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Stability of trapped-particle modes in lower-hybrid pump

The stability of dissipative trapped-particle modes in the presence of a self-consistent lower-hybrid pump is analyzed theoretically. The pump can either be a single coherent wave or a spectrum of turbulent waves. Corresponding dispersion relations modified by the pump are derived and conditions for excitation and suppression of the modes are also discussed.

Date: May 1, 1976

Creator: Chen, L.; Kaw, P. K. & Tang, W. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Studies of tokamak fusion reactor dynamics. Progress report, June 1, 1975--February 15, 1976. [Plasma shape and position effects; transport theory]

An investigation of the effect of plasma shape and position on the inductive coupling between the plasma and the external poloidal field coils is briefly described. Research on a multi-node time-dependent point kinetics code with which to study the operating dynamics of a tokamak reactor is also mentioned. (MOW)

Date: January 1, 1976

Creator: Mills, R. G. & Gralnick, S. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Coalescence instability of magnetic islands

The stability of a periodic magnetic island structure was studied using the ideal MHD equations. An instability is found which describes the tendency toward coalescence of parallel currents in the neighboring islands. It is expected that this instability will proceed at a fast MHD rate as long as the forces driving the instability can overcome the stabilizing forces due to the compression of the magnetic field between the islands. Beyond that phase, resistivity is expected to dominate the tende… more

Date: March 1, 1976

Creator: Finn, J. M. & Kaw, P. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Soft x-ray camera for internal shape and current density measurements on a noncircular tokamak

Soft x-ray measurements of the internal plasma flux surface shaped in principle allow a determination of the plasma current density distribution, and provide a necessary monitor of the degree of internal elongation of tokamak plasmas with a noncircular cross section. A two-dimensional, tangentially viewing, soft x-ray pinhole camera has been fabricated to provide internal shape measurements on the PBX-M tokamak. It consists of a scintillator at the focal plane of a foil-filtered pinhole camera,… more

Date: May 1, 1988

Creator: Fonck, R. J.; Jaehnig, K. P.; Powell, E. T.; Reusch, M.; Roney, P. & Simon, M. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Studies of tokamak fusion reactor dynamics. Final report, June 1, 1975--January 31, 1977

The purpose of this research was to investigate the time dependent phenomena associated with the inherently pulsed nature of the tokamak fusion reactor. A multi-node point kinetics computer code was developed in which the plasma is viewed as a set of conductors inductively coupled to one another and to a system of poloidal field coils. This code incorporates aspects of both the plasma equilibrium problem as well as the plasma diffusion problem. A detailed introduction to the subject of Tokamak … more

Date: January 1, 1977

Creator: Mills, R. G. & Gralnick, S. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Algorithm for locating the extremum of a multi-dimensional constrained function and its application to the PPPL Hybrid Study

A description is presented of a general algorithm for locating the extremum of a multi-dimensional constrained function. The algorithm employs a series of techniques dominated by random shrinkage, steepest descent, and adaptive creeping. A discussion follows of the algorithm's application to a ''real world'' problem, namely the optimization of the price of electricity, P/sub eh/, from a hybrid fusion-fission reactor. Upon the basis of comparisons with other optimization schemes of a survey natu… more

Date: March 1, 1978

Creator: Bathke, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Reduction in fusion-neutron production in nonaxisymmetric tokamak devices

In tokamak plasmas subjected to substantial toroidal-field ripple, sufficiently energetic members of the bulk-iron population can diffuse rapidly away from the hot central region by the superbanana process. The result is a truncation of the ion velocity distribution, causing a marked reduction in the fusion reactivity. This tail-depletion effect may account in part for the anomalously low central ion temperature deduced from the neutron flux emitted from dense deuterium plasmas in the Alcator d… more

Date: May 1, 1977

Creator: Jassby, D. L.; Towner, H. H.; Goldston, R. J. & Parker, R. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Improved rigorous upper bounds for transport due to passive advection described by simple models of bounded systems

