Self-modulation of an intense laser beam in near-critical homogeneous plasma

An investigation of longitudinal intensity modulation of a relativistic las er beam in near-critical homogeneous plasma (n(e) > 1/4 n(cr)) is performed in this paper. On the basis of a nonlinear Schrodinger equation of electro magnetic vector potential, a model equation of the intensity profile is der ived via the variational approach from Action and Lagrangian. Longitudinall y uniform and longitudinally modulated pulse structures are viewed as diffe rent solutions of this model equation. For these two different types of pul se structure, their relative stability under different structure parameters is numerically studied. Numerical results indicate that this relative stab ility depends closely on the transverse structures of the laser pulse. (C) 2001 American Institute of Physics.