Dense pair plasma generation and its modulation dynamics in counter-propagating laser field**Project supported by the National Basic Research Program of China (Grant No. 2013CBA01504), the National Natural Science Foundation of China (Grant Nos. 11347028, 11405083, and 11675075), the Natural Science Foundation of Hunan Province, China (Grant No. 2018JJ2315), and the Youth Talent Projectof Hunan Province, China (Grant No. 2018RS3096).

Abstract

With two-dimensional quantum electrodynamics (QED) particle-in-cell simulations, a dense electron–positron (e−e+) pair generation from laser-solid interactions is demonstrated. When the interaction of two linearly polarized laser pulses with a thin target enters into the relativistic transparency regime, a stable standing wave (SW) field can be formed by the overlap of the two counter-propagating laser pulses directly. The present study aims to clarify the effects of the SW field on the dynamics of e−e+ pair plasmas. Our results indicate that under the combined effect of the SW field and radiation reaction (RR) effect, the created e−e+ pairs can be trapped into the electric field nodes when the field strength is strong. The trapping effect contributes to the generation of γAV ≥ 400 and ultra-dense pair plasmas in the two-side irradiation scheme. Despite different laser intensities, these pair plasmas have a Maxwellian spectral distribution with a peak energy of 150 MeV. Besides, the periodical modulation of the average energy, spatial, phase-space, and angular patterns of the e−e+ pair plasmas can be triggered. In the angular patterns, as long as the SW field exists, pair plasmas can be pinched along the laser polarization direction. These results may offer a better understanding of the laser–solid interactions in the experiments when 10-PW laser facilities come into operation in the future.