In this issue: Foreword Theory and Simulations of Nonlinear SBS in Multispecies PlasmasGas-filled hohlraums are the preferred targets for indirect-drive fusion experiments planned for the National Ignition Facility. However, instabilities like stimulated Brillouin scattering in the gas may reflect large amounts of laser light out of the hohlraum. We report on a method developed to control this instability-small amount of hydrogen added to the gas strongly decreases the reflected light. Modeling of Self-Focusing Experiments by Beam Propagation CodesTo validate the codes PROP1 and PROPZ, we used data from two 1053-nm self-focusing experiments in fused silica. Self-focusing damage in the sample was induced by placing a large wire in the beam in front of the silica sample. Using a small wire, damage to the sample was avoided, and induced lensing in the sample produced an intense image of the wire. Using the measured beam profiles and waveforms as input, and the value 2.7 x cm2/W for the selffocusing coefficient in silica, the codes successfully predicted the length of the self-focusing tracks and the intensity in the induced image.iii 1 7 Gas-Filled Target Designs Produce Ignition-Scale Plasma Conditions with Nova 15Gas-filled targets provide large, uniform underdense plasmas for laser-plasma interaction experiments on Nova. This article discusses design considerations for these targets and presents calculated plasma profiles, target characterization results, and comparisons with underdense plasma parameters in ignition hohlraum designs for the National Ignition FaciIity. Stimulated Brillouin Scattering in Multispecies PlasmasLaser light propagating through the underdense plasma in a hohlraum, or the corona of a direct-drive target, is subject to stimulated Brillouin scattering (SBS). Such scattering can cause significant loss of incident laser energy and/or affect the symmetry of the implosion. This article discusses the use of mixtures (e.g., H/He) to tailor the Landau damping of the SBS driven ion acoustic waves, thereby providing a powerful method to control the instability. Optical Scatter-A Diagnostic Tool to Investigate Laser Damage in KDP and DKDPDetermining and controlling the sources of laser-induced damage in crystals of KH,PO, and deuterated KDP is important for successful production of crystals for the National Ignition Facility. This article describes the implementation of a scatter diagnostic for in situ studies of laserinduced damage and initial results from these studies. Soft X-Ray Interferometry 32The short wavelength of existing soft x-ray lasers makes them well suited to probing lar e highdensity plasmas. We have combined a multilayer optic-based interferometer and a 155 1 x-ray laser source to measure the electron density profile in millimeter-size laser-produced plasmas. Metastable Crystal Structures of Solid HydrogenWe have determined the crystal structure of vapor deposited H, or D, crystals using Raman spectroscopy. While hcp is the equilibrium crystal structure, other metastable crystal s...