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.

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.

For ErRh/sub 4/B/sub 4/, owing to the critical spin fluctuations just above T/sub s/ (> T/sub c2/), the critical temperature at which surface ferromagnetism appears, the reciprocal penetration depth, lambda/sup -1/, decreases smoothly as T decreases toward T/sub s/. For Er/sub 0/ /sub 5/Ho/sub 0/ /sub 5/Rh/sub 4/B/sub 4/, the decrease in lambda/sup -1/ for T > T/sub c2/ is very small, and lambda/sup -1/ decreases abruptly at T/sub c2/.

The design and construction of a new experiment for PEP designed to measure the flux of low energy photons unaccompanied by any additional photons, or charged tracks is described. The device consists of arrays of extruded lead glass bars and PWC's in the central region with lead-scintillator shower counters, drift chambers and PWC's in the forward regions. 9 references.

A review of the phases of stellar evolution relevant to Cepheid variables of both Types I and II is presented. Type I Cepheids arise as a result of normal post-main sequence evolutionary behavior of many stars in the intermediate to massive range of stellar masses. In contrast, Type II Cepheids generally originate from low-mass stars of low metalicity which are undergoing post core helium-burning evolution. Despite great progress in the past two decades, uncertainties still remain in such areas as how to best model convective overshoot, semiconvection, stellar atmospheres, rotation, and binary evolution as well as uncertainties in important physical parameters such as the nuclear reaction rates, opacity, and mass loss rates. The potential effect of these uncertainties on stellar evolution models is discussed. Finally, comparisons between theoretical predictions and observations of Cepheid variables are presented for a number of cases. The results of these comparisons show both areas of agreement and disagreement with the latter result providing incentive for further research.

Recent results for charge-changing collisions of interest for cyclotrons and other particle accelerators are presented. Scaling rules, where available, are emphasized. 45 references, 11 figures.

Unlike most of the specialities treated in this volume, control system design is still an art, not a science. These lectures are an attempt to produce a primer for prospective practitioners of this art. A large modern accelerator requires a comprehensive control system for commissioning, machine studies and day-to-day operation. Faced with the requirement to design a control system for such a machine, the control system architect has a bewildering array of technical devices and techniques at his disposal, and it is our aim in the following chapters to lead him through the characteristics of the problems he will have to face and the practical alternatives available for solving them. We emphasize good system architecture using commercially available hardware and software components, but in addition we discuss the actual control strategies which are to be implemented since it is at the point of deciding what facilities shall be available that the complexity of the control system and its cost are implicitly decided. 19 references.

A very low velocity superconducting heavy-ion linac is proposed which, at least for applications requiring modest beam current, seems to have substantial cost and performance advantages over existing low-velocity room-temperature structures. The proposed linac, together with a 350 kV positive ion source, would replace an FN tandem Van de Graaff accelerator as the injector of the Argonne superconducting heavy-ion linac. 7 references, 5 figures.

A crossed undulator system can produce synchrotron radiation whose polarization is arbitrary and adjustable. The polarization can be linear and modulated between two mutually perpendicular directions, or it can be circular and can be modulated between right and left circular polarizations. The system works on low emittance electron storage rings and can cover a wide spectral range. Topics discussed include the basic principle of the system, the design equations and the limitations in performance.

The new collider facility to be built at Fermilab's Tevatron-I D0 region is described. The data acquisition requirements are discussed, as well as the hardware and software triggers designed to meet these needs. An array of MicroVAX computers running VAXELN will filter in parallel (a complete event in each microcomputer) and transmit accepted events via Ethernet to a host. This system, together with its subsequent offline needs, is briefly presented.

