A comparison matrix decision model is applied to candidates for a D-T ignition tokamak (TNS), including assessment of semi-quantifiable or judgemental factors as well as quantitative ones. The results show that TNS is mission-sensitive with a choice implied between near-term achievability and reactor technology.

Here a more detailed publication is summarized which presents analytical methods with solutions that describe the structural behavior of ohmic heating solenoids to achieve a better understanding of the relationships between the functional variables that can provide the basis for recommended design improvements. The solutions relate the requirements imposed by structural integrity to the need for producing sufficient flux swing to initiate a plasma current in the tokamak fusion machine. A method is provided to perform a detailed structural analysis of every conducting turn in the radial build of the solenoid, and computer programmed listings for the closed form solutions are made available as part of the reference document. Distinction is made in deriving separate models for the regions of the solenoid where turn-to-turn radial contact is maintained with radial compression or with a bond in the presence of radial tension, and also where there is turn-to-turn radial separation due to the absence or the loss of bonding in the presence of would be radial tension. The derivations follow the theory of elasticity for a body possessing cylindrical anisotropy where the material properties are different in the radial and tangential directions. The formulations are made practical by presenting the methods …

The toroidal field coils in two of the four TNS field coil design options are superconducting. NbTi superconductors are used in the low field design option and Nb/sub 3/Sn superconductors are used in the high field design option. The preliminary conceptual design parameters of the coils and the superconductors have been developed. The selected coil shape is the pure tension D-configuration. The superconductors are the multifilamentary, cabled design and are cooled by forced flow supercritical helium. Thermal stability analyses were performed for the superconductors. The cryogenic recovery capability of the NbTi superconductors is more than 10/sup 5/ J/m/sup 3/ of conductor plus helium volume and that of the Nb/sub 3/Sn is more than 3 x 10/sup 5/ j/m/sup 3/.

The matrix isolation spectra of all of the 40 presently known atomic metal species show strong matrix effects. The transition energies are increased, and the bands are broad and exhibit splitting of sublevels which are degenerate in the gas phase. Several models have been proposed for splitting of levels, but basic effects are not yet understood, and spectra cannot be predicted, yet it is possible to correlate gas phase and matrix in many of the systems. Selective production of diatomics and clusters via thermal and optical annealing of atomic species can be monitored by optical spectra, but yields spectroscopically complex systems which, however, especially in the case of transition metals, can be used as precursors in novel chemical reactions. A combination of absorption, emission, ir, Raman, ESR, and other methods is now quickly yielding data which will help correlate the increasing wealth of existing data. 55 references, 6 figures.

Conditions for the stable propagation of a pinched electron beam in low pressure gas (p approximately 0.1 to 100 torr) are described. The observed window of good propagation around p approximately 2 torr air is interpreted as the quenching of the two-stream mode by sufficiently high plasma density and collision frequency, and the simultaneous suppression of the resistive hose mode by sufficiently rapid generation of electrical conductivity from breakdown ionization.

Performance (cost/kWe and efficiency) of generic Compact Fusion Advanced Rankine (CFARII) power conversion is investigated for various working fluids, operating temperatures and pressures, and thermal power levels. A general conclusion is that good CFARII performance is found for a remarkably broad range of materials, temperatures, pressures and power levels, which gives considerable flexibility to future design studies which may apply CFARII energy conversion to specific fusion energy sources such as ICF, MICF, and Mini-PACER. 5 refs, 7 figs., 2 tabs.

The magnetic, structural, and thermal design of superconducting poloidal field coils for a tokamak fusion-fission breeder reactor are described. The design requirements and considerations, with the resulting parameters, are presented.

A model of the interaction between an ignited plasma and a wall is utilized to study the impact of impurities and recycled fuel ions and helium ash on the burn time of the plasma. The model indicates that the impurity concentration, n/sub im/, grows exponentially toward a maximum value determined by the confinement time for impurities, tau/sub im/, the sputtering coefficient, S/sub i/, and the isolation coefficient, ..cap alpha... The time for n/sub im/ to reach a critical value and quench the plasma was determined for representative impurities, C, Mo, W, Fe, under various conditions of plasma temperature. Methods for extending the burn time by minimizing the effective sputtering coefficient of the wall and increasing the isolation of the plasma from the wall are reviewed. The carbides, B/sub 4/C and SiC, are found to have encouraging sputtering properties but their thermal, chemical and mechanical properties need to be evaluated before they can be recommended for use as first walls. The magnetic divertor is the preferred isolation scheme. Because the divertor carries impurities and leaked fuel and helium ions to a burial chamber, required pumping speeds are found to be very high for TNS plasmas and supplemental particle trapping systems must …

The electrical design of the ORNL-Westinghouse next step (TNS) fusion reactor was begun in 1976, using a set of ground rules which were based on the overall program objectives. These objectives were to identify the design of reasonably-priced reactors, which would achieve ignition and be technology forcing. The term ''technology forcing'' was understood to mean the desirability of a large number of ignited D-T pulses and the incorporation of superconducting toroidal field (TF) coils, if at all possible. A trade study methodology was developed to compare different machine sizes and TF coil technologies and to aid in the selection of system and subsystem design approaches. The logic which led from the program objectives to the design ground rules and from the ground rules to the circuit selection is described below. The circuit design approaches were generalized and these models were incorporated into a computer program (COAST) which was used to examine the cost of overall tokamak systems as key design parameters were varied.

