ABSTRACT
A relativistic plasma interacting with an ultrashort, ultraintense laser pulse exhibits new phenomena where the nonlinearity of the relativistic particle kinematics and the nonlinearity of the magnetic part of the Lorentz force become dominant (see e.g., Bulanov S.V. et al. 2001a). Electromagnetic (e.m.) solitons and vortices are part of this complex nonlinear interaction (Pegoraro et al. 2001) and represent the basic ingredients of the long time electron behaviour in the wake of the laser pulse (Naumova et al. 2001a). Electromagnetic solitons are found to occur in regimes where the energy of a laser pulse propagating in an underdense plasma is depleted, resulting in the downshift of the pulse frequency (Bulanov S.V. et al. 1995). This provides a mechanism of e.m. energy trapping in the form of slowly propagating “subcycle-solitons” (Bulanov S.V. et al. 1999).
