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The development of a plasma environment that is appropriate for the study of laser‐plasma processes in laser‐fusion plasma is reported. A material (titanium) with medium atomic number (Z) was used to provide x‐ray measurements of radial and axial plasma symmetry as well as electron temperature. The electron density evolution was measured using stimulated scattering processes and odd half‐harmonic generation from probe lasers of different wavelengths. The plasmas were created by two‐sided irradiation of thin foils with 24 kJ of 351 nm laser light. When the peak electron density had decayed to about 4×1020 cm−3, the density profile was estimated to have a full width at half‐maximum of 2 mm and the electron temperature was measured to be about 3 keV using K‐shell spectroscopy. Two‐dimensional computer simulations were found to reproduce some features of both electron density and temperature evolution.

The amount of interpenetration and stagnation in counterstreaming laser‐produced plasmas is investigated via a kinetic model and a multifluid model in one‐dimensional planar geometry. Each of these models can evolve multiple ion species in the self‐consistent electrostatic field with Coulomb collisional interaction. The two approaches are applied to various colliding plasma systems, ranging from simple homogeneous slowing‐down and temperature‐equilibration problems to colliding plasmas characteristic of laser irradiated thin foils and thick disks. In particular, direct comparisons are made between the kinetic formulation and the multifluid model with various approximations for the multifluid collisional coupling coefficients.

Multiangle, time-resolved, spectroscopic measurements of laser-light scattering from preformed, large, very underdense laser plasmas with finite inhomogeneous flow are reported. Absolutely calibrated spectra of the scattered light were recorded simultaneously at several angles. The variations in the scattering in time and angle indicate that ion-acoustic turbulence, rather than stimulated Brillouin scattering, is dominant in determining the scattering amplitudes.

Near‐forward scattering of laser light in a plasma, in regimes relevant to future inertial‐confinement‐fusion (ICF) experiments, has been investigated experimentally. The intensity scaling of stimulated Raman scattering (SRS) forward scattering at one angle was measured from a low‐Z plasma. It was found that the intensity threshold and scaling were consistent with convective theory. Forward SRS saturated at a relatively low intensity. In a second experiment using Ti plasmas, absolutely calibrated, time‐resolved stimulated Brillouin scattering (SBS) spectra from up to seven different angles were measured simultaneously. It was found that the angular dependence of the scattered energy was qualitatively consistent with convective theory. The spectra provided the first evidence of near‐forward SBS. Contrary to previous estimates, near‐forward SBS was shown to be more efficient than oblique backscattering and may be an important effect for ICF.

A fully kinetic particle‐in‐cell (PIC) model is used to self‐consistently determine the steady‐state potential profile in a collisionless plasma that contacts a floating, absorbing boundary. To balance the flow of particles to the wall, a distributed source region is used to inject particles into the one‐dimensional system. The effect of the particle source distribution function on the source region and collector sheath potential drops, and particle velocity distributions is investigated. The ion source functions proposed by Emmert et al. [Phys. Fluids 23, 803 (1980)] and Bissell and Johnson [Phys. Fluids 30, 779 (1987)] (and various combinations of these) are used for the injection of both ions and electrons. The values of the potential drops obtained from the PIC simulations are compared to those from the theories of Emmert et al., Bissell and Johnson, and Scheuer and Emmert [Phys. Fluids 31, 3645 (1988)], all of which assume that the electron density is related to the plasma potential via the Boltzmann...

Time-resolved, 2D images of x-ray emission from thin, laser-irradiated titanium foils are presented. The foils are irradiated with 0.35 \ensuremath{\mu}m light at intensities of 1 \ifmmode\times\else\texttimes\fi{} ${10}^{15}$ W/${\mathrm{cm}}^{2}$ which produces a plasma with electron densities \ensuremath{\le} ${10}^{22}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ and electron temperature of 3-4 keV. X-ray emission that is characteristic of the thermal heat front is observed to propagate radially outward from the heated region. Comparison of these measurements with 2D hydrodynamic simulations of the experiment suggests the radial heat flux to be about 3% of the free-streaming heat flux.

A soft x-ray laser (wavelength lambda = 15.5 nanometers) was used to create a moiré deflectogram of a high-density, laser-produced plasma. The use of deflectometry at this short wavelength permits measurement of the density spatial profile in a long-scalelength (3 millimeters), high-density plasma. A peak density of 3.2 x 10(21) per cubic centimeter was recorded.

Summary form only given. Contact, transmission, and reflection X-ray laser microscopes have been constructed and are being used for biological microstructure studies. Two-dimensional images are being produced with sub-1000/spl Aring/ resolution. Efforts to improve the resolution and produce three-dimensional images are underway. X-ray lasers are also being used in moire deflectrometry experiments designed to measure electron density gradients in laser plasmas at densities near or above critical. An X-ray laser based interferometer is being designed for measuring two-dimensional electron density profiles in laser plasmas. In materials sciences, X-ray laser based experiments designed to study cluster formation are being developed. All of these applications exploit the unique short pulse, extremely high brightness output of the X-ray laser.