Abstract
When resistive interchange modes (RIMs) are unstable in aStellarator/Heliotron device, they may change the pressure profile even forβ values lower than the ideal β limit. The nonlinear RIM withn/m = 2/3 modifies the density profile in the vicinity of the resonantsurface with ι = 2/3 easily under the assumption of constanttemperature. Here m(n) is a poloidal (toroidal) mode number andι is a rotational transform. Also poloidal shear flow is generatedthere, which limits the region of density profile modificationsubstantially. The sign of the density gradient becomes positive at theresonant surface. A quasi-stationary profile is obtained forlow-collisional plasmas. When the collision frequency is high, localhumps are produced in the background density profile, and they have atendency to move to the resonant surface. It is also shown that thedensity profile including humps is correlated with the poloidal velocityshear profile. Here the typical shearing rate of the poloidal flow at thesaturated state exceeds the linear growth rate of the (m,n) = (3,2) mode.
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