MAGNETIC FIELD EXTRAPOLATION

摘要

Detailed knowledge of the structure of the magnetic fieldrnis crucially important for gaining a better understandingrnof the physical phenomena occurring in the solar atmo-sphere,rnin particular the corona. Despite the progressrnmade in developing methods for the direct measurementrnof the coronal magnetic field, magnetic field extrapola-tionrnmethods are still indispensable for obtaining esti-matesrnof the coronal field structure. In this paper I willrntry to give an overview of the different magnetic field ex-trapolationrnmethods, which have been proposed, focusingrnon theoretical aspects. I will also try to highlight some ofrnthe difficulties that magnetic field extrapolation methodsrnface.