A Moment-Based Quasilinear Theory for Electron Firehose Instability Driven by Solar Wind Core/Halo Electrons

In dilute space plasmas, especially in the solar wind, the microinstabilities are regarded as a major candidate to regulate the unchecked rise in temperature anisotropy near Earth orbit. The present paper considers parallel electron firehose mode, which is driven unstable under the condition of excessive electron temperature along the ambient magnetic field, that is, T-vertical bar vertical bar e > T-perpendicular to e. The present study assumes bi-Maxwellian model of solar wind species comprising ions, core, and halo electron components and, in addition, allowing their temperatures to evolve in time t. Employing the macroscopic quasilinear method, a set of equations has been constructed whose solutions give a dynamical picture of the modification in initial particles distributions and wave energy density associated with unstable electron firehose mode. The present scheme, further, confirms the marginal stability curves corresponding to ions, core, and halo electrons, separately. As we dynamically couple solar wind electrons with ions to determine the dynamics of instability, it may amount a further step toward global kinetic solar wind modeling.