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.

An attempt was made to develop a thesaurus of terminology associated with geothermal energy for use in the information storage and retrieval system of LBL's Geothermal Information Group. The development of the thesaurus is discussed, beginning with an outline of its subject scope, sources, and methods used in compiling the list of terms. The tendency was to include, rather than exclude, terms of unknown usefulness, and to provide paths through the thesaurus to make these terms accessible. The thesaurus structure and links to other vocabularies are described. The thesaurus processing software developed at LBL is briefly mentioned.

The fabrication steps are examined for a complex glass target which is designated as a Ball-in-Plate or Saturn target. The Ball-in-Plate target consists of a hollow, D-T filled glass sphere mounted in a thin glass plate. The glass plate is coplaner with a diametral plane of the sphere.

A computer code was written to describe the alpha particle energy loss. The problem of a symmetric compression of the DT gas by an exploding microsphere is analyzed. The code calculates the energy spectrum of a Gaussian distribution of alpha particles after passing through the compressed gas and the exploded glass. The calculations are being used to determine design parameters for diagnostic instruments for measuring charged particle energy distributions from laser fusion targets. (MOW)

Polyethylene foils and parylene disks 5 to 10 ..mu..m thick have been irradiated by CO/sub 2/ laser pulses focused to flux levels in the 10/sup 13/ to 10/sup 14/ W/cm/sup 2/ range. A CO/sub 2/ laser system, ''Valkyrie,'' fabricated from commercially available components was assembled for these experiments. The switched-out nanosecond pulse is next amplified by two cold-cathode electron-beam sustained amplifiers built by Systems, Science, and Software, Inc. After passing through the beam diagnostics tables, the beam is finally focused on the target in the chamber in the foreground. Some results using this system are described. (MOW)

This paper discusses a series of experiments performed with the LLL two-beam laser system, JANUS. The JANUS laser is capable of focusing approximately 500 Gigawatts of 1.06 ..mu.. power (40 J in 80 psec) on laser fusion type targets. In these experiments, the targets were deuterium tritium (DT) filled glass microshells with aspect ratios of 100 to 200. Targets of this type operate in what is commonly called the exploding pusher mode. The result is that the glass shell surrounding the DT gas (the thermonuclear fuel) effectively explodes, and consequently from geometry, also implodes and compresses and heats the DT gas to TN conditions. The advantages and disadvantages of the exploding pushers type target, as compared with the high density isentropic implosion target of the future, is illustrated.

Data processing for the laser systems in operation at LLL is discussed. Methods for automatic storage, reduction and display using the computers and the Octopus system at LLL are described. This paper briefly describes how this data is compiled, correlated, and displayed. (MOW)

The imaging properties and design principles for an axisymmetric x-ray microscope using a hyperboloid surface preceding an ellipsoidal reflecting surface are discussed. The results of a design study investigating the off-axis resolution of x-ray microcopes are presented. (MOW)

It was found that a new type of solid-state detector known as the self-scanning photodiode array can be used to obtain the active readout of data in wavelength-dispersive x-ray spectrometers. The use of this device to recover x-ray spectral data for glass microspheres heated by Lawrence Livermore Laboratory's CYCLOPS laser is reported. The self-scanning photodiode array is a product of the MOS electronics fabrication technology. It consists of an array of semi-discrete diffused junction photodiodes deployed along a line on a silicon chip. The signals generated in the array of diodes are serially-scanned and multiplexed by a scanning circuit built on the chip. The sensitivity and other aspects of the response of the photodiode arrays to low-energy x-rays has been previously reported. The photodiode array was used in conjunction with a flat KAP single-crystal in a series of spectrometry experiments. Of particular interest has been the analysis of the hydrogen-like and helium-like 1s-2p radiations of silicon in the neighborhood of 2 keV.

During 1974-1975, first generation laser implosion experiments have been performed at the KMSF, Livermore, Los Alamos, and University of Rochester Laboratories. Several significant results were achieved in these experiments. The fuel underwent large entropy changes during implosion and did not reach high densities. Consequently, the sensitivity to fluid and plasma instabilities was greatly reduced. A summary of these implosion experiments is presented.

A brief description is given of techniques that have proved successful in obtaining samples of hot and cold spring waters for x-ray fluorescence, neutron activation, and radiometric analysis. The sampling methods require only lightweight, portable field apparatus. Various types of springs sampled are illustrated. Chemical geothermometer temperatures from these samples have compared well with reported measured subsurface temperatures. (LBS)

CYCLOPS was originally built as a single arm Nd-glass laser prototype for larger multiple arm systems. This paper reports on the characteristics of the laser, describes the diagnostics which monitor its performance, and shows how the output pulse is delivered accurately to the target.

