A three-dimensional finite-element method is used to investigate thermal convection in the earth's mantle. The equations of motion are solved implicitly by means of a fast multigrid technique. The computational mesh for the spherical problem is derived from the regular icosahedron. The calculation described use a mesh with 43,554 nodes and 81,920 elements and were run on a Cray X. The earth's mantle is modeled as a thick spherical shell with isothermal, free-slip boundaries. The infinite Prandtl number problem is formulated in terms of pressure, density, absolute temperature, and velocity and assumes an isotropic Newtonian rheology. Solutions are obtained for Rayleigh numbers up to approximately 10/sup 6/ for a variety of modes of heating. Cases initialized with a temperature distribution with warmer temperatures beneath speading ridges and cooler temperatures beneath present subduction zones yield whole-mantle convection solutions with surface velocities that correlate well with currently observed plate velocities. 8 references, 6 figures.

During the past two years, complete events of relativistic nuclear collisions are being studied with the Plastic Ball, the first electronic nonmagnetic particle-identifying 4..pi.. spectrometer. It is well suited to handle the large multiplicities in these reactions and allows collection of data at a rate sufficient to make further software selections to look at rare events. The analysis of the data follows various lines covering topics like thermalization, stopping or transparency, cluster-production mechanism (--can it tell entropy), search for collective flow through various global analyzing methods that allow determination of the scattering plane, projectile fragmentation (--is there a bounce-off), pion distribution, two-particle correlations: Hanbury-Brown Twiss, and excited nuclear states (--nucleosynthesis at the freezeout point or from chemical equilibrium). We will cover in this contribution only two subjects: stopping and thermalization and cluster production.

Simulation experiments of magnet operating conditions in a fusion reactor are reported. After approximately half of the lifetime dose the results on a variety of NbTi superconductors show moderate changes of the critical current density j/sub c/ (approx. 10%), the percentage change of j/sub c/ is always larger at high fields (8 T) than at 5 T. After a rapid initial change the resistivity ratios of the Cu-stabilizer are found to decrease only slowly with increasing neutron fluence.

A design is presented for a dipole magnet suitable for the proposed SSC facility. Test results are given for model magnets of this design 1 m long and 4.5 m long. Flattened wedge-shaped cables (''keystoned'') are used in a graded, two-layer ''cos theta'' configuration with three wedges to provide sufficient field uniformity and mechanical rigidity. Stainless steel collars 15 mm wide, fastened with rectangular keys, provide structural support, and there is a ''cold'' iron flux return. The outer-layer cable has 30 strands of 0.0255 in. dia NbTi multifilamentary wire with Cu/S.C. = 1.8, and the inner has 23 strands of .0318 in. dia wire with Cu/S.C. = 1.3. Performance data is given including training behavior, winding stresses, collar deformation, and field uniformity.

The 3081/E is a second generation emulator of a mainframe IBM. One of it's applications will be to form part of the data acquisition system of the upgraded Mark II detector for data taking at the SLAC linear collider. Since the processor does not have direct connections to I/O devices a FASTBUS interface will be provided to allow communication with both SLAC Scanner Processors (which are responsible for the accumulation of data at a crate level) and the experiment's VAX 8600 mainframe. The 3081/E's will supply a significant amount of on-line computing power to the experiment (a single 3081/E is equivalent to 4 to 5 VAX 11/780's). A major advantage of the 3081/E is that program development can be done on an IBM mainframe (such as the one used for off-line analysis) which gives the programmer access to a full range of debugging tools. The processor's performance can be continually monitored by comparison of the results obtained using it to those given when the same program is run on an IBM computer. 9 refs.

None

This paper describes very generally the modulator/regulator (Mod/Reg) being built for Transrex by Systems, Science and Software for use on the neutral beam power supplies that Transrex is building for General Atomic Company to power the neutral beam heating systems that will be used on the Doublet III fusion device. The Mod/Reg is required to provide an 80 kV, 100 A pulse for a second every 90 sec. The voltage is to be regulated to 3%, and in case of fault the pulse must be interrupted within 10 ..mu..sec. An additional requirement was that the total system have very low capacity such that the total energy stored would be less than 15 joules. This is a restriction imposed by the source designer to prevent destroying the source in case of an arc within the source.

