The modified Zakharov equations for time-space envelope in magnetoactive plasma*

Considering the presence of an external magnetic field, the modified Zakharov equations are obtained with the help of two-component fluid mechanics and the two-scale method. Based on the nonlinear equations, the effect of the magnetic field on the modulational instability is studied. The numerical results show that the growth rate increases with the intensity of the magnetic field, which means that the magnetic field could enhance the collapse of the Langmuir field.