Effective production of gammas, positrons, and photonuclear particles from optimized electron acceleration by short laser pulses in low-density targets

TL;DR

This study uses 3D PIC simulations to optimize laser-driven electron acceleration in low-density plasma, achieving high-energy electron bunches that efficiently produce gamma rays, positrons, and nuclear particles.

Contribution

It introduces a self-trapping laser propagation regime in low-density plasma that maximizes high-energy electron yield for particle and radiation production.

Findings

High electron yields enable efficient gamma, positron, and nuclear particle generation.

A self-trapping propagation regime prevents relativistic self-focusing, maintaining laser beam stability.

Monte Carlo simulations confirm the production of various nuclear particles from the accelerated electrons.

Abstract

Electron acceleration has been optimized based on 3D PIC simulations of a short laser pulse interacting with low-density plasma targets to find the pulse propagation regime that maximizes the charge of high-energy electron bunches. This regime corresponds to laser pulse propagation in a self-trapping mode where the diffraction divergence is balanced by the relativistic nonlinearity such that relativistic self-focusing on the axis does not happen and the laser beam radius stays unchanged during pulse propagation in a plasma over many Rayleigh lengths. Such a regime occurs for a near-critical density if the pulse length considerably exceeds both the plasma wavelength and the pulse width. Electron acceleration occurs in a traveling cavity filled with a high-frequency laser field and a longitudinal electrostatic single-cycle field ("self-trapping regime"). Monte Carlo simulations demonstrated a high electron yield that allows an efficient production of gamma radiation, electron--positron pairs, neutrons, and even pions from a catcher-target.