Landau Damping and Growth of Proton-Cyclotron Turbulence by the Electron Distribution Function in Downward Auroral-Current Regions

We have identified several FAST satellite passes in downward, field-aligned, auroral-current regions, where Landau damping and Landau growth of proton-cyclotron turbulence is correlated with the shape of the electron distribution function in velocity space. Recently, and for the first time, we have developed and published a new kinetic and multi-moment fluid, anomalous transport theory that contains the effect of electrostatic turbulence in inhomogeneous, non-uniformly magnetized plasmas [1, 2]. We apply the new theory to a downward current sheet and show that a current-driven, generalized, Drummond-Rosenbluth, electrostatic proton-cyclotron instability occurs, where the time-asymptotic state for the spectral density of the turbulent electric field fluctuates between maximum and minimum values; and that these maximum and minimum values are, in turn, correlated with fluctuations in the electron distribution function between unstable and stable configurations, respectively. In this way, the time-asymptotic state for downward, auroral-current regions is characterized by "hot spots" and "cold spots" which are intermittent in space and time. [1] J. R. Jasperse et al.(2006), Phys. Plasmas 13, 072903, and [2] J. R. Jasperse et al. (2006), Phys. Plasmas 13, 112902.