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Title: Stability of the field-reversed mirror

Abstract

The stability of a field reversed mirror plasma configuration is studied with an energy principle derived from the Vlasov equation. Because of finite orbit effects, the stability properties of a field-reversed mirror are different from the stability properties of similar magnetohydrodynamic equilibria. The Vlasov energy principle developed here is applied to a computer simulation of an axisymmetric field-reversed mirror state. It has been possible to prove that the l = 0 modes, called tearing modes, satisfy a sufficient condition for stability. Precessional modes, with l = 1, 2, are found to be unstable at low growth rate. This suggests possible turbulent behavior (Bohm confinement) in the experimental devices aiming at field reversal. Techniques for suppressing these instabilities are outlined, and the applicability of the Vlasov energy principle to more complicated equilibrium models is shown.

Authors:
Publication Date:
Research Org.:
Illinois Univ., Urbana (USA)
OSTI Identifier:
5824050
Report Number(s):
COO-2218-136
TRN: 79-021211
DOE Contract Number:
EY-76-S-02-2218
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; FIELD-REVERSED MIRROR REACTORS; STABILITY; BOLTZMANN-VLASOV EQUATION; EQUILIBRIUM PLASMA; INSTABILITY GROWTH RATES; MAGNETOHYDRODYNAMICS; TEARING INSTABILITY; DIFFERENTIAL EQUATIONS; EQUATIONS; FLUID MECHANICS; HYDRODYNAMICS; INSTABILITY; MAGNETIC MIRROR TYPE REACTORS; MECHANICS; PLASMA; PLASMA INSTABILITY; PLASMA MACROINSTABILITIES; THERMONUCLEAR REACTORS; 700107* - Fusion Energy- Plasma Research- Instabilities

Citation Formats

Morse, E.C.. Stability of the field-reversed mirror. United States: N. p., 1979. Web. doi:10.2172/5824050.
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Morse, E.C.. Stability of the field-reversed mirror. United States. doi:10.2172/5824050.
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Morse, E.C.. Mon . "Stability of the field-reversed mirror". United States. doi:10.2172/5824050. https://www.osti.gov/servlets/purl/5824050.
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@article{osti_5824050,
title = {Stability of the field-reversed mirror},
author = {Morse, E.C.},
abstractNote = {The stability of a field reversed mirror plasma configuration is studied with an energy principle derived from the Vlasov equation. Because of finite orbit effects, the stability properties of a field-reversed mirror are different from the stability properties of similar magnetohydrodynamic equilibria. The Vlasov energy principle developed here is applied to a computer simulation of an axisymmetric field-reversed mirror state. It has been possible to prove that the l = 0 modes, called tearing modes, satisfy a sufficient condition for stability. Precessional modes, with l = 1, 2, are found to be unstable at low growth rate. This suggests possible turbulent behavior (Bohm confinement) in the experimental devices aiming at field reversal. Techniques for suppressing these instabilities are outlined, and the applicability of the Vlasov energy principle to more complicated equilibrium models is shown.},
doi = {10.2172/5824050},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1979},
month = {Mon Jan 01 00:00:00 EST 1979}
}
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Technical Report:
View Technical Report (3.17 MB)
DOI:  10.2172/5824050
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  • The stability of a field reversed mirror plasma configuration is studied with an energy principle derived from the Vlasov equation. Because of finite orbit effects, the stability properties of a field-reversed mirror are different from the stability properties of similar magnetohydrodynamic equilibria. The Vlasov energy principle developed here is applied to a computer simulation of an axisymmetric field-reversed mirror state. It has been possible to prove that the l = 0 modes, called tearing modes, satisfy a sufficient condition for stability. Precessional modes, with l = 1, 2, are found to be unstable at low growth rate. This suggests possiblemore » turbulent behavior (Bohm confinement) in the experimental devices aiming at field reversal. Techniques for suppressing these instabilities are outlined, and the applicability of the Vlasov energy principle to more complicated equilibrium models is shown.« less

  • ; ;
    This paper is largely devoted to tandem mirror and field-reversed mirror experiments at the Lawrence Livermore Laboratory (LLL), and briefly summarizes results of experiments in which field-reversal has been achieved. In the tandem experiment, high-energy, high-density plasmas (nearly identical to 2XIIB plasmas) are located at each end of a solenoid where plasma ions are electrostatically confined by the high positive poentials arising in the end plug plasma. End plug ions are magnetically confined, and electrons are electrostatically confined by the overall positive potential of the system. The field-reversed mirror reactor consists of several small field-reversed mirror plasmas linked together formore » economic reasons. In the LLL Beta II experiment, generation of a field-reversed plasma ring will be investigated using a high-energy plasma gun with a transverse radial magnetic field. This plasma will be further heated and sustained by injection of intense, high-energy neutral beams.« less

  • To model the dynamics of the Field-Reversed Mirror (FRM) as a whole we have developed a 1-D radical hybrid code which also incorporates the above electron null current model. This code, named FROST, models the plasma as azimuthally symmetric with no axial dependence. A multi-group method in energy and canonical angular momentum describes the large-orbit ions from the beam. Massless fluid equations describe electrons and low energy ions. Since a fluid treatment for electrons is invalid near a field null, the null region electron current model discussed above has been included for this region, a unique feature. Results of simulationmore » of neutral beam start-up in a 2XIIB-like plasma is discussed. There FROST predicts that electron currents will retard, but not prevent reversal of the magnetic field at the plasma center. These results are optimistic when compared to actual reversal experiments in 2XIIB, because there finite axial length effects and micro-instabilities substantially deteriorated the ion confinement. Nevertheless, because of the importance of the electron current in a low field region in the FRM, FROST represents a valuable intermediate step toward a more complete description of FRM dynamics. 54 refs., 50 figs., 3 tabs.« less

  • ; ; ; ...
    For this reactor a reference case conceptual design was developed in some detail. The parameters of the design result partly from somewhat arbitrary physics assumptions and partly from optimization procedures. Two of the assumptions--that only 10% of the alpha-particle energy is deposited in the plasma and that particle confinement scales with the ion-ion collision time--may prove to be overly conservative. A number of possible start-up scenarios for the field-reversed plasmas were considered, but the choice of a specific start-up method for the conceptual design was deferred, pending experimental demonstration of one or more of the schemes in a mirror machine.more » Basic to our plasma model is the assumption that, once created, the plasma can be stably maintained by injection of a neutral-beam current sufficient to balance the particle-loss rate. The reference design is a multicell configuration with 11 field-reversed toroidal plasma layers arranged along the horizontal axis of a long-superconducting solenoid. Each plasma layer requires the injection of 3.6 MW of 200-keV deuterium and tritium, and produces 20 MW of fusion power. The reactor has a net electric output of 74 MWe. The preliminary estimate for the direct capital cost of the reference design is $1200/kWe. A balance-of-plant study is now underway and will result in a more accurate cost estimate.« less

  • ; ;
    Approximate expressions are given for important engineering parameters of a field-reversed mirror reactor. Quantities considered are first-wall radius, cell length, and mirror and quadrupole Ioffe-bar currents. The formulae have been incorporated into a subroutine which is callable from the FRR code used for computing plasma properties. Sample results are given.