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in publisher: "Princeton University. Plasma Physics Laboratory."  
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A unified theory of resonant excitation of kinetic ballooning modes by energetic ions/alpha particles in tokamaks

Description: A complete theory of wave-particle interactions is presented whereby both circulating and trapped energetic ions can destabilize kinetic ballooning modes in tokamaks. Four qualitatively different types of resonances, involving wave-precessional drift, wave-transit, wave-bounce, and precessional drift-bounce interactions, are identified, and the destabilization potential of each is assessed. For a characteristic slowing-down distribution function, the dominant interaction is that which taps thos… more
Date: October 1, 1991
Creator: Biglari, H. & Chen, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Stark broadening of isolated lines from high-Z emitters in dense plasmas

Description: The joint distribution of the electric microfield and its longitudinal derivative is required for the calculation of line profiles for the He-like ions in very dense plasmas. We used a molecular dynamics code to compute exact distributions in single- and multi-component plasmas, and then we investigated various analytical approximations to these results. We found that a simplified, two-nearest-neighbor scheme leads to surprisingly accurate distribution functions. Our results are illustrated by … more
Date: September 1, 1980
Creator: Weisheit, J.C. & Pollock, E.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Murakami density limit in tokamaks and reversed-field pinches

Description: A theoretical upper limit for the density in an ohmically heated tokamak discharge follows from the requirement that the ohmic heating power deposited in the central current-carrying channel exceed the impurity radiative cooling in this critical region. A compact summary of our results gives this limit n/sub M/ for the central density as n/sub M/ = (Z/sub e//(Z/sub e/-1)/sup 1/2/n/sub eo/ (B/sub T//1T)(1m/R) where n/sub eo/ depends strongly on the impurity species and is remarkably independent … more
Date: March 1, 1984
Creator: Perkins, F.W. & Hulse, R.A.
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Partner: UNT Libraries Government Documents Department
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The interpretation of reflectometry measurements of plasma fluctuations

Description: Wave reflections from density fluctuations with magnitudes and frequencies typical of drift waves have been investigated. Both drift waves and the reflected phase and amplitude depend on the density gradient scale length, and this common feature implies that both the angular deviation of a normally propagating wave and the phase change on reflection are of order unity. Thus the surface will always appear rough'' and amplitude variations will always be large. For smaller amplitude waves numerica… more
Date: October 1, 1991
Creator: Bretz, N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Methods of driving current by heating a toroidal plasma

Description: In addition to the usual mechanism which utilizes the Ohmic transformer current, which is necessarily pulsed, there exist several steady-state mechanisms. Heating mechanisms which can lend themselves efficiently to continuous current generation include neutral beams, Alfven waves, ion-cyclotron waves, lower-hybrid waves and electron-cyclotron waves.
Date: August 1, 1980
Creator: Fisch, N. J.
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Partner: UNT Libraries Government Documents Department
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Acceleration of beam ions during major radius compression in TFTR

Description: Tangentially co-injected deuterium beam ions were accelerated from 82 keV up to 150 keV during a major radius compression experiment in TFTR. The ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations. In addition, the plasma rotation velocity was observed to rise during compression.
Date: September 1, 1985
Creator: Wong, K. L.; Bitter, M.; Hammett, G. W.; Heidbrink, W.; Hendel, H.; Kaita, R. et al.
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Partner: UNT Libraries Government Documents Department
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Classification of disruptions in PBX

Description: Disruptions in beam-heated plasmas on PBX were studied by classifying precursor oscillations detected by a soft x-ray imaging system and Mirnov coils. A data base consisting of 80 discharges was constructed. In low I/sub p/ operation, attainable ..beta../sub T/ values are limited by disruptions preceded by m = 1 activity at the center and coupled an m/n = even/1 mode. In high I/sub p/ and high ..beta../sub T/ operation with high indentation, the sawtooth activity disappears. At these disruption… more
Date: September 1, 1985
Creator: Itami, K.; Jahns, G.; Yamada, H. & McGuire, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Emission in the 50-80 A region from highly ionized silver in PLT tokamak plasmas

