Generation of shock/discontinuity compound structures through magnetic reconnection in the geomagnetic tail

Weng, C. J.; Lin, C. C.; Lee, L. C.; Chao, J. K.

doi:10.1063/1.4772782

“…However, it is rare for the formation of the Petschektype slow shock to be detected in current sheets by in-situ observations. 13,14 Furthermore, the recent advances in computational power have enabled particle-in-cell and hybrid simulations of collisionless plasmas, [15][16][17][18] but the results do not provide clear evidence for the formation of the slow shock. It is thought that the absence of shocks in kinetic simulations might be caused by the smallness of the simulation box or by the pressure anisotropy due to the PSBL (plasma sheet boundary layer) ion beams accelerated along the magnetic field lines from the diffusion region.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Reconnection under Anisotropic MHD Approximation

Hirabayashi,

Hoshino

2013

Preprint

0

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We study the formation of slow-mode shocks in collisionless magnetic reconnection by using one-and two-dimensional collisionless MHD codes based on the double adiabatic approximation and the Landau closure model. We bridge the gap between the Petschek-type MHD reconnection model accompanied by a pair of slow shocks and the observational evidence of the rare occasion of in-situ slow shock observations. Our results showed that once magnetic reconnection takes place, a firehose-sense (p || > p ⊥ ) pressure anisotropy arises in the downstream region, and the generated slow shocks are quite weak comparing with those in an isotropic MHD. In spite of the weakness of the shocks, however, the resultant reconnection rate is 10 − 30% higher than that in an isotropic case. This result implies that the slow shock does not necessarily play an important role in the energy conversion in the reconnection system, and is consistent with the satellite observation in the Earth's magnetosphere.

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“…However, it is rare for the formation of the Petschektype slow shock to be detected in current sheets by in-situ observations. 13,14 Furthermore, the recent advances in computational power have enabled particle-in-cell and hybrid simulations of collisionless plasmas, [15][16][17][18] but the results do not provide clear evidence for the formation of the slow shock. It is thought that the absence of shocks in kinetic simulations might be caused by the smallness of the simulation box or by the pressure anisotropy due to the PSBL (plasma sheet boundary layer) ion beams accelerated along the magnetic field lines from the diffusion region.…”

mentioning

confidence: 99%

Magnetic reconnection under anisotropic magnetohydrodynamic approximation

Hirabayashi

¹

,

Hoshino

²

2013

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We study the formation of slow-mode shocks in collisionless magnetic reconnection by using one-and two-dimensional collisionless MHD codes based on the double adiabatic approximation and the Landau closure model. We bridge the gap between the Petschek-type MHD reconnection model accompanied by a pair of slow shocks and the observational evidence of the rare occasion of in-situ slow shock observations.Our results showed that once magnetic reconnection takes place, a firehose-sense (p || > p ⊥ ) pressure anisotropy arises in the downstream region, and the generated slow shocks are quite weak comparing with those in an isotropic MHD. In spite of the weakness of the shocks, however, the resultant reconnection rate is 10 − 30% higher than that in an isotropic case. This result implies that the slow shock does not necessarily play an important role in the energy conversion in the reconnection system, and is consistent with the satellite observation in the Earth's magnetosphere.PACS numbers: 94.05.-a,

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