Acceleration of electrons generated during ionization of low density gases by a focused laser pulse

Abstract

The acceleration of electrons generated during ionization of low density gases has been studied using seventh order correction fields of a laser pulse for linearly and circularly polarized laser pulse. The spectrum of energy and angle of emittance of the electrons generated and accelerated during ionization of nitrogen ions N5+, oxygen ions O6+, neon ions Ne8+, krypton ions Kr32+, and argon ions Ar16+ has been obtained for normalized laser intensity parameter a0=4, 6, 12, 20, and 75, respectively, for normalized laser spot size r0=60, 90, and 120. Energy and scattering spectrum for nitrogen, oxygen, and neon ions show two peaks and may generate quasimonoenergetic beams for small laser spot sizes. The energy spectrum is wide and peak lies at low energy for krypton than that for argon. The energy peaks are at higher energy for circularly polarized laser pulse than that for linearly polarized laser pulse. The paraxial approximation may fail to yield accurate results at low values of laser spot size and high laser intensity. The energy associated with spectrum peak tends to saturate with laser intensity.