Plasma Position and Elongation Regulation at FTU Using Dynamic Input Allocation

In this paper we employ and extend the dynamic allocation theory first presented in [1] to guarantee asymptotic tracking of a prescribed plasma elongation on the Frascati Tokamak Upgrade (FTU). This task is hard to accomplish because it can only be achieved using the so-called F poloidal coil, a high bandwidth actuator needed to perform high performance horizontal plasma position regulation. Another actuator, the V poloidal coil, is available for horizontal position regulation but its bandwidth is insufficient to suitably perform the horizontal position regulation task. Via the dynamic allocation technique it is possible to hyerarchically achieve the two goals using the two actuators: the high priority (fast) goal is the horizontal position regulation task, while the low priority (slow) goal is the elongation regulation. We present theoretical results supporting the proposed scheme, as well as simulations and experiments showing the effectiveness of the proposed solution.