On the possibility of a short subterahertz pulse amplification in a plasma channel created in air by intense laser radiation

Abstract

The evolution of the electron energy distribution function in the plasma channel created in air by a UV-laser pulse of femtosecond duration is studied. It is shown that such a channel can be used to amplify few-cycle electromagnetic pulses in the subterahertz frequency range at the time of relaxation of the energy spectrum in air determined by the vibrational excitation of the nitrogen molecules. The gain factor as a function of time, electron concentration and frequency of the amplifying radiation is obtained. The propagation of few-cycle radio-frequency pulses through the amplifying medium is analysed.