Dispersive properties of a magnetized plasma with a field‐aligned drift and inhomogeneous transverse flow

TLDR: In this article, the authors investigated the stability and instability of magnetic field-aligned electron current and transverse electric field in the presence of a transverse velocity shear and showed that in contrast to the homogeneous case of current-driven modes, the modes can be unstable in a wider range of temperature ratio τ and they are broadband in frequency.

Abstract: Electrostatic fluctuations driven by the combination of a magnetic‐field‐aligned electron current and a localized transverse electric field are investigated. Characteristic parameters, such as scale length and magnitude of the sheared E×B velocity, magnitude of the magnetic‐field‐aligned current, and temperature ratio τ≡Ti/Te are varied to include conditions associated with electrostatic waves driven entirely by magnetic‐field‐aligned current, driven entirely by transverse electric field, and driven by a combination of magnetic‐field‐aligned current and transverse electric field. It is shown that, in contrast to the homogeneous case of current‐driven modes, the modes in the presence of a transverse‐velocity shear can be unstable in a wider range of temperature ratio τ and they are broadband in frequency. Using a simplified model, numerical solutions of the nonlocal dispersion relation, and physical arguments, cases of stabilization and destabilization due to the inhomogeneous energy‐density driven instabi...