Realization of reconnection-mediated cascade in other turbulence regimes

Investigate whether the reconnection-driven energy cascade associated with high magnetic Reynolds number plasmoid/tearing instability—characterized by a spectral break scale k* ∼ Rm^{4/7} and an energy spectrum E(k) ∼ k^{-11/5}—is realized in turbulence regimes beyond strong-field, decaying magnetohydrodynamic turbulence, such as driven supersonic, compressible MHD turbulence with dynamo-generated magnetic fields, and determine the conditions under which this cascade emerges.

Background

The paper discusses recent theoretical and numerical advances indicating that at very high magnetic Reynolds numbers (Rm ≳ 10^5), thin current sheets in MHD turbulence become tearing-unstable, yielding a reconnection-driven cascade with a predicted spectral break and slope, and necessitating large dynamical range to observe.

While this behavior has been measured in strong-field, decaying MHD turbulence at Rm ~ 10^5, it remains uncertain whether the same reconnection-mediated cascade occurs under different turbulence conditions, such as driven supersonic, compressible flows without an imposed mean magnetic field, which are common in astrophysical plasmas. Clarifying this would establish the generality of reconnection-mediated turbulence across regimes.