Abstract. Observations from Polar have revealed that electron hole (e-hole) structure critically depends on the plasma magnetization determined by the ratio fl = fl e / C0pe, where fl e and C0pe are the electron cyclotron and plasma frequencies, respectively. Using threedimensional parallel particle-in-c__e!l) simulations, we hav__e studied the formation and structure of e-holes by varying fl showing that (1) for fl <1 e-holes are highly transitory while for gl > 1 long-lasting e-holes form, especially when fl >_ 2, (2) in the transitory eholes for gl < 1, the e-holes are__essentially planar with parallel electric fields E, >> E•_, the perpendicular field, (3)
[1] We study the dynamical behavior of potential structures in the auroral upward current region. The study is based on a large two-dimensional particle-in-cell simulation. A double layer (DL) forms in the auroral potential structure in the counterstreaming expansion of cold and hot plasmas from bottom (ionospheric side) and top (magnetospheric side), respectively. Transversely nonuniform converging perpendicular electric field drives the plasma from the top, generating V-shaped potential structure within the expanding plasmas. The dynamical features include (1) recurring formation of the DL, (2) downward motion of the DL over the distance of thousands of Debye lengths, (3) collapse of the existing double layer after the reformation of a new one near the top in the hot magnetospheric plasma, and (4) generation of electron holes (EHs) on the high-potential side of the DL and their downward propagation over a few thousand of Debye lengths, where they are dissipated. The EHs are associated with broadband plasma waves with spectrum peaked near the lower hybrid frequency. The EH turbulence is temporally modulated by low-frequency plasma waves near the ion cyclotron frequency W i . Electrostatic ion cyclotron waves above W i occur on the low-potential side of the DL. Transverse and parallel acceleration/heating of both electrons and ions are studied. The fast moving electron holes are found effective in transverse heating of the cold ionospheric electrons trapped below the DL. Relevance of our results to satellite observations in the auroral plasma is discussed.Citation: Singh, N., S. Araveti, and E. B. Wells (2011), Mesoscale PIC simulation of double layers and electron holes affecting parallel and transverse accelerations of electrons and ions,
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