The inherent brittleness of the A15 compounds, and the requirement for a filamentary morphology, led to a heavy reliance on a powder approach for the preparation of superconducting tapes and wires. The quench-age technique, a non-powder process, was employed for the niobium-aluminum system, following the special features of the equilibrium phase diagram. The powder approach proved particularly effective for binaries, such as Nb-Sn, and for the ternaries Nb(Al,Ge) and Nb(Al,Si). Two variations of the powder process were assessed. One involved the use of precompounded powder of the desired stoichiometry but required simultaneous application of heat and pressure. The second variation was the infiltration process. This process involves the preparation of a ductile niobium matrix containing a controlled network of interconnected pores which are subsequently infiltrated with liquid metals (Sn) or low melting-point eutectics (e.g., Al-Ge, Al-Si). The composite is then subjected to a thermomechanical treatment to form a multiply connected array of A15 filaments in a niobium matrix. Multifilamentary conductors, based on Nb/sub 3/Sn, Nb/sub 3/Al, Nb/sub 3/ (Al,Ge) and Nb/sub 3/ (Al,Si), were readily obtained. Nb/sub 3/Sn conductors made by the infiltration process exhibit a critical temperature (Tc) of 18.1 K and a critical current carrying capacity (I/sub c/) …

We discuss here theoretical studies of magnetic acceleration of Compact Torus plasma rings in a coaxial, rail-gun accelerator. The rings are formed using a magnetized coaxial plasma gun and are accelerated by injection of B/sub theta/ flux from an accelerator bank. After acceleration, the rings enter a focusing cone where the ring is decelerated and reduced in radius. As the ring radius decreases, the ring magnetic energy increases until it equals the entering kinetic energy and the ring stagnates. Scaling laws and numerical calculations of acceleration using a O-D numerical code are presented. 2-D, MHD simulations are shown which demonstrate ring formation, acceleration, and focusing. Finally, 3-D calculations are discussed which determine the ideal MHD stability of the accelerated ring.

Spin physics in the past has provided an acid test of many models and theories and over the last decade has revealed new and unexpected phenomena to confront present day theories. This work received great impetus from the experiments at the ZGS, where for the first time multi-GeV polarized beams became available. This, in conjunction with polarized targets, allowed the complete specification of the initial quantum states in high energy proton-proton interactions and led to many startling new results. Although spin effects were important at the previously measured lower energies, practically all theorists felt that spin effects would become negligible at higher energies. Instead, the ZGS results showed in many cases even larger effects than those observed at lower energies. By the time the ZGS was shut down in 1979, high energy polarized proton projects were planned for KEK in Japan, SATURNE in France, and the AGS at Brookhaven. At present, serious thought is being given to high energy polarized proton beams at Fermilab, CERN, and indeed in planning for the Superconducting Super Collider. Today, I would like to describe the facility at Brookhaven and give you the present status of the project. We have been in the commissioning phase …

Besides the optics measurements described elsewhere, machine experiments were done at the SLC damping ring to determine some of its parameters. The synchrotron radiation energy loss which gives the damping rates was measured by observing the rf-voltage dependence of the synchronous phase angle. The emittance was obtained from the synchrotron light monitor, scraper measurements and by extracting the beam through a doublet and measuring its size for different quadrupole settings. Current dependent effects such as parasitic mode losses, head tail instabilities, synchrotron and betatron frequency shifts were measured to estimate the impedance. Rf-cavity beam loading and its compensation were also studied and ion collection was investigated. All results agree reasonably well with expectations and indicate no limitations to the design performance.

Rapid changes of ion, intensity, beam line, and output energy between two modes have been achieved. The techniques for switching among the Bevalac's several injectors are described. Energy level limits at the output (for q/A = 1/2) are 470 to 2100 MeV/n (high power) or 50 to 1050 MeV/n (low power). Depending on specific field value differences, the total time required for a mode change is less than one minute. This mode of operation greatly improves program efficiency in interleaving medical and nuclear science programs at the Bevalac.

The ACP Branchbus, a high speed differential bus for data movement in multiprocessing and data acquisition environments, is described. This bus was designed as the central bus in the ACP multiprocessing system. In its full implementation with 16 branches and a bus switch, it will handle data rates of 160 MByte/sec and allow reliable data transmission over inter rack distances. We also summarize applications of the ACP system in experimental data acquisition, triggering and monitoring, with special attention paid to FASTBUS environments.

