Simulations of the anisotropic kinetic and magnetic alpha effects

Keywords magnetohydrodynamics (MHD) –turbulence Using simulations of isotropically forced helical turbulence thec ontributions to kinetic and magnetic alpha effectsa re computed. It is shown that forthe parameterregimes considered in an earlierpublication(Brandenburg&Subramanian 2005), the expressions for isotropica nd anisotropic alpha effects give quantitatively similar results. Bothk inetic and magnetic alpha effectsa re proportional to ar elaxationt imew hose value, in units of thet urnovert ime, is shown to be approximatelyunity and independent of themagnetic Reynolds number. Key words magnetohydrodynamics (MHD) – turbulence Using simulations of isotropically forced helical turbulence the contributions to kinetic and magnetic alpha effects are computed. It is shown that for the parameter regimes considered in an earlier publication (Brandenburg & Subramanian 2005), the expressions for isotropic and anisotropic alpha effects give quantitatively similar results. Both kinetic and magnetic alpha effects are proportional to a relaxation time whose value, in units of the turnover time, is shown to be approximately unity and independent of the magnetic Reynolds number.