Creating solid density warm matter by laser heating in external magnetic field

Abstract

Summary form only given. Solid state density matter can be heated to high temperatures by ultrafast energy deposition. Using 1018 W/cm2 laser pulses, volumes of the order of 105 I??m3 can in principle be heated to several hundred electronvolts for several picoseconds. This is achievable if the hot electrons generated by the intense laser can be confined laterally in the region of the laser focal spot. Collisional two-dimensional particle-in-cell simulations suggest novel ways of achieving this goal. The simulations have shown that high intensity laser-generated hot electrons are confined laterally by self-generated resistive magnetic fields [1]. While these resistive fields decay on a time scale comparable with the duration of the laser pulse, according to other simulations the confinement may be possible to be maintained for a longer time by applying external megagauss magnetic fields [2]. In addition, shock waves generated in layered solids by ultrafast laser deposition are predicted by simulations to enhance the local heating [1]. By ultrafast laser heating of solid targets, conditions can be achieved similar to those found in the interiors of stars and in the atmospheres of neutron stars. Based on simulation results, an experiment has been developed to study the isochoric heating based on the magnetic control of heat transport in laser irradiated targets. The experiments involve target irradiation with the 1018W/cm2, 0.35 ps laser Leopard and megagauss external magnetic fields created by the pulsed power generator Zebra (0.6 MA, 200 ns) [3]. To investigate the confinement efficiency and the heating of Si targets tamped with polyethylene, x-ray spectroscopy and diagnostics of proton beams were developed.