Radiative instabilities in a sheared magnetic field

Drake, J. F. ; Sparks, L. ; Van Hoven, G.

[S.l.] : American Institute of Physics (AIP)
Published 1988
ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The structure and growth rate of the radiative instability in a sheared magnetic field B have been calculated analytically using the Braginskii fluid equations. In a shear layer, temperature and density perturbations are linked by the propagation of sound waves parallel to the local magnetic field. As a consequence, density clumping or condensation plays an important role in driving the instability. Parallel thermal conduction localizes the mode to a narrow layer where k(parallel) =k⋅B/||B|| is small and stabilizes short wavelengths k〉kc, where kc depends on the local radiation and conduction rates. Thermal coupling to ions also limits the width of the unstable spectrum. It is shown that a broad spectrum of modes is typically unstable in tokamak edge plasmas and it is argued that this instability is sufficiently robust to drive the large-amplitude density fluctuations often measured there.
Type of Medium:
Electronic Resource
URL: