The determination of the coronal magnetic field

Abstract
Measurements of magnetic fields in the solar corona are needed to improve our understanding of structures, dynamics and heating of the corona and of the acceleration of the fast and slow modes of the solar wind expending into the heliosphere. However, those measurements are very difficult and still very scarce. I revue the main methods proposed to access the direction and the strength of the coronal magnetic field and discuss what seem the main avenues to improve its determination in the future.