The extension of the field experience data base includes the following: key corrosive species, updated field experiences, corrosion of secondary loop components or geothermal binary power plants, and suitability of conventional water-source heat pump evaporator materials for geothermal heat pump service. Twenty-four conference papers are included. Three were abstracted previously for EDB. Separate abstracts were prepared for twenty-one. (MHR)

Although Hamiltonians of various kinds have previously been used to derive Green-Kubo relations for the transport coefficients, the particular choice described is uniquely related to thermodynamics. This nonequilibrium Hamiltonian formulation of fluid flow provides pedagogically simple routes to nonequilibrium fluxes and distribution functions, to theoretical understanding of long-time effects, and to new numerical methods for simulating systems far from equilibrium. The same methods are now being applied to solid-phase problems. At the relatively high frequencies used in the viscous fluid calculations described, solids typically behave elastically. Lower frequencies lead to the formation of dislocations and other defects, making it possible to study plastic flow. A property of the nonequilibrium equations of motion which might be profitably explored is their effective irreversibility. Because only a few particles are necessary to generate irreversible behavior, simulations using adiabatic deformations of the kind described here could perhaps elucidate the instability in the equations of motion responsible for irreversibility.

Beams of metallic ion species can be produced by the ECR (electron cyclotron resonance) ion source and by the MEVVA (metal vapor vacuum arc) ion source. Although the ECR source is fundamentally a gaseous ion source, metal ion beams can be produced by introducing metallic feed material into the plasma discharge using a number of techniques. The ion charge states can be very high, which is a significant advantage to most applications. The MEVVA ion source, on the other hand, is specifically a metal ion source. It has produced metallic ion beams from virtually all the solid metallic elements at a current of typically hundreds of milliamperes; the ions produced are in general multiply ionized, but not as highly stripped as those generated in the ECR source. Although the MEVVA source at present operates in a pulsed mode with a low duty cycle (less than or equal to 1%), work is in progress to increase the duty cycle significantly. In this paper the operation and performance of the LBL ECR and MEVVA ion sources, with respect to metal ion generation, are described.

The Tandem Mirror exhibits several distinctive features which make the reactor embodiment of the principle very attractive: Simple low-technology linear central cell; steady-state operation; high-..beta.. operation; no driven current or disruptions; divertorless operation; direction conversion of end-loss power; low-surface heat loads; and advanced fusion fuel capability. In this paper, we examine these features in connection with two tandem mirror reactor designs, MARS and MINIMARS, and several advanced reactor concepts including the wall-stabilized reactor and the field-reversed mirror. With a novel compact end plug scheme employing octopole stabilization, MINIMARS is expressly designed for short construction times, factory-built modules, and a small (600 MWe) but economic reactor size. We have also configured the design for low radioactive afterheat and inherent/passive safety under LOCA/LOFA conditions, thereby obviating the need for expensive engineered safety systems. In contrast to the complex and expensive double-quadrupole end-cell of the MARS reactor, the compact octopole end-cell of MINIMARS enables ignition to be achieved with much shorter central cell lengths and considerably improves the economy of scale for small (approx.250 to 600 MWe) tandem mirror reactors. Finally, we examine the prospects for realizing the ultimate potential of the tandem mirror with regard to both innovative configurations and novel neutron …

A development program has been carried out at the Hanford Engineering Development Laboratory (HEDL) with the purpose of developing and proof testing air cleaning components and systems for use under severe sodium fire conditions, including those involving high levels of radioactivity. The air cleaning components tested can be classified as either dry filters or aqueous scrubbers. Test results are presented.

Oxygen concentration monitors were installed in a vault where numerous pipes carried inert cryogens and gases to the Mirror Fusion Test Facility (MFTF-B) experimental vessel at Lawrence Livermore National Laboratory (LLNL). The problems associated with oxygen-monitoring systems and the reasons why such monitors were installed were reviewed. As a result of this review, the MFTF-B monitors were set to sound an evacuation alarm when the oxygen concentration fell below 18%. We chose the 18% alarm criterion to minimize false alarms and to allow time for personnel to escape in an oxygen-deficient environment.

