Kinetic theory of tearing instabilities
The transition of the tearing instability from the collisional to the collisionless regime is investigated kinetically using a Fokker--Planck collision operator to represent electron-ion collisions. As a function of the collisionality of the plasma, the tearing instability falls into three regions, which are referred to as collisionless, semi-collisional, and collisional. The width ..delta.. of the singular layer around kxB/sub 0/=0 is limited by electron thermal motion along B/sub 0/ in the collisional and semi-collisional regimes and is typically smaller than rho/sub i/, the ion Larmor radius. Previously accepted theories, which are based on the assumption ..delta..very-much-greater-thanrho/sub i/, are found to be valid only in the collisional regime. The effects of density and temperature gradients on the instabilities are also studied. The tearing instability is only driven by the temperature gradient in the collisional and semi-collisional regimes. Numerical calculations indicate that the semi-collisional tearing instability is particularly relevant to present day high temperature tokamak discharges.
- Research Organization:
- Department of Physics, University of California, Los Angeles, California 90024
- OSTI ID:
- 7093640
- Journal Information:
- Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 20:8; ISSN PFLDA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700107* -- Fusion Energy-- Plasma Research-- Instabilities
CLOSED PLASMA DEVICES
COLLISIONAL PLASMA
COLLISIONLESS PLASMA
COLLISIONS
ELECTRON COLLISIONS
ELECTRON-ION COLLISIONS
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
ION COLLISIONS
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES