A tandem mirror configuration can be created by combining hot electron end cell plasmas with neutral beam pumping. A region of large negative potential formed in each end cell confines electrons in the central cell. The requirement of charge neutrality causes the central cell potential to become negative with respect to ground in order to confine ions as well as electrons. We discuss the method of producing and calculating the desired axial potential profile, and show the calculated axial potential profile and plasma parameters for a negative configuration of TMX-Upgrade.

The nuclear criticality safety program at LLNL began in the 1950's with a critical measurements program which produced benchmark data until the late 1960's. This same time period saw the rapid development of computer technology useful for both computer modeling of fissile systems and for computer-aided management and display of the computational benchmark data. Database management grew in importance as the amount of information increased and as experimental programs were terminated. Within the criticality safety program at LLNL we began at that time to develop a computer library of benchmark data for validation of computer codes and cross sections. As part of this effort, we prepared a computer-based bibliography of criticality measurements on relatively simple systems. However, it is only now that some of these computer-based resources can be made available to the nuclear criticality safety community at large. This technology transfer is being accomplished by the DOE Technology Information System (TIS), a dedicated, advanced information system. The NCIS database is described.

A time dependent, bounce-averaged Fokker-Planck code, with quasi-linear diffusion at fundamental and second harmonic frequencies, has been used to study cold plasma trapping and heating of hot electrons in mirror geometry. Both electron-electron and electron-ion Coulomb collisions are included. The code can model either cavity heating (electric field throughout cavity as in EBT) or beam controlled heating (electric field spatially restricted as in the TMX-Upgrade tandem mirror). The heating method has implications for the equilibrium energy and anisotropy of the hot electrons. In TMX-Upgrade, off-midplane heating at the second harmonic in the thermal barrier is planned as a means to control anisotropy (T/sub parallel//T/sub perpendicular/. By spatially limiting (limit in B) the microwave beam and with strong single-pass absorption, the mean hot electron energy may also be controlled since the heating rate decreases at high energy due to the relativistic mass shift of the resonance to higher magnetic field.

Instabilities with frequencies in the neighborhood of the electron cyclotron frequency are of interest in determining stable operating regimes of hot-electron plasmas in EBT devices and in tandem mirrors. Previous work used model distributions significantly different than those suggested by recent Fokker-Planck studies. We use much more realistic model distributions in a computer code that solves the full electromagnetic dispersion relation governing longitudinal and transverse waves in a uniform plasma. We allow for an arbitrary direction of wave propagation. Results for the whistler and upper-hybrid loss-cone instabilities are presented.

We use a test particle simulation code to investigate electron cyclotron heating in a magnetic mirror well. A comparison is made between heating with one frequency and heating with two closely spaced frequencies. The code follows electron orbits in the presence of one or two monochromatic ECRH waves using guiding center equations and an equation for the electron gyrophase. Coulomb collisions with electrons and ions are simulated as a Monte Carlo scattering process. We find for the parameters of SM-1 that at the fundamental resonance the heating rate, or velocity rf diffusion coefficient, begins to decrease significantly from the quasilinear value for epsilon/sub e/ greater than or equal to 10 keV due to superadiabatic effects. As suggested by Howard et al., using multiple frequencies pushes the superadiabatic boundary to higher energies. For a given energy, the optimum frequency separations for two frequencies are those which cause the axial bounce resonances to interlace; i.e., odd multiples of the bounce frequency, ..omega../sub b/. This interlacing increases the chance of resonance overlap and thus stochasticity. If the frequency difference is equal to an even multiple of ..omega../sub b/, the diffusion coefficient returns to near its one frequency value. More generally, for more than …

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A system has been developed to perform neutron radiographic analysis of dynamic events having a duration of several milliseconds. The system has been operated in the range of 2000 to 10,000 frames/second. Synchronization has provided high-speed-motion neutron radiographs for evaluation of the firing cycle of 7.62 mm munition rounds within a steel rifle barrel. The system has also been used to demonstrate the ability to produce neutron radiographic movies of two-phase flow. The equipment uses the Oregon State University TRIGA reactor capable of pulsing to 3000 MW peak power, a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16 mm high speed movie camera. The peak neutron flux incident at the object position is approximately 4 x 10/sup 11/ n/cm/sup 2/s with a pulse, full width at half maximum, of 9 ms. Special studies have been performed on the scintillator conversion screens and on the effects of statistical limitations on the image quality. Modulation transfer function analysis has been used to assist in the evaluation of the system performance.

Ten papers were presented at the meeting. A separate abstract was prepared for each paper. (LCL)

Inertial confinement fusion (ICF) targets are made as simple flat discs, as hollow shells or as complicated multilayer structures. Many techniques have been devised for producing the targets. Glass and metal shells are made by using drop and bubble techniques. Solid hydrogen shells are also produced by adapting old methods to the solution of modern problems. Some of these techniques, problems and solutions are discussed. In addition, the applications of many of the techniques to fabrication of ICF targets is presented.

