Data analysis of wave propagation and boundary interactions in the ion cyclotron range of frequencies at LaPD

Plasma heating using waves in the ion cyclotron range of frequencies is common in fusion experiments but frequently causes an unacceptable rise in metallic impurities. This is attributed to RF rectification, a nonlinear sheath phenomenon that can increase both electron current and plasma voltage across the sheath. Experiments to study this phenomenon have been performed at the Large Plasma Device located at UCLA using a single-strap antenna with about 100 kW of power and include measurements from floating and emissive probes. We develop Python code to visualize the spatially-dense two-dimensional data sets to resolve differences in the rectified response between the field lines connecting to the antenna at low plasma densities (below 1e18 m^-3) and field lines with longer connection lengths (of order 10 m) in a denser plasma (around 5e18 m^-3). This will help determine the penetration depth of the rectified effects into the central plasma and how their nature changes at different densities and magnetic-connection lengths.