Laser-triggered stochastic volumetric heating of sub-microwire array target

The interaction of an ultrashort laser pulse of moderate intensity ( ≳ 1018 W/cm2) with an innovative high-average-density target consisting of numerous sub-microwires was examined using 3D PIC simulations. We geometrically optimize the target to increase the absorption of laser light and energy (temperature) and the number of hot electrons. To explain the production of super-ponderomotive electrons (with energies significantly exceeding the ponderomotive energy), we use the test particle approach and stochastic dynamics methods to study the electron dynamics in a complicated EM field consisting of incident and reflected laser waves, the Coulomb field of charge separation at wire–vacuum interfaces, and the quasistatic magnetic field. The research demonstrates the stochastic nature of high-energy electron production in such a complicated EM field using Lyapunov exponent analysis. We describe the practical fabrication of such targets in the context of possible experiments. The considered laser–target design has a potential for use in compact laser-based neutron, x-ray sources.