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- Ogawa, Y., et al.
(författare)
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Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions
- 2008
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:A5, s. A05306-
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between bulk ion upflows and suprathermal ions was investigated using data simultaneously obtained from the European Incoherent Scatter (EISCAT) Svalbard radar (ESR) and the Reimei satellite. Simultaneous observations were conducted in November 2005 and August 2006, and 14 conjunction data sets have been obtained at approximately 630 km in the dayside ionosphere. Suprathermal ions with energies of a few eV were present in the dayside cusp region, and the ion velocity distribution changed from an isotropic Maxwellian near the cusp region to tail heating at energies above a few eV in the cusp region. The velocity distribution of the suprathermal ions has a peak perpendicular or oblique to the geomagnetic field, and the temperature of the suprathermal ions was 0.9-1.4 eV. An increase in the phase space density (PSD) of the suprathermal ions, measured with the Reimei, was correlated with bulk ion upflow observed at the same altitude using EISCAT, and with the energy flux of precipitating electrons with energies of 50-500 eV. The PSD also has a good correlation with the electron temperature, which was increased by precipitation, but not with the ion temperature (0.1-0.3 eV) at the same altitude measured with EISCAT. These results suggest that plasma waves such as broadband extremely low frequency (BBELF) wavefields associated with precipitation are connected to the bulk ion upflows in the cusp and effectively cause the heating of suprathermal ions. The heating of suprathermal ions disagrees with anisotropic heating due to O+-O resonant charge exchange.
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- Armesto, N., et al.
(författare)
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Heavy-ion collisions at the LHC-Last call for predictions
- 2008
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:5, s. 054001-
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Forskningsöversikt (refereegranskat)abstract
- This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from 14th May to 10th June 2007.
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| 10. |
- Ogawa, Y., et al.
(författare)
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Characteristics of ion upflow and downflow observed with the European Incoherent Scatter Svalbard radar
- 2009
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 114:5, s. A05305-
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated how geomagnetic activity, the solar wind (SW), and the interplanetary magnetic field (IMF) influence the occurrence of the F-region/topside ionospheric ion upflow and downflow. Occurrence of dayside ion upflow observed with the European Incoherent Scatter Svalbard radar (ESR) at 75.2 degrees magnetic latitude is highly correlated with the SW density, as well as with the strength of the IMF By component. We suggest that this correlation exists because the region where ion upflow occurs is enlarged owing to SW density and IMF By magnitude, but it does not move significantly in geomagnetic latitude. The occurrence frequency of dayside ion upflow displays peaks versus the geomagnetic activity index (Kp), SW velocity, and negative IMF Bz component; that is, ion upflow is less frequently seen at the highest values of these parameters. Dayside ion downflow in the F-region/topside ionosphere occurs only when the Kp index and/or SW velocity are high or when IMF Bz is largely negative. The ion downflow is likely due to ballistic return of the ion upflow. We suggest that the region of ion upflow not only becomes larger but also moves equatorward with increasing Kp, SW velocity, and negative IMF Bz. The ESR can so be poleward of the upflow region and observe ions convecting poleward and returning ballistically downward.
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