Resource Type

Quench observation using quench antennas on RHIC IR quadrupole magnets (open access)

Quench observation using quench antennas on RHIC IR quadrupole magnets

Quench observation using quench antennas is now being performed routinely on RHIC dipole and quadrupole magnets. Recently, a quench antenna was used on a RHIC IR magnet which is heavily instrumented with voltage taps. It was confirmed that the signals detected in the antenna coils do not contradict the voltage tap signals. The antenna also detects a sign of mechanical disturbance which could be related to a training quench. This paper summarizes signals detected in the antenna and discusses possible causes of these signals.
Date: July 1995
Creator: Ogitsu, T.; Terashima, A.; Tsuchiya, K.; Ganetis, G.; Muratore, J. & Wanderer, P.
System: The UNT Digital Library
Solar two: A molten salt power tower demonstration (open access)

Solar two: A molten salt power tower demonstration

A consortium of United States utility concerns led by the Southern California Edison Company (SCE) is conducting a cooperative project with the US Department of Energy (DOE), Sandia National Laboratories, and industry to convert the 10-MW Solar One Power Tower Pilot Plant to molten nitrate salt technology. The conversion involves installation of a new receiver, a new thermal storage system, and a new steam generator; it utilizes Solar One`s heliostat field and turbine generator. Successful operation of the converted plant, called Solar Two, will reduce economic risks in building initial commercial power tow projects and accelerate the commercial acceptance of this promising renewable energy technology. The estimated cost of Solar Two, including its three-year test period, is $48.5 million. The plant will begin operation in early 1996.
Date: August 1995
Creator: Tyner, C. E.; Sutherland, J. P. & Gould, W. R., Jr.
System: The UNT Digital Library
Tuning shims for high field quality in superconducting magnets (open access)

Tuning shims for high field quality in superconducting magnets

A high field quality in interaction region quadrupoles is crucial to the luminosity performance of high energy colliders such as the Relativistic Heavy Ion Collider (RHIC). The field quality in magnets is limited in part by manufacturing tolerances in the parts and assembly. A tuning shim method has been developed to reduce the relative field errors ({Delta}B/B) from {approximately}10{sup {minus}4} to {approximately}10{sup {minus}5} at 2/3 of the coil radius. Eight tuning shims having a variable thickness of iron are inserted after the construction and measurement of field harmonics in the magnet. In this paper the tuning shim technique is described for RHIC interaction region quadrupoles. The results of calculations and measurement are also presented.
Date: August 1995
Creator: Gupta, R.; Anerella, M. & Cozzolino, J.
System: The UNT Digital Library
Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor (open access)

Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5{times}10{sup 17} W/cm{sup 2}) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime.
Date: April 1, 1995
Creator: Wilks, S. C.; Kruer, W. L.; Young, P. E.; Hammer, J. & Tabak, M.
System: The UNT Digital Library
The magnet system of the Relativistic Heavy Ion Collider (RHIC) (open access)

The magnet system of the Relativistic Heavy Ion Collider (RHIC)

The Relativistic Heavy Ion Collider now under construction at Brookhaven National Laboratory (BNL) is a colliding ring accelerator to be completed in 1999. Through collisions of heavy ions it is hoped to observe the creation of matter at extremely high temperatures and densities, similar to what may have occurred in the original "Big Bang." The collider rings will consist of 1740 superconducting magnet elements. Some of elements are being manufactured by industrial partners (Northrop Grumman and Everson Electric). Others are being constructed or assembled at BNL. A description is given of the magnet designs, the plan for manufacturing and test results. In the manufacturing of the magnets, emphasis has been placed on uniformity of their performance and on quality. Results so far indicate that this emphasis has been very successful.
Date: July 1995
Creator: Greene, A.; Anerella, M. & Cozzolino, J.
System: The UNT Digital Library
Properties of a new average power Nd-doped phosphate laser glass (open access)

