Surrogate Model of Electron Cyclotron Heating and Current Drive in a Compact Advanced Tokamak

The complex and iterative nature of plasma scenario optimization in fusion devices necessitates the use of reduced models in early stages of the design process to filter through a large parameter space in an efficient manner. Ray-tracing codes, such as TORAY, offer considerable advantages in run time for electron cyclotron (EC) heating and current drive (H/CD) cases over full-wave codes while maintaining a high degree of fidelity. We deploy the Fusion Reactor Design and Assessment (FREDA)–TokDesigner workflow to enable training of a surrogate model for EC H/CD radial profiles based on the TORAY ray-tracing code, coupled to the Integrated Plasma Simulator (IPS)–FASTRAN framework. The surrogate model is trained to predict key H/CD profile characteristics for EC cases based on a subset of plasma and EC launcher parameters for a Compact Advanced Tokamak (CAT) design point. The CAT was selected as a baseline to assess the performance of the surrogate model trained in the fusion pilot plant regime. The surrogate model is able to accomplish this an order of magnitude faster than TORAY coupled to IPS-FASTRAN while still maintaining a high level of accuracy. The surrogate model demonstrates invertibility, being able to solve the inverse problem to generate an accurate parameter space for a set of desired H/CD profile characteristics.