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  • 1990-1994  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 1842-1849 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The rotational instability of a field-reversed configuration (FRC) can be suppressed by applying a multipole magnetic field. The multipole field, however, breaks the axisymmetry and may compromise configuration. An alternative method using injected "beam'' ions would preserve the symmetry. This method is studied here within the framework of a multifluid model for which a variational principle has been developed and solved using the Rayleigh–Ritz technique. This approach leads to an analytic solution for a rigid-rotor equilibrium and allows the straightforward derivation of marginal stability conditions. This was not possible with a previous hybrid simulation which, though more complete, was cumbersome to apply. It is found that if the ratio of the rotational frequency of beam ions to that of the background ions exceeds a critical value, the radial displacement of the plasma and beam ions are opposite, and the rotational instability can be suppressed. The effect of compressibility of beam ions on the stability is also examined. The stability analysis is applied to present or near-term experimental devices and a future reactor. The beam energy and current need only be a small fraction of those of the background plasma in order to stabilize the rotational instability. These results are in qualitative agreement with previous results from a hybrid particle simulation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 645-650 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental evidence is presented for a regulatory principle governing field-reversed configuration (FRC) equilibria. This leads to a form of "profile consistency'' with which the current profile exhibits a remarkable correlation with xs (the ratio of the separatrix radius to the coil radius). The proposed explanation is that these equilibria are regulated by an instability which maintains the profile at a marginally stable condition.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of oceanography 50 (1994), S. 295-316 
    ISSN: 1573-868X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The transport and vertical structure of the Antarctic Circumpolar Current (ACC) are examined, especially the component of the current driven by buoyancy, by using a three-layer model. We investigate the effects of the South American peninsula, the island arc to the east, and the Macquarie ridge, which are modeled as partial meridional barriers overlapping meridionally each other. We found that the buoyancy-driven component is given as a function of the transport out of the Weddell Sea (S W ) and the sum of the transports into the North Atlantic (S A ) and the North Pacific (S P ) out of the Southern Ocean. The buoyancy-driven current flows westward, ifS W andS A +S P are positive. The transport depends on the value ofS W more thanS A +S P by one order of magnitude within a realistic range of parameters. The most predominant term in the transport equation is inversely proportional to the difference between the Coriolis parameters at the tips of the partial meridional barriers. Thus, the magnitude of the transport strongly depends on the overlapping length of the meridional barriers. The eastward current of the ACC is driven by the predominant eastward wind stress in the Southern Ocean, although a part of the wind-driven component is canceled by the westward buoyancy-driven component. The vertical structure of the ACC is found to be attributed to the surface wind-driven circulation and the deep and bottom buoyancy-driven circulation.
    Type of Medium: Electronic Resource
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