Description: The spectrum of silver emitted by Princeton Large Torus (PLT) tokamak plasmas has been recorded in the 25 to 150 A region by a multichannel time-resolving grazing-incidence spectrometer. Silver atoms have been introduced in the tokamak plasma using the laser blow-off technique. For the first time, lines emitted within the 3p-3d transitions of Ag XXIX, Ag XXX, and Ag XXXI ions, between 50 and 80 A, have been identified.
Date: September 1, 1985
Creator: Schwob, J.L.; Wouters, A.; Suckewer, S.; Cohen, S.A. & Finkenthal, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Resonant decay of finite extent cold electron plasma waves

Description: The parametric decay of a finite extent cold electron plasma wave (slow wave) was studied experimentally. Using a frequency of ..omega../sub 0/ approximately greater than 10..omega../sub pi/, it was found that the decay waves propagated along the pump wave rather than in the Vector E/sub 0/ x Vector B direction. This is in agreement with the recent theoretical predictions of finite length stabilization.
Date: February 1, 1978
Creator: Wong, K. L.; Bellan, P. & Porkolab, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neoclassical transport in stellarators

Description: The stellarator neoclassical transport due to particles trapped in local helical wells is calculated in the low-collisionality regime using a systematic expansion. The behavior of electron transport is found to be the same over a wide range of energies, but the behavior of ion transport for low energy ions is found to be different than that for high energy ions. Furthermore, the electron fluxes do not vary with the change in the radial ambipolar electric field nearly as much as do the ion fluxe… more
Date: September 1, 1985
Creator: Ho, D.D.M. & Kulsrud, R.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Direct spectroscopic observation of charge-exchange recombination of medium-Z elements in the PLT tokamak

Description: We report the first observation of line emission resulting directly from charge-exchange recombination of medium-Z elements (Al, Sc) injected into a PLT discharge. Transitions due to the radiative cascade immediately following charge-exchange of He-like Al and Sc were observed by a VUV spectrograph and two air monochromators. In two cases, AlXI 3209 A and ScXIX 112.1 A, the observed transition had not previously been experimentally identified. Spatial scans provided information on the profile o… more
Date: March 1, 1984
Creator: Skinner, C. H.; Suckewer, S.; Cohen, S. A.; Schilling, G.; Wilson, R. & Stratton, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Efficiencies of gas neutralizers for multi-MeV beams of light negative ions

Description: Measurements are reported of the neutral and charged particle fractions produced by running beams of Li/sup -/, C/sup -/, O/sup -/, and Si/sup -/ at energies up to 7 MeV through gas cells of N/sub 2/, Ar, or CO/sub 2/. We discuss the implications of these measurements for the design of neutralizers to produce high energy light atom beams for heating or current drive in tokamaks.
Date: November 1, 1981
Creator: Grisham, L. R.; Post, D. E.; Johnson, B. M.; Jones, K. W.; Barette, J.; Kruse, T. H. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Toroidal plasma equilibrium with gravity

Description: Toroidal magnetic field configuration in a gravitational field is calculated both from a simple force-balance and from the calculation using magnetic surfaces. The configuration is found which is positionally stable in a star. The vibrational frequency near the equilibrium point is proportional to the hydrostatic frequency of a star multiplied by the ratio (W/sub B//W/sub M/)/sup 1/2/ where W/sub B/ is the magnetic field energy density, and W/sub M/ is the material pressure at the equilibrium p… more
Date: September 1, 1980
Creator: Yoshikawa, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Performance study of the TFTR diagnostic neutral beam for active charge exchange measurements

Description: A neutral beam source will be incorporated in the Tokamak Fusion Test Reactor (TFTR) charge exchange diagnostic to provide a time modulated, spatially localized enhancement of the charge exchange efflux. Two autonomous Charge Exchange Neutral Analyzer (CENA) systems are being designed for the TFTR. One system measures the plasma ion temperature along twelve vertical line-of-sight chords spaced approximately equidistantly across the torus minor diameter. The other system is dedicated primarily t… more
Date: June 1, 1980
Creator: Medley, S. S.; Goldston, R. J. & Towner, H. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Radially resolved measurements of ''q'' on the ATC tokamak

