Three-Dimensional Magnetohydrodynamic Simulation of Nonlinear Magnetic Buoyancy Instability of Flux Sheets with Magnetic Shear

Publications of the Astronomical Society of Japan

Nozawa, Satoshi¹ 

[1] Department of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512

关键词: instabilities;    "magnetohydrodynamics (MHD)";    plasmas;    "Sun: magnetic fields";   

DOI  :  10.1093/pasj/57.6.995

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Aseriesofthree-dimensionalmagnetohydrodynamicsimulationsisusedtostudythenonlinearevolutionofthemagneticbuoyancyinstabilityofamagneticfluxsheetwithmagneticshear.AhorizontalfluxsheetthatisinitiallyplacedbelowthesolarphotosphereissusceptibletoboththeinterchangeinstabilityandtheParkerinstability(theundularmodeofthemagneticbuoyancyinstability).Thegrowthrateinthelinearstageoftheinstabilityinthenumericalsimulationisconsistentwiththatpredictedbylineartheory.Inthenonlinearstage,thedevelopmentdependsontheinitialperturbationaswellastheinitialmagneticfieldconfiguration(i.e.,thepresenceofmagneticshear).Whenaninitialperturbationisassumedtobeperiodic,theemergingfluxrisestothecoronaandthemagneticfieldexpandslikeapotentialfield,asobservedin2Dsimulations.Whenaninitialnon-periodicperturbationorrandomperturbationsareassumed,themagneticfluxexpandshorizontallywhenthemagneticfieldemergesalittleintothephotosphere.Thedistributionofthemagneticfieldandgastendstobeinanewstateofmagnetohydrostaticequilibrium.Whenmagneticshearispresentintheinitialmagneticfluxsheets,theinterchangemodeisstabilizedsothattheemergingloopishigherthaninthenomagneticshearcase.WediscusshowthepresentedresultsarerelatedtotheemergingfluxobservedontheSun.

【 授权许可】

Unknown