Kappa distributions: theory and applications in space plasmas

TL;DR

This paper reviews the theory and applications of Kappa distributions in space plasmas, highlighting their role in modeling non-Maxwellian particle velocity distributions and their impact on plasma dynamics.

Contribution

It provides a comprehensive overview of the theoretical foundations and practical applications of Kappa distributions in space plasma physics.

Findings

Kappa distributions effectively model suprathermal tails in space plasma VDFs.

Suprathermal particles influence plasma temperature and acceleration.

Kinetic approaches reveal the importance of non-Maxwellian distributions in wave-particle interactions.

Abstract

Particle velocity distribution functions (VDF) in space plasmas often show non Maxwellian suprathermal tails decreasing as a power law of the velocity. Such distributions are well fitted by the so-called Kappa distribution. The presence of such distributions in different space plasmas suggests a universal mechanism for the creation of such suprathermal tails. Different theories have been proposed and are recalled in this review paper. The suprathermal particles have important consequences concerning the acceleration and the temperature that are well evidenced by the kinetic approach where no closure requires the distributions to be nearly Maxwellians. Moreover, the presence of the suprathermal particles take an important role in the wave-particle interactions.