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An attractive mechanism for radiation transport by electron holes from the magnetospheric auroral cavity source region down to the ionosphere and possibly even down to the atmosphere is examined. Because of the excitation and propagation properties of the X mode, this mechanism turns out to be highly improbable for the usual resonant excitation of radiation of frequency just below the local electron cyclotron frequency, $\omega \lesssim \omega_{ce}$. It could work only, if the auroral ionosphere would be locally perforated being of sufficiently low density for allowing electron holes riding down to low altitudes on the auroral electron beam. If resonant excitation of higher electron cyclotron harmonics, $\omega \sim \ell \omega_{ce}, ~\ell= 2,3,...$, becomes possible, a still unexplored mechanism, then radiation excited inside the hole could be transported to lower altitudes than generated. If this happens, radiation would provide another mechanism of coupling between the magnetospheric plasma and the atmosphere. Keywords: Electron cyclotron maser, electron holes, auroral acceleration, auroral radiation fine structure, auroral kilometric radiation, Jupiter radio emission, Planetary radio emission, Comment: 4 pages, 1 figure, submitted to Ann. Geophys

The electron-cyclotron maser emission from electron holes is applied to holes generated in the downstream current region of the aurora. We suggest that part of the fine structure observed in the auroral kilometric radiation is generated by the electron-cyclotron maser mechanism in the downstream current region. The argument goes that the main background auroral kilometric radiation source is still located in the partial electron ring (horseshoe) distribution of the upward current region while the fine structure is caused by electron holes generated predominantly in the downward current region. Since both regions always exist simultaneously they are acting in tandem in generating auroral kilometric radiation by the same mechanism though in different ways., Comment: This paper extends the former theory from the auroral downstream to the auroral upstream current region. Submitted to Ann. Geophys., 9 Journal pages, 3 Figures

Electron holes are suggested to be an important source for generation of electron-cyclotron maser radiation. We demonstrate that electron holes generated in a ring-horseshoe distribution in the auroral-kilometric radiation source region have the capacity to emit band-limited radiation. The radiation is calculated in the proper frame of a circular model hole and shown to be strictly perpendicular in this frame. Its bandwidth under auroral conditions is of the order of $\sim1$ kHz, which is a reasonable value. {It is also shown that much of the drift of fine structure in the radiation can be interpreted as Doppler shift. Estimates based on data are in good agreement with theory. Growth and absorption rates have been obtained for the emitted radiation. However, the growth rate of a single hole obtained under conservative conditions is small, too small for reproducing the observed fine structure flux. Trapping of radiation inside the hole for the hole's lifetime helps amplifying the radiation additionally but introduces other problems. This entire set of questions is discussed at length and compared to radiation from the global horseshoe distribution.} The interior of the hole produces a weak absorption at slightly higher frequency than emission. The absorptivity is roughly two orders of magnitude below the growth rate of the radiation thus being weak even when the emission and absorption bands overlap. Transforming to the stationary observer's frame it is found that the radiation becomes oblique against the magnetic field. For approaching holes the radiated frequencies may even exceed the local electron cyclotron frequency., Comment: 19 pages, 9 figures, revised version to appear in Ann. Geophys. vol 29, 2011

We present auroral evidence for multiple and, most probably, small scale reconnection in the near Earth magnetospheric plasma sheet current layer during auroral activity. Hall currents as the source of upward and downward field-aligned currents require generation of the corresponding electron fluxes. The auroral spatial ordering in a multiple sequence of these fluxes requires the assumption of the existence of several -- and possibly -- even many tailward reconnection sites., Comment: Original MS in EPL Latex style, 5 figures

This Letter shows that for particularly shaped background particle distributions momentum exchange between phase space holes and the distribution causes acceleration of the holes along the magnetic field. In the particular case of a non-symmetric ring distribution (ring with loss cone) this acceleration is nonuniform in phase space being weaker at larger perpendicular velocities thus causing deformation of the hole in phase space., Comment: Original MS in EPL style, 1 Figure

A qualitative discussion is given of the role electron holes play in generating fine structure on the electron cyclotron maser radiation. It is argued that electron holes become deformed in phase space when interacting with an incomplete ring or horseshoe distribution which occurs in the presence of strong field aligned electric fields in the upward current region and in the presence of a loss cone. This interaction is based on momentum balance considerations. Deformed narrow electron holes cause steep velocity space gradients on the ring distribution that lead to intense but narrow band emission from their high speed sides and absorption at slightly higher frequency from their low speed sides. The twins of banded emission and absorption move in frequency space due to the average real space displacement of the deformed electron hole., Comment: pdf-LaTex, 3 Figures

The diffusion expected from the quasi-linear theory of the lower hybrid drift instability at the earth's magnetopause is recalculated. The resulting diffusion coefficient is marginally large enough to explain the thickness of the boundary layer under quiet conditions, based on observational upper limits for the wave intensities. Thus, one possible model for the boundary layer could involve equilibrium between the diffusion arising from lower hybrid waves and various loss processes.

The diffusion expected from the quasilinear theory of the lower hybrid drift instability at the Earth's magnetopause is recalculated. The resulting diffusion coefficient is in principle just marginally large enough to explain the thickness of the boundary layer under quiet conditions, based on observational upper limits for the wave intensities. Thus, one possible model for the boundary layer could involve equilibrium between the diffusion arising from lower hybrid waves and various low processes. However, some recent data and simulations seems to indicate that the magnetopause is not consistent with such a soft diffusive equilibrium model. Furthermore, investigation of the nonlinear equations for the lower hybrid waves for magnetopause parameters indicates that the quasilinear state may never arise because coalescence to large wavelengths, followed by collapse once a critical wavelengths is reached, occur on a time scale faster than the quasilinear diffusion. In this case, an inhomogeneous boundary layer is to be expected. More simulations are required over longer time periods to explore whether this nonlinear evolution really takes place at the magnetopause.