Current diffusive interchange mode turbulence at low magnetic shear

Nonlinear structures in interchange mode turbulence.

Generation of linearly unstable streamers and nonlinearly saturated zonal flows have been investigated using two-dimensional simulations of interchange mode turbulence. It has been shown that nonlinear diamagnetic interactions tend to inhibit spectral cascades towards larger length scales and consequently suppress the nonlinear excitation of zonal flows. The latter has also been found to be in ...

Coherent structures in electrostatic interchange mode turbulence

shear suppression of turbulence in diverted H-mode plasmas; role of edge magnetic shear

s. We show that strong edge magnetic shear which is generic to divertor plasmas makes the shearing of turbulence eddys in toroidal geometry more effective. From calculations of the shearing rates for KSTAR edge parameters, we conclude that the enhanced magnetic shear at the diverted KSTAR plasma edge facilitates shear suppression of turbulence and ensuing H-mode transition.

Nonlinear dynamics of magnetic islands in presence of interchange turbulence

In this work, we study the interaction between a tearing mode and a pressure gradient instability (resistive interchange) by solving reduced MHD equations numerically. The numerical study shows existence of regimes where thetearing instability is driven by the pressure gradient. An interplay between the pressure and the magnetic flux controls the dynamics of the saturated state. A secondary ins...

Compressibility effect on magnetic-shear-localized ideal magnetohydrodynamic interchange instability

Sangeeta Gupta, J. D. Callen and C. C. Hegna Department of Engineering Physics, University of Wisconsin, Madison, WI 53706-1687 (Dated: July 8, 2004) Abstract Eigenmode analysis of a magnetic-shear-localized ideal magnetohydrodynamic (MHD) interchange instability in the presence of plasma compressibility indicates the marginal stability criterion (DI = 1/4) is not affected by the compressibilit...