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Multiple-gap theory of toroidal Alfven waves with kinetic effects

Description: The stability of kinetic toroidal Alfven waves with multi-gap coupling is analyzed by using the two-dimensional ballooning transform. An alternate convergence scheme, based on the smallness of the inverse aspect ratio, is devised. The resulting wave functions are oscillatory and do not balloon in contrast to the wave functions of conventional ballooning theory. It is shown that the single-gap theory is a special, weak shear (s {yields} 0) limit of the formalism. Analytical and numerical results… more
Date: September 1, 1992
Creator: Zhang, X. D.; Zhang, Y. Z. & Mahajan, S. M.
Partner: UNT Libraries Government Documents Department
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Comparative analysis of a fusion reactor blanket in cylindrical and toroidal geometry using Monte Carlo

Description: Differences in neutron fluxes and nuclear reaction rates in a noncircular fusion reactor blanket when analyzed in cylindrical and toroidal geometry are studied using Monte Carlo. The investigation consists of three phases--a one-dimensional calculation using a circular approximation to a hexagonal shaped blanket; a two-dimensional calculation of a hexagonal blanket in an infinite cylinder; and a three-dimensional calculation of the blanket in tori of aspect ratios 3 and 5. The total blanket rea… more
Date: March 1, 1976
Creator: Chapin, D. L.
Partner: UNT Libraries Government Documents Department
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CTR plasma engineering studies. Progress report, 1 September 1975--30 Jun 1976

Description: During the past contract period, this research has been concerned with three principal tasks, namely: (1) Fusion-product studies. The primary objective of this work is to study potential effects (e.g. instabilities, changes in heating profile and wall loadings, etc.) caused by high-energy fusion products. A second objective is to establish the operating conditions and measurements required for use of D-/sup 3/He in early experiments such as TFTR to simulate D-T burns. (2) Mirror system studies.… more
Date: April 15, 1976
Creator: Miley, G. H.
Partner: UNT Libraries Government Documents Department
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Effects of density gradient modification on fluid instability in thermonuclear micro-implosions

Description: The presence of hydrodynamic fluid instability at the ablation surface puts constraints on the kinds of targets, surface finish, and energy sources that one can use for thermonuclear micro-implosions. If Taylor-like modes grow at near the classical value, one is limited to low aspect ratio shells and surface finishes of 10-100 A. These surface finish requirements can be reduced by 1 to 2 orders of magnitude by exploiting density gradient modification techniques to obtain a shallow density gradi… more
Date: September 24, 1976
Creator: Lindl, J. D.; Bangerter, R. O.; Nuckolls, J. H.; Mead, W. C. & Thomson, J. J.
Partner: UNT Libraries Government Documents Department
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ELMO Bumpy Torus Reactor (EBTR) reference design

Description: The goal of the ELMO Bumpy Torus Reactor (EBTR) study is the evaluation of the EBT confinement concept as the basis for development of a commercial fusion power reactor. A multidisciplinary, self-consistent treatment of EBT reactor scaling and design has been completed and a reference design (EBTR-48) has been developed. This design, based on a realistic plasma model and relatively conservative engineering parameters (i.e., 1 MW/m/sup 2/ neutron wall loading and a 7.3 T maximum toroidal field),… more
Date: November 1, 1976
Creator: McAlees, D. G.; Uckan, N. A. & Bettis, E. S.
Partner: UNT Libraries Government Documents Department
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Theoretical considerations of magnetic cusps for electron-beam fusion systems

Description: Single particle motion of relativistic electrons in cusp magnetic fields has been studied analytically and numerically to evaluate some aspects of this approach to beam transport and trapping in inertial confinement schemes. It is found that angular momentum is a serious problem, and that at least one mirror loss cone exists for any initial injection conditions. Specular and randomizing reflections are investigated. It is found that charge and current neutral injection into a cusp will not prov… more
Date: April 1, 1977
Creator: Wright, T. P.
Partner: UNT Libraries Government Documents Department
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EPR and TNS. [Technological next step after an experimental power reactor]

Description: The recognition of the need for an intermediate CTR experiment, to be constructed before the first experimental power reactor (EPR) is discussed. This device, called the next step (TNS), is the logical successor of the Technology Test Assembly with Plasma (TTAP) concept. The TNS has derived its basic function from the TTAP; namely, operational testing of EPR-relevant technologies and plasma control techniques. The technical reasons which militate against the possibility of successful EPR constr… more
Date: June 1, 1976
Creator: Clarke, J. F.
Partner: UNT Libraries Government Documents Department
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Elmo Bumpy Torus Reactor. [Reference design]

