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A New Mechanism for the Field Line Twisting in the Ionospheric Magnetic Flux Rope
Author(s) -
Xie Lianghai,
Lee LouChuang
Publication year - 2019
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja026621
Subject(s) - physics , ionosphere , magnetic flux , magnetic field , rope , dynamo , magnetic reconnection , flux (metallurgy) , magnetic energy , flux tube , azimuth , geophysics , computational physics , magnetization , optics , materials science , structural engineering , quantum mechanics , engineering , metallurgy
Magnetic flux ropes (MFRs) with twisted magnetic field lines are common in the solar system, most of which can be caused by magnetic reconnection or velocity shear. However, these two mechanisms have difficulties in explaining the formation of MFRs observed in the planetary ionosphere. Here we find that a dynamo process can be caused by the differential compression at different parts of a flux tube when it is sinking into the partially ionized ionosphere, leading to an increase in the magnetic energy. The differential compression also produces an azimuthal component of ▽× E , which generates azimuthal magnetic fields with twisted magnetic field lines and gives rise to an ionospheric MFR.