Distortion of an amplitude modulated electromagnetic signal with time-dependent dust charging

A large amplitude modulated Gaussian electromagnetic beam propagating in a dusty plasma with dust charge fluctuations has been studied. The electrons are heated non-uniformly by the electromagnetic beam. For non-steady state, we obtain nonlinear current density in the presence of dust grains. This expression has been used to study the non-stationary self-focusing and resulting self-distortion of the amplitude modulated electromagnetic beam. It has been observed that the dust charge fluctuation increases the self-focusing of electromagnetic beam. It is also found that the effect of dust charge fluctuations is significant on the modulation index.