Spline-based reconstruction of plasma boundary

Future fusion reactors will require a new method of reconstructing the plasma last closed flux surface (LCFS). A potential alternative is to develop a set of parameters that are used to create splines describing the plasma boundary. A fitting algorithm is then used to clean a set of noisy boundary location measurements and produce a realistic fit of the LCFS. On future devices, a control algorithm for the plasma shape and position can act upon these fitted parameters. Work is in progress to create a set of spline basis functions to reproduce the LCFS for different shapes, such as elongated limited or diverted configurations. Optimization of these functions to use the fewest fitting parameters will also help determine the minimum number of measurements required in each scenario. A fitting algorithm that uses existing boundary data and synthetic noise allows for the study of the limitations and potential trade-offs between expected uncertainty and number of measurements to the accuracy of the reconstructed boundary.