Thermal coupling of ions and electrons by collective effects in two-temperature accretion flows

The authors have discovered a plasma instability which may lead to the thermal coupling of ions and electrons in two-temperature accretion flows (Ti very large Te), on a time scale shorter than the Coulomb coupling time. The unstable modes include acoustic waves, drift waves, and electromagnetic waves, which propagate nearly perpendicular to the magnetic field in a plasma in which the electron gyroradius is much smaller than the ion Debye length. The instability has time to grow only in regions of large-amplitude, small-scale MHD turbulence, such as one might expect to find near collisionless shocks or sites of magnetic reconnection.