High-flux positrons generation via two counter-propagating laser pulses irradiating near-critical-density plasmas

A scheme for generating high-flux positrons by two counter-propagating laser pulses colliding in near-critical-density plasmas is proposed, which might be realized with current laser facilities. Positrons of number 2.79 × 105 and with a maximum density of 9.63 × 1024 m−3 can be generated for a laser with an intensity of 1022 W cm−2. This is attributed to the increase in the cross sections for photon radiation and positron generation in the colliding scheme. In order to improve the positron generation, the relevant parameters are discussed in detail. This scheme will facilitate the observation of the Breit-Wheeler positrons in the laboratory.