Spectra of a MHD plasma forced by power-law noise

Abstract

Scalings of a noise-driven two-dimensional homogeneous MHD plasma are considered by using numerical simulations. The noise is a Gaussian random process whose two-point correlation function is delta-correlated in time while obeying a power-law spectrum k (2-2 delta) that determines the input rate of the energy where k is the inverse of the scale length. For the case of infrared forcing, delta > 2, the scaling of the energy spectrum is found to closely follow the phenomenological prediction of k (-3/2). In the other case of ultraviolet forcing where delta < 2, the renormalization-group scale, which is k (1-4 delta/3), is found to approximately hold for the energy spectrum.