Preparing for Heliopolarimetry using New-generation Ground-based Radio Telescopes

Coronal mass ejections (CMEs) are large-scale ejections of magnetized plasma from the Sun and are associated with the most extreme space weather events. The southward component of CME magnetic fields (CME-Bz) is one of the crucial parameters determining its geoeffectiveness. Recent studies have shown that CMEs evolve significantly in the innermost part of the heliosphere (∼ 20 - 90 R⊙), and relying on extrapolations from low coronal heights can lead to wrong predictions of CME-Bz in the vicinity of Earth. Hence, measuring CME magnetic fields at these heights is important to improve CME-Bz prediction. A promising method to measure the CME-entrained magnetic field in the larger coronal heights and the innermost heliosphere is by measuring the changes in Faraday rotation (FR) of linearly polarized emission from back-ground radio sources as their line-of-sight crosses the CME plasma. Here, we present the current preparation of new-generation ground-based radio telescopes for this purpose.