LBL has designed and tested a heavy ion RFQ linac for ions in the mass range of 1 to 40. Designed as part of a preinjector package for synchrotron applications, it is a low duty factor device, operating at 200 MHz with maximum surface fields as high as 28 MV/meter. It is a loop-driven, four vane structure employing several innovative design concepts. These include an exit matcher section, to ensure efficient capture by a following Alvarez linac; advanced mechanical design features, to ensure accurate positioning of the vane pole-tips; and vane coupling rings, to ensure field stabilization and balance. This RFQ has been used on a test bench to accelerate a variety of ions as heavy as silicon, with charge to mass ratios as low as 1/7. Results of the initial operation show that the structure meets all of the design performance criteria, and that it holds promise for a long lifetime of simple and reliable service. This RFQ linac will soon be incorporated into the Bevatron operations program as part of th 200 MHz injector upgrade. A further application of this same RFQ design is in the dedicated Heavy Ion Medical Accelerator presently under study at LBL. Details of …

A proposed design for a tensor polarized deuterium target (approx. 10/sup 15/ atoms/cm/sup 2/) for nuclear physics studies in an electron storage ring accelerator is presented. The deuterium atoms undergo electron spin exchange with a highly polarized sodium vapor; this polarization is transferred to the deuterium nuclei via the hyperfine interaction. The deuterium nuclei obtain their tensor polarization through repeated electron spin exchange/hyperfine interactions. The sodium vapor polarization is maintained by standard optical pumping techniques. Model calculations are presented in detail leading to a discussion of the expected performance and the technical obstacles to be surmounted in the development of such a target. 15 references, 10 figures.

The dynamical evolution of the correlated angular momentum distribution in a damped nuclear reaction is discussed within the framework of the nucleon exchange transport model. 13 references.

Recent advances in a unified macroscopic-microscopic description of large-amplitude collective nuclear motion such as occurs in fission and heavy ion reactions are discussed. With the goal of finding observable quantities that depend upon the magnitude and mechanism of nuclear dissipation, one-body dissipation and two-body viscosity within the framework of a generalized Fokker-Planck equation for the time dependence of the distribution function in phase space of collective coordinates and momenta are considered. Proceeding in two separate directions, the generalized Hamilton equations of motion for the first moments of the distribution function with a new shape parametrization and other technical innovations are first solved. This yields the mean translational fission-fragment kinetic energy and mass of a third fragment that sometimes forms between the two end fragments, as well as the energy required for fusion in symmetric heavy-ion reactions and the mass transfer and capture cross section in asymmetric heavy-ion reactions. In a second direction, we specialize to an inverted-oscillator fission barrier and use Kramers' stationary solution to calculate the mean time from the saddle point to scission for a heavy-ion-induced fission reaction for which experimental information is becoming available. 25 references.

The Brookhaven National Laboratory polarized H/sup -/ injection program for the AGS utilizes a Radio Frequency Quadrupole (RFQ) for acceleration between the polarized H/sup -/ source and the Alvarez Linac. The RFQ accelerator is now in operation with low beam currents. The results of low and high power rf testing will be reported together with initial results of operation in the polarized H/sup -/ beam line.

Starting with the pioneering work of R. Geller and his group in Grenoble (France), at least 14 ECR sources have been built and tested during the last five years. Most of those sources have been extremely successful, providing intense, stable and reliable beams of highly charged ions for cyclotron injection or atomic physics research. However, some of the operational features of those sources disagreed with commonly accepted theories on ECR source operation. To explain the observed behavior of actual sources, it was found necessary to refine some of the crude ideas we had about ECR sources. Some of those new propositions are explained, and used to make some extrapolations on the possible future developments in ECR sources.

The possibilities for colliding electrons with the 20 TeV proton beams of the SSC are considered. Kinematics of ep colliding beams is reviewed. Energies that may be possible and interesting are suggested, and detector problems associated with the highly imbalanced collisions are briefly considered.

Mixtures of Linde Ionsiv IE-96 and Ionsiv A-51 were evaluated for use in the Submerged Demineralizer System (SDS) that was installed at the Three Mile Island Unit 2 Nuclear Power Station to decontaminate approx. 2780 m/sup 3/ of high-activity-level water. The original SDS flowsheet was conservatively designed for removal of cesium and strontium and would have required the use of approx. 60 SDS columns. Mixed zeolite tests were made on a 10/sup -5/ scale and indicated that the appropriate ratio of IE-96/A-51 was 3/2. A mathematical model was used to predict the performance of the mixed zeolite columns in the SDS configuration and with the intended method of operation. Actual loading results were similar to those predicted for strontium and better than those predicted for cesium. The number of SDS columns needed to process the HALW was reduced to approx. 10. 6 references, 4 figures, 2 tables.