The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, …

A FORTRAN code for the COsting And Sizing of Tokamaks (COAST) is described. The code was written to conduct detailed analyses on the engineering features of the next tokamak fusion device following TFTR. The ORNL/Westinghouse study of TNS (The Next Step) has involved the investigation of a number of device options, each over a wide range of plasma sizes. A generalized description of TNS is incorporated in the code and includes refined modeling of over forty systems and subsystems. Considerable detailed design and analyses have provided the basis for the thermal, electrical, mechanical, nuclear, chemical, vacuum, and facility engineering of the various subsystems. Currently, the code provides a tool for the systematic comparison of four toroidal field (TF) coil technologies allowing both D-shaped and circular coils. The coil technologies are: (1) copper (both room temperature and liquid-nitrogen cooled), (2) superconducting NbTi, (3) superconducting Nb/sub 3/Sn, and (4) a Cu/NbTi/ hybrid. For the poloidal field (PF) coil systems copper conductors are assumed. The ohmic heating (OH) coils are located within the machine bore and have an air core, while the shaping field (SF) coils are located either within or outside the TF coils. The PF coil self and mutual inductances are …

We have improved the impulse response characteristics of the LLNL 50 ps detector significantly. The detector has also been improved mechanically to permit much greater ease of assembly and repair. We are investigating modified versions of this design for optical applications. The detector was developed to complement the recording capability of our Thomson-CSF 4 GHz oscilloscopes in laser driven ICF fusion experiments research.

This paper gives an in-depth discussion on the various methodologies currently available to predict the near-field ground motion from an earthquake. The limitations of the various methods are discussed in some detail in light of recently available data. It is shown that, (at least for California earthquakes) for an earthquake with a given magnitude a wide variation in the peak ground motion can occur. The change in the spectral content of the ground motion is given as a function of earthquake magnitude and peak ground acceleration. It is shown that the large g values associated with small earthquakes are relatively unimportant in the design provided the structures have a modest amount of ductility. Data recently obtained from the Friuli earthquake are also examined. Although not all the geophysical data are currently available, the provisional conclusion is reached that the relation between the strong ground motion from this earthquake and its source parameters is the same as for the western United States.

Tritium breeding in a fusion-fission tokamak reactor is optimized by the technique of geometric programming. The neutronic processes are represented as an objective function found by fitting a generalized quadratic function of the zone widths to the breeding ratio found from planned computational experiments. The results of this technique are examined, and the predicted performance compared to neutronic calculations with the optimized values of the design variables.

TF-ripple loss of alphas below the critical energy is calculated for a noncircular ITER plasma. For 14 toroidal field (TF) coils, the particle loss was found to be about 6%. About 0.6% of the initial alpha energy (3.5 MeV) is lost. 26 refs., 9 figs., 3 tabs.

The theory of optical flashes created by x- and ..gamma..-ray burst heating of stars in binaries is reviewed. Calculations of spectra due to steady-state x-ray reprocessing and estimates of the fundamental time scales for the non-steady case are discussed. The results are applied to the extant optical data from x-ray and ..gamma..-ray bursters. Finally, I review predictions of flashes from ..gamma..-ray bursters detectable by a state of the art all-sky optical monitor.

We report on the discovery of a very bright z = 2.00 star-forming galaxy that is strongly lensed by a foreground z = 0.422 luminous red galaxy (LRG). This system was found in a systematic search for bright arcs lensed by LRGs and brightest cluster galaxies in the Sloan Digital Sky Survey Data Release 5 sample. Follow-up observations on the Subaru 8.2m telescope on Mauna Kea and the Astrophysical Research Consortium 3.5m telescope at Apache Point Observatory confirmed the lensing nature of this system. A simple lens model for the system, assuming a singular isothermal ellipsoid mass distribution, yields an Einstein radius of {theta}{sub Ein} = 3.82 {+-} 0.03{double_prime} or 14.8 {+-} 0.1h{sup -1} kpc at the lens redshift. The total projected mass enclosed within the Einstein radius is 2.10 {+-} 0.03 x 10{sup 12}h{sup -1}M{sub {circle_dot}}, and the magnification factor for the source galaxy is 27 {+-} 1. Combining the lens model with our gVriz photometry, we find an (unlensed) star formation rate for the source galaxy of 32 h{sup -1} M{sub {circle_dot}} hr{sup -1}, adopting a fiducial constant star formation rate model with an age of 100 Myr and E(B-V) = 0.25. With an apparent magnitude of r …

During the past several years, an International Scoping Study (ISS) of a Neutrino Factory was carried out, with the aim of developing an internationally accepted baseline facility design. Progress toward that goal will be described. Many of the key technical aspects of a Neutrino Factory facility design are presently being investigated experimentally, and the status of these investigations will be mentioned. Plans for the recently launched International Design Study (IDS), which serves as a follow-on to the ISS, will be briefly described.

