Fluid simulations of edge turbulence for stellarators and axisymmetric configurations

摘要

Nonlinear electromagnetic fluid simulations in a flux tube are used to compute the edge turbulence for a family of axisymmetric configurations with different rotational transform profiles (iota) and the stellarator Wendelstein 7-X (W7-X) [Grieger , Plasma Physics and Controlled Nuclear Fusion Research, 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525]. The influence of the iota profile on anomalous transport and the strength of zonal flows in these axisymmetric equilibria are studied and the results are connected to simulations for the W7-X equilibrium. A strong decrease in transport is found by increasing iota or switching the sign of the shear from tokamak-(iota(')< 0) to stellarator-like (iota(')>0). The effect of pressure-induced changes in the W7-X equilibrium geometry on the transport at fixed parameters is studied and a decrease in the transport following changes in the zonal flows is found.