Low frequency instabilities in confined plasmas, concepts and theoretical framework

Rogister, A.

Journal Article

PreJuSER-32986

Low frequency instabilities in confined plasmas, concepts and theoretical framework

Rogister, A.FZJ*

2004
American Nuclear Society La Grange Park, Ill.

Fusion science and technology 45, 338 - 345 (2004)

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Please use a persistent id in citations: http://hdl.handle.net/2128/2723

Abstract: Most experts consider that anomalous energy and particle transport in fusion devices are due to low frequency waves whose free energy sources are the equilibrium gradients and the associated drifts across the confining magnetic field (drift waves). We consider successively the cases where k(\\)qR much greater than 1 and k(\\)qR similar to 1 where k(\\) is the parallel wave number, qR being the connection length. The first limit is particularly adequate if the gradient of the parallel flow velocity is significant; exact stability criteria are then obtained with the help of the Nyquist diagram in the framework of the local dispersion relation which applies. That is not the case if k(\\)qR similar to 1 : here, the stability analysis leads to second order differential equations whose complex eigenvalues provide the wave frequencies and the growth/decay rates. The theoretical concepts are developed successively for cylindrical and axi-symmetric toroidal geometries. Electrons are considered to be adiabatic.

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