LAUSR

Abstract The propagation of an ultrashort terahertz (THz) pulse in a nonequilibrium plasma channel produced by a UV femtosecond laser pulse in air is investigated theoretically. The analysis is carried out based on joint solution of the second-order wave equation and the Boltzmann kinetic equation in the binomial approximation for the electron velocity distribution function in the channel plasma. We assume that a THz pulse is quite weak and does not produce a reverse action on the electron energy spectrum in the channel plasma. It is shown that the plasma channel in air under a pressure of several atmospheres is a medium for effective amplification of ultrashort THz pulses in the frequency range up to several terahertz.