80 research outputs found
Signatures of Secondary Collisionless Magnetic Reconnection Driven by Kink Instability of a Flux Rope
The kinetic features of secondary magnetic reconnection in a single flux rope
undergoing internal kink instability are studied by means of three-dimensional
Particle-in-Cell simulations. Several signatures of secondary magnetic
reconnection are identified in the plane perpendicular to the flux rope: a
quadrupolar electron and ion density structure and a bipolar Hall magnetic
field develop in proximity of the reconnection region. The most intense
electric fields form perpendicularly to the local magnetic field, and a
reconnection electric field is identified in the plane perpendicular to the
flux rope. An electron current develops along the reconnection line in the
opposite direction of the electron current supporting the flux rope magnetic
field structure. Along the reconnection line, several bipolar structures of the
electric field parallel to the magnetic field occur making the magnetic
reconnection region turbulent. The reported signatures of secondary magnetic
reconnection can help to localize magnetic reconnection events in space,
astrophysical and fusion plasmas
Current driven rotating kink mode in a plasma column with a non-line-tied free end
First experimental measurements are presented for the kink instability in a
linear plasma column which is insulated from an axial boundary by finite sheath
resistivity. Instability threshold below the classical Kruskal-Shafranov
threshold, axially asymmetric mode structure and rotation are observed. These
are accurately reproduced by a recent kink theory, which includes axial plasma
flow and one end of the plasma column that is free to move due to a
non-line-tied boundary condition.Comment: 4 pages, 6 figure
Observation of An Evolving Magnetic Flux Rope Prior To and During A Solar Eruption
Explosive energy release is a common phenomenon occurring in magnetized
plasma systems ranging from laboratories, Earth's magnetosphere, the solar
corona and astrophysical environments. Its physical explanation is usually
attributed to magnetic reconnection in a thin current sheet. Here we report the
important role of magnetic flux rope structure, a volumetric current channel,
in producing explosive events. The flux rope is observed as a hot channel prior
to and during a solar eruption from the Atmospheric Imaging Assembly (AIA)
telescope on board the Solar Dynamic Observatory (SDO). It initially appears as
a twisted and writhed sigmoidal structure with a temperature as high as 10 MK
and then transforms toward a semi-circular shape during a slow rise phase,
which is followed by fast acceleration and onset of a flare. The observations
suggest that the instability of the magnetic flux rope trigger the eruption,
thus making a major addition to the traditional magnetic-reconnection paradigm.Comment: 13 pages, 3 figure
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