Properties of a new average power Nd-doped phosphate laser glass

The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime.
Date: March 9, 1995
Creator: Payne, S. A.; Marshall, C. D.; Bayramian, A. J.; Wilke, G. D. & Hayden, J. S.
System: The UNT Digital Library
Plasma gate switch experiment on Pegasus II (open access)

Plasma gate switch experiment on Pegasus II

The plasma gate switch is a novel technique for producing a long conduction time vacuum opening switch. The switch consists of an aluminum foil which connects the cathode to the anode in a coaxial geometry. The foil is designed so that the maximum axial acceleration is in the center of the foil and that at the appropriate time, the center opens up and magnetic flux is carried down the gun to the load region. The switch is designed to minimize the amount of mass transported into the load region. We have completed the first experimental test of this design and present results from the test. These results indicate there were some asymmetry problems in the construction of the switch but that otherwise the switch performed as expected.
Date: September 1995
Creator: Wysocki, F. J.; Benage, J. F., Jr. & Shlachter, J. S.
System: The UNT Digital Library
Deep x-ray lithography for micromechanics (open access)

Deep x-ray lithography for micromechanics

Extensions of the German LIGA process have brought about fabrication capability suitable for cost effective production of precision engineered components. The process attributes allow fabrication of mechanical components which are not capable of being made via conventional subtractive machining methods. Two process improvements have been responsible for this extended capability which involve the areas of thick photoresist application and planarization via precision lapping. Application of low-stress x-ray photoresist has been achieved using room temperature solvent bonding of a preformed photoresist sheet. Precision diamond lapping and polishing has provided a flexible process for the planarization of a wide variety of electroplated metals in the presence of photoresist. Exposure results from the 2.5 GeV National Synchrotron Light Source storage ring at Brookhaven National Laboratory have shown that structural heights of several millimeter and above are possible. The process capabilities are also well suited for microactuator fabrication. Linear and rotational magnetic microactuators have been constructed which use coil winding technology with LIGA fabricated coil forms. Actuator output forces of 1 milliNewton have been obtained with power dissipation on the order of milliWatts. A rotational microdynamometer system which is capable of measuring torque-speed data is also discussed.
Date: August 1995
Creator: Christenson, T. R. & Guckel, H.
System: The UNT Digital Library
Material and processing issues for the monolithic integration of microelectronics with surface-micromachined polysilicon sensors and actuators (open access)

Material and processing issues for the monolithic integration of microelectronics with surface-micromachined polysilicon sensors and actuators

The monolithic integration of micromechanical devices with their controlling electronics offers potential increases in performance as well as decreases in cost for these devices. Analog Devices has demonstrated the commercial viability of this integration by interleaving the micromechanical fabrication steps of an accelerometer with the microelectronic fabrication steps of its controlling electronics. Sandia`s Microelectronics Development Laboratory has integrated the micromechanical and microelectronic processing sequences in a segregated fashion. In this CMOS-first, micromechanics-last approach, conventional aluminum metallization is replaced by tungsten metallization to allow CMOS to withstand subsequent high-temperature processing during the micromechanical fabrication. This approach is a further development of an approach originally developed at UC Berkeley. Specifically, the issues of yield, repeatability, and uniformity of the tungsten/CMOS approach are addressed. Also, material issues related to the development of high-temperature diffusion barriers, adhesion layers, and low-stress films are discussed. Processing and material issues associated with alternative approaches to this integration such as micromechanics- first, CMOS-last or the interleaved process are also discussed.
Date: August 1, 1995
Creator: Smith, J.H.; Montague, S. & Sniegowski, J.J.
System: The UNT Digital Library
Using the CAVE virtual-reality environment as an aid to 3-D electromagnetic field computation (open access)

Using the CAVE virtual-reality environment as an aid to 3-D electromagnetic field computation

