HR: 0830h
AN: SM41B-0561    [PDF]
TI: Dynamic Planar Double Layers: Filamentary Substructures, Electron Holes and Ion Heating
AU: Khazanov, I
EM: khazanov@eng.uah.edu
AF: Electrical and Computer Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 United States
AU: * Singh, N
EM: singh@ece.uah.edu
AF: Electrical and Computer Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 United States
AB: High-resolution measurements from FAST in the auroral return current plasma have revealed a wealth of information on the myriads of small-scale structures imbedded in large-scale ones. The fine structures appear in electric fields both parallel and perpendicular to the ambient Earth's magnetic field associated with the so-called diverging electrostatic shocks. The upward-accelerated electron flux and, therefore, the downward parallel current also show filamentary behavior. Using 2.5-D particle-in-cell (PIC) simulations, we study here the formation of a double layer (DL) and its stability. We find that the ion beam accelerated by the DL generates waves, which trigger fragmentation of the DL into substructures (DLSSs) like U- and V-shaped electrostatic shocks. The DL and DLSSs are seen to continually emit electron holes of varied shapes and sizes into the high-potential plasma above them, while below them in the low-potential plasma ions are transversely heated. Our simulation suggests important coupling between various auroral processes, namely, formation of DL, acceleration of electrons and ions, ion instabilities below the DL, filamentation of the DL by the waves generating DLSS, and continual emission of electron holes from them. In addition to revealing the coupling processes, simulations also bring out some of the quantitative features of return current plasma.
DE: 2471 Plasma waves and instabilities
DE: 2483 Wave/particle interactions
DE: 2704 Auroral phenomena (2407)
DE: 2712 Electric fields (2411)
DE: 2772 Plasma waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting