(Color online) Beam width parameters f₊ and g₊ plotted against the dimensionless distance of propagation ζ for different values of magnetic field parameter ω_c/ω_o, at a = 0.06. The other parameters are the same as that of Fig. 2. (a) Variation of f₊ in the absence of self-compression effect; (b) Variation of f₊ in the presence of self-compression effect; (c) Variation of g₊.