The Polarization Ratio and PUNCH

The white-light polarization ratio (PR) obtained by PUNCH provides a useful tool for analyzing structures in the inner heliosphere. Given a simple line-of-sight electron number density, we derive closed form expressions for PR in the small-Sun limit. We discuss the polarization ratio in the infinite-feature approximation and show how it is related to the radial fall-off in solar wind density. We discuss the polarization ratio in the small-feature approximation and show how it is related to the location of a solar wind transient. Finally, we discuss the error introduced by using the small-feature approximation to locate a solar wind transient in 3D space.