Laser-Plasma Interaction Diagnostics for ICF Fusion Research

Abstract

Understanding of the coupling of laser light to the plasma corona is essential for the success of laser-driven inertial confinement fusion (ICF). The most desirable way of imparting laser energy to the target plasma is via inverse bremsstrahlung absorption.1 In addition, at elevated intensities, the thresholds for various instabilities may be exceeded, channeling laser energy into scattered electromagnetic (EM) waves and various electrostatic waves. As a result, part of the incident laser energy may be unavailable for heating the plasma and the target may be irradiated less uniformly. Furthermore, some of the laser energy may ultimately be transferred to energetic electrons that can preheat the fuel and degrade target performance. Many of these processes, such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), two-plasmon-decay (TPD) instability, and filamentation, have been studied extensively.2 Presently, however, the understanding of these processes is not sufficient to predict their importance under realistic ICF plasma conditions. Therefore continued surveying of laser-plasma interaction processes is required to guard against unforeseen surprises. This paper surveys the plasma diagnostics used on the OMEGA laser facility at the University of Rochester’s Laboratory for Laser Energetics (LLE).