PPPS-2013: Generation, detection and control of ultrafast nonlinear optical processes in high energy density plasmas using spike trains of uneven duration and delay

摘要

The success of Inertial Confinement Fusion (ICF) is to achieve controlled thermonuclear burn in the laboratory which will lead to the commercialization of clean, carbon-free and safe Inertial Fusion Energy (IFE). Both ICF and IFE demand a detailed understanding of the rapidly evolving high energy density plasmas (HEDP) as intense lasers create and nonlinearly modify them. We have developed and tested new design tools for novel ultrafast diagnostics that use nonlinear optical (NLO) techniques to ferret out the complex, nonlinear, kinetic, microscopic dynamics of HEDP. Measuring the slope of the velocity distribution function of a plasma electron or ion species in a velocity sector of interest is one such paramount goal. We accomplish this by (i) adopting the appropriate method of generating a pump laser composed of spike trains of uneven duration and delay (STUD pulses)1, 2, (ii) adopting the appropriate method of detecting and diagnosing the amplified transmission of a stimulated Raman or stimulated Brillouin scattered (SRS or SBS) probe beam, and (iii) utilizing the gain variations of the scattered signal to develop a detailed map of background plasma instabilities. This GeDeCo code is being tested using output from state of the art kinetic simulations3 to emulate the microscopic state of an HED plasma. High-repetition-rate, high-average-power future drivers of IFE will use STUD pulses in order to control undesirable instabilities adaptively.