Double Layers in Converging Magnetic Fields of Terrestrial Auroral Region

English Abstract:

We report two dimensional structures of double layers (DLs), as seen from particle-in-cell (PIC) simulations, which form in the converging magnetic field of the auroral region of the Earth’s magnetosphere. The simulations include hot plasma of the magnetospheric origin and cold plasma from the ionosphere including the backscattered and secondary warm electrons flowing upward. The DL structure is dominated by electron holes below the double layer and ion holes above it. Specifically we study the phase-space structures of the hot electrons within the structures of the phase-space holes that are believed to generate the Aurora Kilometric Radiation (AKR). We find that relatively slowly upward moving ion holes enhance the slopes in the velocity distribution of the electron holes that could generate AKR. We discuss the spatial structural relationship between the DL and the ion holes and their motions that cause drifts in the fine spectral features of the AKR.