Helicity-flux-driven α effect in laboratory and astrophysical plasmas

The constraint imposed by magnetic helicity conservation on the α effect is considered for both magnetically and flow dominated self-organizing plasmas. Direct numerical simulations are presented for a dominant contribution to the α effect, which can be cast in the functional form of a total divergence of an averaged helicity flux, called the helicity-flux-driven α (Hα) effect. Direct numerical simulations of the Hα effect are presented for two examples - the magnetically dominated toroidal plasma unstable to tearing modes, and the flow-dominated accretion disk.