A recent re-determination of the non-thermal component of the hard X-ray to soft {gamma}-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary electrons and positrons contribute to the emission. The prediction uses the GALPROP model and includes a new calculation of the interstellar radiation field. This may solve a long-standing mystery of the origin of this emission, and potentially opens a new window on Galactic cosmic rays.

Lipid microdomains within supported lipid bilayers composed of binary phosphocholine mixtures were chemically imaged by high-resolution secondary ion mass spectrometry performed with the NanoSIMS 50 (Cameca Instruments). This instrument images the sample components based on the elemental or isotopic composition of their atomic and small molecular secondary ions. Up to five different secondary ions can be simultaneously detected, and a lateral resolution of 50 nm can be achieved with high sensitivity at high mass resolution. In our experiments, the NanoSIMS 50 extensively fragmented the supported membrane, therefore an isotopic labeling strategy was used to encode the identities of the lipid components. Supported lipid membranes that contained distinct lipid microdomains were freeze-dried to preserve their lateral organization and analyzed with the NanoSIMS 50. Lipid microdomains as small as 100 nm in diameter were successfully imaged, and this was validated by comparison to AFM images taken at the same region prior to chemical imaging. Quantitative information on the lipid distribution within the domain was also determined by calibrating against supported membranes of known composition. We believe this will be a valuable approach for analyzing the composition of complex membrane domains with high spatial resolution.

Generation of attosecond x-ray pulses is attracting much attention within the x-ray free-electron laser (FEL) user community. Several schemes have been proposed based on manipulations of electron bunches with extremely short laser pulses. In this paper, we extend the attosecond two-color ESASE scheme proposed by Zholents et al. to the long optical cycle regime using a detuned second laser and a tapered undulator. Both lasers can be about ten-optical-cycles long, with the second laser frequency detuned from the first one to optimize the contrast between the central and side current spikes. A tapered undulator mitigates the degradation effect of the longitudinal space charge (LSC) force in the undulator and suppresses the FEL gain of all side current spikes. Simulations using the LCLS parameters show a single attosecond x-ray spike of {approx} 110 attosecond can be produced with a good contrast ratio.

We present an algorithm to photometrically calibrate widefield optical imaging surveys, that simultaneously solves for thecalibration parameters and relative stellar fluxes using overlappingobservations. The algorithm decouples the problem of "relative"calibrations from that of "absolute" calibrations; the absolutecalibration is reduced to determining a few numbers for the entiresurvey. We pay special attention to the spatial structure of thecalibration errors, allowing one to isolate particular error modes indownstream analyses. Applying this to the SloanDigital Sky Survey imagingdata, we achieve ~;1 percent relative calibration errors across 8500sq.deg/ in griz; the errors are ~;2 percent for the u band. These errorsare dominated by unmodelled atmospheric variations at Apache PointObservatory. These calibrations, dubbed ubercalibration, are now publicwith SDSS Data Release 6, and will be a part of subsequent SDSS datareleases.

A wireless ad-hoc networking protocol is presented. The protocol is designed to be flexible, easy to use and adaptable to a wide variety of potential applications. The primary considerations in design are small code size, guaranteed bandwidth access, limited delay, and error resilience in a highly dynamic ad-hoc environment. These considerations are achieved through the use of token ring protocol.

We consider a 6D extension of the Randall-Sundrum (RS) model, RS6, where the Standard Model (SM) gauge fields are allowed to propagate in an additional dimension, compactified on S{sup 1} or S{sup 1}/Z{sub 2}. In a minimal scenario, fermions propagate in the 5D RS subspace and their localization provides a model of flavor. New Kaluza-Klein (KK) states, corresponding to excitations of the gauge fields along the 6th dimension, appear near the TeV scale. The new gauge KK modes behave differently from those in the 5D warped models. These RS6 states have couplings with strong dependence on 5D field localization and, within the SM, only interact with heavy fermions and the Higgs sector, to a very good approximation. Thus, the collider phenomenology of the new gauge KK states sensitively depends on the 5D fermion geography. We briefly discuss inclusion of SM fermions in all 6 dimensions, as well as the possibility of going beyond 6D.