Spectra of a MHD plasma forced by power-law noise

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 k2−2δ that determines the input rate of the energy where k is the inverse of the scale length. For the case of infrared forcing, δ > 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 δ < 2, the renormalization-group scale, which is k1−4δ/3, is found to approximately hold for the energy spectrum.