Spectral breaks of Alfvenic turbulence in a collisionless plasma

TL;DR

This paper investigates the spectral breaks in Alfvenic turbulence within collisionless plasmas, emphasizing the influence of plasma parameters and proposing an explanation for observed spectral transitions from large-scale to kinetic turbulence.

Contribution

It highlights the role of plasma parameters in the transition to kinetic turbulence and offers a new explanation for the spectral breaks observed in solar wind turbulence.

Findings

Spectral breaks are influenced by plasma beta and temperature ratios.

Transition scales depend on turbulence obliquity and plasma conditions.

A new model explains the observed spectral transitions.

Abstract

Recent observations reveal that magnetic turbulence in the nearly colisionless solar wind plasma extends to scales smaller than the plasma microscales, such as ion gyroradius and ion inertial length. Measured breaks in the spectra of magnetic and density fluctuations at high frequencies are thought to be related to the transition from large-scale hydromagnetic to small-scale kinetic turbulence. The scales of such transitions and the responsible physical mechanisms are not well understood however. In the present work we emphasize the crucial role of the plasma parameters in the transition to kinetic turbulence, such as the ion and electron plasma beta, the electron to ion temperature ratio, the degree of obliquity of turbulent fluctuations. We then propose an explanation for the spectral breaks reported in recent observations.