Impact of 3D error fields on toroidal asymmetries and consequent erosion, deposition patterns on the divertor in DIII-D*

We present analysis from a set of DIII-D L-mode discharges with externally applied 3D magnetic fields to explore how toroidally asymmetric striations observed at the divertor target change as different error field compensation recipes are applied. The DiMES sample exposure station is critical to diagnosing plasma material interactions (PMI) across many different experiments in DIII-D. Such diagnosis banks on modeling edge plasma in the Scrape-Off Layer (SOL) to interpret plasma diagnostic data. However, to reduce a 3D problem to 2D to save computational complexity, modeling PMI in the SOL often assumes toroidal symmetry. Toroidally asymmetric striations, likely from uncompensated error fields, are often observed close to the walls in the SOL. DIII-D is equipped with coils that are routinely used to compensate for low-n global modes in the core (I & C coils), but lead to mode structure which cause striations that were monitored using the DiMES TV camera, viewing the divertor around the DiMES head location. Fast camera was also used to monitor striations. Since the fast camera and DiMES TV field of view are toroidally separated by around 90 degrees, the position and strength of the striations is monitored simultaneously as the I & C coils are tuned. Details of the analysis will be presented along with compensation recipes that minimizes striations around the DiMES head.