One of the major problems in three-dimensional (3-D) field computation is visualizing the resulting 3-D field distributions. A virtual-reality environment, such as the CAVE, (CAVE Automatic Virtual Environment) is helping to overcome this problem, thus making the results of computation more usable for designers and users of magnets and other electromagnetic devices. As a demonstration of the capabilities of the CAVE, the elliptical multipole wiggler (EMW), an insertion device being designed for the Advanced Photon Source (APS) now being commissioned at Argonne National Laboratory (ANL), wa made visible, along with its fields and beam orbits. Other uses of the CAVE in preprocessing and postprocessing computation for electromagnetic applications are also discussed.
Date: August 1995
Creator: Turner, L. R.; Levine, D.; Huang, M.; Papka, M. & Kettunen, L.
System: The UNT Digital Library
Multidimensional DDT modeling of energetic materials (open access)

Multidimensional DDT modeling of energetic materials

A nonequilibrium continuum mixture model has been incorporated into the CTH shock physics code to describe deflagration-to-detonation transition in granular energetic materials. This approach treats multiple thermodynamic and mechanics fields including the effects of relative material motion, rate-dependent compaction and interphase exchange of mass, momentum and energy. A finite volume description is formulated and internal state variables are solved using an operator-splitting method. Numerical simulations of low-velocity impact on a weakly-confined porous propellant bed are presented which display lateral wall release leading to curved compaction and reaction wave behavior.
Date: August 1, 1995
Creator: Baer, M. R.; Hertel, E. S. & Bell, R. L.
System: The UNT Digital Library
Light U(1) gauge boson coupled to baryon number (open access)

Light U(1) gauge boson coupled to baryon number

The authors discuss the phenomenology of a light U(1) gauge boson, {gamma}{sub B}, that couples only to baryon number. Gauging baryon number at high energies can prevent dangerous baryon-number violating operators that may be generated by Planck scale physics. However, they assume at low energies that the new U(1) gauge symmetry is spontaneously broken and that the {gamma}{sub B} mass m{sub B} is smaller than m{sub z}. They show for m{sub {Upsilon}} < m{sub B} < m{sub z} that the {gamma}B coupling {alpha}{sub B} can be as large as {approximately} 0.1 without conflicting with the current experimental constraints. The authors argue that {alpha}{sub B} {approximately} 0.1 is large enough to produce visible collider signatures and that evidence for the {gamma}{sub B} could be hidden in existing LEP data. They show that there are realistic models in which mixing between the {gamma}{sub B} and the electroweak gauge bosons occurs only as a radiative effect and does not lead to conflict with precision electroweak measurements. Such mixing may nevertheless provide a leptonic signal for models of this type at an upgraded Tevatron.
Date: June 1, 1995
Creator: Carone, C.D. & Murayama, Hitoshi
System: The UNT Digital Library
Nonlinear Waves in Reaction Diffusion Systems: The Effect of Transport Memory (open access)

Nonlinear Waves in Reaction Diffusion Systems: The Effect of Transport Memory

Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wavefronts in reaction diffusion systems. We obtain new results such as the possibility of spatial oscillations in the wavefront shape for certain values of the system parameters and high enough wavefront speeds. We also generalize earlier known results concerning the minimum wavefront speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piece-wise linear representation of the nonlinearity.
Date: November 4, 1999
Creator: Hurd, Alan J.; Kenkre, v. M. & Manne, K. K.
System: The UNT Digital Library
Characterization of the LiSi/CsBr-LiBr-KBr/FeS(2) System for Potential Use as a Geothermal Borehole Power Source (open access)

Characterization of the LiSi/CsBr-LiBr-KBr/FeS(2) System for Potential Use as a Geothermal Borehole Power Source

