64 research outputs found
Superthermal electron energy interchange in the ionosphereâplasmasphere system
A selfâconsistent approach to superthermal electron (SE) transport along closed field lines in the inner magnetosphere is used to examine the concept of plasmaspheric transparency, magnetospheric trapping, and SE energy deposition to the thermal electrons. The dayside SE population is generated both by photoionization of the thermosphere and by secondary electron production from impact ionization when the photoelectrons collide with upper atmospheric neutral particles. It is shown that a selfâconsistent approach to this problem produces significant changes, in comparison with other approaches, in the SE energy exchange between the plasmasphere and the two magnetically conjugate ionospheres. In particular, plasmaspheric transparency can vary by a factor of two depending on the thermal plasma content along the field line and the illumination conditions of the two conjugate ionospheres. This variation in plasmaspheric transparency as a function of thermal plasma and ionospheric conditions increases with L âshell, as the field line gets longer and the equatorial pitch angle extent of the flyâthrough zone gets smaller. The inference drawn from these results is that such a selfâconsistent approach to SE transport and energy deposition should be included to ensure robustness in ionosphereâmagnetosphere modeling networks. Key Points A selfâconsistent approach alters the SE energy exchange in the IâP system Plasmaspheric transparency varies with the thermal plasma and illumination SE transport and energy dep should be included in MâI modeling networksPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97456/1/jgra50127.pd
Comparing the Dynamic Global Core Plasma Model (DGCPM) With Ground-Based Plasma Mass Density Observations
The MHD nature of ionospheric wave packets excited by the solar terminator
We obtained the first experimental evidence for the magnetohydrodynamic (MHD)
nature of ionospheric medium-scale travelling wave packets (MSTWP). We used
data on total electron content (TEC) measurements obtained at the dense
Japanese network GPS/GEONET (1220 stations) in 2008-2009. We found that the
diurnal, seasonal and spectral MSTWP characteristics are specified by the solar
terminator (ST) dynamics. MSTWPs are the chains of narrow-band TEC oscillations
with single packet's duration of about 1-2 hours and oscillation periods of
10-20 minutes. Their total duration is about 4--6 hours. The MSTWP spatial
structure is characterized by a high degree of anisotropy and coherence at the
distance of more than 10 wavelengths. The MSTWP direction of travelling is
characterized by a high directivity regardless of seasons. Occurrence rate of
daytime MSTWPs is high in winter and during equinoxes. Occurrence rate of
nighttime MSTIDs has its peak in summer. These features are consistent with
previous MS travelling ionosphere disturbance (TID) statistics obtained from
630-nm airglow imaging observations in Japan. In winter, MSTWPs in the northern
hemisphere are observed 3-4 hours after the morning ST passage. In summer,
MSTWPs are detected 1.5-2 hours before the evening ST occurrence at the point
of observations, at the moment of the evening ST passage in the
magneto-conjugate point. Both the high Q-factor of oscillatory system and
synchronization of MSTWP occurrence with the solar terminator passage at the
point of observations and in the magneto-conjugate area testify the MHD nature
of ST-excited MSTWP generation. The obtained results are the first experimental
evidence for the hypothesis of the ST-generated ion sound waves.Comment: 12 pages, 3 figure
Plasma Flow Crisis and the Limiting Electron Temperature in a Vacuum Arc in Axial Magnetic Field
Influence of the magnetic self-field on the formation of a cathode plasma jet in steady-state vacuum arcs
Heating of a current filament and formation of constrictions in a pulsed vacuum discharge
On the mechanism of the external magnetic field action on the electron temperature and ion charge state distribution in a vacuum arc plasma
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