During the past decade, various semi-implicit finite-difference schemes such as that used in version PD2 of the Transient Reactor Analysis Code (TRAC-PD2) have been applied to problems in fluid flow. The stability-enhancing two-step (SETS) method was created to improve the running time of the existing TRAC code with inimal impact on the code structure and results. The SETS method eliminates the material Courant stability limit simply by adding a stabilizer step to the basic semi-implicit equations. The SETS method has been extended successfully to equations for three-dimensional, two-phase flow and the demonstration computer code used for this extension has been written in a form that can be adapted by other researchers. The method currently is being incorporated into our reactor safety systems code to provide the numerical foundation for a multidimensional code that can run faster than real time.

A twist reflector plate is described that linearly polarizes and focuses the TE/sub O/sub 1// circular waveguide mode for heating hot electrons in the thermal barrier of the Tandem Mirror Experiment-Upgrade (TMX-U). The plate polarizing efficiency is 95%, and it has operated satisfactorily at 150 kW power level.

This paper draws attention to episodic events in the geologic time scale of the evolution of life on earth, and discusses potentially cyclic behavior relative to galactic structure. The question is a simple one: Do galactic processes affect the solar system. It is known that the sun is moving at about 220 +- 15 km/sec at a distance of about 8.5 +- 0.5 kpc from the galactic center. This motion, if circular and unperturbed, implies an orbital period of 237 +- 21 My for the solar system around the galaxy. The Milky Way also evidences structure typically interpreted as spiral arms, in the distribution of gas clouds in its central plane. The relative motion of the spiral arms, known as the pattern speed, is about 2/3 that of the sun. Consequently the solar system gains upon and passes through all the structure in its orbital plane once in three rotations or approx.700 My. If this structure is persistent over times longer than 700 My, it is clear that the interaction (if any) can be called cyclic. Furthermore, if there is any sub-structure or inner pattern to the 700 My cycle, it may show up as higher harmonics. Age estimates for …

Drilling is the only method available to obtain unambiguous information on processes occurring in the earth's crust. When core and virgin formation fluid samples are available, the geological state of the formation may be defined in the vicinity of the borehole with little ambiguity. Unfortunately, core recovery is expensive and often not complete, and drilling muds contaminate formation fluids. Thus, investigations turn to downhole instrumentation systems to evaluate in situ formation parameters. Some such instruments and the associated interpretative techniques are well developed, especially if they find usage in the evaluation of hydrocarbon reservoirs. Other sytems, particularly those that yield geochemical information are, at best, shallow-hole devices, but they could be engineered for deep-hole applications. Interpretations of logs obtained in igneous and metamorphic systems are not well developed. Finally, measurements away from the immediate vicinity of the borehole are possible but the technology is primitive. In situ instrumentation capabilities and needs for research in boreholes will be reviewed; the review will include details from recent US and European discussions of instrumentation needs. The capability and availability of slim hole logging tools will be summarized. Temperature limitations of the overall logging system will be discussed (current limits are 300/sup 0/C) and …

Recent results from PEP on quark and gluon fragmentation are reviewed. Topics include: inclusive stable particle production and resonance production, particle distributions in jets, heavy quark fragmentation, flavor correlation studies and tests of fragmentation models. 37 references.

This paper describes health and environmental impacts of coal-fired electric power plants. Effects on man, agriculture, and natural ecosystems are considered. These effects may result from direct impacts or exposures via air, water, and food chains. The paper is organized by geographical extent of effect. Occupational health impacts and local environmental effects such as noise and solid waste leachate are treated first. Then, regional effects of air pollution, including acid rain, are analyzed. Finally, potential global impacts are examined. Occupational health concerns considered include exposure to noise, dust, asbestos, mercury, and combustion products, and resulting injury and disease. Local effects considered include noise; air and water emissions of coal storage piles, solid waste operations, and cooling systems. Air pollution, once an acute local problem, is now a regional concern. Acute and chronic direct health effects are considered. Special attention is given to potential effects of radionuclides in coal and of acid rain. Finally, potential global impacts associated with carbon dioxide emissions are considered. 88 references, 9 tables.