scholarly journals Theory of azimuthally small-scale Alfvén waves in an axisymmetric magnetosphere with small but finite plasma pressure

2002 ◽  
Vol 107 (A11) ◽  
Author(s):  
Pavel N. Mager
Keyword(s):  
Alfven Waves ◽  
Plasma Pressure ◽  
Alfvén Waves ◽  
Small Scale

scholarly journals Parallel electric field in the auroral ionosphere: excitation of acoustic waves by Alfvén waves

2004 ◽  
Vol 22 (8) ◽  
pp. 2797-2804 ◽  
Author(s):  
P. L. Israelevich ◽  
L. Ofman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Acoustic Waves ◽  
Finite Amplitude ◽  
Alfven Waves ◽  
Plasma Pressure ◽  
Alfvén Waves ◽  
Small Scale ◽  
Auroral Ionosphere ◽  
Parallel Electric Field

Abstract. We investigate a new mechanism for the formation of a parallel electric field observed in the auroral ionosphere. For this purpose, the excitation of acoustic waves by propagating Alfvén waves was studied numerically. We find that the magnetic pressure perturbation due to finite amplitude Alfvén waves causes the perturbation of the plasma pressure that propagates in the form of acoustic waves, and gives rise to a parallel electric field. This mechanism explains the observations of the strong parallel electric field in the small-scale electromagnetic perturbations of the auroral ionosphere. For the cases when the parallel electric current in the small-scale auroral perturbations is so strong that the velocity of current carriers exceeds the threshold of the ion sound instability, the excited ion acoustic waves may account for the parallel electric fields as strong as tens of mV/m.

SMALL-SCALE SOLAR WIND TURBULENCE DUE TO NONLINEAR ALFVÉN WAVES

2015 ◽  
Vol 812 (1) ◽  
pp. 69 ◽  
Author(s):  
Sanjay Kumar ◽  
R. P. Sharma ◽  
Y.-J. Moon
Keyword(s):  
Solar Wind ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Small Scale ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

On the propagation of transversally small-scale standing Alfven waves in a three-dimensionally inhomogeneous magnetosphere

1995 ◽  
Vol 100 (A6) ◽  
pp. 9527 ◽  
Author(s):  
Dmitrii Yu. Klimushkin ◽  
Anatolii S. Leonovich ◽  
Vitalii A. Mazur
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Small Scale

Streamers generation by small-scale drift-Alfvén waves

2014 ◽  
Vol 21 (10) ◽  
pp. 102302
Author(s):  
J. S. Zhao ◽  
M. Y. Yu
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Small Scale

Small scale structures in the footprint tails of the Galilean moons observed by JIRAM

2021 ◽  
Author(s):  
Alessandro Moirano ◽  
Alessandro Mura ◽  
Alberto Adriani ◽  
Roberto Sordini ◽  
Alessandra Migliorini ◽  
...  
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Small Scale ◽  
Potential Candidate ◽  
Orbital Parameters ◽  
Auroral Emission ◽  
Galilean Moons ◽  
Order Of Magnitude ◽  
Scale Structures ◽  
Small Scale Structures

<p>The Jovian Infrared Auroral Mapper (JIRAM) on board Juno is a spectro-imager which is observing the<br>atmosphere of Jupiter and its auroral emission using its two imagers in the L (3.3-3.6μm) and M bands (4.5-<br>5.0μm) and a spectrometer (2-5 μm spectral range).<br>The highly elliptic orbit of Juno and the unprecedented resolution of the JIRAM imager allowed to retrieve<br>wealth of details about the morphology of moon-related aurorae. This phenomenon is due to the jovian magnetic<br>field sweeping past the Galiean moons, which generate Alfven waves travelling towards the ionosphere and set<br>up field aligned currents. When the associated electrons reach the ionosphere, they interact with the hydrogen<br>and make it to glow. In particular, the tails of the footprints showed a spot-like substructure consistently, which<br>were investigated using the L-band of the imager from perijove 4 to perijove 30. This feature was observed close<br>to the footprints, where the the typical distance between spots lies between 250km and 500km. This distance<br>decreases to 150km in a group of three observations in the northern emisphere when each moon is close to 250 ◦<br>west longitude. No correlation with orbital parameters such as the longitude of the moons was found so far,<br>which suggests that such morphology is almost purely due to ionospheric processes.<br>Moreover, during PJ 13 a long sequence of images of the Io footprint was shot and it revealed that the<br>secondary spots appears to corotate with Jupiter. This behaviour is observed also during orbits 14 and 26.<br>During these sequences JIRAM clearly observed the Io footprint leaving behind a trail of ”footsteps” as bright<br>spots.<br>The characteristics of these spots are incompatible with multiple reflection of Alfven waves between the two<br>emispheres. Instead, we are currently investigating ionospheric processes like the feedback instability (FI) as a<br>potential candidate to explain the generation of the observed small scale structure. This process relies on local<br>enhacement of conductivity in the ionosphere, which is affected by electron precipitation. Order of magnitude<br>estimates from the FI are compatible with the inter-spot distance and the stillness of the spots.</p>

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