We discuss an improvement to the algorithm developed by Yu for modelling rf cavities in klystrons using the port approximation. In this method, the cavity is simulated by imposing an rf voltage as a boundary condition across the outer wall. The voltage and phase are chosen to be consistent with the cavity impedence and with the rf current induced by the electron beam. In the original method, each cavity was calculated successively using either linear theory or an iterative method to achieve a self-consistent voltage. The new method relaxes the voltage and phase of several cavities simultaneously during the simulation. The time dependence of the voltages are calculated from a relaxation equation. The new algorithm reduces the total computation time by about a factor of five for a complete klystron.

The ALT-I (Advanced Limiter Test-I) was installed on TEXTOR to benchmark the ability of a pump limiter as an efficient particle collector and to determine the physics of pump limiter operation. Experiments continue to show its capability of removing particles from the plasma edge under different operating conditions. In this paper we report first experimental results using ALT-I in conjunction with high power ICRF heating. The particle removal rate increases as the edge flux and density increase during the ICRF pulse. For a head geometry that collects flux from both electron and ion drift sides, the plasma temperature rise is asymmetric with electron temperature on the electron side increasing more than on the ion side during the ICRF pulse. When ALT-I is the major limiter, the particle fluxes on both sides increase by about the same factor and the particle flux on the ion side is always larger, by a factor of 1.5 to 2 than on the electron side during both ohmic and ICRF periods. The degradation of particle confinement inferred from Langmuir probe measurement is more than a factor of two at a maximum achieved power of 2 MW.

The ALT-I (Advanced Limiter Test-I) was installed on TEXTOR to benchmark the ability of a pump limiter as an efficient particle collector and to determine the physics of pump limiter operation. Experiments continue to show its capability of removing particles from the plasma edge under different operating conditions. In this paper we report first experimental results using ALT-I in conjunction with high power ICRF heating. The particle removal rate increases as the edge flux and density increase during the ICRF pulse. For a head geometry that collects flux from both electron and ion drift sides, the plasma temperature rise is asymmetric with electron temperature on the electron side increasing more than on the ion side during the ICRF pulse. When ALT-I is the major limiter, the particle fluxes on both sides increase by about the same factor and the particle flux on the ion side is always larger, by a factor of 1.5 to 2 than on the electron side during both ohmic and ICRF periods. The degradation of particle confinement inferred from Langmuir probe measurement is more than a factor of two at a maximum achieved power of 2 MW.

A dipole magnet, intended as a possible alternative for the ISABELLE main-ring magnet, was designed at LBL. Three layers of FNAL Doubler/Saver conductor were used. Two 1.3-m-long models were built and tested, both with and without an iron core, and in both helium I and helium II. The training behavior, cyclic energy loss, point of quench initiation, and quench velocity were determined. A central field of 6.5 tesla was obtained in He I (4.4 K), and 7.6 tesla in He II (1.8K).

The chemical stability and conductivity of boron and aluminum phosphates in steam are reported for P/B and P/A1 atomic ratios greater than unity at temperatures from 100/sup 0/ to 280/sup 0/C and steam pressures to 5 atmospheres. Al(PO/sub 3/)/sub 3/ and H/sub 2/ A1P/sub 3/O/sub 10/ undergo the reactions Al (PO/sub 3/)/sub 3/ + H/sub 2/) in equilibrium H/sub 2/AlP/sub 3/O/sub 10/ and H/sub 2/AlP/sub 3/O/sub 10/ ..-->.. AlPO/sub 4/ + H/sub 2/O.P/sub 2/O/sub 5/(g). At 280/sup 0/C and a steam pressure of 5 atmospheres gauge the product is mixture of AlPO/sub 4/ and H/sub 2/ALP/sub 3/O/sub 10/, while the conductivity of this solid is in the range of 10/sup -2/ ohm/sup -1/ cm/sup -1/. The boron phosphates lose material and exhibit poor conductivity under similar conditions due to the instability of the BPO/sub 4/ phase as a result of the reaction 2BPO/sub 4/ + 6 H/sub 2/O ..-->.. B/sub 2/O/sub 3/.3H/sub 2/O(g) + P/sub 2/O/sub 5/. 3H/sub 2/O(g). As a result of dehydration or hydrolytic reactions an increase in water vapor pressure does not always lead to increased conductivity even at higher temperature.