Bubbles are concentrations of electromagnetic energy in the region of the critical density that force out the plasma to form a void. Since the critical density surface is cratered, absorption may be greater than a smooth surface since a larger area will be available for absorption and the reflected light will have a large probability of restriking the critical density. The distance between bubbles is several wavelengths and consequently they may encourage Rayleigh--Taylor instabilities. The threshold, magnetic field generation, and possible experimental evidence for bubbles are discussed. Also, the competition between sidescatter and self focusing in an entirely underdense plasma is studied and it is found that sidescatter dominates for polarization out of the simulation plane.

ARGUS is a two-beam Nd: glass laser system built for laser fusion irradiation experiments. It is the first glass laser system planned and built with the understanding that small-scale beam break-up is the dominant performance limiting factor in obtaining high output power. Accordingly, five vacuum spatial filters are located at strategic intervals along each chain to eliminate the accumulated small-scale filamentation. This strategy permits cascading of amplifiers to obtain a focusable output of more than one terawatt per arm in a spatially clean beam of 20 centimeter diameter. Beam diagnostics which characterize each shot include the time-integrated spatial profile and the time resolved intensity/power at the target. Demonstrated performance to date includes: (1) Peak power in excess of 2 TW at the target is achieved with regularity. (2) Maximum system brightness is in excess of 10/sup 17/ watts/cm/sup 2/ ster. (3) Shot-to-shot pointing stability within 50 ..mu.. radians is achieved over periods of days. (4) Successful target experiments have been performed with pulses of from 30 to 500 ps duration.

An analysis of the scheme to heat magnetically confined plasma columns to kilovolt temperatures with a laser beam requires consideration of two propagation problems. The first question to be answered is whether stable beam trapping is possible. Since the laser beam creates its own density profile by heating the plasma, the propagation of the beam becomes a nonlinear phenomenon, but not necessarily a stable one. In addition, the electron density at a given time depends on the preceding history of both the medium and the laser pulse. A self-consistent time dependent treatment of the beam propagation and the medium hydrodynamics is consequently required to predict the behavior of the laser beam. Such calculations have been carried out and indicate that propagation of a laser beam in an initially uniform plasma can form a stable filament which alternately focuses and defocuses. An additional question that is discussed is whether diffractive losses associated with long propagation paths are significant.

The formation of ozone from oxygen and the dissociation carbon dioxide to carbon monoxide and oxygen is studied in a gamma-neutron chemical process blanket associated with a controlled thermonuclear reactor. Materials used for reactor tube wall will affect the efficiency of the energy absorption by the reactants and consequently the yield of reaction products. Three kinds of materials, aluminum, stainless steel and fiber (Al/sub 2/O/sub 3/)-aluminium are investigated for the tube wall material in the study.

Copper and uranium were melted together in an electron beam furnace, rolled and vacuum annealed at 900/sup 0/C. Several samples were examined, varying in uranium content from 0.074 to 1.82 wt. percent. Each sample was mounted in a resin and polished for optical microscope and electron microprobe work. These samples, when viewed under an optical microscope exhibited three distinct phases: featureless grain surfaces, a light gray phase in the grain boundaries, and an occasional dark gray phase also found in the grain boundaries. It is shown that the Count Rate Discriminator technique used in coincidence with a target current detector provides a powerful tool to map and to determine quantitatively the distribution of minor phases in grain boundaries and inclusions. (DLC)

The gain of thermonuclear pellets containing a pusher-tamper of high density high-Z material surrounding the DT fuel is considered. Other significant characteristics of such capsules are briefly mentioned. (MOW)

In analyzing CaF/sub 2/:Dy (TLD-200) data from the environmental monitoring program at the Lawrence Livermore Laboratory, a quantity of significance is the dose to the thermoluminescence dosimeters during shielded storage. This paper describes a method for determining this shield dose, which can then be related to the dose from cosmic radiation. Data, based on quarterly TLD exposure periods, show a range of 43-56 ..mu..rads per day in a 75 mm thick lead shield. Observed variations in the shield dose have led to studies of prolonged exposure of TLDs to elevated and reduced temperatures typical of those in the Livermore Valley.

Simultaneous measurements of enthalpy, specific volume, temperature, and electrical resistivity for lead and uranium were measured. From the measured data, estimates of the bulk modulus and sound velocity in these metals are made. (GHT)

A method for calculating quasi-one-dimensional, steady-state, two-phase dispersed droplet-in-vapor flow has been developed. The technique is applicable to both subsonic and supersonic single component flow in which normal shock waves may occur, and is the basis for a two-dimensional model. The flow is assumed to be inviscid except for droplet drag. Temperature and pressure equilibrium between phases is assumed, although this is not a requirement of the technique. Example calculations of flow in one-dimensional nozzles with and without normal shocks are given and compared with experimentally measured pressure profiles for both low quality and high quality two-phase steam/water flow.

