Effect of laser polarization and target location on acceleration of electrons generated during ionization of gases by a laser pulse

Abstract

We investigate the effect of the target position, laser polarization, and focusing on the energy spread and the angle of emittance for the acceleration of electrons generated during the ionization of rarefied gases, neon ions Ne8+, krypton ions Kr32+, and argon ions Ar16+ by a laser pulse. The electrons generated from the ions at the position after laser focus interact with the laser pulse for a longer duration and gain more energy than those electrons generated from the ions at the position before laser focus. There are two peaks in the energy spectrum for linear polarization and only one peak for circular polarization. The energy spectrum peak is sharper for circular polarization than that for linear polarization. The energy gained by the electrons increases with the laser spot size due to the increase in the laser energy. The spectrum of the angle of emittance for electrons shows the sharpest peak at the lowest angle for linear polarization for ions at the position after laser focus. The circular polarization is good to obtain quasi-monoenergetic electron beams and linearly polarized laser pulse is good to generate collimated electron beams. The required laser intensity to ionize electrons from the ions Ne8+, Kr32+, and Ar16+ increases and the electron energy peaks are at higher energies and scattering angles are at lower values for these gases, in their respective orders.