The conceptual design of a laser fusion power plant has been undertaken to exploit recent developments in target design. Advanced high-gain targets which have been developed make it possible to significantly relax the laser and optical system requirements. The power plant design features a reactor concept which utilizes a thick falling region of liquid lithium to protect the first-wall from the neutrons, x-rays, and charged particles that are produced in the thermonuclear microexplosion. The lithium waterfall has also been designed to be thick enough to significantly reduce the effects of 14 MeV neutrons and cyclical stresses on the blanket structure; thereby allowing us to consider smaller blanket structures which could last the lifetime of the plant. Fusion targets producing 700 MJ of thermonuclear energy are ignited by a 2 percent efficient, 1 MJ laser system at the rate of 1.4 Hz. Schemes for protecting the final focusing optics are described which are both compatible with this reactor system, and show promise of surviving a full year in order to minimize costly downtime.

A double arm lead-glass lead-scintillator calorimeter system was used to search for narrow states, such as the eta/sub c/, produced in the exclusive reactions ..pi../sup -/p ..-->.. ..gamma gamma..n, ..pi../sup -/p ..-->.. ..pi../sup 0/..gamma..n, and ..pi../sup -/p ..-->.. ..pi../sup 0/..pi../sup 0/n at 13 GeV/c. A 90% c.l. upper limit sigma.BR < 260 pb was found for ..gamma gamma.. states with masses from 2.6 to 3.1 GeV/c/sup 2/. Corresponding limits on narrow ..pi../sup 0/..gamma.. and ..pi../sup 0/..pi../sup 0/ states are also given.

A key issue in the design of fusion research experiments and their related facilities is the control of ground currents. Because of the large magnetic field, high voltages and high currents present in most of these installations, it is essential to avoid ground loops, and to control ground currents during both normal operations and fault conditions. This paper describes the grounding policy that was developed for MTX. The vault area was divided into zones, and each of the four walls was treated as a separate grounding area. Cable runs and magnet buss bars were run into the machine radially. The paper also describes the steps taken to isolate diagnostic signals and power for pumps and instruments. The paper outlines some of the field calculations used to predict problem areas, and to reveal voltage isolation levels that were required. The paper includes the active ground fault detection system used to insure the integrity of the ground system. 2 refs., 5 figs.

The microwave transmission system for ERCH on MFTF-B will utilize quasi-optical transmission techniques. The system consists of ten gyrotron oscillators: two gyrotrons at 28 GHz, two at 35 GHz, and six at 56 GHz. The 28 and 35 GHz gyrotrons both heat the electrons in the end plug (potential peak) while the 56 GHz sources heat the minimum-B anchor region (potential minimum). Microwaves are launched into a pair of cylindrical mirrors that form a pseudo-cavity which directs the microwaves through the plasma numerous times before they are lost out of the cavity. The cavity allows the microwave beam to reach the resonance zone over a wide range of plasma densities and temperatures. The fundamental electron cyclotron resonance moves to higher axial positions as a result of beta-depression of the magnetic field, doppler shifting of the resonance, and relativistic mass corrections for the electrons. With this system the microwave beam will reach the resonance surface at the correct angle of incidence for any density or temperature without active aiming of the antennas. The cavity also allows the beam to make multiple passes through the plasma to increase the heating efficiency at low temperatures and densities when the single pass absorption is …

Superconducting magnets for mirror fusion have evolved considerably since the Baseball II magnet in 1970. Recently, the Mirror Fusion Test Facility (MFTF-B) yin-yang has been tested to a full field of 7.7 T with radial dimensions representative of a full scale reactor. Now the emphasis has turned to the manufacture of very high field solenoids (choke coils) that are placed between the tandem mirror central cell and the yin-yang anchor-plug set. For MFTF-B the choke coil field reaches 12 T, while in future devices like the MFTF-Upgrade, Fusion Power Demonstration and Mirror Advanced Reactor Study (MARS) reactor the fields are doubled. Besides developing high fields, the magnets must be radiation hardened. Otherwise, thick neutron shields increase the magnet size to an unacceptable weight and cost. Neutron fluences in superconducting magnets must be increased by an order of magnitude or more. Insulators must withstand 10/sup 10/ to 10/sup 11/ rads, while magnet stability must be retained after the copper has been exposed to fluence above 10/sup 19/ neutrons/cm/sup 2/.

