No abstract available

No abstract available

[en] Experiments at LLNL using the 10 TW Novette laser have led to significantly increased understanding of laser/plasma coupling. Tests using 1.06 μm, 0.53 μm and 0.26 μm light have shown increased light absorption, increased efficiency of conversion to x-rays, and decreased production of suprathermal electrons as the wavelength of the incident light decreases. The data indicate that stimulated Raman scattering is the source of the excessive hot electrons and that the effect can be controlled by the proper selection of laser frequency and target material. The control of these effects has led to achievement of higher inertial fusion target compressions and to production of the first laboratory x-ray laser

[en] Bremsstrahlung radiation can be used to excite nearly monoenergetic x rays in secondary targets, which are then used to study the energy response of radiation detectors if the intensity and purity are known. A method is suggested for calculating the spectral intensity of the secondary target radiation, including K-fluorescent x rays, and the bremsstrahlung and characteristic line radiation scattered from the target. Coherent and incoherent scatter are included in the calculation. To test the theory, bremsstrahlung radiation from an x-ray unit operating in the 100- to 300-kV potential range was used to excite K-fluorescent radiation in secondary targets that range in atomic number from 29 to 90. The primary and secondary spectra were measured with NaI, silicon, and germanium detectors. The measured primary spectral intensities were used as input to the secondary spectral intensity calculation. Calculated secondary spectra were within 20 percent agreement with measurement. Optimization of the secondary target intensity and purity is discussed as a function of target thickness, potential, and selective filtration

[en] A 1985-1986 Review of the US inertial confinement fusion program by the National Academy of Sciences concluded that five more years might be required to obtain enough data to determine the future course of the program. Since then, data from the Nova laser and from the Halite/Centurion program have resolved most of the outstanding problems identified by the NAS review. In particular, we now believe that we can produce a sufficiently uniform target; that we can keep the energy content in hot electrons and high-energy photons low enough (/approximately/1--10% of drive energy, depending on target design) and achieve enough pulse-shaping accuracy (/approximately/10%, with a dynamic range of 100:1) to keep the fuel on a near-Fermi-degenerate adiabat; that we can produce an /approximately/100-Mbar pressure pulse of sufficient uniformity (/approximately/1%), and can we control hydrodynamic instabilities so that the mix of the pusher into the hot spot is low enough to permit marginal ignition. These results are sufficiently encouraging that the US Department of Energy is planning to complete a 10-MJ laboratory microfusion facility to demonstrate high-gain ICF in the laboratory within a decade. 22 refs., 1 fig

[en] A process for the detection of carbon-containing ions, particularly uranyl tricarbonate, adsorbed on an ion-exchange resin, comprising introducing a sample of the ion-exchange resin to nuclear magnetic resonance (nmr) spectroscopy

[en] Tables of electron elastic scattering differential cross sections of elements (Z = 1 to 100) are given for electron energies in the range of 1 keV to 100 MeV and scattering angles in the range of 1 to 179⁰. The function describing the asymmetry of a polarized electron beam after the scattering process is also included in the tables

[en] Controlled fusion, pursued by investigators in both the magnetic and inertial confinement research programs, continues to be a strong candidate as an intrinsically safe and virtually inexhaustible long-term energy source. We describe the status of magnetic and inertial confinement fusion in terms of the accomplishments made by the research programs for each concept. The improvement in plasma parameters (most frequently discussed in terms of the Tn tau product of ion temperature, T, density, n, and confinement time, tau) can be linked with the construction and operation of experimental facilities. The scientific progress exhibited by larger scale fusion experiments within the US, such as Princeton Plasma Physics Laboratory's Fusion Test Reactor for magnetic studies and Lawrence Livermore National Laboratory's Nova laser for inertial studies, has been optimized by the theoretical advances in plasma and computational physics. Both TFTR and Nova have exhibited ion temperatures in excess of 10 keV at confinement parameters of n tau near 10¹³ cm^-3 . sec. At slightly lower temperatures (near a few keV), the value of n tau has exceeded 10¹⁴ cm^-3 . sec in both devices. Near-term development plans in fusion research include experiments within the US, Europe, and Japan to improve the plasma performance to reach conditions where the rate of fusion energy production equals or exceeds the heating power incident upon the plasma. 9 refs., 7 figs

[en] The objectives of the Lawrence Livermore National Laboratory Laser Fusion program are to understand and develop the science and technology of inertial confinement fusion (ICF), and to utilize ICF in short- and long-term military applications, and, in the long-term, as a candidate for central-station civilian power generation. In 1984, using the Novette laser system, the authors completed experiments showing the very favorable scaling of laser-plama interactions with short-wavelength laser light. Their Novette experiments have unequivocally shown that short laser wavelength, i.e., less than 1 μm, is required to provide the drive necessary for efficient compression, ignition, and burn of DT fusion fuel. In other experiments with Novette, the authors made the first unambiguous observation of amplified spontaneous emission in the soft x-ray regime. The authors also conducted military applications and weapons physics experiments, which they discuss in detail in the classified volume of our Laser Program Annual Report. In the second thrust, advanced laser studies, they develop and test the concepts, components, and materials for present and future laser systems. Over the years, this has meant providing the technology base and scientific advances necessary to construct and operate a succession of six evermore-powerful laser systems. The latest of these, Nova, a 100-TW/100-kJ-class laser system, was completed in 1984. The Nd:glass laser continues to be the most effective and versatile tool for ICF and weapons physics because of its scalability in energy, the ability to efficiently convert its 1=μm output to shorter wavelengths, its ability to provide flexible, controlled pulse shaping, and its capability to adapt to a variety of irradiation and focusing geometries. For these reasons, many of our advanced laser studies are in areas appropriate to solid state laser technologies

[en] The requirements for high gain in inertial confinement are given in terms of target implosion requirements. Results of experimental studies of the laser/target interaction and of the dynamics of laser implosion. A report of the progress of advanced laser development is also presented. 3 refs., 8 figs., 1 tab