We are continuing to study the suitability of modified thermal-battery technology as a potential power source for geothermal borehole applications. Previous work focused on the LiSi/FeS{sub 2} couple over a temperature range of 350 C to 400 C with the LiBr-KBr-LiF eutectic, which melts at 324.5 C. In this work, the discharge processes that take place in LiSi/CsBr-LiBr-KBr eutectic/FeS{sub 2} thermal cells were studied at temperatures between 250 C and 400 C using pelletized cells with immobilized electrolyte. The CsBr-LiBr-KBr eutectic was selected because of its lower melting point (228.5 C). Incorporation of a quasi-reference electrode allowed the determination of the relative contribution of each electrode to the overall cell polarization. The results of single-cell tests and limited battery tests are presented, along with preliminary data for battery stacks tested in a simulated geothermal borehole environment.
Date: October 18, 1999
Creator: GUIDOTTI, RONALD A. & REINHARDT, FREDERICK W.
System: The UNT Digital Library
Challenges in the Twentieth Century and Beyond: Computer codes and data (open access)

Challenges in the Twentieth Century and Beyond: Computer codes and data

The second half of the twentieth century has seen major changes in computer architecture. In the early fifties to the early seventies, the word ``computes`` demanded reverence, respect and even fear. Computers, then, were almost ``untouchable``. Today, computers have become the mainstreams of communication on the rapidly expanding communication highways. They have become necessities of life. With the computers came the establishment of information centers -- tasked with the dissemination of newly developed computer codes and generated data. The Radiation Shielding Information Center (RSIC) was founded in 1962 as a valuable resource for programs and cross section data concerned with the effects of radiation. Through the years, RSIC has collected computer codes developed for the early machines (IBM 360, DEC PDP-10, CDC 660, UNIVAC 1100), to the more modern and powerful desktops (Pentium based Personal Computers, UNIX workstations like the IBM RISC 6000, DEC Alpha, SUN) and supercomputers (Cray XMP, Cray YMP, Cray C90, IBM SP2).
Date: December 1, 1995
Creator: Kirk, B.L.
System: The UNT Digital Library
Network improvement problems (open access)

Network improvement problems

The authors study budget constrained optimal network improvement problems. Such problems aim at finding optimal strategies for improving a network under some cost measure subject to certain budget constraints. As an example, consider the following prototypical problem: Let G = (V, E) be an undirected graph with two cost values L(e) and C(e) associated with each edge e, where L(e) denotes the length of e and C(e) denotes the cost of reducing the length of e by a unit amount. A reduction strategy specifies for each edge e, the amount by which L(e) is to be reduced. For a given budget B, the goal is to find a reduction strategy such that the total cost of reduction is at most B and the minimum cost tree (with respect to some measure M) under the modified L costs is the best over all possible reduction strategies which obey the budget constraint. Typical measures M for a tree are the total weight and the diameter. They provide both hardness and approximation results for the two measures M mentioned above. For the problem of minimizing the total weight of a spacing tree, they provide an algorithm that, for any fixed {gamma},{var_epsilon} > 0, …
Date: September 1, 1995
Creator: Krumke, S. O.; Noltemeier, H.; Drangmeister, K. U.; Marathe, M. V. & Ravi, S. S.
System: The UNT Digital Library
Using artificial neural networks to predict the performance of a liquid metal reflux solar receiver: Preliminary results (open access)

Using artificial neural networks to predict the performance of a liquid metal reflux solar receiver: Preliminary results

Three and four-layer backpropagation artificial neural networks have been used to predict the power output of a liquid metal reflux solar receiver. The networks were trained using on-sun test data recorded at Sandia National Laboratories in Albuquerque, New Mexico. The preliminary results presented in this paper are a comparison of how different size networks train on this particular data. The results give encouragement that it will be possible to predict output power of a liquid metal receiver under a variety of operating conditions using artificial neural networks.
Date: December 31, 1995
Creator: Fowler, M.M.
System: The UNT Digital Library
Conceptual design of the National Ignition Facility (open access)

