Weak and strong regimes of incompressible magnetohydrodynamic turbulence

TL;DR

This paper clarifies that in incompressible magnetohydrodynamic turbulence, weak turbulence theory predicts similar autocorrelation and cascade timescales, challenging models requiring many wave packet collisions like Iroshnikov-Kraichnan.

Contribution

It demonstrates that models with many wave collisions are incompatible with weak turbulence theory due to equal autocorrelation and cascade timescales.

Findings

Autocorrelation and cascade timescales are of the same order.

Models with many wave collisions are incompatible with weak turbulence theory.

Challenges the validity of the Iroshnikov-Kraichnan model in this context.

Abstract

It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade timescales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence which implies a large number of collisions among wave packets for an efficient energy cascade (such as the Iroshnikov-Kraichnan model) are not compatible with the weak turbulence theory.