The work of Krommes and Smith on rigorous upper bounds for the turbulent transport of a passively advected scalar (/ital Ann. Phys./ 177:246 (1987)) is extended in two directions: (1) For their ''reference model,'' improved upper bounds are obtained by utilizing more sophisticated two-time constraints which include the effects of cross-correlations up to fourth order. Numerical solutions of the model stochastic differential equation are also obtained; they show that the new bounds compare quite… more

Date: August 1, 1988

Creator: Kim, Chang-Bae & Krommes, J. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Integration of the three-dimensional Vlasov equation for a magnetized plasma

A second order splitting scheme is developed to integrate the three dimensional Vlasov equation for a plasma in a magnetic field. The integration of the Vlasov equation is divided into a series of intermediate steps and Fourier interpolation and the ASD method with a third order Taylor expansion are used to integrate the fractional equations. Numerical experiments related to cyclotron waves in 2 and 2/sup 1///sub 2/ D are demonstrated with high accuracy and efficiency. The computer storage requ… more

Date: April 1, 1976

Creator: Cheng, C Z

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Chemical engineering side of nuclear fusion power

It is widely recognized that chemical engineering has important roles to play in the development of national and world wide energy resources through optimal utilization of fossil fuel reserves. It is much less appreciated that there are crucial chemical engineering problems in the development of energy production from other sources. In particular the successful development of nuclear fusion power generating systems will require the solution of many problems that are uniquely suited to chemical … more

Date: October 1, 1976

Creator: Johnson, E. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Implementation of vertically asymmetric toroidal-field ripple for beam heating of tokamak reactor plasmas

The neutral-beam energy required for adequate penetration of tokamak plasmas of high opacity can be reduced by a large factor if the beam is injected vertically into a region of large TF (toroidal-field) ripple. Energetic ions are trapped in local magnetic wells and drift vertically toward the midplane (z = 0). If the ripple is made very small on the opposite side of the midplane, drifting ions are detrapped and thermalized in the central plasma region. This paper discusses design consideration… more

Date: October 1, 1976

Creator: Jassby, D. L.; Sheffield, G. V.; Towner, H. H. & Weissenburger, D. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Multichannel wave interferometry

The analysis of multichannel wave interferometry for a variety of density profiles reveals that the phase shift as a function of horn position normalized to that through the center of the plasma, is relatively insensitive to K = n/sub o//n/sub c/ (the ratio of maximum density to cutoff density) when refraction effects are minimized. Thus, this ratio may be easily inverted to obtain a reasonably accurate measurement of the density profile even for values of K approaching 1.

Date: December 1, 1975

Creator: Hosea, J. C. & Jobes, F. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutronic calculation and cross section sensitivity analysis of the Livermore mirror fusion/fission hybrid reactor blanket

The neutronic calculation for the Livermore mirror fusion/fission hybrid reactor blanket was performed using the PPPL cross section library. Significant differences were found in the tritium breeding and plutonium production in comparison to the results of the LLL calculation. The cross section sensitivity study for tritium breeding indicates that the response is sensitive to the cross section of /sup 238/U in the neighborhood of 14 MeV and 1 MeV. The response is also sensitive to the cross sec… more

Date: August 1, 1977

Creator: Ku, L. P. & Price, W. G. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Tokamak Fusion Test Reactor. Final conceptual design report. [Overall cost and scheduling program]

The TFTR is the first U.S. magnetic confinement device planned to demonstrate the fusion of D-T at reactor power levels. This report addresses the physics objectives and the engineering goals of the TFTR project. Technical, cost, and schedule aspects of the project are included. (MOW)

Date: February 1, 1976

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Molten salt blanket calculations for a tokamak fusion-fission hybrid reactor

Several possible blanket designs for use in a tokamak fusion-fission hybrid reactor are investigated. The main constituent of the blanket is a molten salt, possibly with a separate convertor region for multiplication of the source neutrons. Both the thorium and uranium fuel cycles are analyzed subject to constraints on the blanket performance such as high blanket energy multiplication and sufficient breeding of tritium and fissile fuel. It is found that the behavior depends strongly on the salt… more

Date: April 1, 1976

Creator: Chapin, D. L.

