125 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Aspect Ratio"  
Results: 1 - 24 next
open access

Continuum damping of low-n toroidicity-induced shear Alfven eigenmodes

Description: The effect of resonant continuum damping is investigated for the low-mode-number, toroidicity-induced, global shear Alfven eigenmodes, which can be self-excited by energetic circulating alpha particles in an ignited tokamak plasma. Resonant interaction with the shear Alfven continuum is possible for these eigenmodes, especially near the plasma periphery, leading to significant dissipation, which is typically larger than direct bulk plasma dissipation rates. Two perturbation methods are develope… more
Date: September 1, 1991
Creator: Berk, H.L.; Van Dam, J.W.; Guo, Z. & Lindberg, D.M.
Partner: UNT Libraries Government Documents Department
open access

RMF concept: a rotating-magnetic-field technique for driving steady plasma currents in compact toroid devices

Description: The generation and/or sustaining of a Compact Toroid (CT) configuration using the RMF technique is a relatively new and unknown concept. In this report the basic principles, historical development, and current theoretical understanding of this concept are reviewed. Significant experimental and theoretical results, potential problem areas, and recommendations for the direction of future work are discussed. An illustrative analysis of the application of the RMF technique to a CT reactor is presen… more
Date: September 1, 1980
Creator: McKenna, K.F.
Partner: UNT Libraries Government Documents Department
open access

Compact Toroid Theory Planning Workshop. A panel report to the Director, Division of Applied Plasma Physics, Office of Fusion Energy

Description: The purpose of the Workshop was to identify the most important physics issues that need to be addressed in the near term in order to assure the optimal design and timely interpretation of Compact Toroid (CT) experiments. The Panel was also asked to assess the levels of effort required to obtain priority information on appropriate time scales compatible with DOE plans to design a CT proof-of-principle experiment. The fiscal year cost anticipated for the effort recommended by the Workshop Panel (… more
Date: July 1, 1980
Partner: UNT Libraries Government Documents Department
open access

Control of alpha particle transport by spatially inhomogeneous ion cyclotron resonance heating

Description: Control of the radial alpha particle transport by using Ion Cyclotron Range of Frequency waves is investigated in a large-aspect-ratio tokamak geometry. It is shown that spatially inhomogeneous ICRF-wave energy with properly selected frequencies and wave numbers can induce fast convective transport of alpha particles at the speed of order {upsilon}{sub alpha} {approximately} (P{sub RF}/n{sub {alpha}}{epsilon}{sub 0}) {rho}{sub p}, where P{sub RF} is the ICRF-wave power density, n{sub {alpha}} i… more
Date: February 1, 1990
Creator: Chang, C. S.; Imre, K.; Weitzner, H. (New York Univ., NY (USA). Courant Inst. of Mathematical Sciences) & Colestock, P. (Princeton Univ., NJ (USA). Plasma Physics Lab.)
Partner: UNT Libraries Government Documents Department
open access

Finite order polynomial moment solutions of the homogeneous Grad-Shafranov equation

Description: A method for generating the finite positive order polynomial moment solutions of the homogeneous Grad-Shafranov equation to arbitrary order and the explicit form of the first few moments are given. A criticism of the method is discussed, and several practical examples are given.
Date: February 1, 1984
Creator: Reusch, M. F. & Neilson, G. H.
Partner: UNT Libraries Government Documents Department
open access

Conceptual design study of spheromak reactors

Description: Preliminary design studies are carried out for a spheromak fusion reactor. Simplified circuit theory is applied to obtain characteristic relations among various parameters of the spheromak configuration for an aspect ratio A greater than or equal to 1.6. These relations are used to calculate the parameters for the conceptual designs of three types of fusion reactor: (1) DT two-component, (2) DT ignited, and, (3) catalyzed DD ignited reactors. With a total wall loading of approx. 4 MWm/sup -2/, … more
Date: July 1, 1980
Creator: Katsurai, M. & Yamada, M.
Partner: UNT Libraries Government Documents Department
open access

Quasi-steady operation of reversed field pinches

Description: A three fluid, Lagrangian mesh, transport and stability code (RFPBRN) has been developed and applied to the Reversed Field Pinch reactor concept. Using a circular cylinder, quasi-static approximation, RFPBRN follows the time evolution of the temperature, density, and magnetic field profiles for the RFP while simultaneously monitoring ideal MHD stability. Local stability is monitored for Suydam modes while global stability is monitored using a Rayleigh-Ritz expansion of the energy principle.
Date: January 1, 1980
Creator: Nebel, R.A.
Partner: UNT Libraries Government Documents Department
open access

Natural convection characteristics of flat plate collectors. Progress report

Description: The results of an experimental investigation into the convective heat losses in large aspect ratio flat-plate solar collectors are described. An experimental study has been undertaken on a specially designed test cell using a 3 inch Mach-Zehnder interferometer. Air at atmospheric pressure was used as the heat-transfer fluid. The experimental results include interferograms which show the thermal boundary layer formations and the temperature profiles. Local temperature profiles have been analyzed… more
Date: September 1, 1977
Creator: Randall, K. R.; Wl-Wakil, M. M. & Mitchell, J. W.
Partner: UNT Libraries Government Documents Department
open access

