DSHARK: A dispersion relation solver for obliquely propagating waves in bi‐kappa‐distributed plasmas

Abstract

AbstractSatellite measurements suggest that space plasmas often exhibit bi‐kappa particle distributions with high‐energy tails instead of simple Maxwellians. The presence of suprathermal particles significantly alters the plasmas' dispersion properties compared to purely Maxwellian scenarios. In the past, wave propagation in magnetized, bi‐kappa plasmas was almost exclusively addressed for parallel propagating modes only. To enable a systematic study of both parallel and oblique wave propagation, the new kinetic dispersion relation solver Dispersion Solver for Homogeneous Plasmas with Anisotropic Kappa Distributions (DSHARK) was developed and is presented in this work. DSHARK is an iterative root‐finding algorithm which is based on Summers et al. (1994) who derived the dielectric tensor for plasmas with bi‐kappa‐distributed particles. After a brief discussion of kappa distributions, we present the kinetic theory and the numerical methods implemented in DSHARK and verify the code by considering several test cases. Then, we apply DSHARK to the oblique firehose instability to initiate a more extensive work which will be addressed in the future. A systematic investigation of the dispersion properties of bi‐kappa‐distributed plasmas is expected to lead to a deeper understanding of wave propagation and instability growth in the solar wind.