Ion beam stabilization of rotational instability in a field-reversed configuration with rigid rotation

Journal Article · Tue Jun 01 00:00:00 EDT 1993 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860821· OSTI ID:6565187

Ohnishi, M ^[1]; Ishida, A; Akasaka, T ^[2]

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1. Institute of Atomic Energy, Kyoto University, Uji 611 (Japan)
2. Department of Physics, Faculty of Science, Niigata University, Niigata 950-21 (Japan)

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.

• OSTI ID: 6565187
• Journal Information: Physics of Fluids B; (United States), Vol. 5:6; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ION BEAMS
REVERSE-FIELD PINCH
STABILIZATION
ANALYTICAL SOLUTION
COMPRESSIBILITY
INSTABILITY
RITZ METHOD
THERMONUCLEAR REACTORS
VARIATIONAL METHODS
BEAMS
CALCULATION METHODS
MECHANICAL PROPERTIES
PINCH EFFECT
700350* - Plasma Production
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