Because of the increase in cost of foreign oil, ethylene costs have increased markedly within the last several years. There is presently a sizable incentive to reduce raw material cost for basic polymer manufacture. The polyketones, synthesized from ethylene and CO, and the polysulfones, synthesized from ethylene and SO/sub 2/, utilizing high energy radiation, offers one such possibility. The process has the additional advantage in that CO and SO/sub 2/ usually considered as wastes and pollutants from fossil fuel burning power plants are converted to useful materials. The polyketones and polysulfones formed from the gas phase below 100/sup 0/C have been found to be high molecular weight polymers which, depending on composition either melt with difficulty, or decompose at temperatures of 250/sup 0/C or higher. The higher temperature (greater than 100/sup 0/C) catalyst-induced reaction produces low molecular weight waxes. Design calculations indicate that for a G value of 10,000 and 50 percent energy deposition efficiency, it would take 331 M Ci of /sup 60/Co to conserve 2 billion pounds of ethylene or 25 percent of the overall U.S. market by substituting CO and SO/sub 2/. This savings amounts to as much as $280 million at today's market price. Electron machine …

Absolute spectral measurements were made of electrons escaping from plasmas produced by focusing 5-10 J, 50-100 picosecond, 1.06 ..mu..m laser pulses on 10 ..mu..m thick Parylene disk targets. Nine spectral bands with 3 to 7.5 keV resolution were obtained from 30 to 190 keV using a 90/sup 0/ focusing permanent magnet spectrometer and appropriately positioned silicon electron detectors.

This paper is a discussion of curved crystal x-ray spectrometry of laser induced plasmas for h..nu.. < 4 keV. The plasmas were produced by a short pulse (<200 ps) of 1.06 ..mu.. (neodymium glass) radiation on glass shells on the order of a hundred ..mu..m in diameter and a micron thick. Total absorbed laser energy is of the order of 10 joules and x-radiation .01-.1 joule/sr. The shells were filled with DT gas under compression.

The initial results of a comparative study of the radiation strengthening and damage structures produced in Cu and Nb by D-T fusion and fission reactor neutrons are described. The radiation strengthening produced by a given fluence of fusion neutrons above about 10$sup 17$n/cm$sup 2$ is equal to that produced by a fluence of fission reactor neutrons (E greater than 0.1 MeV) ten times as great. This difference is about twice as large as would be expected if the strengthening scaled with damage energy or dpa. Initial transmission electron microscopy observations of the damage structures in fusion and fission reactor neutron irradiated copper indicate that the same type of primary structural defects, vacancy and interstitial point defect clusters and small dislocation loops with a/3 (111) and a/2 (110) Burgers vectors, are produced in both cases. The difference in the radiation strengthening produced by fusion and fission reactor neutrons in Cu appears to result from a substantially greater rate of accumulation of damage, in the form of point defect clusters, during irradiation with fusion neutrons than during irradiation with fission reactor neutrons plus a significant difference in the size and spatial distributions of the damage clusters. (auth)

Using the time-of-flight technique, energy distribution measurements were made of the fusion produced $alpha$ particles emitted from laser implosions of DT gas contained in glass microshells. The number of nuclear reactions was determined by an absolute measurement of both the number of $alpha$ particles and the number of neutrons. From the FWHM of the $alpha$ particle energy distributions, upper limits of the plasmas ion temperature have been inferred. By applying corrections for the broadening of the distribution due to the fuel and the pusher, ion temperatures of 2-3 keV have been calculated. These measurements constitute significant evidence that the implosions produced thermonuclear burn of the DT fuel. (auth)

A scanning electron microscope (SEM) facility for the examination of tritium-containing materials is operational at Mound Laboratory. The SEM is installed with the sample chamber incorporated as an integral part of an inert gas glovebox facility to enable easy handling of radioactive and pyrophoric materials. A standard SEM (ERTEC Model B-1) was modified to meet dimensional, operational, and safety-related requirements. A glovebox was designed and fabricated which permitted access with the gloves to all parts of the SEM sample chamber to facilitate detector and accessory replacement and repairs. A separate console combining the electron optical column and specimen chamber was interfaced to the glovebox by a custom-made, neoprene bellows so that the vibrations normally associated with the blowers and pumps were damped. Photomicrographs of tritiated pyrophoric materials show the usefulness of this facility. Some of the difficulties involved in the investigation of these materials are also discussed.

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