Dynamic tests on the new front-steering ECH&CD launcher for FTU

The new Electron Cyclotron Resonance Heating and Current Drive launcher for real-time control experiments on FTU consists of two antennas with front fast-steering mirrors, aiming to test new strategies for MHD stabilization and plasma heating. The description and experimental identification of the mirror dynamics, for the design of both an optimized position controller and a model predictive protection system, are the main objectives of this paper. Each mirror is steered by a couple of AC brushless motors for toroidal and poloidal movements and each motor is controlled by a drive with embedded PI speed and torque controllers. A position controller, based on plasma feedback, is realized externally with a set of hardware and software also described in this paper. Several tests have been carried out to evaluate the system dynamic performance compared with the target specifications and to identify a state-space model of the mechanical system to be used for a model predictive protection, whose aim is to avoid that the mirror goes out of the workspace boundaries.