Item Type: Report

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

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.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Observation of inverted population levels in the FM-1 Spherator

Inversions in the populations of excited levels in hydrogen and HeII were observed in the FM-1 Spherator. The inversion increases strongly as the ratio of the decay time of the electron temperature to the decay time of the electron density was decreased. Time dependent numerical calculations of the populations were in good agreement with the experimental measurements. More general calculations for high Z hydrogen-like ions are discussed.

Date: April 1, 1976

Creator: Suckewer, S.; Hawryluk, R. J.; Okabayashi, M. & Schmidt, J. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Particle diffusion in a spheromak

The local carbon particle diffusion coefficient was measured in the Proto S-1/C spheromak using a test particle injection scheme. When the plasma was not in a force-free Taylor state, and when there were pressure gradients in the plasma, the particle diffusion was five times that predicted by Bohm and was consistent with collisional drift wave diffusion. The diffusion appears to be driven by correlations of the fluctuating electric field and density. During the decay phase of the discharge when… more

Date: January 1, 1988

Creator: Meyerhofer, D. D.; Levinton, F. M. & Yamada, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Observation of magnetic islands in the FM-1 spherator

Time independent spatially periodic variations in the density and floating potential have been observed in the FM-1 spherator. On the exterior of the plasma/ sup ..delta..n//n and/ sup ..delta..phi//phi are found to be as much as 0.3. Experimental evidence indicates these variations are due to magnetic islands created by small field errors produced by the levitated ring. Calculations of the expected island size agree well with observations.

Date: June 1, 1976

Creator: Davis, S. L.; Hawryluk, R. J. & Schmidt, J. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Study of drift wave turbulence by microwave scattering in a toroidal plasma

A study of drift wave turbulence by microwave scattering technique was carried out in a toroidal plasma confinement device, the FM-1 spherator. The principal results are; (a) Observation of the linear dispersion relation of drift waves in the high magnetic shear condition. The linear dispersion relation is followed up to weak turbulence state (..gamma.. approximately less than ..omega..). (b) An experimental demonstration of the stabilization of the drift waves with an increase of the shear str… more

Date: January 1, 1977

Creator: Okabayashi, M. & Arunasalam, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Heavy-impurity recycling at a limiter and power-loss limitation to a limiter in tokamak

Since the density of high-z impurities in tokamaks is generally observed to saturate, the heavy-impurity recycling rate is presumed to be less than unity. On this basis, plasma edge temperature is calculated to be low and an upper limit to power carried out by charged particles is estimated to be small as observed in experiment. This result suggests that the total radiation loss by low- and high-z impurities is always large in a conventional tokamak with high power input and small charge-exchan… more

Date: May 1, 1977

Creator: Shimomura, Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Microinstability theory in tokamaks: a review

Significant investigations in the area of tokamak microinstability theory are reviewed. Emphasis is given to the work covering the period from 1970 through 1976. Special attention is focused on low-frequency electrostatic drift-type modes, which are generally believed to be the dominant tokamak microinstabilities under normal operating conditions. The basic linear formalism including electromagnetic (finite beta) modifications is presented along with a general survey of the numerous papers inve… more

Date: June 1, 1977

Creator: Tang, W. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Bistable equilibrium of tokamak and its application to magnetic pumping

It has been experimentally demonstrated in the ATC device that, with appropriate adjustments of the external magnetic circuitry, the tokamak plasma may be stable for two different major radii. The dynamics of transition between the two equilibria involves a faster compression and expansion of the plasma, than is practical in the monostable case; thus may be useful in the Artsimovich-Furth-Ellis axisymmetric magnetic pumping scheme.

Date: March 1, 1977

Creator: Hsuan, H. & Bol, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Anomalous transport due to shear-Alfven waves

The behavior of shear-Alfven eigenmodes and the accompanied anomalous transport have been investigated. In the particle simulation, equilibrium thermal fluctuations associated with the eigenmodes have been observed to nullify the zeroth-order shear near the rational surface through the induced second-order eddy current, and, in turn, give rise to the formation of magnetic islands which cause rapid electron energy transport in the region. The theoretical verification of the observed behavior is … more

Date: October 1, 1980

Creator: Lee, W. W.; Chance, M. S. & Okuda, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department