Description: This paper describes a new technique for directly measuring the safety factor, or q, profile in a tokamak. A tightly collimated neutral beam capable of injecting approximately 100 mA of 30 keV deuterium atoms was mounted on the ATC tokamak. By proper tangential aiming of the beam a strong concentration of circulating fast ions was created at a chosen plasma minor radius. By examining the orbits of these ions with a multi-sight-line charge exchange detector, it was possible to measure the shifts… more
Date: April 1, 1978
Creator: Goldston, R.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Thermonuclear inverse magnetic pumping power cycle for stellarator reactors

Description: A novel power cycle for direct conversion of alpha-particle energy into electricity is proposed for an ignited plasma in a stellarator reactor. The plasma column is alternately compressed and expanded in minor radius by periodic variation of the toroidal magnetic field strength. As a result of the way a stellarator is expected to work, the plasma pressure during expansion is greater than the corresponding pressure during compression. Therefore, negative work is done on the plasma during a compl… more
Date: September 1, 1985
Creator: Ho, D.D.M. & Kulsrud, R.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Three novel tokamak plasma regimes in TFTR

Description: Aside from extending ''standard'' ohmic and neutral beam heating studies to advanced plasma parameters, TFTR has encountered a number of special plasma regimes that have the potential to shed new light on the physics of tokamak confinement and the optimal design of future D-T facilities: (1) High-powered, neutral beam heating at low plasma densities can maintain a highly reactive hot-ion population (with quasi-steady-state beam fueling and current drive) in a tokamak configuration of modest bul… more
Date: October 1, 1985
Creator: Furth, H.P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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DAS performance analysis

Description: This report begins with an overview of the Data Acquisition System (DAS), which supports several of PPPL's experimental devices. Performance measurements which were taken on DAS and the tools used to make them are then described.
Date: February 1, 1984
Creator: Bates, G.; Bodine, S.; Carroll, T. & Keller, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Convective equilibrium and mixing-length theory for stellarator reactors

Description: In high ..beta.. stellarator and tokamak reactors, the plasma pressure gradient in some regions of the plasma may exceed the critical pressure gradient set by ballooning instabilities. In these regions, convective cells break out to enhance the transport. As a result, the pressure gradient can rise only slightly above the critical gradient and the plasma is in another state of equilibrium - ''convective equilibrium'' - in these regions. Although the convective transport cannot be calculated pre… more
Date: September 1, 1985
Creator: Ho, D.D.M. & Kulsrud, R.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dynamic modeling of transport and positional control of tokamaks

Description: We describe here a numerical model of a free boundary axisymmetric tokamak plasma and its associated control systems. The plasma is modeled with a hybrid method using two-dimensional velocity and flux functions with surface-averaged MHD equations describing the evolution of the adiabatic invariants. Equations are solved for the external circuits and for the effects of eddy currents in nearby conductors. The method is verified by application to several test problems and used to simulate the form… more
Date: October 1, 1985
Creator: Jardin, S. C.; Pomphrey, N. & DeLucia, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Islets of stability beyond period doubling

Description: Period doubling of a periodic orbit of an area preserving map appears to lead to the elimination of all closed invariant curves in the vicinity. We show, however, that there are always islets of stabilhty again beyond the accumulation point of the period doubling sequence.
Date: November 1, 1981
Creator: Mackay, R.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ion transport in stellarators

Description: Stellarator ion transport in the low-collisionality regime with a radial electric field is calculated by a systematic expansion of the drift-Boltzmann equation. The shape of the helical well is taken into account in this calculation. It is found that the barely trapped ions with three to four times the thermal energy give the dominant contribution to the diffusion. Expressions for the ion particle and energy fluxes are derived.
Date: September 1, 1985
Creator: Ho, D.D.M. & Kulsrud, R.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Profile correction to electron temperature and enhancement factor in soft x-ray pulse-height-analysis measurements in tokamaks

Description: Because soft x-ray pulse-height-analysis (PHA) spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. Assuming that the profile Ansatz for the electron temperature and density is of the form n/sub eo/(1-(ra)/sup 2/)/sup ..cap alpha../ and kT/sub eo/(1--(ra)/sup 2/)/sup ..beta../, we obtain the correction factors for the electron temperature and the enhancement factor as a function of the prof… more
Date: April 1, 1988
Creator: Sesnic, S.; Diesso, M.; Hill, K.; Holland, A. & Pohl, F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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