Liquid Lithium Flow Flow Tracking in LTX-β Tokamak*

The LTX-β tokamak liquid lithium utilization is now thick and clean enough to have macroscopic liquid behavior and appearance. One of its main benefits is its low recycling regime that can produce gradient-free temperature profiles aiding in the plasma's ability to maintain a hot edge, resulting in flattened electron temperature profiles from the pumping of hydrogenic elements. The lithium builds up from evaporation and flows up the tokamak's central wall. Using a fast capture camera, the flow was captured during a 50-60 millisecond shot length, which includes plasma breakdown, current ramp up, a short flat top, and plasma termination. The lithium flow up the center wall is observed to be very fast, with a toroidal field of 0.7 T, and a plasma current of 110-125 kA. However, the mechanism behind this lithium droplet motion remains unclear. Here we are developing an algorithm to identify and measure molten lithium flow velocity via video motion tracking. The algorithm conditions the input data and tracks brightness changes between frames. With more accurate velocity measurements, we hypothesized that JxB Lorentz force from local non ambi currents at the center wall reacting with a toroidal B-field is causing the fast-moving lithium. With this algorithm, we hope to confirm our hypothesis and provide a better understanding of liquid lithium movement in a tokamak environment. With the knowledge gained from LTX-β we can begin trying to understand how the forces will scale for future fusion pilot plants.