A 3D Particle Simulation Code for Heavy Ion Fusion Accelerator Studies (open access)

A 3D Particle Simulation Code for Heavy Ion Fusion Accelerator Studies

We describe WARP, a new particle-in-cell code being developed and optimized for ion beam studies in true geometry. We seek to model transport around bends, axial compression with strong focusing, multiple beamlet interaction, and other inherently 3d processes that affect emittance growth. Constraints imposed by memory and running time are severe. Thus, we employ only two 3d field arrays ({rho} and {phi}), and difference {phi} directly on each particle to get E, rather than interpolating E from three meshes; use of a single 3d array is feasible. A new method for PIC simulation of bent beams follows the beam particles in a family of rotated laboratory frames, thus straightening'' the bends. We are also incorporating an envelope calculation, an (r, z) model, and 1d (axial) model within WARP. The BASIS development and run-time system is used, providing a powerful interactive environment in which the user has access to all variables in the code database. 10 refs., 3 figs.
Date: June 8, 1990
Creator: Friedman, A.; Bangerter, R. O.; Callahan, D. A.; Grote, D. P.; Langdon, A. B. & Haber, I.
System: The UNT Digital Library
Accelerators for research and applications (open access)

Accelerators for research and applications

The newest particle accelerators are almost always built for extending the frontiers of research, at the cutting edge of science and technology. Once these machines are operating and these technologies mature, new applications are always found, many of which touch our lives in profound ways. The evolution of accelerator technologies will be discussed, with descriptions of accelerator types and characteristics. The wide range of applications of accelerators will be discussed, in fields such as nuclear science, medicine, astrophysics and space-sciences, power generation, airport security, materials processing and microcircuit fabrication. 13 figs.
Date: June 1, 1990
Creator: Alonso, J. R.
System: The UNT Digital Library
Anomalous surface phase formation on Pt sub 3 Sn <110> (open access)

Anomalous surface phase formation on Pt sub 3 Sn <110>

LEED analysis of the clean annealed surface of a {l angle}110{r angle} oriented Pt{sub 3}Sn single crystal surface indicates the formation of a multilayer surface phase which does not have the L1{sub 2} bulk structure. LEISS analysis indicates a surface stoichiometry of ca. 1:1 with Sn atoms displaced ca. 1.4 above the plane of Pt atoms. The surface phase is hypothesized to be a rhombic distortion of the {l angle}0001{r angle} plant of PtSn, which has a B8{sub 1} (NiAs-type) bulk structure. It is not clear whether the phase forms by precipitation of PtSn due to a slight (0.5%) stoichiometric excess of Sn in the bulk, or due to multilayer reconstruction driven by surface segregation. 20 refs., 3 figs.
Date: June 1, 1990
Creator: Haner, A.N.; Ross, P.N. (Lawrence Berkeley Lab., CA (USA)) & Bardi, U. (Florence Univ. (Italy). Dipt. di Chimica)
System: The UNT Digital Library
An asymmetric B Factory based on PEP (open access)

An asymmetric B Factory based on PEP

The study of rare and CP-violating B meson decays is well suited to a high-luminosity e{sup +} e{sup {minus}} collider. For studying certain decay processes there are also substantial benefits associated with asymmetric beam energies, which give a moving center of mass for the B mesons. We describe a design for a 9 GeV {times} 3.1 GeV B Factory in the PEP tunnel that would operate initially at a luminosity of 3 {times} 10{sup 33} cm{sup {minus}2}s{sup {minus}1}. Technical problems include issues related to high currents (e.g., beam instabilities, feedback systems, lifetime degradation and detector radiation power dissipation) and those related to the hetero-energetic beams (e.g., beam separation, beam-beam interaction and detector requirements). Issues requiring R D effort are identified. 8 refs., 2 figs., 2 tabs.
Date: June 1, 1990
Creator: Hutton, A. & Zisman, M. S.
System: The UNT Digital Library
Beam diagnostics in circular machines: Review of new developments (open access)

Beam diagnostics in circular machines: Review of new developments

Recent developments in beam diagnostic equipment and measurement techniques have been driven by commercial technological advances, better data analysis algorithms, and the need to measure complex beam properties. The need for such developments is due to the increased diversity, beam intensity, and luminosity/brightness requirements of charged particle circular accelerators. In addition, the advent of fast analog-to-digital converters and cheap, powerful microprocessors have fundamentally changed the approach to beam diagnosis, allowing designers to create systems where signal processing is performed locally at each detector. New beam monitors from a wide variety of circular accelerators are reviewed. A number of interesting or innovative ideas are presented in detail. 56 refs.
Date: June 1990
Creator: Jackson, G.
System: The UNT Digital Library
Beam impedance measurements on the ALS sector tank (open access)

