Electron dynamics and photon-emission spectra in an ultrashort laser pulseand a uniform magnetic field

We present exact trajectory solutions for a relativistic electron in the pr esence of a superintense linearly polarized laser pulse and a uniform magne tic field. To be concrete, the pulse envelope is taken in the form sin(2)[( kappa/2) eta], where eta is the phase and 0<kappa<1. Using the analytical t rajectories, we study numerically the spectra of radiation, emitted by the accelerated electron, along various observation directions. In particular, we find that light in the forward direction can be emitted essentially at t wo frequencies omega(0) and r omega(0), where omega(0) is the laser frequen cy and r is related to the ratio of cyclotron frequency to the laser freque ncy. Spectra emitted in the directions of the electric and the magnetic com ponents of the laser held are, in contrast, very rich in structure with hig hly irregular distributions of positions and strengths. [S1050-2947(99)0580 9-6].