Research On New Method Of Extrapolation Of Coronal Magnetic Field

The various violent eruptive activities occurring in the solar corona are the main driving sources of space weather in the sun and earth.Studying these activities and their effects on geospatial activities is an important part of space physics research.Because of the low plasma beta characteristics in the coronal environment,the essence of explosive activity is the expression of the unstable and violent release of magnetic energy in the coronal magnetic field system.However,the direct measurement of the coronal magnetic field can not be achieved.At present,the magnetic field extrapolation method is widely used in the research,even using the photosphere vector magnetogram as the bottom boundary condition to solve the numerical model,so as to obtain the three-dimensional magnetic field of the corona.There are many methods for extrapolation of coronal magnetic field.However,there are some problems in various methods,such as unclear physical meaning,slow solving speed,and so on.At the same time,all methods can not completely reconstruct the highly complex coronal magnetic structure in reality.In this paper,two new algorithms for solving the coronal magnetic field have been developed on the basis of predecessors.The first one is the relaxation method based on Newtonian viscous fluid,and the second one is the Grad-Rubin fast iteration method of current and magnetic field.Several typical examples of coronal magnetic field extrapolation are tested strictly in this paper,and good results are obtained,which prove the feasibility of the two methods.Based on these works,it is expected that a new method of extrapolation of the global coronal magnetic field with higher accuracy and larger computational domain will be developed in the future.