Density Diagnostics in Cavities: Incorporating and Bypassing Projection Effects

The highly ionized corona emits strongly in EUV atomic emission lines. Comparison of relative emission in various lines provides the temperature and density of the coronal plasma. We use an Fe XII line ratio to probe the density of a prominence cavity at heights generally only accessible to spectroscopic instruments. We take a novel approach in this diagnostic by fully accounting for the 3D structure of the corona so as to compensate for the projection effects in optical thin emission. The density inside the cavity and the streamer are constrained using a forward model where in emission is synthesized with CHIANTI. The synthetic emission and scattering is compared to Hinode/EIS and MLSO MKIV data. A least squares minimization is conducted using a genetic algorithm. In particular, this work addresses the degree to which we can answer the question, “Is there a density jump at all heights?”.