Scalings of forced Hasegawa-Mima equation by power-law noise

초록

For the plasma modeled by the Hasegawa-Mima equation forced by a noise, Kolmogorov-type phenomenology (KP) predicts the power-law scaling in two inertial regimes. In the spatial scale, which is larger than the ion gyroradius, the energy spectrum scales as k(-11/3) where the energy cascades to larger scales and k(-5) where the enstrophy is transferred to smaller scales down to the dissipation range. The renormalization-group (RG) approach, however, provides different scaling k(-1-4 delta/3) that strongly depends on the power exponent delta of the noise spectrum. Through numerical simulations it is found that, for delta <= 2 or delta >= 3, the energy spectrum follows KP while, for 2 <= delta <= 3, RG scaling prevails.

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