Multiscale nature of the dissipation range in gyrokinetic simulations of Alfv\'enic turbulence

TL;DR

This study uses gyrokinetic simulations to analyze energy transfer and dissipation across all scales in Alfvénic turbulence, revealing that multiple coupled mechanisms operate throughout the kinetic range.

Contribution

First comprehensive gyrokinetic simulation covering scales from MHD to electron gyroradius, highlighting multiscale dissipation mechanisms in Alfvénic turbulence.

Findings

Approximately 30% of energy transfer near electron scales is mediated by MHD tail modes.

Dissipation occurs across the entire kinetic range, not just at small scales.

Multiple coupled mechanisms are essential for understanding turbulence dissipation.

Abstract

Nonlinear energy transfer and dissipation in Alfv\'en wave turbulence are analyzed in the first gyrokinetic simulation spanning all scales from the tail of the MHD range to the electron gyroradius scale. For typical solar wind parameters at 1 AU, about 30% of the nonlinear energy transfer close to the electron gyroradius scale is mediated by modes in the tail of the MHD cascade. Collisional dissipation occurs across the entire kinetic range $k_\perp\rho_i\gtrsim 1$. Both mechanisms thus act on multiple coupled scales, which have to be retained for a comprehensive picture of the dissipation range in Alfv\'enic turbulence.