Beam impedance measurements on the ALS sector tank

The 10 m long ALS curved sector tank is formed from two shells out of which the beam chamber is machined. Vacuum pumping and photon stops are located in an antechamber connected to the beam tube through a 1cm slot. In order to determine whether the beam is significantly coupled to the antechamber, measurements of longitudinal beam impedance were performed up to 26 GHz, well above the cutoff frequency of the beam pipe. Two different schemes were used: In the first, the wire method was adapted for use above cutoff; in the second, the impedance was detected from the response to TM-waves propagated in the aperture without a wire. Temperature at various locations in the setup was recorded for later phase corrections. Antennas were placed in the antechamber to detect radiated power or possible resonances. A reference measurement was made with the slot sealed by a flexible gasket of knitted wire. The seal was then removed and the response with antechamber recorded. The response was checked by inserting obstacles of known impedance. Both measurement methods provided low numbers with Z/n<0.001 Ohm over the whole frequency range. No resonances attributable to the antechamber were observed. 3 refs., 6 figs.
Date: June 1, 1990
Creator: Rimmer, R.A.; Goldberg, D.A.; Jacob, A.F.; Lambertson, G.R. & Voelker, F.
System: The UNT Digital Library
Binary rf pulse compression experiment at SLAC (open access)

Binary rf pulse compression experiment at SLAC

Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC …
Date: June 1, 1990
Creator: Lavine, T. L.; Spalek, G.; Farkas, Z. D.; Menegat, A.; Miller, R. H.; Nantista, C. et al.
System: The UNT Digital Library
Calculated Non-Linear Magnetic Field Penetration of Plasma Opening Switches (open access)

Calculated Non-Linear Magnetic Field Penetration of Plasma Opening Switches

We examine magnetic field penetration in the Plasma Opening Switch, exploring, in particular, advective field penetration arising in conjunction with radial density gradients across the cathode anode gap. Our calculations have been completed with the implicit multi-fluid, ANTHEM code. We show favored penetration along a radial density jump, unstable plain wave penetration for a 1/(y {minus} y{sub {alpha}+{epsilon}}) density dependence (with y measured from cathode to anode at Y{sub {alpha}}) in planar switches, and the penetration of finger-like magnetic field perturbations, when the fill plasmas bears initial sinusoidal disturbances on its generator interface. 7 refs., 4 figs.
Date: June 15, 1990
Creator: Mason, R. J.; Jones, M. E.; Wilson, D. C.; Bergman, C.; Thiem, K.; Grossmann, J. M. et al.
System: The UNT Digital Library
Characterization of Nb-Ti superconductors with artificial pinning structures (open access)

Characterization of Nb-Ti superconductors with artificial pinning structures

A series of multifilamentary APC Nb-Ti superconductors have been made with Nb added as a normal second phase to provide flux pinning centers. Two compositions, 12.5% vol % and 25 vol % Nb in Nb-Ti, have fabricated into multifilamentary composites using two different fabrication methods. One method used hot isostatic compaction and hot extrusion thoughout the processing. The other method (bundle-and-draw process) discontinued all hot processing at an intermediate level. While the J{sub c} values of the bundle-and-draw wires are quite promising, the critical current of the extruded wires appears to be limited by poor uniformity of the filament cross-sectional area along the conductor length. The large values of the index of the resistive transition and small filament standard-deviation-to-average area ratios observed in the wires produced by the bundle-and-draw process suggest extrinsic factors have little effect on J{sub c}. The variation in J{sub c} as the wire diameter is reduced appears to be most strongly affected by intrinsic factors: Nb distribution and pinning strength. The final filament microstructure and Nb spacing are shown to be difficult to calculate, e.g., the mean Nb spacing near the final wire size may be {1/2} to 1/3 that of the calculated value. 5 refs., …
Date: June 1, 1990
Creator: Dietderich, D. R. & Scanlan, R. M.
System: The UNT Digital Library
The Coastal Ocean Prediction Systems program: Understanding and managing our coastal ocean (open access)

The Coastal Ocean Prediction Systems program: Understanding and managing our coastal ocean