The siting and construction of a radioactive waste disposal operation is likely to be controversial in the communities being considered, and at the state and national levels as well. Public response can be conceptualized at two levels: individual, and group or organizational. At the individual level, public response is the behavior of people motivated by their attitudes, knowledge, and perceptions of radioactive waste and its hazards and risks. On the group or organizational level, public response is the organized activity of individuals. Organizations provide the ability to pool resources and talents, set up a division of labor, hire experts, develop a skilled leadership, take legal action, and so on. A broad range of organizations is possible: ad hoc, existing community groups with an added purpose, nationally-recognized organizations, or government offices and agencies. Two cases of response to radioactive waste disposal sites illustrate these sources and kinds of response and lead to indicators to estimate the nature and level of response. Finally, drawing from the theoretical discussion of the sources and levels of public response, on the estimation techniques, and on the examples, specific coping strategies are developed. These strategies take different forms, based on the nature and level of response …

Interpretation of ultrasonic inspection data from stainless steel welds is difficult because the signal-to-noise ratio is very low. The three main reasons for this are the granular structure of the weld, the high attenuation of stainless steel, and electronic noise. Averaging in time at the same position in space reduces electronic noise, but does not reduce ultrasonic noise from grain boundary scattering. Averaging wave-forms from different spatial positions helps reduce grain noise, but desired signals can destructively interfere if they shift in time. If the defect geometry is known, the ultrasonic waveforms can be shifted before averaging, ensuring signal reinforcement. The simplest geometry results in a linear time shift. An averaging algorithm has been developed which finds the optimum shift. This algorithm computes the averaged, or composite waveform as a function of the time shift. The optimum occurs when signals from a reflector become aligned in time, producing a large amplitude composite waveform. This algorithm works very well, but requires significant computer time and storage. This paper discusses this linear shift averaging algorithm, and considers an implementation using frequency domain techniques. Also, data from several weld defects are presented and analyzed.

The system configuration, layout, and general philosophy for the MTX magnet power system is described. The vast majority of the magnet power equipment was quite successfully used on the ALCATOR-C experiment at the Massachusetts Institute of Technology. The AC power for the magnet system at MIT was obtained from a 225MVA alternator. The power for the system at LLNL is obtained directly from the local utility's 230 kV line. This installation, therefore, necessitates the addition of a great deal of equipment in ranges from new switchgear in the substation to using existing switchgear obtained from MIT as contractors for intershop electrical isolation as well as safety isolation for personnel entry into the experimental area. Additionally, some discussion is made of the unique layout of this facility and the tradeoffs made to accommodate them. 2 refs., 6 figs.

We present a first principles method for calculating positron lifetimes in solids, based on self-consistent calculations using the Linear Muffin-Tin Orbital method. Local density approximations are used for both electron-electron and electron-positron interactions. Results are presented for a variety of elemental metals and vacancies to demonstrate the reliability of this approach. Theoretical calculations of positron lifetimes can be used to interpret experimental data. As an examples of this, we interpret our experimental lifetime data for the oxide superconductor Ba{sub 1-x}K{sub x}BiO{sub 3} using calculations based on this method. 12 refs., 3 figs.

The quadrature conversion scheme is a method of generating the second harmonic. The scheme, which uses two crystals in series, has several advantages over single-crystal or other two crystal schemes. The most important is that it is capable of high conversion efficiency over a large dynamic range of drive intensity and detuning angle.

We have investigated problems associated with inferring cross sections for neutron reactions on unstable nuclei in the mass-90 region from charged-particle reactions on nearby stable targets. We conclude that effects due to precompound evaporation, isospin, and multiple reaction paths severely limit the circumstances under which charged-particle studies may be directly and easily converted to neutron cross sections of useful accuracy. 4 refs., 2 figs.

This article summarizes our current understanding of hydrodynamic instabilities as relevant to ICF. First we discuss classical, single mode Rayleigh-Taylor instability, and nonlinear effects in the evolution of a single mode. Then we discuss multimode systems, considering: (1) the onset of nonlinearity; (2) a second order mode coupling theory for weakly nonlinear effects, and (3) the fully nonlinear regime. Two stabilization mechanisms relevant to ICF are described next: gradient scale length and convective stabilization. Then we describe a model which is meant to estimate the weakly nonlinear evolution of multi-mode systems as relevant to ICF, given the short-wavelength stabilization. Finally, we discuss the relevant code simulation capability, and experiments. At this time we are quite optimistic about our ability to estimate instability growth on ICF capsules, but further experiments and simulations are needed to verify the modeling. 52 refs.

A major concern of every designer of large, three-phase power-supply systems is the protection of system components from overvoltage transients. At present, three computer-aided circuit design programs are available in the Magnetic Fusion Energy (MFE) National Computer Center that can be used to analyze three-phase power systems: MINI SCEPTRE, SPICE I, and SPICE II. These programs have been used at Lawrence Livermore Laboratory (LLL) to analyze the operation of a 200-kV dc, 20-A acceleration power supply for the High Voltage Test Stand. Various overvoltage conditions are simulated and the effectiveness of system protective devices is observed. The simulated overvoltage conditions include such things as circuit breaker openings, pulsed loading, and commutation voltage surges in the rectifiers. These examples are used to illustrate the use of the computer-aided, circuit-design programs discussed in this paper.

