Someone will correct me if I am wrong but that looks like half a hypocycloidal pinch device with a spiral. I have read the final NASA reports written by Dr. Lee. It formed two hot spots that were relatively long lived(that may not be a good thing). As I see it, it might be very hard to predict because you are combining the runup phase with the radial inward phase and that changes velocities, currents, forces, etc. In addition I don’t know that it will form the type of hot spot(collapsing plasmoid) that we all want. I think you are correct that filaments are essential for formation of a structure with the type of instabilities desired. It seems to me as complicated as the models are the only way to know is to build one and see. Anyone else?