Elusive Upper Hybrid Waves in the Auroral Topside Ionosphere

Author(s):  
Robert F. Benson
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paola De Michelis ◽  
Giuseppe Consolini ◽  
Alessio Pignalberi ◽  
Roberta Tozzi ◽  
Igino Coco ◽  
...  

AbstractThe present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE < 50 nT) and active (AE > 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude—magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy.


The instruments which measure electron density and temperature are quite separate and independent in operation, but on account of the limitations in power supply and telemetry data rate the two experiments share the same power lines and some data channels.


1981 ◽  
Vol 26 (2) ◽  
pp. 359-367 ◽  
Author(s):  
M. Y. Yu ◽  
P. K. Shukla ◽  
H. U. Rahman

Nonlinear excitation of electrostatic and magnetostatic zero-frequency modes by finite-amplitude lower-hybrid waves is considered. It is found that modulational instabilities can give rise to enhanced plasma vortices. Dispersion relations, as well as analytical expressions for the growth rates, are obtained. The enhanced vortices may cause anomalous cross-field diffusion which can affect plasma confinement in tokamak devices when lower-hybrid waves are used for plasma heating or current drive. We found that magnetic fluctuations associated with the parametrically driven magnetostatic mode are of particular importance in tokamak plasmas.


1988 ◽  
Vol 38 (1) ◽  
pp. 64-65
Author(s):  
V I Berezhiani ◽  
S D Pichkhadze ◽  
P K Shukla

2020 ◽  
Author(s):  
Binbin Tang ◽  
Wenya Li ◽  
Daniel Bruce Graham ◽  
Chi Wang ◽  
Yuri V. Khotyaintsev ◽  
...  

1986 ◽  
Vol 26 (8) ◽  
pp. 1106-1111 ◽  
Author(s):  
R. Bartiromo ◽  
M. Hesse ◽  
F.X. Söldner ◽  
R. Burhenn ◽  
G. Fussmann ◽  
...  

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