Description: In the Elmo Bumpy Torus Reactor (EBTR) study the feasibility of achieving a fusion power plant based on the EBT confinement concept was evaluated. If the present understanding of the physics can be extrapolated to reactor scale devices the reactor could operate at high beta, high power density, and at steady state. The high aspect ratio of the device eases the accessibility, structural design and remote maintenance problems which are common to low aspect ratio machines. A version of the EBTR re… more
Date: September 17, 1976
Creator: McAlees, D. G.; Uckan, N. A. & Lidsky, L. M.
Partner: UNT Libraries Government Documents Department
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Theory of continuum damping of toroidal Alfven Eigenmodes in finite-[beta] tokamaks

Description: We have formulated a general theoretical approach for analyzing two-dimensional structures of high-n Toroidal Alfven Eigenmodes (TAE) in large aspect-ratio, finite-[beta] tokamaks. Here, n is the toroidal wave number and [beta] is the ratio between plasma and magnetic pressures. The present approach generalizes the standard ballooning-mode formalism and is capable of treating eigenmodes with extended global radial structures as well as finite coupling between discrete and continuous spectra. Em… more
Date: May 1, 1993
Creator: Zonca, F. & Chen, Liu.
Partner: UNT Libraries Government Documents Department
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Moment equation approach to neoclassical transport theory

Description: The neoclassical cross-field fluxes for a toroidally confined, axisymmetric plasma are calculated in terms of the thermodynamic forces from the fluid continuity and momentum balance equations. This macroscopic formulation of neoclassical transport theory unifies the numerous complex expressions for the transport coefficients, previously obtained by solving the Fokker-Planck equation, and elucidates their physical basis. In the large aspect ratio limit, the continuous transition in the scaling o… more
Date: September 1, 1977
Creator: Hirshman, S. P.
Partner: UNT Libraries Government Documents Department
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ITER plasma equilibrium and poloidal field system design

Description: Several poloidal field coil design issues are identified when assessing the benefits of high plasma elongaton in an ITER device. Among these are the sensitivity of PF ampere-turens and coil energy to specific constraints on the plasma shape and profiles and the optimal placement of PF coils subject to assumed operating scenarios. Two versons of free boundary equilibrium codes presently under development at the Oak Ridge National Laboratory (ORNL), HEQ and VEQ, are used to solve several PF desig… more
Date: January 1, 1988
Creator: Strickler, D. J.; Galambos, J. D. & Peng, Y. K. M.
Partner: UNT Libraries Government Documents Department
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Continuous tokamaks

Description: A tokamak configuration is proposed that permits the rapid replacement of a plasma discharge in a ''burn'' chamber by another one in a time scale much shorter than the elementary thermal time constant of the chamber first wall. With respect to the chamber, the effective duty cycle factor can thus be made arbitrarily close to unity minimizing the cyclic thermal stress in the first wall. At least one plasma discharge always exists in the new tokamak configuration, hence, a continuous tokamak. By … more
Date: April 1, 1978
Creator: Peng, Y. K. M.
Partner: UNT Libraries Government Documents Department
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Bootstrap dependence on plasma profile parameters

Description: The bootstrap fraction, I{sub bs}/I{sub p}, and the shape of the bootstrap current density, J{sub bs}(r), can depend sensitively on the shape of the plasma profiles. Beginning with Hirshman's form for the bootstrap current density, and making a large aspect ratio expansion (proceeding two orders in the square root of the inverse aspect ratio, {epsilon}), we derive an expression for the bootstrap fraction of the form I{sub bs}/I{sub p} = {epsilon}{sup {1/2}}{beta}{sub p}C{sub bs}({alpha}{sub n},… more
Date: August 1, 1992
Creator: Pomphrey, N.
Partner: UNT Libraries Government Documents Department
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Atomic layer deposition of ZnO on ultra-low-density nanoporous silica aerogel monoliths

Description: We report on atomic layer deposition of an {approx} 2-nm-thick ZnO layer on the inner surface of ultralow-density ({approx} 0.5% of the full density) nanoporous silica aerogel monoliths with an extremely large effective aspect ratio of {approx} 10{sup 5} (defined as the ratio of the monolith thickness to the average pore size). The resultant monoliths are formed by amorphous-SiO{sub 2}/wurtzite-ZnO nanoparticles which are randomly oriented and interconnected into an open-cell network with an ap… more
Date: September 2, 2004
Creator: Kucheyev, S O; Biener, J; Wang, Y M; Baumann, T F; Wu, K J; van Buuren, T et al.
Partner: UNT Libraries Government Documents Department
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Stability Affects of Artificial Viscosity in Detonation Modeling

