Scale hierarchy created in plasma flow

The cooperation of nonlinearity ~producing collapsed characteristics! and dispersion ~unfolding singularities! underlies a robust mechanism that imparts two distinct scales (L measuring the system size, and d i typically of the order of the ion skin depth! to the double Beltrami states of a two-fluid plasma. It is shown that the conventional single-fluid model @magnetohydrodynamic ~MHD!# seemingly valid for a large system (d i /L'0), fails to capture the small scale that is created by the singular perturbation of the two-fluid effect ~dispersion!. The small-scale component plays an important role in various plasma phenomena, such as coronal heating. The double Beltrami model is compared and contrasted with the standard MHD pathway ~Parker’s model of current sheet, for instance!. © 2004 American Institute of Physics. @DOI: 10.1063/1.1762877#