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[en] The effect of the rotating dielectric property of the plasma on the radiation pattern has been discussed. It can be pointed out that the plasma column (cylindrical shaped) while excited with the help of electric ring source gives more radiations for higher modes. (author)
[en] The Regions 1 and 2 Birkeland current patterns in the ionosphere can be idealized as two nearly concentric, bipolar circles or rings. The Region 1 ring is electrically connected to the outer (or poleward) boundary of the plasma sheet and the Region 2 ring to its inner (or equatorward) boundary. The physics governing the radii of these two rings are therefore different. In particular, in the absence of substorms, the rate of change of the radius of the Region 1 ring is proportional to the polar cap potential, but the rate of change of the radius of the Region 2 ring is proportional to the rate of change of the polar cap potential. Thus, the rates of growth and decay of the radii of these rings will in general be different. Calculation shows that during dayside merging intervals, Ring 1 expands about 16 times faster than Ring 2. Under typical merging potentials, Ring 1 will cross the initial ring separation in about 1 hour. Situations are identified in which the circles approach very near to each other (or actually attempt to cross each other) as necessitating the onset of a substorm to cause a sudden reduction in the radius of the inner ring. Thus, the rings, which would otherwise be nearly independent of each other, are instead strongly coupled by the substorm process. The theory predicts the common radius of the coupled ring system (approximately 19 degrees to 22 degrees) and its dependence on the cross-polar-cap potential (approximately phi 0.2). 23 references
[en] Complete text of publication follows. The plasma sheet is an important region in the magnetosphere that contains electrons and ions with peak energy fluxes in the few keV range. The hot particles in the plasma sheet are the source of substorm injected particles with higher energy. The plasma sheet ions may move Earthwards and enter the inner magnetosphere during the time of enhanced magnetospheric convection, and become the source population for the ring current. The TC-1 satellite in an equatorial elliptical orbit with an apogee of ∼14 Re provides a good opportunity to study the penetration of plasma sheet into the inner magnetosphere, especially outside the geosynchronous orbit. We use the data of ion and electron measured by HIA and PEACE of TC-1 to study the penetration of plasma sheet ions and electrons, and the relation of inner boundary of plasma sheet with Kp,AE and Dst. Finally we compared the observations with theoretic results based on the model in Korth et al. .
[en] Complete text of publication follows. It is known that the stable auroral red (SAR) arcs are the consequence of interaction of the outer plasmasphere (plasmapause) with energetic ions of the ring current. The diffuse aurora (DA) is caused by the low-energy electron precipitation from the plasma sheet. During substorms we observe the intensity increase of DA and its equatorward extension up to the plasmapause projection which is mapped by the SAR arc appearing at that time. At a recovery phase period of intense substorms at latitudes of SAR arc the luminosity pulsations in the 427,8 nmN2+ emission owing to the pulsating precipitations of the ring current energetic particles in the outer plasmasphere usually occur (Ievenko et al., Adv. Space Res., 2008). Here we present the new results of the spectrophotometric observations at the Yakutsk meridian (199deg E geomagnetic longitude). The detailed relationship of the development of pulsating variations of the N2+ band intensity to the formation of SAR arc equatorward of the DA boundary in the 557,7 nm emission is shown. The basic types of the luminosity pulsation spectra in the frequency region 0.02-1 Hz are analyzed. The delay of 0.1 - 0.5 s in the luminosity pulsation development at SAR arc latitude relative to a pulsation in DA (EMBED Equation 3L = 0,5 - 0,7 RE) has been revealed. It is supposed that the appearance of pulsating precipitations at latitudes of the SAR arc (outer plasmasphere) in these cases can be caused by the propagation of hydromagnetic waves from the region of source (pulsations in the diffuse aurora) inwards the magnetosphere.
[en] Complete text of publication follows. In this paper it is demonstrated that the precipitation of the ring current ions represents a second heat source for the neutral upper-atmosphere. Its energy comes from the solar corpuscular heating and acts around equatorial latitudes. The ring current is heating the neutral atmosphere in addition to the auroral heat source. Contrary to this latter, however, the ring current acts not only in the main phase, but also during the recovery phase of a geomagnetic storm. The additional density increases connected to the ring current precipitation have only a two hours delay with respect to the dDst/dt. As the Dst characterizing the intensity of the ring current is proportional to the dDst/dt, we have modeled the density increase using Dst as an index in an improved empirical model (ddMSIS). The model takes into account the height and local solar time dependence of this additional density increase as well.
[en] Complete text of publication follows. In this paper, a new substorm model which overcomes the difficulty of present current wedge model is developed from the analysis of numerical substorm obtained from the global MHD simulation. In the current wedge model, the region 1 field-aligned current (FAC) that causes the first brightening is the diverted cross-tail current due to the flow from the near earth neutral line (NENL). However, a well known difficulty for this model is the fact that a sudden brightening starts in the most equatorward preexisting arc without any perturbation in poleward arcs. In the present model, the onset is triggered by the abrupt formation of high-pressure region in the inner magnetosphere. This high-pressure region results from the magnetic tension released from the NENL, and intensifies the partial ring current. The tail disturbance is primary transmitted to the ionosphere by the region 2 FAC which is generated together with the partial ring current through the conversion of thermal energy to electromagnetic energy by convection crossing the high-pressure region. Since the ionospheric closure of region 2 FAC by midnight eastward current is equivalent to the dusk to dawn electric field that interrupt the convection, the closure of substorm region 2 FAC occurs by connecting with the newly developed nightside region 1 FAC, forming a grand loop. This connection with the region 1 FAC takes place through the nearest (most equatorward) arc. Associated nightside region 1 FAC does not connected to the traditional current wedge but to the cusp region.