The advantages and disadvantages of four new high-resolution difference schemes, namely the von Neumann-Richtmyer, Godunovs, MUSCL and Glimms, for mathematically representing physical conditions in compressible gas flows are compared. (LCL)

Two recent conference papers on the use of cellulose nitrate and CR-39 to diagnose laser fusion targets are combined with a chronological introduction and update to efforts in this area.

A high-voltage trigger system capable of triggering 30, 250 kV spark gaps; each with less than +- 1 ns jitter has been constructed. In addition to low jitter rates, the trigger system must be capable of delivering the high voltage pulses to the spark gaps either simultaneously or sequentially as determined by other system requirements. The trigger system consists of several stages of pulse amplification culminating in 160 kV pulses having 30 ns risetime. The trigger system is described and test data provided.

A pulsed electron accelerator has been constructed and is now in operation at the Lawrence Livermore Laboratory. This Experimental Test Accelerator (ETA) a 5 MeV, 10 kA, 50 ns FWHM, five pulse burst at 1 kHz, was designed to be the front end or injector for the Advanced Test Accelerator (ATA). The ATA is presently under construction and will have the following parameters: beam energy - 50 MeV, beam current - 10 kA, pulse length - 70 ns, repetition rate in a ten pulse burst - 1 kHz. The parameters which make the pulse power components unique for these machines are the high repetition rate in a burst and a high degree of regulation in the system to insure pulse to pulse repeatability. Because of the larger number of components requird for ATA, a much higher degree of reliability will be required. Improvements and modifications continue to be made on the ETA, which is serving as a base of development for all ATA pulse power components. Furthermore, all ATA pulse power components will be tested at length in a test stand before beginning mass production to insure proper design to meet voltage, current, rep-rate and life requirements.

Some of the changes since 1970 in procedures for plating on such materials as titanium, molybdenum, silicon, aluminum, and gallium arsenide are summarized. While basic procedures for plating some of these materials were developed as many as 30 to 40 years ago, changes in the end uses of the plated products have necessitated new plating processes. In some cases, vacuum techniques - such as ion bombardment, ion implantation, and vacuum metallization - have been introduced to improve the adhesion of electrodeposits. In other cases, these techniques have been used to deposit materials upon which electrodeposits are required.

The heat transfer equation of an arc discharge has been solved. The arc is assumed to be a cylinder with negligible axial variation and the dominant heat transfer process is conduction radially inside the column and radiation/convection at the outside edge. The symmetric consideration allows a simple one-dimensional formulation. By taking into account proper variation of the electrical conductivity as function of temperature, the heat balance equation has been solved analytically. The radius of the arc and its current-field characteristics have also been obtained. The conventional results that E approx. I/sup 0/ /sup 5385/ and R approx. I/sup 0/ /sup 7693/ with E being the applied field, I the current, and R the radius of the cylindrical arc, have been proved to be simply limiting cases of our more general characteristics. The results can be applied quite widely including, among others, the neutral beam injection project in nuclear fusion and MHD energy conversion.

The neutrino emission resulting from stellar collapse and supernova formation is reviewed. The electron capture and consequent neutronization of the collapsing stellar matter at the end of evolution determines both the initial adiabat of core collapse as well as the trapped lepton fraction. The initial lepton fraction, Y/sub l/ = .48 supplies the pressure for neutral support of the star at the Chandrasekhar limit. High trapping values, Y/sub l/ = .4, lead to soft core collapses; low values to harder collapses. The value of Y/sub l/ is presently in dispute. The neutrino emission from initial electron capture is relatively small. A strong core-bounce shock releases both electron neutrino as well as thermal muon and tau neutrinos. Subsequent neutrino emission and cooling can sometimes lead to an unstable buoyancy gradient in the core in which case unstable core overturn is expected. Calculations have already shown the importance of the largest possible eddy or equivalently the lowest mode of overturn. Present models of low lepton trapping ratio lead to high entropy creation by the reflected shock and the stabilization of the core matter against overturn. In such cases the exterior matter must cool below an entropy of approximately s/k approx. = 2 …

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The detection of losses of special nuclear materials has been the subject of much research in recent years. The standard industry practice using ID/LEID will detect large magnitude losses. Time series techniques such as the Kalman Filter or CUSUM methods will detect small magnitude losses if they occur regularly over a sustained period of time. To date no technique has been proposed which adequately addresses the problem of detecting a small magnitude loss occurring in a single period. This paper proposes a method for detecting a small magnitude loss. The approach makes use of the influence function of Hempel. The influence function measures the effect of a single inventory difference on a group of statistics. An inventory difference for a period in which a loss occurs can be expected to produce an abnormality in the calculated statistics. This abnormality is measurable by the influence function. It is shown that a one period loss smaller in magnitude than the LEID can be detected using this approach.