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In this paper the architecture of the MHD control system for the Frascati Tokamak Upgrade (FTU) is presented. This control is aimed to stabilize tearing modes (TM) in the plasma by EC heating and current drive. TMs are detected and spatially localized by correlating several ECE channels and Mirnov coil signals; two independent antennas are steered in order to track the TM instability. To guarantee short locking time a fast real-time plasma equilibrium code is used to locate the instability when there is no TM evidence and real-time ray tracing code is used to estimate the location where EC power is deposited. A set of hardware consisting of FPGA and DSP modules on PXI bus for executing the diagnosis and control algorithms is proposed. The overall system layout is introduced together with a description of the data communication among the processors. [ABSTRACT FROM PUBLISHER]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: A new electron cyclotron (EC) antenna for real time control experiments on FTU tokamak has been tested at IFP-CNR laboratory. mm-Wave characterization was performed at the operating frequency of 140GHz with low power measurements, primarily to test the internal optics of the launcher in terms of focusing properties and beam directivity. The antenna is devoted to the injection of high power EC waves in different working configurations using a front steering setup. The beam direction is controlled with a fast mirror (steerable both toroidally and poloidally) and the available launching angles have been determined to fix the steering mirror working space. Beam dimension can also be controlled, using a sliding structure in the plug-in system, equipped with a focusing mirror that provides zooming capabilities. This paper contains results of low power tests performed on the antenna in order to characterize the launcher in its quasi-optical design. Beams are found to be slightly astigmatic (maximum ratio ) and with an expected beam radius in the plasma ranging from 18.6 to 26.0mm due to cited zooming effects. Additional beam patterns and linear scans of the launched mm-wave power for different injection angles have been measured, in some cases in realistic conditions (using a mock-up of the FTU port provided with metallic side-walls) to evaluate diffraction and beam truncation effects. [Copyright &y& Elsevier]