Nonlinear transformation of electromagnetic wave in time-varying plasma medium: Longitudinal propagation

Abstract

The nonlinear transformation of a linearly polarized source plane electromagnetic wave, propagating along an external static magnetic field in free space for t<0, due to the sudden creation of homogeneous plasma at t=0 and sudden switching off the external magnetic field after an elapsed time interval τ, is studied. This transformation has been analyzed by using the second order perturbation theory in radio approximation. For t>τ, the stationary (rectification and space-varying) modes, the electron and electromagnetic plasma oscillations and traveling electron and electromagnetic plasma waves have been created. Among the large variety of nonlinear longitudinal electric modes the appearance of rectification mode was observed. The efficiency of excitation of the longitudinal electric rectification mode has been studied for different values of source wave angular frequency, electron cyclotron angular frequency, and duration time τ of external static magnetic field.

On Maxwell's equations in non-stationary media

“…Infinitely fast (step-like) temporal variations were investigated in detail for different incident fields, media and geometry, as in Nerukh & Shavorykina (Vorgul) (1992), Aberg et al (1995), Vorgul & Marciniak (2001) and Trifkovic & Stanic (2006). Gradual change in medium parameters with time and its influence on propagating field usually were solved numerically or approximately (Harfoush & Taflov 1991;Vorgul & Nerukh 1998;Nerukh et al 2001;Bakunov & Grachev 2002;Porti et al 2003) and only a few types of continuous dependences were considered, as time-harmonic variations in Harfoush & Taflov (1991) or approximation of continuous change by a sequence of abrupt ones as in Vorgul & Nerukh (1998).…”