Conceptual design of the National Ignition Facility

DOE commissioned a Conceptual Design Report (CDR) for the National Ignition Facility (NIF) in January 1993 as part of a Key Decision Zero (KDO), justification of Mission Need. Motivated by the progress to date by the Inertial Confinement Fusion (ICF) program in meeting the Nova Technical Contract goals established by the National Academy of Sciences in 1989, the Secretary requested a design using a solid-state laser driver operating at the third harmonic (0.35 {mu}m) of neodymium (Nd) glass. The participating ICF laboratories signed a Memorandum of Agreement in August 1993, and established a Project organization, including a technical team from the Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and the Laboratory for Laser Energetics at the University of Rochester. Since then, we completed the NIF conceptual design, based on standard construction at a generic DOE Defense Program`s site, and issued a 7,000-page, 27-volume CDR in May 1994.2 Over the course of the conceptual design study, several other key documents were generated, including a Facilities Requirements Document, a Conceptual Design Scope and Plan, a Target Physics Design Document, a Laser Design Cost Basis Document, a Functional Requirements Document, an Experimental Plan for Indirect Drive …
Date: August 2, 1995
Creator: Paisner, J.A.; Kumpan, S.A.; Lowdermilk, W.H.; Boyes, J.D. & Sorem, M.
System: The UNT Digital Library
CP Violation in B Decays at the Tevatron (open access)

CP Violation in B Decays at the Tevatron

Between 1992 to 1996, the CDF and D0 detectors each collected data samples exceeding 100 pb{sup {minus}1} of p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. These data sets led to a large number of precision measurements of the properties of B hadrons including lifetimes, masses, neutral B meson flavor oscillations, and relative branching fractions, and to the discovery of the B{sub 0} meson. Perhaps the most exciting result was the first look at the CP violation parameter sin ({vert_bar}2{beta}){vert_bar} using the world's largest sample of fully reconstructed B{sup 0}/{bar B}{sup 0} {r_arrow} J/{psi}K{sub s}{sup 0} decays. A summary of this result is presented here. In the year 2000, the Tevatron will recommence p{bar p} collisions with an over order of magnitude expected increased in integrated luminosity (1 fb{sup {minus}1} per year). The CDF and D0 detectors will have undergone substantial upgrades, particularly in the tracking detectors and the triggers. With these enhancements, the Tevatron B physics program includes precision measurements of sin(2{beta}) and B{sub s}{sup 0} flavor oscillations, as well as studies of rare B decays that are sensitive to new physics. The studies of B{sub s}{sup 0} mesons will be particularly interesting as this …
Date: September 17, 1999
Creator: Kroll, I. Joseph
System: The UNT Digital Library
Diphoton production in p{bar p} collisions at {radical}s = 1.8 TeV (open access)

Diphoton production in p{bar p} collisions at {radical}s = 1.8 TeV

We present measurements of the inclusive {gamma}{gamma} cross section (as a function of invariant mass and photon {epsilon}{sub {tau}}), in p{bar p} collisions at {radical}s = 1.8 TeV, made using the D0 detector at the Fermilab Tevatron collider. The next is leading order (NLO) QCD prediction is found to be in good agreement with the data. The effects of invariant mass and diphoton balance cuts, which test the next-to-leading order contributions to the cross section, are investigated. We also compare the distribution of {kappa}{sub {tau}} between samples of diphotons and highly electromagnetic jets, and find that the NLO QCD prediction models the shape of the {gamma}{gamma} {kappa}{sub {tau}} distribution quite well.
Date: July 1, 1995
Creator: Abachi, S.
System: The UNT Digital Library
Radiation dose modeling using IGRIP and Deneb/ERGO (open access)

