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Fundamentals of interruption in vacuum. Eleventh progress report

Description: During the past three months effort has concentrated on formulating a method to predict the enhancement of electrode surface field and power input occasioned by the presence of a projection on the electrode surface, during the ion sheath development period which attends the scavenging a contact gap following current interruption in vacuum. In addition, experimental evidence has been obtained to support the theory, postulated earlier, of a turn-around interval for electrons left in the gap, whic… more
Date: February 28, 1981
Creator: Greenwood, A. N. & Sullivan, J. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Physics of laser fusion. Vol. I. Theory of the coronal plasma in laser-fusion targets

Description: This monograph deals with the physics of the coronal region in laser fusion targets. The corona consists of hot plasma which has been evaporated from the initially solid target during laser heating. It is in the corona that the laser light is absorbed by the target, and the resulting thermal energy is conducted toward cold high-density regions, where ablation occurs. The topics to be discussed are theoretical mechanisms for laser light absorption and reflection, hot-electron production, and the… more
Date: December 1, 1981
Creator: Max, C.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transport of molecular impurities at the edge of tokamaks

Description: The transport of molecules at the plasma edge in tokamaks is discussed in order to compare how light impurities enter the plasma if they are released either in atomic or molecular forms. Differences in their transport arise because of the dissimilarities between the atomic and molecular reactions with the bulk of the plasma. It is found that recycling to the walls is more efficient for the light impurities released in molecular form, but, also, that a substantial fraction of those atoms which o… more
Date: November 1, 1981
Creator: Langer, W. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fusion plasma control using TRAIL: a nondamageable limiter

Description: An attractive new limiter system is described, termed TRAIL (Tokamak Rail Gun Limiter), which can inject streams of pellets into the plasma to: (a) define the plasma boundary, (b) absorb plasma disruption energy, and (c) control plasma temperature profiles. Using EM (Electromagnetic) guns now being developed for military applications, particles can be injected at velocities in the range of meters to several kilometers per second. Transient heat transfer analyses are presented for various pellet… more
Date: January 1, 1981
Creator: Yu, W. S.; Powell, J. R.; Fillo, J. A. & Usher, J. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-beta studies with beam-heated, non-circular plasmas in ISX-B

Description: In this paper we describe some preliminary results of high beta studies on ISX-B for mildly D shaped discharges. ISX-B is a modest size tokamak (R/sub 0/ = 93 cm, a = 27 cm) equipped with two tangantially-aligned neutral beam injectors giving a total power up to 3 MW. The poloidal coil system allows choice of plasma boundary shapes from circular to elongated (kappa less than or equal to 1.8), with D, elliptical, or inverse D cross sections. The non-circular work discussed here is for kappa appr… more
Date: January 1, 1981
Creator: Lazarus, E.A.; Bates, S.C. & Bush, C.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Mode-conversion induced tearing effects in a plasma neutral sheet

Description: A new collisionless dissipation mechanism which can drive tearing modes in a plasma neutral sheet is described. The new mechanism relies on the presence of a background cold plasma which leads to mode conversion into a continuous spectrum of cold plasma waves.
Date: January 1, 1981
Creator: Kaw, P.K. & Sudan, R.N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of plasma-edge conditions for a commercial tokamak reactor

Description: Particle and energy fluxes to the first wall and pumped limiter of a commercial-size tokamak power reactor have been studied with a one-dimensional, time-dependent plasma transport code. The plasma is operated in an enhanced radiation mode, with iodine as the high-Z impurity, whereby the transport power to the limiter is held to about half of the alpha-heating power. Recycling of neutral hydrogen and helium is followed in detail. The ion flux to the limiter and the neutral flux to the first wal… more
Date: January 1, 1981
Creator: Boley, C. D. & Brooks, J. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Deposition probe measurements of impurity and plasma fluxes near the wall in ISX-B

Description: It was shown that metallic impurity fluxes to the wall are far lower (x 3000) than those to limiter-like probes located 2 cm outside the limiter radius. Deuterium fluxes are also lower (x 10) at the wall position and are in reasonable agreement with single crystal silicon damage data. Finally, both wall and limiter position data are consistent with an impurity introduction model in which charge exchange neutral sputtering of the wall is the dominant introduction mechanism.
Date: January 1, 1981
Creator: Zuhr, R. A.; Roberto, J. B. & Withrow, S. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Plasma sheath region near a boundary with positive ion backscattering

Description: The sheath region at a boundary perpendicular to a magnetic field has been studied by numerically solving time-independent Vlasov-Poisson equations for a DT plasma. Boundary conditions are specified for particles entering the sheath region and for particles returning from the boundary. The effect of hydrogen ion backscatter as well as electron reemission has been examined. For a space-charge limited electron reemission condition, even a small amount of ion backscatter can change the sheath para… more
Date: April 1, 1981
Creator: Brooks, J. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Electrostatic analysis of the tokamak edge plasma

Description: The intrusion of an equipotential poloidal limiter into the edge plasma of a circular tokamak discharge distorts the axisymmetry in two ways: (1) it (partially) shorts out the top-to-bottom Pfirsch-Schlueter driving potentials, and (2) it creates zones of back current flow into the limiter. The resulting boundary mismatch between the outer layers and the inner axisymmetric Pfirsch-Schlueter layer provides free energy to drive the edge plasma unstable. Special limiters are proposed to symmetrize… more
Date: July 1, 1981
Creator: Motley, R. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Internal magnetic probe data from ZT-40

Description: Measurements of magnetic field distribution as a function of time and radius were made in ZT-40 with its ceramic vacuum vessel. Data were obtained with a 10-station, 20-coil magnetic probe, measuring the B/sub p/ and B/sub epsilon/ orthogonal field components in deuterium plasma discharges. Sheath formation and diffusion, magnetic axis location and motion, the effect of the probe on the plasma, and the consistency of flux measurements with external probes are examined.
Date: May 1, 1981
Creator: Burkhardt, L.C. & Phillips, J.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Hydrogen-deuterium changeover experiments in a plasma-wall interaction simulator

Description: Hydrogen recycling from walls and limiters of tokamaks constitutes the major source of plasma particles after the initial few milliseconds of a plasma pulse. The physical processes involved in recycling are thus very important to the control of plasma density and composition. Isotope changeover experiments in the laboratory show that thermally activated processes such as recombination and diffusion play significant roles in recycling. These processes are important not only during the plasma pul… more
Date: January 1, 1981
Creator: Clausing, R. E.; Heatherly, L. & Emerson, L. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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