A. Sorokovikova

Investigation of high-intensity laser-plasma interaction in multi-picosecond laser pulse length regime

Intense (Ilaser>1018 W/cm2) laser-plasma interaction offers a very efficient source of fast electrons at relativistic energies, which can be used for fast-ignition inertial confinement fusion, ultra-short x-ray sources and heating matter to warm dense states. We report theoretical and particle-in-cell simulation results for characterization of fast electron source produced from intense laser interaction with solid targets at the time scale of multi-picosecond and energy scale of kilojoule. A substantial increase in both fast electron average energy and laser-electron conversion efficiency has been observed when the laser pulse length was extended from 1 to 10 picoseconds. The enhanced electron acceleration is attributed to a significant thermal preplasma expansion on several picosecond time scale that forms a long flat “shelf” at near-critical (0.1nc~nc) density region, and ponderomotive piling-up of electrons that leads to a sharp interface at relativistic critical density γnc. Both of these eventually result in large amplitude increase and volume broadening of the electrostatic potential for electron acceleration.

Characterization of MeV electron generation using 527nm laser pulses for fast ignition

Summary form only given. Fast Ignition [1] holds the promise of improved efficiency and reduced laser energy requirements for Laser Fusion Energy systems. The main approach proposed to date is by coupling a beam of 1 to 2 MeV electrons from the laser interaction spot to a 40 micron spot in the compressed fuel core using a metal cone insert to get close to the compressed core [2]. However, multi-millijoule level laser prepulse can create extended preplasmas within the cone, effectively moving the electron generation source region far back from the cone tip and core [3]. By employing second harmonic pulses much reduced levels of prepulse can be achieved and at the same time colder electron distribution can be obtained, closer to those required ultimately for Fast Ignition.