A unified approach to plasma shape control with coil current allocation in magnetic confinement fusion

Shape control is crucial in plasma magnetic confinement due to its direct impact on fusion efficiency. Traditional controllers focus on minimizing plasma shape errors but often overlook other critical aspects, such as maintaining coil currents within operational limits. Neglecting these factors can lead to confinement loss or an inability to respond during emergency shutdowns. Previous studies have addressed these challenges using control allocation techniques, exploiting coil redundancy relative to the number of controlled shape outputs to optimize current requests without altering the plasma shape. This work introduces a novel unified approach by formulating the plasma shape control and the coil current allocation as a nonlinear optimal control problem, which is solved using a gradient descent algorithm. The effectiveness of this approach is evaluated through simulations conducted on the Tokamak à Configuration Variable (TCV) model and data.