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Title: Formation of toroidal plasma confinement configurations by using hot electrons

Abstract

Two possible means are described for producing closed, toroidal pinch-like configurations with hot electrons starting from a microwave-heated, hot electron plasma confined in open fields. The final configurations are directly related to Spheromak and Tormac.

Authors:
Publication Date:
Research Org.:
California Univ., Livermore (USA). Lawrence Livermore Lab.
OSTI Identifier:
5783791
Report Number(s):
UCID-18239
TRN: 79-021932
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MAGNETIC MIRRORS; PLASMA CONFINEMENT; THERMONUCLEAR DEVICES; ECR HEATING; ELECTRON TEMPERATURE; PLASMA; SHAPE; SPHEROMAK DEVICES; TORMAC DEVICES; TOROIDAL CONFIGURATION; ANNULAR SPACE; CLOSED PLASMA DEVICES; CONFIGURATION; CONFINEMENT; HEATING; HIGH-FREQUENCY HEATING; OPEN PLASMA DEVICES; PLASMA HEATING; TOKAMAK DEVICES; 700101* - Fusion Energy- Plasma Research- Confinement, Heating, & Production

Citation Formats

Hartman, C.W.. Formation of toroidal plasma confinement configurations by using hot electrons. United States: N. p., 1979. Web. doi:10.2172/5783791.
Hartman, C.W.. Formation of toroidal plasma confinement configurations by using hot electrons. United States. doi:10.2172/5783791.
Hartman, C.W.. Thu . "Formation of toroidal plasma confinement configurations by using hot electrons". United States. doi:10.2172/5783791. https://www.osti.gov/servlets/purl/5783791.
@article{osti_5783791,
title = {Formation of toroidal plasma confinement configurations by using hot electrons},
author = {Hartman, C.W.},
abstractNote = {Two possible means are described for producing closed, toroidal pinch-like configurations with hot electrons starting from a microwave-heated, hot electron plasma confined in open fields. The final configurations are directly related to Spheromak and Tormac.},
doi = {10.2172/5783791},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Aug 09 00:00:00 EDT 1979},
month = {Thu Aug 09 00:00:00 EDT 1979}
}

Technical Report:

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  • The transport of high energy plasma within a hybrid toroidal field stellarator and Tokamak was studied. The optimization of the plasma heating mechanism and a reduction of heat loss were attempted in order to increase the toroidal field confinement time by increasing ion temperature. The problem of MHD instability and current distribution control is discussed. A description of the stellarator toroidal field coils, ohmic heating coils, equilibrium coils, and helical coils is presented.
  • The tandem mirror experiment-upgrade (TMX-U) at the Lawrence Livermore National Laboratory (LLNL) is the first experiment to investigate the thermal-barrier tandem-mirror concept. One attractive feature of the tandem magnetic mirror as a commercial power reactor is that the fusion reactions occur in an easily accessible center-cell. On the other hand, complicated end-cells are necessary to provide magnetohydrodynamic (MHD) stability and improved particle confinement of the center-cell plasma. In these end-cells, enhanced confinement is achieved with a particular axial potential profile that is formed with electron-cyclotron range-of-frequency heating (ECRF heating, ECRH). By modifying the loss rates of electrons at spatially distinctmore » locations within the end-cells, the ECRH can tailor the plasma potential profile in the desired fashion. Specifically, the thermal-barrier concept requires generation of a population of energetic electrons near the midplane of each end-cell. To be effective, the transverse (to the magnetic field) spatial structure of the hot-electron plasma must be fairly uniform. In this dissertation we characterize the spatial structure of the ECRH-generated plasma, and determine how the structure builds up in time. Furthermore, the plasma should efficiently absorb the ECRF power, and a large fraction of the electrons must be well confined near the end-cell midplane. Therefore, we also examine in detail the ECRH power balance, determining how the ECRF power is absorbed by the plasma, and the processes through which that power is confined and lost. 43 refs., 69 figs., 6 tabs.« less
  • An explicit formulation is developed to determine the width of a magnetic island separatrix generated by magnetic field perturbations in a general toroidal stellarator geometry. A conventional method is employed to recast the analysis in a magnetic flux coordinate system without using any simplifying approximations. The island width is seen to be proportional to the square root of the Fourier harmonic of B{sup {rho}}/B{sup {zeta}} that is in resonance with the rational value of the rotational transform, where B{sup {rho}} and B{sup {zeta}} are contravariant normal and toroidal components of the perturbed magnetic field, respectively. The procedure, which is basedmore » on a representation of three-dimensional flux surfaces by double Fourier series, allows rapid and fairly accurate calculation of the island widths in real vacuum field configurations, without the need to follow field lines through numerical integration of the field line equations. Numerical results of the island width obtained in the flux coordinate representation for the Advanced Toroidal Facility agree closely with those determined from Poincare puncture points obtained by following field lines. 22 refs., 5 tabs.« less