Transport in present day Spheromaks is dominated by impurity radiation. Fortunately, this is largely from oxygen and carbon, not metal vapor from the walls of the vessel on plasma guns and it is expected this loss can be eliminated by improved technique. The formation and gross MHD stability properties of these plasmas are quite well understood and so the reactor predictions depend on estimates of the energy loss rates from the plasma. In the absence of significant experimental data one is driven to consider other related devices. Tokamaks show classical ion transport, scaling with 1/B/sup 2/, but anomalous electron transport which is very insensitive to magnetic field, the well known Alcator scaling. The scaling of the Spheromak to a reactor size still produces favorable Q values with these pessimistic results. The reactor is small, with power output in the 10 to 50 MW range, but this could be deployed as a multiple unit power station, with good reliability due to the duplication, or as a small power unit for a ship or remote site. It also makes an attractive test reactor for the near term.

The coaxial-gun, compact-torus experiments at LLNL and LASNL are believed to be radiation-dominated, in the sense that most or all of the input energy is lost by impurity radiation. This paper presents a simple analytic model of the radiation-dominated decay of a compact torus, and demonstrates that several striking features of the experiment (finite lifetime, linear current decay, insensitivity of the lifetime to density or stored magnetic energy) may also be explained by the hypothesis that impurity radiation dominates the energy loss. The model incorporates the essential features of the more elaborate 1 1/2-D simulations of Shumaker et al., yet is simple enough to be solved exactly. Based on the analytic results, a simple criterion is given for the maximum tolerable impurity density.

The LLNL Nuclear Chemistry Counting Facility (NCCF) is being converted to a modern production facility. A computer network has been designed and built to implement this conversion. The outermost node of the computer network is a dedicated EPROM-based controller. The controller handles the details of driving the attached nuclear instrumentation, providing a standard interface to the remainder of the network. This paper addresses the design and the implementation of the dedicated instrumentation controller.

This paper addresses the stability aspects of several successful dc superconducting magnets such as large bubble chamber magnets, and magnets for the Mirror Fusion Test Facility and MHD Research Facility. Specifically, it will cover Argonne National Laboratory 12-Foot Bubble Chamber magnets, the 15-foot Bubble Chamber magnets at Fermi National Laboratory, the MFTF-B Magnet System at Lawrence Livermore National Laboratory, the U-25B Bypass MHD Magnet, and the CFFF Superconducting MHD magnet built by Argonne National Laboratory. All of these magnets are cooled in pool-boiling mode. Magnet design is briefly reviewed. Discussed in detail are the adopted stability critera, analyses of stability and disturbance, stability simulation, and the final results of magnet performance and the observed coil disturbances.

A design study of 12-T yin-yang coils for a conceptual Tandem Mirror Next Step (TMNS) facility has been recently performed by Lawrence Livermore National Laboratory in conjunction with the Convair Division of General Dynamics. The large magnets have major and minor radii of 3.7 and 1.5 m, 0.70 x 3.75 m/sup 2/ cross section, 46.3 MA turns, and an overall current density of 1765 A/cm/sup 2/, obtained by the use of Nb/sub 3/Sn and Nb-Ti superconductors. Each coil is composed of several subcoils separated by internal strengthening substructure to react the enormous electromagnetic forces. The size of the yin-yang coils, and hence the current density, was reduced by utilizing subcooled, superfluid He-II at 1.8 K for the coolant. This paper reviews the design study, with emphasis on He-II heat transport and conductor stability. Methods are also presented which allow the extension of Gorter-Mellink-channel calculations to encompass multiple, interconnecting coolant channels.

When the large Doppler shifts of hot-electron-ring ECRH absorption are taken into account, the spatial location of the bulk of the energy absorption can be significantly shifted from the cold-plasma resonance region. The high parallel velocity electrons absorb most of the wave energy, thereby shielding the bulk of the electron distribution from the heating source. A simple one-dimensional model of this process has been formulated, based on a right-hand circularly polarized wave which is incident from the high-field side in the parallel direction. In this model, less than 1% of the electrons absorb more than 90% of the wave energy for the case of 30-keV maximum parallel electron energy, 28-GHz microwaves, and a 1-m magnetic field scale length. The effect should be included in power balance models and Fokker-Planck velocity distribution calculations. The Doppler shift also appears for a variety of ray-tracing code calculations in the MFTF-B thermal barrier region.

In our quest to understand radiation damage in materials, it is vital that we characterize radiation sources in terms of neutron flux and spectra as well as the more-fundamental displacement damage, gas production, and transmutation rates. Such data are crucial to correlations of materials-property changes in different environments and to predictions of materials performance in inaccessible environments, such as fusion reactors. Dosimetry techniques have been developed to measure the neutron flux and spectra in diverse facilities including thermal, fast, and mixed reactors, T (d,n) and Be (d,n) accelerator sources, and high-energy spallation sources. Displacement-damage cross sections have been calculated for 36 elements spanning the periodic table. All of these exposure parameters can now be routinely measured with 10 to 15% relative accuracy at all existing radiation-effect facilities. 4 tables.

This paper discusses some of the general difficulties and problems encountered during the development of the technology of superconductors and superconducting magnets for fusion and expresses some personal concerns.