The goal of COPS is to couple a program of regular observations to numerical models, through techniques of data assimilation, in order to provide a predictive capability for the US coastal ocean including the Great Lakes, estuaries, and the entire Exclusive Economic Zone (EEZ). The objectives of the program include: determining the predictability of the coastal ocean and the processes that govern the predictability; developing efficient prediction systems for the coastal ocean based on the assimilation of real-time observations into numerical models; and coupling the predictive systems for the physical behavior of the coastal ocean to predictive systems for biological, chemical, and geological processes to achieve an interdisciplinary capability. COPS will provide the basis for effective monitoring and prediction of coastal ocean conditions by optimizing the use of increased scientific understanding, improved observations, advanced computer models, and computer graphics to make the best possible estimates of sea level, currents, temperatures, salinities, and other properties of entire coastal regions.
Date: June 1, 1990
Creator: Eden, H. F. & Mooers, C. N. K.
System: The UNT Digital Library
Considerations for an active and passive scanner to assay nuclear waste drums (open access)

Considerations for an active and passive scanner to assay nuclear waste drums

Radioactive wastes are generated at many DOE laboratories, military facilities, fuel fabrication and enrichment plants, reactors, hospitals, and university research facilities. At all of these sites, wastes must be separated, packaged, categorized, and packed into some sort of container--usually 208-L (55-gal) drums--for shipment to waste-storage sites. Prior to shipment, the containers must be labeled, assayed, and certified; the assay value determines the ultimate disposition of the waste containers. An accurate nondestructive assay (NDA) method would identify all the radioisotopes present and provide a quantitative measurement of their activity in the drum. In this way, waste containers could be routed in the most cost-effective manner and without having to reopen them. Currently, the most common gamma-ray method used to assay nuclear waste drums is segmented gamma-ray scanning (SGS) spectrometer that crudely measures only the amount of {sup 235}U or {sup 239}Pu present in the drum. This method uses a spatially-averaged, integrated, emitted gamma-ray-intensity value. The emitted intensity value is corrected by an assumed constant-attenuation value determined by a spatially-averaged, transmission (or active) measurement. Unfortunately, this typically results in an inaccurate determination of the radioactive activities within a waste drum because this measurement technique is valid only for homogeneous-attenuation or known drum …
Date: June 8, 1990
Creator: Martz, H. E.; Azevedo, S. G.; Roberson, G. P.; Schneberk, D. J.; Koenig, Z. M. & Camp, D.C. (Lawrence Livermore National Lab., CA (USA))
System: The UNT Digital Library
Contractor-Style Tunnel Cost Estimating (open access)

Contractor-Style Tunnel Cost Estimating

Keeping pace with recent advances in construction technology is a challenge for the cost estimating engineer. Using an estimating style that simulates the actual construction process and is similar in style to the contractor's estimate will give a realistic view of underground construction costs. For a contractor-style estimate, a mining method is chosen; labor crews, plant and equipment are selected, and advance rates are calculated for the various phases of work which are used to determine the length of time necessary to complete each phase of work. The durations are multiplied by the cost or labor and equipment per unit of time and, along with the costs for materials and supplies, combine to complete the estimate. Variations in advance rates, ground support, labor crew size, or other areas are more easily analyzed for their overall effect on the cost and schedule of a project. 14 figs.
Date: June 1, 1990
Creator: Scapuzzi, D.
System: The UNT Digital Library
Development of deep drawn aluminum piston tanks (open access)

Development of deep drawn aluminum piston tanks

An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.
Date: June 8, 1990
Creator: Whitehead, J. C.; Bronder, R. L.; Kilgard, L. W.; Evans, M. C.; Ormsby, A. E.; Spears, H. R. et al.
System: The UNT Digital Library
Electron identification at CDF (open access)

Electron identification at CDF

Electron identification at CDF is performed using the information of lateral and longitudinal shower spread, the track-cluster position match and the energy-momentum match. The tracking chamber with a solenoidal magnetic field at CDF is powerful for rejecting the backgrounds such as the {pi}{sup {plus minus}} {minus} {pi}{sup 0} overlaps, the {pi}{sup 0}/{gamma} conversions and interactive {pi}{sup {plus minus}} in electromagnetic calorimeter: The energy- momentum match cut can decrease the background due to the {pi}{sup {plus minus}} {minus} {pi}{sup 0} overlaps for non-isolated electrons with Et above 10 GeV by a factor of 20. The conversion electrons are identified using track information with an efficiency of 80 {plus minus} 3%. The charge of electrons from W decay can be determined in the pseudorapidity range of {vert bar}{eta}{vert bar} < 1.7 at CDF. The charge determination is useful for background estimation of Drell-Yan physics and heavy flavor physics. 5 refs., 5 figs.
Date: June 1, 1990
Creator: Kim, Shinhong
System: The UNT Digital Library
Electronic technology and the SLD detector (open access)