The resources and talents of many national and international organizations and laboratories, both governmental and industrial, are being used to establish analysis methods for predicting the embritlement condition of light water reactor (LWR) primary systems.. The exact interrelationships and responsibilites between those developing, uderstanding, combining, and apply state-of-the-art technology in dosimetry, metallurgy, and fracture mechanics for reactor systems analysis are being carefully reviewed and studied. This has resulted in a more comprehensive definition of the scope of new and updated ASTM standards required for the analysis and interpretation of LWR pressure vessel survillance results. Fifteen new and updated ASTM standards have now been identified, together with a restructuring of the main interfaces between the individual standard practices, guides, and methods. This paper briefly discusses these standards and the initial results of multi-laboratory research work involved in their validation and calibration.

A six-inch radius mass spectrometer has been constructed and demonstrated to adequately analyze water samples for uranium concentrations down to 5 to 10 ng/liter (ppt). The precision and accuracy of the isotope-dilution, thermal emission method is sufficient to meet the needs of the Uranium Resources Evaluation (URE) project. A single analyst can analyze in excess of 50 samples per day, including all preparation and instrument time. This analysis rate will meet the economic constraints of the URE analytical program.

Bronze-processed Nb/sub 3/Sn composite wire conductors exhibit changes in their superconducting parameters when strained in tension. This paper describes a detailed study of the effect of strain on critical current and an analysis by optical and SEM techniques of crack formation in the Nb/sub 3/Sn layer under strain. The effect of strain history on both reversible and irreversible changes in critical current and the roles of differential thermal contraction induced residual strains and of Nb/sub 3/Sn cracking are discussed.

Figure-of-merit equations for material selection and detailed design equations have been developed to aid in the design of a linear electrooptic deflector element for use in a 10-ps streak camera. The figure of merit indicates that BaTiO/sub 3/, KTN, and ammonium oxalate (AMO) are suitable materials. Possible deflector designs, including that of a current AMO prototype development program, are discussed. Quadratic (Kerr-effect) operation and materials are discussed along with the possibility for 10.6-..mu..m-wavelength use.

As part of Lawrence Livermore Laboratory's Enhanced Filtration Program, we are investigating the use of an externally applied electric field to improve the performance of fibrous filters. Our objective in this program is to develop filtration systems for the nuclear industry that will reduce the cost and volume of nuclear waste associated with present systems. We have developed a new theory of the electrostatic filter that is consistent with experimental tests made during transient and steady-state conditions. For these tests, we used ac and dc electric fields, insulated and noninsulated electrodes, and conducting and nonconducting filter media; all tests were conducted in our small-scale 25 l/s test system, using sodium chloride aerosols. Our theory employs a new mechanism based on the attraction between charged particles and charged fibers in addition to the previously proposed mechanism based on the attraction between charged particles and polarized fibers. In this theory, fibers are charged when charged particles deposit on them. We have also developed a theoretical model that explains the increase in filter efficiency and pressure drop when particles load on the filter. The filter loading tests we conducted to evaluate this model verify its accuracy to a remarkable degree. By using the …

The Lawrence Livermore Laboratory undertook an investigation of the properties of ferrite materials to be used in a 5-MeV, 50-ns linear induction accelerator. The investigation, on a part-time basis, lasted about one year and had the cooperation and helpful suggestions of several manufacturers: TDK of Japan, Phillips of Holland, and Stackpole of the U.S.A. Ferrites have been widely used as tuning cavities for proton synchrotron accelerators at radio frequencies. In such an application, the ..mu..Qf factor is used in describing the figure of merit for ferrites where a high duty factor requires low loss ferrites. In a linear induction accelerator with an average reprate of 5-Hz, the ferrite losses are negligible and the concept of complex permeability in describing the losses will not be introduced, but a large signal ..delta..B/..delta..H will be used to describe their properties. The properties of interest in designing the accelerating cavity were (1) flux swing ..delta..B = B/sub r/ + B/sub m/ greater than 0.5T; (2) a residual flux density B/sub r/ greater than or = to 0.15T with a reset no greater than 2 Oer; (3) a relatively high incremental ..mu.. greater than 400 to keep the excitation current small in relation to the …

This paper examines the fidelity of a dielectric, encapsulated magnetic probe in the adverse plasma environment encountered in plasma focus experiments. The ionization of the surface of the probe produces a conductive layer that tends to shield it from external magnetic fields. The solution of the wave equation is used to show the allowed regions of conductivity, sigma, and thickness, d, for the ionized layer. The results show that as d approaches the penetration depth, delta = (..omega mu..sigma)/sup /sup 1///sub 2//, severe attenuation and distortion results, rendering the probe useless. When d is much less than delta, we encounter attenuation only, which also may be too severe for use. Finally, an experiment is described, which allows the experimenter to determine the fidelity of the probe.

