Positron generation via ultra-intense circularly polarized laser pulses colliding in near-critical-density plasmas with different thickness

Abstract

The pulses collision scheme has been demonstrated to be an effective way for the Breit–Wheeler positron generation. In this work, positron generation via two circularly polarized laser pulses colliding in near-critical-density plasmas with different thicknesses is further studied. The results show that high flux and high density positrons are generated and collected in 14  μm thick plasmas as extra backflow electrons contribute to radiation. Though the positron yield in 4  μm thick plasmas is lower than that in the thick plasmas, partial positrons are accelerated out of the collision region with a small divergence and quasi-monoenergetic energy. It is found that the Lorentz field dominates positron acceleration and collection. This investigation will further facilitate quality positron generation and application.