Generalization of Connor and Hastie's ripple-trapping coefficient, G(. cap alpha. )

Description: In their calculation of transport due to ripple trapping, Connor and Hastie employ a factor G(..cap alpha..) to take into account the poloidal variation of the depth and shape of the local magnetic wells. They assume, however, that the toroidal-field ripple strength, delta, is independent of the poloidal angle. This letter generalizes G to treat any arbitrary poloidal variation of delta, and also high-beta, non-circular plasma configurations of arbitrary aspect ratio.
Date: February 1, 1980
Creator: Goldston, R. J. & Towner, H. H.
Partner: UNT Libraries Government Documents Department
open access

Determination of nonaxisymmetric equilibrium

Description: The Princeton Equilibrium Code is modified to determine the equilibrium surfaces for a large aspect ratio toroidal system with helical magnetic fields. The code may easily be made to include any variety of modes. Verification of the code is made by comparison with an analytic solution for l = 3. Previously observed shifting of the magnetic axis with increasing pressure or with a changed externally applied vertical field is obtained. The case l = 0, a bumpy torus, gives convergence only for the … more
Date: January 1, 1980
Creator: Elkin, D.
Partner: UNT Libraries Government Documents Department
open access

Stability of high. beta. large aspect ratio tokamaks

Description: High {beta}({beta}{much gt} {epsilon}/q{sup 2}) large aspect ratio ({epsilon} {much gt} 1) tokamak equilibria are shown to be always stable to ideal M.H.D. modes that are localized about a flux surface. Both the ballooning and interchange modes are shown to be stable. This work uses the analytic high {beta} large aspect ratio tokamak equilibria developed by Cowley et.al., which are valid for arbitrary pressure and safety factor profiles. The stability results make no assumption about these prof… more
Date: October 1, 1991
Creator: Cowley, S.C.
Partner: UNT Libraries Government Documents Department
open access

High-aspect-ratio silicon-cell metallization technical status report. Final report

Description: Two features of the silicon concentrator solar cell are addressed which affect output at high concentration levels. The first is the development of narrow but high electroplated grid lines with improved conductivity. The object is a reduction in cell series resistance without increase in shadowing. This goal is accomplished by electroplating through a thick photo resist mask to produce lines .7 mil wide by .7 mil high. Advance pulse plating techniques are combined with pure silver plating baths… more
Date: January 1, 1982
Partner: UNT Libraries Government Documents Department
open access

Wind loading on solar collectors

Description: The present design methodology for the determination of wind loading on the various solar collectors has been reviewed and assessed. The total force coefficients of flat plates of aspect ratios 1.0 and 3.0, respectively, at various angles of attack obtained by using the guidelines of the ANSI A58.1-1982, have been compared with those obtained by using the methodology of the ASCE Task Committee, 1961, and the experimental results of the full-scale test of heliostats by Peglow. The turbulent ener… more
Date: June 1, 1985
Creator: Bhaduri, S. & Murphy, L.M.
Partner: UNT Libraries Government Documents Department
open access

Note for the Mirnov signal analysis in tokamaks

Description: The relation between Mirnov coil signals and the current perturbation on the rational surface is examined analytically by using the approximate Green's function for the case of large aspect ratio circular tokamaks. Satellite island formation, phase modulation effect due to the poloidal variation of the field line pitch, and the shift effect of the plasma column with respect to the center of the vacuum chamber are examined. The detectability of these effects from Mirnov coil signals is discussed… more
Date: May 1, 1985
Creator: Kikuchi, M.
Partner: UNT Libraries Government Documents Department
open access

SMARTOR: a small-aspect-ratio torus for demonstrating thermonuclear ignition

Description: A tokamak with 2.6-m major radius and aspect ratio of 1.9 is proposed for demonstrating thermonuclear ignition in deuterium-tritium. The 6-MA plasma current is established in part by coinjection only of 40 MW of 80-keV neutral beams (inducing approximately 2 MA at low density) and in part by the flux swing of the equilibrium-field system (inducing approximately 4 M as the plasma pressure is increased)--there is no central current transformer and no poloidal-field coils inboard of the plasma. Th… more
Date: September 1, 1977
Creator: Jassby, D. L.
Partner: UNT Libraries Government Documents Department
open access

PBX experimental results in 1984

Description: Experimental activities of the PBX project during its first seven months of operation are summarized.
Date: July 1, 1985
Creator: Takahashi, H.; Bol, K.; Buchenauer, D.; Couture, P.; Fishman, H.; Fonck, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Formation and Sustainment of a Very Low Aspect Ratio Tokamak Using Coaxial Helicity Injection (the Helicity Injected Torus (HIT) Experiment)

