Slow shock and rotational discontinuity in MHD and Hall MHD models with anisotropic pressure

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Title:	Slow shock and rotational discontinuity in MHD and Hall MHD models with anisotropic pressure
Authors:	郝玲妮;Hau, L.‐N.;Wang, B.‐J.
Contributors:	地球科學學院太空科學與工程學系
Keywords:	Anisotropy;Cauchy problems;Current sheets;Density;Discontinuity;Handedness;Magnetic fields;Magnetic reconnection;Magnetohydrodynamic waves;Magnetohydrodynamics;Mathematical analysis;Mathematical models;MHD;MHD and Hall MHD;nonlinear waves;Polarization;pressure anisotropy;Riemann problem;shock and discontinuity;Space plasmas;Wave packets
Date:	2016-07-01
Issue Date:	2026-04-23 11:06:01 (UTC+8)
Publisher:	Wiley-Blackwell;Washington: Blackwell Publishing Ltd
Abstract:	摘要： Pressure anisotropy may modify the characteristics of magnetohydrodynamic (MHD) waves, in particular, the slow mode wave and the corresponding shocks and discontinuities. In this study the formation of slow shocks (SSs) in anisotropic plasmas is examined by solving the gyrotropic MHD and Hall MHD equations numerically for one‐dimensional Riemann problem. The MHD shocks and discontinuities are generated by imposing a finite normal magnetic field on the Harris type current sheet with a guide magnetic By component. It is shown that anomalous SSs moving faster than the intermediate wave or with positive density‐magnetic field correlation may be generated in gyrotropic MHD and Hall MHD models. Moreover, for some parameter values SSs may exhibit upstream wave trains with right‐handed polarization in contrast with the earlier prediction that SSs shall possess downstream left‐hand polarized wave trains based on the isotropic Hall MHD theory. For the cases of By ≠ 0, SSs with increased density and decreased magnetic field followed by noncoplanar intermediate mode or rotational discontinuity (RD)‐like structures similar to the compound SS‐RD structures observed in space plasma environments may possibly form in symmetric and asymmetric current layers. The Walén relation of these anomalous RDs without the correction of pressure anisotropy may significantly be violated. Key Points The paper reports original and new results on anisotropic shocks based on MHD and Hall MHD models Significant theoretical frameworks on the MHD shocks and discontinuities in anisotropic plasmas have been developed for the first time Anomalous structures are derived and the results have important applications for magnetic reconnection and space plasma observation 出版者： Washington: Blackwell Publishing Ltd 出版日期： 2016-07 出處： Journal of geophysical research : Space physics (2013 - Present), 2016-07, Vol.121 (7), p.6245-6261 資源來源： Wiley Online Library - AutoHoldings Journals 版權： 2016. The Authors. 版權： 2016. American Geophysical Union. All Rights Reserved. 識別號： ISSN: 2169-9380 識別號： ISSN: 2169-9402 識別號： EISSN: 2169-9402 識別號： DOI: 10.1002/2016JA022722
Appears in Collections:	[太空科學與工程學系] 期刊論文

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