7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Magnetic reconnection driven by merging of magnetic flux
ropes/tubes in space plasma turbulence
Abraham C.-L. Chian1,2, Rodrigo A. Miranda3 and Erico L. Rempel1,4National Institute for Space Research (INPE), São José dos Campos-SP 12227-010, Brazil
2
School of Computer and Mathematical Sciences, University of Adelaide, Adelaide, SA 5005,
Australia
3UnB-Gama Campus and Institute of Physics, University of Brasília, Brasília, DF 70910-900,
Brazil4Aeronautics Institute of Technology (ITA), São José dos Campos, Sao Paulo 12228-900, Brazil
e-mail (speaker): abraham.chian@gmail.com
1

The interaction of coherent structures such as
magnetic flux ropes/tubes and current sheets can lead tothe generation of turbulence in cosmic and laboratory
plasmas. Magnetic reconnection and magnetic merging
involving the interaction of magnetic flux ropes/tubes
plays a key role in space plasma turbulence, e.g., in solar
wind and in solar photosphere.
The interplanetary medium is a natural laboratory forprobing the link between magnetic reconnection andturbulence. Recently there has been a growing interest in
the study of the interaction of multiple magnetic flux
ropes/tubes in plasmas and multiple coronal massejections in space and astrophysics. We report theobservation of magnetic reconnection at the interface
region of two interplanetary magnetic flux ropes (Chian etal. 2016, 2022). Our analysis is based on in situ data ofACE, Wind, and Cluster on 2002 February 1-2 when ACE
and Wind were located in the vicinity of the L1 point andCluster was upstream of the Earth’s bow shock. During
this interval, the front and rear boundary layers of threeinterplanetary magnetic flux ropes are identified.
Evidence of magnetic reconnection between two magnetic
flux ropes and the associated bifurcated current sheet isobtained. The structures of magnetic flux ropes arereconstructed by the Grad-Shafranov method. The
relation between current sheet, magnetic reconnection,
dynamic pressure pulse and turbulence in the region ofrope-rope magnetic reconnection is investigated. A
quantitative analysis of the reconnection condition and thedegree of intermittency by comparing kurtosis, phasecoherence index, and scaling exponent of five different
regions in this triple magnetic flux rope event reveals thatrope-rope magnetic reconnection is the most likely site forgenesis of interplanetary intermittency turbulence in thisevent, as confirmed by the kurtosis-skewness andcomplexity-entropy relations (Miranda et al. 2018, 2021).
The dynamic pressure pulse resulting from this magnetic
reconnection triggers the onset of a geomagnetic storm.
Our results render support for recent studies showing that
turbulence can be self-generated by magnetic
reconnection resulting from the instability of a current
sheet.

The network magnetic fields at solar supergranularjunctions are organized into predominantly verticalkilogauss flux tubes and form patches of intense magnetic
flux concentrations that can persist for hours and evendays. Magnetic switchbacks observed by Parker Solar
Probe in the near-Sun solar wind may be driven byinterchange magnetic reconnection events, with thefootpoints of merging closed and open magnetic flux
ropes rooted at supergranular junctions, just above thesolar transition region and the spacecraft measurements
represent the extended regions of a turbulent outflow ofmagnetic reconnection exhaust. Switchbacks are likely
formed in the low corona and modulated by the solar
surface convection patterns of supergranulation andgranulation; the large scales detected for switchback
patches are compatible with supergranulation scales andthe smaller scales are compatible with granulation scales.
We study the spatiotemporal dynamics of vorticity andmagnetic field in the region of a persistent photosphericvortex at a supergranular junction of the quiet Sun using
Hinode observation on 2010 November 2 by showing thatin a 30-min interval during the vortex lifetime, themagnetic field is intensified at the centers of two merging
magnetic flux tubes trapped inside the vortex boundary(Chian et al. 2023; Rempel et al. 2023). Moreover, weshow that the electric current density is intensified at theinterface boundary boundary layers of merging tubes,
resulting from strong vortical downflows in asupergranular vertex. Evidence of Lagrangian chaos andvortex stretching in the photospheric plasma turbulence
responsible for driving the intensification of magnetic
fields is analyzed. In particular, we report the first solar
observation of the intensification of electromagnetic
energy flux resulting from the merger of magnetic flux
tubes.
References[1] A. C.-L. Chian et al., Astrophys. J. 783, 517 (2016)[2] A. C.-L. Chian et al., RMPP 6, 34 (2022)[3] A. C.-L. Chian et al., MNRAS 518, 4930 (2023)[4] R. A. Miranda et al., Ann. Geophys. 36, 497 (2018)[5] R. A. Miranda et al., Astrophys. J. 923, 132 (2021)[6] E. L. Rempel et al., RMPP, submitted (2023)