Modeling Differential Faraday Rotation in the Solar Corona

Faraday Rotation Methods to Detect Coronal Currents and MHD Wave Activity

“…the distance from the Sun to the proximate point along the LOS) and the location where the LOS intercepts the HCS, β c , but was rather insensitive to the small offset between the two LOS. Kooi & Kaplan [2020] also showed that the HCS accounted for up to 10 % − 20 % of the observed ∆RM reported by Spangler [2007] and that the small bias in DFR measurements detected on all three days reported in Spangler [2007] and Kooi et al [2014] was fully consistent with the expected contribution from the HCS. The most important conclusion reported in Kooi & Kaplan [2020], though, was that DFR can more accurately distinguish between coronal magnetic field models compared to standard, single-LOS FR observations alone at heliocentric distances < 5 R ⊙ .…”

“…Kooi & Kaplan [2020] also showed that the HCS accounted for up to 10 % − 20 % of the observed ∆RM reported by Spangler [2007] and that the small bias in DFR measurements detected on all three days reported in Spangler [2007] and Kooi et al [2014] was fully consistent with the expected contribution from the HCS. The most important conclusion reported in Kooi & Kaplan [2020], though, was that DFR can more accurately distinguish between coronal magnetic field models compared to standard, single-LOS FR observations alone at heliocentric distances < 5 R ⊙ . Consequently, future observations of DFR could provide a deeper understanding of the innerand middle-corona magnetic-field structure, where, e.g., the magnetic field structure evolves from closed loops to open field lines.…”

“…More recently, Kooi & Kaplan [2020] investigated the expected DFR associated with the largescale HCS and found that the HCS DFR depended strongly on the impact parameter (i.e. the distance from the Sun to the proximate point along the LOS) and the location where the LOS intercepts the HCS, β c , but was rather insensitive to the small offset between the two LOS.…”

How to Advance Studies of Coronal Faraday Rotation

“…FR could be observed over multiple (downlink) frequencies; 2. satellite constellations would provide multiple LOS, but with the added benefit of each LOS providing a much stronger signal than those typical for radio galaxies extended on the sky; 3. satellite constellations would provide multiple, closely-spaced LOS to detect electric currents using differential FR methods [e.g. Spangler 2007;Kooi et al 2014;Kooi & Kaplan 2020]. Constellations of multi-frequency satellites with linearly polarized transmitters could also be tracked by simpler radio telescopes or telescope networks on a regular basis.…”

Progressing Towards Faraday Rotation Tomography of the Solar Wind

“…Further, such spacecraft could be observed by multiple receiving stations (either current ground-based or future space-based); for n receiving stations located far enough apart (e.g. on opposite sides of the Earth), each spacecraft would provide n closely-spaced LOS suitable for measuring differential FR [Bird 2007], which provides information on the coronal electric currents enclosed between these LOS [Spangler 2007;Kooi & Kaplan 2020].…”