In order to explore the changing role of angular momentum transfer to the heavy target-like fragment in heavy-ion reactions, the gamma-ray multiplicities associated with projectile residues were measured in the reaction of /sup 20/Ne with /sup 181/Ta in the energy range of 7.5 to 42 MeV/nucleon. From the gamma-ray multiplicities, the intrinsic spin of the target-like nucleus was determined and corrected for the spin removed by evaporated particles. Comparisons of the measured intrinsic spin with that expected from the missing linear momentum were found to be good at low energies but failed around a bombarding energy of 17 MeV/nucleon. From the results of these studies we infer that angular momentum and therefore linear momentum is being carried away in significant amounts by particles which were not detected.

The present work assumes that any intrinsic structure in the nuclei involved is not important. Only spin, parity, and energy are considered. Quantities such as half-life, average beta energy, or average gamma energy can be obtained by integrals over the beta strength function weighted by kinematic and other factors. The beta strength function is proportional to the level density multiplied by a reduced transition probability. Delayed neutron emission is calculated by assuming that the daughter is a compound nucleus which then statistically decays as in the Hauser-Feshbach approach. Using the ENDF/B-V fission product file which contains 877 nuclei, energy-dependent reduced transition probabilities were found for allowed 0/sup +/ ..-->.. 1/sup +/ transitions (50 cases) and for other allowed transitions (over 600 cases), corresponding to log ft values of 4.3 and 5.6 respectively. No dependence on either transition energy or on mass was found. A reduced transition probability corresponding to log ft of 7.1 was used for first forbidden transitions. Some results are presented and discussed. (WHK)

Theoretical investigations and system studies indicate safeguards material balance data from reprocessing plants can be used to detect unauthorized removals. Plant systems have been modeled and simulated data used to demonstrate the techniques. But how sensitive are the techniques when used with actual plant data. What is the effect of safeguards applications on plant operability. Can safeguards be acceptable to plant operators, and are there any benefits to be derived. The Barnwell Nuclear Fuel Plant (BNFP) has been devoted to answering these and other questions over the past several years. A computerized system of near-real-time accounting and in-process inventory has been implemented and demonstrated during actual plant test runs. Measured inventories and hourly material balance closures have been made to assess safeguards in an operating plant application. The tests have culminated in actual removals of material from the operating plant to investigate the response and measure the sensitivity of the safeguards and data evaluation system.

A data acquisition and experiment control system for experiments at the Biology Small-Angle X-ray Scattering Station at the National Synchrotron Light Source has been developed based on a multiprocessor, functionally distributed architecture. The system controls an x-ray monochromator and spectrometer and acquires data from any one of three position-sensitive x-ray detectors. The average data rate from the position-sensitive detector is approx. 10/sup 6/ events/sec. Data is stored in a one megaword histogramming memory. The experiments at this Station require that x-ray diffraction patterns be correlated with timed stimuli at the sample. Therefore, depending on which detector is in use, up to 10/sup 3/ time-correlated diffraction patterns may be held in the system memory simultaneously. The operation of the system is functionally distributed over four processors communicating via a multiport memory.

From measurements made at 4.2 K, the residual resisitivity increases produced by reactor irradiation near room temperature were studied in pure Cu up to fluences of 4.2 x 10/sup 23/ n/m/sup 2/ > 1 MeV and 12 x 10/sup 23/ thermal n/m/sup 2/ by methods which resolved the effects due to transmutations and to defects. While the increase in resistivity due to transmutations is linear, that due to defects falls off rapidly with increasing fluence. The defect damage rates at low doses depend upon initial sample conditions that are related to impurities, but they become equal above approx. 6 x 10/sup 21/ n/m/sup 2/ (E > 1 MeV). Computations of defect concentrations using these resistivity data and earlier x-ray results, which measure dislocation loops, can be brought into reasonable agreement if the specific resistivity attributed to a single defect is decreased when that defect becomes part of a dislocation loop.

This article is a summary of a short course lecture given in conjunction with the 1981 Nuclear Science Symposium. The basic physical properties of elemental semiconductors are reviewed. The interaction of energetic radiation with matter is discussed in order to develop a feeling for the appropriate semiconductor detector dimensions. The extremely low net dopant concentrations which are required are derived directly from the detector dimensions. A survey of the more recent techniques which have been developed for the analysis of detector grade semiconductor single crystals is presented.

Using a surface barrier detector and standard nuclear instrumentation, the energetic charged products of fusion reactions between deuterium neutralizer gas and accelerated deuterium ions are sorted in energy to yield a measurement of the species from a neutral beam source, i.e., the proportions of accelerated D/sup +/, D/sub 2//sup +/, and D/sub 3//sup +/. Such sources have been designed at LBL for the TFTR project at Princeton University to accelerate currents of 65 amps to 120 kilovolts, and the species distribution affects the power deposition within the target plasma. An integral measurement over the entire area of the beam can be performed with Doppler shift spectroscopy, but it involves a large number of cross sections, of which not all are known, and it is also dependent upon the neutralizer gas distribution. The present species measurement complements other measurements because it is integrated over the entire beam, is independent of the neutralizer gas distribution, and only requires one well known cross section.