Human sperm tests provide a direct means of assessing chemically induced spermatogenic dysfunction in man. Available tests include sperm count, motility, morphology (seminal cytology), and Y-body analyses. Over 70 different human exposures have been monitored in various groups of exposed men. The majority of exposures studied showed a significant change from control in one or more sperm tests. When carefully controlled, the sperm morphology test is statistically the most sensitive of these human sperm tests. Several sperm tests have been developed in nonhuman mammals for the study of chemical spermatotoxins. The sperm morphology test in mice has been the most widely used. Results with this test seem to be related to germ-cell mutagenicity. In general, animal sperm tests should play an important role in the identification and assessment of potential human reproductive hazards. Exposure to spermatotoxins may lead to infertility, and more importantly, to heritable genetic damage. While there are considerable animal and human data suggesting that sperm tests may be used to detect agents causing infertility, the extent to which these tests detect heritable genetic damage remains unclear. (ERB)

A summary is presented of theoretical expectations for the total cross sections for bottom quark production, for longitudinal and transverse momentum distributions, and for b, /bar b/ momentum correlations at Fermilab fixed target and collider energies.

This paper investigates the effects of chemistry and heat treatment variation on the 4-K tensile properties of A-286, a candidate sheath material for force-cooled superconductors. Currently, full use of A-286 and similar superalloys is limited by the observed low yield and ultimate tensile strengths in the welded and aged condition. The low strength is shown to be associated with the formation of precipitate-free zones as a result of alloying-element segregation during weld pool solidification. It has been determined that minor modifications of the weld-metal chemistry by the addition of Ti reduce precipitate-free-zone formation, resulting in matching weld-metal and base-plate strengths at 4 K. Furthermore, nucleation of the ..gamma..' hardening phase has been found to be a strong function of temperature and composition. Modified heat-treatment schedules have been determined that are amenable to superconductor fabrication and that resulted in increased weld hardening and improved 4-K tensile properties.

A technique based on discrete energy levels rather than energy level densities is presented for nuclear reaction calculations. The validity of the technique is demonstrated via theoretical and experimental agreement for cross sections, isomer-ratios and gamma-ray strength functions. 50 refs., 7 figs. (WRF)

Article on social capital and self-rated health among middle-aged and older adults in China.

A program is described for development of an automated supernova search based upon complete remote computer control of a telescope and vidicon digital imaging system. (GHT)

The poloidal-field (PF) coil set for the Tokamak Ignition/Burn Engineering Reactor (TIBER-II) consists of 24 solenoid modules, 16 of which are stacked inside the toroidal-field (TF) system at the center of the machine. These central solenoid modules operate at high-current densities, and maximum fields at the windings approach 14 T. Although TIBER-II is designed for steady-state operation with noninductive current drive, other operating scenarios are also considered. In the pulsed or inductive mode, PF coil currents are ramped to induce plasma current. In this mode, peak fields approaching 14 T appear on the central solenoid modules at the ends of the stack; the required current densities in these modules approach 40 A . mm/sup 2/. The central solenoid modules are layer wound using cable-in-conduit conductor (CICC) with (NbTi)/sub 3/Sn composite strands for improved high-field performance. Layer winding permits grading the conductor for maximum overall winding-pack current density and also results in less wasted space in the radial build of the machine. Cooling connections may be made at each layer of a module as needed. Current leads to the modules are routed through the high-field central bore. The central solenoid modules can easily support the centering load of the PF system, …

The superconducting, toroidal-field (TF) coils in the Tokamak Ignition/Burn Engineering Reactor (TIBER II) are designed with cable-in-conduit conductor (CICC) using Nb/sub 3/Sn composite strands. To design the CICC winding pack, we used an optimization technique that maximizes the conductor stability without violating the constraints imposed by the structure, electrical insulation, quench protection, and fabrication technique. Detailed helium-properties codes calculate the heat removal along a flow path, and detailed field calculations determine the temperature, current, and stability margins. The conductor sheath is designed as distributed structure to partially support the combined in-plane and out-of-plane loads generated within the winding pack. Pancakes of the coil are wound, reacted, and insulated before being potted in the case. This design is aggressive but fully consistent with good engineering practice. 5 refs., 4 figs., 2 tabs.

The reel support has three main functions. It must support the reel, which is 134 in. in diameter, 40 in. wide, and stores up to 8,600 ft of superconductor weighing 8,600 lb. It also must serve as a tensioning device for the superconductor, exerting a force of up to 600 lb. Further, the support must move the reel vertically and laterally to facilitate the winding of the magnets. The support has been designed and is now being fabricated. This paper describes the performance requirements of this device and the evolution of design from concept to completion.

Creep behavior of Type 304 LN plate and 316 L shielded-metal-arc (SMA)-deposited stainless weld metal was investigated at 4/sup 0/K. Testing was performed at constant load in a creep machine with a cryostat designed for long-term stability. Both transient and steady-state creep were observed during tests lasting over 2000 hours. Steady-state creep rates were much greater than expected from extrapolations of 300-K creep data. Creep rates on the order of 10/sup -10/ s/sup -1/ were observed at stresses around the yield stress for both materials. The stress exponent under these conditions if approx.2.3. Possible creep mechanisms at this temperature and the impact of these results on the design of engineering structures for long-term structural stability at cryogenic temperatures are discussed.

The role of effective theories in probing a more fundamental underlying theory and in indicating new physics thresholds is discussed, with examples from the standard model and more speculative applications to superstring theory. 38 refs.