| In the adiabatic approximation,the magnetic moment of a particle is a constant.When particles move along the magnetic field lines from weak field region to strong field region,there is a force pointing to the weak field region.Therefore,some charged particles could be reflected,and the magnetic structure is called magnetic mirror.In the interplanetary space,fast solar wind could compress slow solar wind ahead,and strengthen the magnetic field to form a magnetic mirror.At the same time,the magnetic field structure near the sun is also a magnetic mirror,then two mirrors form a magnetic bottle in the interplanetary space.The reservoir phenomenon is that solar energetic particle fluxes observed by satellites at different latitudes,different longitudes and different distances are very close in the decay phase.Reames et al.attributed the formation of the reservoir phenomenon to the effect of a magnetic bottle.We calculate the focusing length of the magnetic mirror and compare it with the mean free path of solar energetic particles to study the effect of the interplanetary magnetic mirror.We selected two typical events,a Corotating Interaction Region(CIR)event in solar minimum July 2007 and an Interplanetary Coronal Mass Ejection(ICME)event in solar maximum July 2013.We use a Stream interaction model to fit the solar wind velocity and the magnetic field strength of CIRs and ICMEs,and use this magnetic field to calculate the focusing length compared with mean free path of particles to study the effect of magnetic mirror.Furthermore,the divergence of solar wind speed is calculated to study particle acceleration.We get the minimum values of the focusing length at different distances,and the divergence of solar wind speed along magnetic field line.Our conclusions are as follows: with a more intensely compression,(1)the scope of influence of the magnetic mirror is wider;(2)the effect of the mirror is stronger;(3)the acceleration efficiency is greater. |
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