Electron acceleration in interaction of magnetic islands in large temporal-spatial turbulent magnetic reconnection

(整期优先)网络出版时间:2019-01-11
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AnewcombinedFermi,betatron,andturbulentelectronaccelerationmechanismisproposedininteractionofmagneticislandsduringturbulentmagneticreconnectionevolutioninexplosiveastrophysicalphenomenaatlargetemporal-spatialscale(LTSTMR),theratioofobservedcurrentsheetsthicknesstoelectroncharacteristiclength,electronLarmorradiusforlow-βandelectroninertiallengthforhigh-β,isontheorderof10^10–10^11;theratioofobservedevolutiontimetoelectrongyroperiodisontheorderof10^7–10^9).Theoriginalcombinedaccelerationmodelisknowntobeoneofgreatestimportanceintheinteractionofmagneticislands;itassumesthatthecontinuouskinetic-dynamictemporal-spatialscaleevolutionoccursastwoseparateindependentprocesses.Inthispaper,wereconsiderthecombinedaccelerationmechanismbyintroducingakinetic-dynamic-hydrofull-coupledmodelinsteadoftheoriginalmicro-kineticormacro-dynamicmodel.Weinvestigatedifferentaccelerationmechanismsinthevicinityofneutralpointsinmagneticislandsevolution,fromthestageofshrinkandbreakupintosmallerislands(kineticscale),tothestageofcoalescenceandgrowthintolargerislands(dynamicscale),tothestagesofconstantandquasi-constant(contracting-expanding)islands(hydroscale).Asaresult,wegiveforthefirsttimetheaccelerationefficienciesofdifferenttypesofaccelerationmechanismsinmagneticislands’interactionsinsolaratmosphereLTSTMRactivities(pico-,10^–2–10^5m;nano-,10^5–10^6m;micro-,10^6–10^7m;macro-,10^7–10^8m;large-,10^8–10^9m).