Cross helicity and magnetic helicity cascades in MHD turbulence

R. Stepanov^{1, 2} - P. Frick¹ - I. Mizeva¹

¹ Institute of Continuous Media Mechanics, 1 Korolyov str., Perm 614013, Russia
² Perm State National Research Polytechnical University, 29 Komsomolskii ave., 614990 Perm, Russia

Abstract
The high Reynolds number turbulence of an electrically conducting fluid along with energy transfers two additional quadratic quantities within the inertial range: cross helicity and magnetic helicity. We study the role of these two quantities in forced and freely decaying turbulence using a shell model of MHD turbulence. We show that the presence of helicities strongly affects the scenario of evolution of the turbulence decay at late stages. With forced MHD turbulence, the stationary injection of cross helicity reduces the spectral energy transfer and leads to energy accumulation, whereas the injected magnetic helicity condenses at largest scales. Figs 3, Refs 12.