ca se, and (b) a strongly driven case. The comparisons of the results bet ween the two models for each case are carried out in detail. It is fou nd that the dynamic behavior of the plasma can be changed dramatically by varying the external driving field. The electron temperature incre ases only approximately 10% in the weakly driven case, while it increa ses approximately 200% in the strongly driven case during a single Lan gmuir collapse. The two models agree with each other during the first collapse after the saturation of modulational instability. Dynamic dif ferences appear after the first collapse, caused by the electron heati ng in the hybrid model, which is not accounted for in the standard iso thermal Zakharov model.