Electron firehose instability in kappa-Maxwellian-distributed space plasmas

Abstract

Temperatures of charge species are observed to be constrained due to collisional and collective processes. In collision-poor plasma from space, microinstabilities appeared as a major candidate to regulate the observed temperature anisotropies. This manuscript investigates the electron parallel electron firehose instability, which might be excited by the temperature anisotropy in a direction parallel to the background magnetic field in space plasmas. Based on the observed data, we employ a kappa-Maxwellian model distribution function to unlock the dispersion characteristics of the electron firehose mode. We find that in the regions where there are large populations of suprathermal electron, the real mode propagation, growth rates, and associated domains of the unstable wave numbers tend to increase. Maximum growth levels of the instability get enhanced with an increase in the temperature anisotropy in direction parallel to the background magnetic field and electron plasma beta. Furthermore, we decoded the instability threshold and maximum growth rate for the choice of input parameters suitable to excite the electron firehose instability.