Electronic technology and the SLD detector

The SLD detector consists of five major subsystems, each with associated front-end electronics and an integrated FASTBUS control and data acquisition system. This paper highlights the choices among electronic technologies that have been developed for the SLD detector electronics. The common control, calibration, and data acquisition architectures are described. The functions of selected SLD integrated circuits, standard cells, gate arrays, and hybrids are summarized, and the integration of these functions into the common data acquisition path is described. Particular attention is directed to four areas of electronic technology developed for the SLD detector: the preamplifier hybrid designs are compared to their performance and implementation examined; the application of full custom CMOS digital circuits in SLD is compared to gate array and EPLD (electrically programmable logic device) implementations; the fiberoptic signal transmission techniques in SLD are examined and the data rates and link topology are presented; and finally, the packaging, power consumption, and cooling requirements for system functions resident inside the detector structure are explored. The rationale for the implementation choices in the SLD electronics is presented so that others might benefit from our experience.
Date: June 1, 1990
Creator: Fox, John D.; Dean, T.; Fox, M. J.; Freytag, D.; Gioumousis, A.; Haller, G. et al.
System: The UNT Digital Library
Emission assessment from full-scale co-combustion tests of binder- enhanced dRDF pellets and high sulfur coal at Argonne National Laboratory (open access)

Emission assessment from full-scale co-combustion tests of binder- enhanced dRDF pellets and high sulfur coal at Argonne National Laboratory

Argonne National Laboratory (ANL) and University of North Texas (UNT) research teams collected over 800 emissions and ash samples during the combustion of over 650 tons of binder enhanced densified refuse-drived fuel (b-dRDF) pellets with high sulfur coal in a spreader-stoker boiler at ANL. This full-scale test burn was conducted to validate predictions from laboratory and pilot scale test results that indicated substantial reductions of SO{sub 2}, NO{sub x} and CO{sub 2} in the flue gas, and the reduction of heavy metals and organics in the ash residue, when combusting the b-dRDF pellets with coal. Effects of varying fuel composition on performance of the boiler's spray-dryer/fabric filter emissions control system was also evaluated. This paper describes the b-dRDF pellet/coal cofiring tests, the emission and ash samples that were taken, the analyses that were conducted on these samples, and the final test results. 5 refs., 1 fig., 1 tab.
Date: June 4, 1990
Creator: Ohlsson, O. O.; Livengood, C. D. (Argonne National Lab., IL (USA)) & Daugherty, K. E. (University of North Texas, Denton, TX (USA))
System: The UNT Digital Library
Empirical identification of user information requirements in command and control system evaluation (open access)

Empirical identification of user information requirements in command and control system evaluation

This paper summarizes a study that was conducted to address user information requirements for the Force Level Control System. It was the first in a series being conducted at the US Army Tactical Command and Control System Experimentation Site (AES). User information requirements were determined via monitoring and classification of communications during a command and control exercise, as well as through subsequent exercise participant input. Separate measures of observed communication frequency, rated importance, and rated perishability were obtained for a set of information elements that comprised a comprehensive taxonomy of tactical command and control communications content. Analyses were then conducted to explore the relationships between frequency, importance, and perishability as well as develop a comprehensive index of criticality. The resulting comprehensive index of criticality is intended to be used by systems developers in selecting the information to be conveyed and processed by the Force Level Control System. 2 refs., 2 figs.
Date: June 1, 1990
Creator: McCallum, M.C.; Bittner, A.C. Jr. (Battelle Human Affairs Research Center, Seattle, WA (USA)) & Badalamente, R.V. (Pacific Northwest Lab., Richland, WA (USA))
System: The UNT Digital Library
Evolution of facility layout requirements and CAD (computer-aided design) system development (open access)

Evolution of facility layout requirements and CAD (computer-aided design) system development

The overall configuration of the Superconducting Super Collider (SSC) including the infrastructure and land boundary requirements were developed using a computer-aided design (CAD) system. The evolution of the facility layout requirements and the use of the CAD system are discussed. The emphasis has been on minimizing the amount of input required and maximizing the speed by which the output may be obtained. The computer system used to store the data is also described.
Date: June 1, 1990
Creator: Jones, M. (RTK-Joint Venture, Oakland, CA (USA))
System: The UNT Digital Library
Experimental results concerning global observables from the CERN SPS heavy ion program (open access)

Experimental results concerning global observables from the CERN SPS heavy ion program

