Investigation of QED Effects With Varying Z in Thin Foil Targets

Abstract

Quantum electrodynamics (QED) effects in intense laser plasma interaction were investigated using Particle in Cell (PIC) simulations, specifically the generation of electron-positron pairs. Linearly polarized intense laser pulses were used to irradiate a thin foil (1 μm) with an intensity of 4×10 23 Wcm -2 . A scan of targets with varying Z (Al, Cu and Au) is investigated to determine the effect of target Z/density on electron-positron pair production. The total number of pairs created for Al and Cu targets is 10 14 and 10 13 respectively. In the case of Au, we did not observe any pair production to occur. We have also calculated the variation in electron energy in these targets. The results indicate that target Z plays a very important role with the laser interaction in the pair production process, which will be explained in this paper.

Enhanced positron acceleration driven by femto-second laser pulses irradiating structured targets

“…As shown in figure 3(c), the sheath field is notably stronger for the structured target. Figure 4 presents the density distribution of electrons and photons, revealing two orders of significant enhancement in photon density compared to our previous work [32]. In a recent simulation study by Zi et al suggests that the pair production can be enhanced using an aluminum (Al) target with varying transverse target sizes, employing two laser beams.…”

“…We have compared the results of the structured target with a solid flat target, and found that the Breit-Wheeler (BW) process dominates over the positron generation process. Using the two-dimensional (2D) PIC code EPOCH [31], we were able to demonstrate by modelling over 10 9 positrons with a cutoff energy 2.5 GeV, which was twice the energy achieved in our previous work with the same laser intensity [32]. We have proposed a new theoretical model for magnetic field associated with the phenomenon and shown relevancy between theoretical and simulation results of some important parameters.…”

Photon emission enhancement studies from the interaction of ultraintense laser pulses with shaped targets

“…In ultra-intense laser-plasma interactions(I > 10 22 W/cm 2 ), quantum electrodynamics (QED) effects play a dominant role [11,12], leading to the emission of high-energy gamma rays and pair production. Nonlinear Compton scattering and the resulting radiation reaction and pair production by the Breit-Wheeler processes [13] have been incorporated into particle-in-cell (PIC) codes like EPOCH [14] to study the QED processes in laser-plasma interactions [15][16][17][18]. When an ultra-intense laser interacts with a foil, the two main processes leading to emission of gamma rays are bremsstrahlung and nonlinear Compton scattering (NCS).…”