The Lawrence Livermore Laboratory (LLL) is currently in the construction stage of the Mirror Fusion Test Facility (MFTF). MFTF will be the next large mirror fusion experiment and employs a large set of superconducting Yin-Yang coils. These coils contain 54,430 kg of stabilized NbTi conductor and will generate a peak field of 7.68 T with a stored energy of 409 MJ. This paper presents details of the design of these coils and the status of the fabrication.

Schemes that could be used for detection of superheavy elements (SHE) are briefly discussed first. The question of producing SHE in other than complete fusion reactions (e.g., in deep inelastic reactions) is addressed at greater length. Production cross sections are estimated. A heavy ion lens spectrometer for the detection of reaction products is described. 18 figures, 3 tables. (RWR)

Imaging techniques that can be used to translate seismic and electromagnetic wave signals into visual representation are briefly discussed. The application of these techniques is illustrated on the example of determining the subsurface structure of a proposed power plant. Imaging makes the wave signals intelligible to the non-geologists. R and D work needed in this area are tabulated. (JSR)

Background information concerning how and why Bendix Kansas City became interested in numerical control of machine tools and what the approach was in determining whether it would prove beneficial is presented. The present status of implementation and future plans are discussed. The material is presented by 22 slides. (TFD)

The results of the search for superheavy elements are negative with respect to the finding of such elements. However, by assuming 2 spontaneous fission events as the lower limit of detection, the limits to their formation cross sections are calculated and plotted. It is noted that the half-life limits, also shown are easily within the huge uncertainties of the theoretical predicted half lives for any superheavy element nuclides produced in the experiment. 19 references. (JFP)

To view and align Shiva laser targets, two new telemicroscopic instruments integral with TV camera and HeNe laser illuminator have been designed. The common requirement of both instruments is the capability of imaging two objects of different sizes on a TV screen: the large surrogate target (5 mm diameter) and the laser fusion target (0.250 mm diameter) with the same resolution (better than 7 ..mu..m). Both instruments have an optical relay which images the targets on a fixed reference reticle; the object is to center each target on the reticle. One of the instruments reimages the reticle plane onto the TV dectector using a zoom arrangement. This instrument translates the TV camera-zoom assembly in three axes and is thereby capable of exploring an object-space volume of 1 cm/sup 3/. In the other instrument, the reticle plane is reimaged by a zoom lens and this enlarged image is relayed to the TV detector by a cluster of five lenses. Four lateral lenses image the periphery of the surrogate target and the reticle for coincidence. The central objective images the center of the reticle and the fusion target when it is centered.

A numerical analysis has been performed on the time-dependent equations of heat balance, gas convection, pressure drop, and mass-flow rate for supercritical helium gas flowing through a tubular superconductor. Three dimensional graphs of wall temperature, gas temperature, and mass-flow rate as functions of position and time are used to show the evolution of normal zones. In contrast to other methods of studying stability in superconductors by a quasi-steady-state analysis of critical-sized normal zones (minimum propagating zone), our analysis shows that stability is influenced by both the magnitude and the time dependence of the disturbance. As the current is increased in a system subjected to certain types of thermal disturbances, propagating normal zones may originate at positions well downstream from the site of the disturbance. At higher currents, propagating zones may originate both downstream and at the disturbed site, coalescing into a large propagating normal zone. With certain types of disturbances (such as an extraneous heat source over a short length of conductor), higher critical currents may be reached by fast current ramping, while with other types of disturbances (such as self heating in a degraded section of conductor), slow current ramping leads to higher critical currents.

The Performance Measurement System (PMS), a system for managing a given project or program, is described; this system incorporates the value earned for work accomplished approach. Development and application of this system is discussed under the following headings: PMS vs conventional management control systems; PMS implementation on a project/program; PMS data elements (organization, planning and budgeting, accounting, analysis, reports, and performance measurement data elements); recent PMS applications (FFTF, CRBRP, FMEF, and FMIT); and future of PMS. 25 references, 6 figures, 3 tables. (RWR)