Radiation dose modeling using IGRIP and Deneb/ERGO

The Radiological Environment Modeling System (REMS) quantifies dose to humans in radiation environments using the IGRIP (Interactive Graphical Robot Instruction Program) and Deneb/ERGO (Ergonomics) simulation software products. These commercially available products are augmented with custom C code to provide the radiation exposure information to and collect the radiation dose information from the workcell simulations. The emphasis of this paper is on the IGRIP and Deneb/ERGO parts of REMS, since that represents the extension to existing capabilities developed by the authors. Through the use of any radiation transport code or measured data, a radiation exposure input database may be formulated. User-specified IGRIP simulations utilize these database files to compute and accumulate dose to human devices (Deneb`s ERGO human) during simulated operations around radiation sources. Timing, distances, shielding, and human activity may be modeled accurately in the simulations. The accumulated dose is recorded in output files, and the user is able to process and view this output. REMS was developed because the proposed reduction in the yearly radiation exposure limit will preclude or require changes in many of the manual operations currently being utilized in the Weapons Complex. This is particularly relevant in the area of dismantlement activities at the Pantex Plant …
Date: December 31, 1995
Creator: Vickers, D. S.; Davis, K. R.; Breazeal, N. L.; Watson, R. A. & Ford, M. S.
System: The UNT Digital Library
Automatic history matching of geothermal field performance (open access)

Automatic history matching of geothermal field performance

We have developed inverse modeling capabilities for the multiphase multicomponent numerical simulator TOUGH2 to facilitate automatic history matching, and parameter estimation based on data obtained during exploitation of Geothermal fields. The ITOUGH2 code allows one to estimate TOUGH2 input parameters based on any type of observation for which a corresponding TOUGH2 output can be calculated. Furthermore, a detailed residual and error analysis is performed, and the uncertainty of model predictions can be evaluated. This paper focuses on the solution of the inverse; problem, i.e. the determination of model-related parameters by automatically calibrating a conceptual model of the Geothermal system against data obtained during field operation. We first describe the modeling, approach used to simulate fluid and heat flow in fractured-porous media. The inverse problem is then formulated, followed by a brief discussion of the optimization algorithm. A sample problem is given to demonstrate the application of the method to Geothermal reservoir data.
Date: August 1, 1995
Creator: Finsterle, S. & Pruess, K>
System: The UNT Digital Library
Integrated models for plasma/material interaction during loss of plasma confinement. (open access)

Integrated models for plasma/material interaction during loss of plasma confinement.

A comprehensive computer package, High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS), has been developed to evaluate the damage incurred on plasma-facing materials during loss of plasma confinement. The HEIGHTS package consists of several integrated computer models that follow the start of a plasma disruption at the scrape-off layer (SOL) through the transport of the eroded debris and splashed target materials to nearby locations as a result of the energy deposited. The package includes new models to study turbulent plasma behavior in the SOL and predicts the plasma parameters and conditions at the divertor plate. Full two-dimensional comprehensive radiation magnetohydrodynamic models are coupled with target thermodynamics and liquid hydrodynamics to evaluate the integrated response of plasma-facing materials. A brief description of the HEIGHTS package and its capabilities are given in this work with emphasis on turbulent plasma behavior in the SOL during disruptions.
Date: July 29, 1998
Creator: Hassanein, A.
System: The UNT Digital Library
Probing coal reactivity by time-resolved small angle x-ray scattering. (open access)

Probing coal reactivity by time-resolved small angle x-ray scattering.

The objective of this study is to observe changes in coal structure in situ with small angle X-ray scattering (SAXS) during solvent swelling and during pyrolysis. We have built a SAXS instrument at the Basic Energy Sciences Synchrotrons Research Center at the Advanced Photon Source that allows us to obtain scattering patterns in the millisecond time domain. The eight Argonne Premium Coal samples were used in this study. The information that can be derived from these experiments, such as changes in fractal dimensionality and in size and type of porosity, was found to be very rank-dependent. In the swelling experiments, it was noted that for certain coals, structural changes occurred in just a few minutes.
Date: January 22, 1999
Creator: Winans, R. E.
System: The UNT Digital Library