Local effect of equilibrium current on tearing mode stability

Technical Report · Sun Dec 01 04:00:00 EST 1985

OSTI ID:6514140

Cozzani, F

The local effect of the equilibrium current on the linear stability of low poloidal number tearing modes in tokamaks is investigated analytically. The plasma response inside the tearing layer is derived from fluid theory and the local equilibrium current is shown to couple to the mode dynamics through its gradient, which is proportional to the local electron temperature gradient under the approximations used in the analysis. The relevant eigenmode equations, expressing Ampere's law and the plasma quasineutrality condition, respectively, are suitably combined in a single integral equation, from which a variational principle is formulated to derive the mode dispersion relations for several cases of interest. The local equilibrium current is treated as a small perturbation of the known results for the m greater than or equal to 2 and the m = 1 tearing modes in the collisional regime, and the m greater than or equal to 2 tearing mode in the semicollisional regime; its effect is found to enhance stabilization for the m greater than or equal to 2 drift-tearing mode in the collisional regime, whereas the m = 1 growth rate is very slightly increased and the stabilizing effect of the parallel thermal conduction on the m greater than or equal to 2 mode in the semicollisional regime is slightly reduced.

• Research Organization: Texas Univ., Austin (USA). Inst. for Fusion Studies
• DOE Contract Number: FG05-80ET53088
• OSTI ID: 6514140
• Report Number(s): DOE/ET/53088-217; IFSR-217; ON: DE86002641
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ANALYTICAL SOLUTION
CLOSED PLASMA DEVICES
CURRENTS
DISPERSION RELATIONS
EIGENVALUES
ELECTRIC CURRENTS
EQUILIBRIUM PLASMA
INSTABILITY
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
TEARING INSTABILITY
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VARIATIONAL METHODS