Suppression of Rayleigh--Taylor and bulk convective instabilities in imploding plasma liners and pinches

Journal Article · Fri Jun 01 00:00:00 EDT 1990

DOI:https://doi.org/10.1063/1.859252· OSTI ID:6765206

Bud'ko, A B; Liberman, M A; Velikovich, A L ^[1]; Felber, F S ^[2]

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1. Institute for Physical Problems, Moscow 117334, U.S.S.R (SU)
2. JAYCOR, P.O. Box 85154, San Diego, CA (USA)

Linear growth of instabilities during implosion of annular and columnar plasma pinches having sharp outer boundaries is analyzed. The dominant modes of the Rayleigh--Taylor instability differ in time, radius, and growth rate from the dominant modes of the bulk convective instability. The spectra of growth rates of perturbations localized azimuthally or axially suggest explanations for filamentation and stratification of plasmas. Localized Rayleigh--Taylor modes grow fastest initially in an implosion. These modes can be suppressed completely, however, by a relatively modest axial magnetic field, which produces magnetic shear in a Z pinch. Similarly, bulk convective modes can be substantially reduced by magnetic shear. The window of stability'' produced by magnetic shear occurs for an axial field magnitude about equal to the azimuthal. Properly shaped current pulses in Z pinches with axial fields may therefore produce stable implosions to high compression ratios, in agreement with recent experiments. The most dangerous Rayleigh--Taylor modes for the symmetry of an annular pinch of initial aspect ratio {ital R}{sub 0}/{delta}{sub 0} are those with wavenumber {ital k}{similar to}{ital R}{sub 0}/{delta}{sup 2}{sub 0}, where {ital R}{sub 0} is the initial pinch radius. To suppress pinch instabilities optimally, both the liner thickness and axial magnetic field should be chosen properly.

• OSTI ID: 6765206
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ALIGNMENT
ANNULAR SPACE
ASPECT RATIO
CONFIGURATION
CONVECTIVE INSTABILITIES
DIMENSIONS
EQUILIBRIUM
FLUID MECHANICS
HYDRODYNAMICS
IMPLOSIONS
INHIBITION
INSTABILITY
INSTABILITY GROWTH RATES
LINERS
MAGNETIC FIELDS
MECHANICS
OPTIMIZATION
PINCH DEVICES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
RAYLEIGH-TAYLOR INSTABILITY
SHEAR
SPACE
STABILITY
STEADY-STATE CONDITIONS
THERMONUCLEAR DEVICES
THICKNESS