Description: In the paper we will detail the progress of the HIT experiment construction, including the following components: preliminary data and interpretation; diagnostic systems; vacuum vessel and pumping system; helicity source and power supplies; toroidal field coil and power supply; data acquisition system; collaboration with general atomics, with a brief summary given on each.
Date: January 1, 1992
Creator: Jarboe, T. R. & Nelson, B. A.
Partner: UNT Libraries Government Documents Department
open access

Advanced tokamak reactors based on the spherical torus (ATR/ST). Preliminary design considerations

Description: Preliminary design results relating to an advanced magnetic fusion reactor concept based on the high-beta, low-aspect-ratio, spherical-torus tokamak are summarized. The concept includes resistive (demountable) toroidal-field coils, magnetic-divertor impurity control, oscillating-field current drive, and a flowing liquid-metal breeding blanket. Results of parametric tradeoff studies, plasma engineering modeling, fusion-power-core mechanical design, neutronics analyses, and blanket thermalhydraul… more
Date: June 1, 1986
Creator: Miller, R. L.; Krakowski, R. A.; Bathke, C. G.; Copenhaver, C.; Schnurr, N. M.; Engelhardt, A. G. et al.
Partner: UNT Libraries Government Documents Department
open access

OCLATOR II (One Coil Low Aspect Toroidal Reactor)

Description: Following the general description of OCLATOR (I), more thoughts are presented here. It suggests that the blanket may not be changed for the plant lifetime. Also miniaturization of OCLATOR is discussed, especially if the ripple turbulence could be improved upon the presently set limit which applies to a large number of ripples.
Date: March 1, 1980
Creator: Yoshikawa, S.
Partner: UNT Libraries Government Documents Department
open access

Nonlinear saturation of the internal kink mode

Description: A numerical study shows that in a cylindrical tokamak the internal kink mode (m = 1) develops nonlinearly into a helical equilibrium state that possesses a singular current sheet. In the large aspect ratio limit, the neighboring equilibria obtained agree well with the asymptotic analytic theory of Rosenbluth et al.
Date: February 1, 1980
Creator: Park, W.; Monticello, D. A.; White, R. B. & Jardin, S. C.
Partner: UNT Libraries Government Documents Department
open access

Temperature rise of the mask-resist assembly during LIGA exposure.

Description: Deep X-ray lithography on PMMA resist is used in the LIGA process. The resist is exposed to synchrotron X-rays through a patterned mask and then is developed in a liquid developer to make high aspect ratio microstructures. The limitations in dimensional accuracies of the LIGA generated microstructure originate from many sources, including synchrotron and X-ray physics, thermal and mechanical properties of mask and resist, and from the kinetics of the developer. This work addresses the thermal a… more
Date: November 1, 2004
Creator: Ting, Aili
Partner: UNT Libraries Government Documents Department
open access

Near net shape forming processes for chemically prepared zinc oxide varistors.

Description: Chemically prepared zinc oxide powders are fabricated for the production of high aspect ratio varistor components. Colloidal processing in water was performed to reduce agglomerates to primary particles, form a high solids loading slurry, and prevent dopant migration. The milled and dispersed powder exhibited a viscoelastic to elastic behavioral transition at a volume loading of 43-46%. The origin of this transition was studied using acoustic spectroscopy, zeta potential measurements and oscill… more
Date: January 1, 2005
Creator: Lockwood, Steven John; Voigt, James A.; Tuttle, Bruce Andrew & Bell, Nelson Simmons
Partner: UNT Libraries Government Documents Department
open access

Large batch dimensional metrology demonstrated in the example of a LIGA fabricated spring.

Description: Deep x-ray lithography in combination with electroforming is capable of producing high precision metal parts in small lot series. This study deals with a high aspect ratio structure with overall dimensions on the order of 10 mm x 7 mm x 1.5 mm, with the smallest line width being 150 {micro}m. The lateral deviation from the design is to be kept to a minimum, preferably below 5 {micro}m. To ensure adequate quality control, a semi-automated metrology technique has been established to measure all p… more
Date: April 1, 2004
Creator: Aigeldinger, Georg; Skala, Dawn M. & Ceremuga, Joseph T.
Partner: UNT Libraries Government Documents Department
open access

System studies of compact ignition tokamaks

Description: The new Tokamak Systems Code, used to investigate Compact Ignition Tokamaks (CITs), can simultaneously vary many parameters, satisfy many constraints, and minimize or maximize a figure of merit. It is useful in comparing different CIT design configurations over wide regions of parameter space and determining a desired design point for more detailed physics and engineering analysis, as well as for performing sensitivity studies for physics or engineering issues. Operational windows in major radi… more
Date: August 1, 1987
Creator: Galambos, J. D.; Blackfield, D. T.; Peng, Y. K. M.; Reid, R. L.; Strickler, D. J. & Selcow, E.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen