Coalescence of magnetic flux ropes in the ion diffusion region of magnetic reconnection

• Published in: Nature physics 2016-03, Vol.12 (3), p.263-267
• Main Authors: Wang, Rongsheng, Lu, Quanming, Nakamura, Rumi, Huang, Can, Du, Aimin, Guo, Fan, Teh, Waileong, Wu, Mingyu, Lu, San, Wang, Shui
• Format: Article
• Language: English
• Subjects: 639/33/525/869; 639/766/1960/1134; 639/766/525/869; Atomic; Classical and Continuum Physics; Coalescence; Coalescing; Complex Systems; Condensed Matter Physics; Current sheets; Diffusion; Fluctuations; Kinetic energy; Kinetics; letter; Magnetic fields; Magnetic flux; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Physics; Plasma; Plasmas; Theoretical; Turbulence
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys3578

Merging magnetic flux ropes, which are believed to play an important role in magnetic reconnection, have now been clearly identified. Observations show that coalescence is indeed closely related to reconnection dynamics and also to turbulence. Magnetic reconnection is an important process in space 1 , 2 , 3 , 4 , 5 and laboratory 6 plasmas that effectively converts magnetic energy into plasma kinetic energy within a current sheet. Theoretical work 7 suggested that reconnection occurs through the growth and overlap of magnetic flux ropes that deconstruct magnetic surfaces in the current sheet and enable the diffusion of the magnetic field lines between two sides of the sheet. This scenario was also proposed as a primary mechanism for accelerating energetic particles during reconnection 8 , but experimental evidence has remained elusive. Here, we identify a total of 19 flux ropes during reconnection in the magnetotail. We found that the majority of the ropes are embedded in the Hall magnetic field region and 63% of them are coalescing. These observations show that the diffusion region is filled with flux ropes and that their interaction is intrinsic to the reconnection dynamics, leading to turbulence.