Analytical approximations are used to clarify the effect of Larmour radius on rf ponderomotive forces and on poloidal flows induced by them in tokamak plasmas. The electromagnetic force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation. The first part, called the gradient electromagnetic stress force, is combined with fluid dynamic (Reynolds) stress force, and gyroviscosity is included into viscosity force to model finite ion Larmour radius effects in the momentum response to the rf fields in plasmas. The expressions for the relative magnitude of different forces for kinetic Alfven waves and fast waves are derived.
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http://dx.doi.org/10.1103/PhysRevLett.84.1200 | DOI Listing |
Phys Rev Lett
August 2008
Center for Plasma Theory and Computation, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
The dominant finite-Larmour-radius (FLR) stabilization effects on interchange instability can be retained by taking into account the ion gyroviscosity or the generalized Ohm's law in an extended MHD model. However, recent simulations and theoretical calculations indicate that complete FLR stabilization of the interchange mode may not be attainable by ion gyroviscosity or the two-fluid effect alone in the framework of extended MHD. For a class of plasma equilibria in certain finite-beta or nonisentropic regimes, the critical wave number for complete FLR stabilization tends toward infinity.
View Article and Find Full Text PDFPhys Rev Lett
May 2007
P.N. Lebedev Physics Institute, Moscow 117924, Russia.
We study the electric potential of a charge placed in a strong magnetic field B>>B(0) approximately 4.4x10(13) G, as modified by the vacuum polarization. In such a field the electron Larmour radius is much less than its Compton length.
View Article and Find Full Text PDFPhys Rev Lett
February 2000
Physics Institute, University of Sao Paulo, 05315-970, Sao Paulo, SP, Brazil.
Analytical approximations are used to clarify the effect of Larmour radius on rf ponderomotive forces and on poloidal flows induced by them in tokamak plasmas. The electromagnetic force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation. The first part, called the gradient electromagnetic stress force, is combined with fluid dynamic (Reynolds) stress force, and gyroviscosity is included into viscosity force to model finite ion Larmour radius effects in the momentum response to the rf fields in plasmas.
View Article and Find Full Text PDFPhys Rev Lett
September 2000
Department of Plasma Physics, Umea UniversityS-90187 Umea, Sweden.
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