A brief overview is given of experimental results obtained during the initial operation of the heavy-ion program at the CERN SPS during the period 1986--1988. This paper confines itself to a presentation of results on so-called global observables, such as energy flow and multiplicity distributions, and on information extracted from them. Of particular interest among the latter are an estimate of the magnitude and spatial distribution of the energy density attained. 3 refs., 27 figs.
Date: June 1990
Creator: Young, G. R.
System: The UNT Digital Library
Experimental results from studies on nucleus-nucleus collisions at high energy (open access)

Experimental results from studies on nucleus-nucleus collisions at high energy

A short overview is presented of results from the initial accelerator-based studies of collisions of heavy nuclei at high energies. Some comments are made on the global observables studied and their implications for achieving conditions for deconfinement. Finally, information available from certain more specific probes selected for their ability to test whether a deconfined system of quarks and gluons is created in such collisions is presented. 5 refs., 4 figs., 1 tab.
Date: June 1, 1990
Creator: Young, G. R.
System: The UNT Digital Library
Experiments at high elongations in DIII-D (open access)

Experiments at high elongations in DIII-D

In this paper we discuss the limitation to elongation observed in D-shaped plasmas in the DIII-D tokamak. We find that as the triangularity is increased and {ell}{sub i} is decreased that the n = 0 mode takes on an increasingly non-rigid character. Our analysis shows two aspects of the behavior; first, an increasing variation of the m/n = 1/0 component across flux surfaces and second, an increase in the relative amplitude of a m/n = 3/0 component which couples to the m/n = 1/0 component and further destabilizes the mode.
Date: June 1, 1990
Creator: Lazarus, E. A.; Turnbull, A. D.; Kellman, A. G.; Ferron, J. R.; Helton, F. J.; Lao, L. L. et al.
System: The UNT Digital Library
Flashlamp pumping of Nd:glass disk amplifiers (open access)

Flashlamp pumping of Nd:glass disk amplifiers

We present experimental results and a model of Nd:glass disk amplifiers which are used in inertial confinement fusion research. We first review our previous measurements on pulsed xenon flashlamps. We then discuss out measurements on the enhancement of the Nd fluorescence decay rate in laser disks by amplified spontaneous emission. Using these data, we have constructed a model of flashlamp pumping which treats the transfer efficiency of pump light from the flashlamps to the disks as an empirical function. We have found a simple description of this cavity transfer function which provides an excellent fit to the amplifier results for various pump pulselengths. We discuss the concept of the pump area ratio for describing the flashlamp packing density and show that amplifier performance is optimized for values of this parameter near unity. We finally present results for both a single-segment and a multisegment disk amplifier. We have used these devices to investigate new amplifier designs for a large scale fusion driver. 11 refs., 13 figs.
Date: June 12, 1990
Creator: Powell, H. T.; Erlandson, A. C.; Jancaitis, K. S. & Murray, J. E.
System: The UNT Digital Library
Future physics with a proposed radioactive beam facility in the United States (open access)

Future physics with a proposed radioactive beam facility in the United States

A brief overview of the physics at a proposed radioactive beam facility or ISOSPIN LABORATORY is presented. Its impact on future directions in nuclear structure, nuclei far from stability, reaction physics, nuclear astrophysics, and several applied fields is pointed out. Of particular interest are neutron rich beams. Radioactive beams with energies on the order of {approximately}10 MeV/nucleon or less are emphasized rather than the more energetic beams obtainable through projectile fragmentation. A concept of a high-intensity radioactive beam facility based on the post-acceleration of radioactive ions from an isotope-separator linked to a high-current, high-energy, light ion accelerator is discussed. 21 refs., 1 figs.
Date: June 1, 1990
Creator: Nitschke, J.M.
System: The UNT Digital Library
Geotechnical characterization and construction methods for SSC tunnel excavation (open access)

Geotechnical characterization and construction methods for SSC tunnel excavation

The site for the Superconducting Super Collider (SSC) facility was selected in 1988 after a nationwide proposal competition. The selected site is located in Ellis County, Texas, surrounding the town of Waxahachie which is about 30 miles (48 km) south of the City of Dallas central business district. This paper will describe the geotechnical conditions anticipated for excavation at the SSC site. A general geologic and geomechanical description of the rock present will be followed by a summary of the site-specific conceptual design for the tunneled components of the SSC machine. The Supercollider project will include about 70 miles (113) km of tunnel excavation.
Date: June 1, 1990
Creator: Nelson, P.P. & Lundin, T.K. (Texas Univ., Austin, TX (USA) Superconducting Super Collider Lab., Dallas, TX (USA))
System: The UNT Digital Library