Ideal MHD Instabilities with Finite β-Effect in Reversed Field Pinch

The growth rates of m =1 ideal MHD instabilities in RFP configurations are calculated by the use of the Hain and L ust equation in RFP configuration with finite pressure. Two kinds of m =1 instabilities are studied in this paper; one is a current-driven internal mode whose plasma displacement is localized around the plasma center region, and the other is a pressure-driven external mode whose plasma displacement is localized on the plasma surface. The contours of the growth rate of both instabilities are present in a \(₀{-}\) diagram \((q₀{=}a/R₀\)), in which each point corresponds to a RFP configuration with a different current profile. This diagram shows that the growth rate of the internal mode is closely related to the degree of relaxation.