Resonant MHD modes with toroidal coupling

Technical Report · Wed Feb 28 23:00:00 EST 1990

OSTI ID:6931232

Connor, J W; Hastie, R J ^[1]; Taylor, J B ^[2]

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1. UKAEA Culham Lab., Abingdon (UK)
2. Texas Univ., Austin, TX (USA). Inst. for Fusion Studies

In a cylindrical plasma, tearing modes can be calculated by asymptotic matching of ideal mhd solutions across a critical layer. This requires a quantity {Delta}{prime} which represents the discontinuity' in the ideal solution across the layer. In a torus, poloidal harmonics are coupled and there are many critical surfaces for each toroidal mode number, and correspondingly many discontinuities {Delta}{prime}{sub m}. The ideal mhd solutions do not determine the {Delta}{prime}{sub m} but only a relation between them--described by an E-matrix.'' We discuss the calculation of the E-matrix for a large aspect-ratio tokamak. In a weak-coupling approximation it is tri-diagonal and can be computed from integrals over the uncoupled eigenfunctions or from simple basis-functions'' comprising triplets of coupled poloidal harmonics. This weak coupling approximation fails if {Delta}{prime}{sub m} is already small for an uncoupled harmonic. An alternative strong-coupling approximation is developed for this case. 9 refs.

• Research Organization: Texas Univ., Austin, TX (USA). Inst. for Fusion Studies
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG05-80ET53088
• OSTI ID: 6931232
• Report Number(s): DOE/ET/53088-426; IFSR--426; ON: DE90010077
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700103 -- Fusion Energy-- Plasma Research-- Kinetics
700107* -- Fusion Energy-- Plasma Research-- Instabilities
CLOSED PLASMA DEVICES
DISPERSIONS
EQUILIBRIUM
INSTABILITY
MAGNETIC FIELDS
MATHEMATICAL MODELS
MHD EQUILIBRIUM
NUCLEAR MODELS
PARTICLE MODELS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
STRONG-COUPLING MODEL
TEARING INSTABILITY
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
WEAK-COUPLING MODEL