Description: Accurate multi-dimensional modeling of detonation waves in solid HE materials is a difficult task. To treat applied problems which contain detonation waves one must consider reacting flow with a wide range of length-scales, non-linear equations of state (EOS), and material interfaces at which the detonation wave interacts with other materials. To be useful numerical models of detonation waves must be accurate, stable, and insensitive to details of the modeling such as the mesh spacing, and mesh… more
Date: June 3, 2002
Creator: Vitello, P & Souers, P C
Partner: UNT Libraries Government Documents Department
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Surface Dynamics during Environmental Degradation of Crystal Surfaces

Description: Using in situ optical microscopy and scattering measurements, we have followed the evolution of surface morphology during etching and measured surface etching rates as a function of humidity and undersaturation. From our experiments to date we have developed the following picture of etch pit formation on KDP crystal surfaces. Pit formation is characterized by a nucleation and growth process: the introduction of water creates a condition of undersaturation at the crystal surface. The equilibrium… more
Date: February 21, 2001
Creator: Whitman, P; DeYoreo, J; Land, T; Miller, E; Suratwala, T; Thorsness, C et al.
Partner: UNT Libraries Government Documents Department
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ELMs and the H-Mode Pedestal in NSTX

Description: We report on the behavior of ELMs in NBI-heated H-mode plasmas in NSTX. It is observed that the size of Type I ELMs, characterized by the change in plasma energy, decreases with increasing density, as observed at conventional aspect ratio. It is also observed that the Type I ELM size decreases as the plasma equilibrium is shifted from a symmetric double-null toward a lower single-null configuration. Type III ELMs have also been observed in NSTX, as well as a high-performance regime with small E… more
Date: June 4, 2004
Creator: Maingi, R.; Sabbagh, S.; Bush, C.; Fredrickson, E.; Menard, J.; Stutman, D. et al.
Partner: UNT Libraries Government Documents Department
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Special session: computational predictability of natural convection flows in enclosures

Description: Modern thermal design practices often rely on a ''predictive'' simulation capability--although predictability is rarely quantified and often difficult to confidently achieve in practice. The computational predictability of natural convection in enclosures is a significant issue for many industrial thermal design problems. One example of this is the design for mitigation of optical distortion due to buoyancy-driven flow in large-scale laser systems. In many instances the sensitivity of buoyancy-… more
Date: August 14, 2000
Creator: Christon, M A; Gresho, P M & Sutton, S B
Partner: UNT Libraries Government Documents Department
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Monitoring Permeable Reactive Barriers using Electrical Resistance Tomography

Description: An electrical resistivity tomography (ERT) method is being evaluated as a measurement tool to determine the integrity of permeable reactive barriers (PRBs) during and after construction of the barrier and as a monitoring tool to determine the long-term operational health of the barrier. The method is novel because it inserts the electrodes directly into the barrier itself. Numerical modeling calculations indicate that the ERT method can detect flaws (voids) in the barrier as small as 0.11 m{sup… more
Date: December 8, 2003
Creator: Ramirez, A.; Bratton, W.; Maresca, J.; Daily, W. & Dickerson, W.
Partner: UNT Libraries Government Documents Department
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Manufacturing technology

Description: The mission of the Manufacturing Technology thrust area at Lawrence Livermore National Laboratory (LLNL) has been to have an adequate base of manufacturing technology, not necessarily resident at LLNL, to conduct their future business. The specific goals were (1) to develop an understanding of fundamental fabrication processes; (2) to construct general purpose process models that have wide applicability; (3) to document their findings and models in journals; (4) to transfer technology to LLNL p… more
Date: January 1, 1998
Creator: Blaedel, Kenneth L.
Partner: UNT Libraries Government Documents Department
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Feasibility study of beam-beam compensation in the Tevatron with wires

Description: We explore the possibility of compensating long-range beam-beam interactions in the Tevatron by current carrying wires. Compensation strategies depend on whether the compensation is done close to the interaction or nonlocally, on the aspect ratio of the strong beam and on other details. Strategies for each case have been developed and applied to the Tevatron. We discuss the results of these strategies at injection and collision energy.
Date: May 1, 2005
Creator: Sen, Tanaji; /Fermilab; Erdelyi, Bela & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department
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Multilayer Dielectric Gratings for Petawatt-Class Laser Systems

Description: Existing Petawatt class lasers today based on Nd:glass architectures operating at nominally 500 J, 0.5 ps use meter-scale aperture, gold-overcoated master photoresist gratings to compress the amplified chirped pulse. Many lasers operating in the >lkJ, >Ips regime are in the planning stages around the world. These will require multilayer dielectric diffraction gratings to handle larger peak powers than can be accommodated with gold gratings. Models of the electric field distribution in the… more
Date: December 3, 2003
Creator: Britten, J A; Molander, W; Komashko, A M & Barty, C P J
Partner: UNT Libraries Government Documents Department
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