A Comparison of SuperDARN-Derived Plasma Convection and DMSP Ion Drift Measurements

Recently several studies indicated possible deterioration of accuracy in the SuperDARN convection measurements at large distances （〉2 500 km）. In this study, the SuperDARN-derived convection was compared with ion drift measurements given by the DMSP satellites, focused on SuperDARN far-range measurements, to investigate the above-mentioned problem. Two different procedures of SuperDARN convection estimation were applied. An overall reasonable agreement between two observation systems were found though individual points in some passes show significant differences. Besides, a tendency is also clear that the SuperDARN-derived velocities were slightly smaller than those of DMSP ion drift measurements. Potential factors contributing to the velocity differences were explained.

Interfacial phenomena in electric field-assisted anodic bonding of Kovar/Al film-glass

Anodic bonding of glass to Kovar alloy coated with Al film (Glass Al film/Kovar) was performed in the temperature range of 513 ～ 713?K under the static electric voltage of 500?V in order to investigate the interfacial phenomena of Al glass joint. The results reveal that Na and K ions within the glass are displaced by the applied field from the anode side surface of the glass to form depletion layers of them. The K ion depletion layer is narrow and followed by a K pile up layer, and both the two layers are formed within the Na depletion layer. The width of the Na and K depletion layers is increased with increasing bonding temperature and time. The activation energies for the growth of both depletion layers were close to that for Na diffusion in the glass. TEM observations reveal that Al film coated at the surface of Kovar alloy is oxidized to amorphous Al 2O 3 containing a few of Fe, Ni and Co by oxygen ions from the glass drifted by high electric field during bonding. The amount of Fe ions diffusing into the glass adjacent to the anode is significantly low due to the presence of Al film between Kovar alloy and the glass. As a result, the amorphous reaction layer of Fe Si O in the glass near the interface is avoided which is formed in Kovar glass joints.

Plasmaspheric trough evolution under different conditions of subauroral ion drift

The statistical characteristics of the subauroral ion drift (SAID) in the ionosphere and the plasmaspheric trough evolution under different conditions of SAID were investigated in this paper, based on 566 SAID events observed by Akebono, Astrid-2, DE-2, and Freja satellites. The relationships between the latitudinal location of SAID and the Kp, AL, and Dst indices for these events were also discussed. It was found that the SAID events happened mainly at invariant latitude (ILAT) of 60.4° and magnetic local time (MLT) of 21.6 MLT and that 92.4% of the events happened when the Kp index was below 5.0, indicating a medium geomagnetic activity. The latitudinal half-width of SAID varied from 0.5° to 3.0° with a typical half-width of 1.0°. The SAID would happen at low latitudes if the geomagnetic activity was high. The effects of SAID on equatorial outer plas- masphere trough evolutions were studied with the dynamic global core plasma model (DGCPM) driven by the statistical results of SAID signatures. It was noted that locations, shapes and density of troughs vary with ILAT, MLT, latitudinal width, cross polar cap potential and lifetime of SAID events. The evolution of a trough is determined by the extent of SAID electric field penetrating into plasmasphere and not all SAID events can result in trough formations.

Effect of temporal variation rate of cross polar cap potential on the equatorial ionospheric vertical drift: A statistical study

Based on the equatorial vertical ion drift measured by DMSP and cross polar cap potential （Фcpc） from AMIE output during 2001 to 2003, this paper investigates the relationship of Фcpc and its temporal variation rate （△Фcpc） with the disturbed ion velocity （△Vx） which is the difference between the disturbed days （Kp〉4） and quiet days （Kp〈2）. The statistical analysis shows： （1） The △Vx correlates better with AФcpc than with Фcpc, indicating that the electric field penetration is more easily to occur when solar wind input rapidly varies with time. （2） The optimal delay time of electric field penetration from the high-latitude magnetosphere to equatorial ionosphere has local time dependence which is longer on the nightside than on the dayside. It may be due to more complicated electrodynamic process on the nightside. （3） With the linear relationship between △Фcpc and △Vx, it is obtained that the penetration efficiency is about 4.5%-13.9% at day and 31%-42% at night, coinciding well with former studies.

An experimental research on the instability of ion acoustic wave with electron drift

As electron temperature Te is much higher than ion temperature Ti, and electron driftspeed Vd is larger than the critical value Vdc of Vd, the ω=KVφ mode ion acoustic wave（IAW） will be instable. Under a long wave condition （KλD【【1, where λD is Deby length,K is weve number）, the growing rate γ（K） of the IAW may be written