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

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.

[1]  H. Zohm,et al.  Cross–machine benchmarking for ITER of neoclassical tearing mode stabilization by electron cyclotron current drive , 2006 .

[2]  G. Gantenbein,et al.  Control of MHD instabilities by ECCD: ASDEX Upgrade results and implications for ITER , 2007 .

[3]  T. T. Suzuki,et al.  Stabilization of neoclassical tearing modes by electron cyclotron current drive in JT-60U , 2007 .

[4]  D. Farina,et al.  Crucial issues of multi-beam feed-back control with ECH/ECCD in fusion plasmas , 2005 .

[5]  A. Manini,et al.  Algorithms for the Control of NTM by Localized ECRH. Principles and Requirements of the Real Time Diagnostic and Control System , 2008 .

[6]  Giovanni Ramponi,et al.  Overview of the ITER EC upper launcher , 2008 .

[7]  G. Gantenbein,et al.  Status of the new multi-frequency ECRH system for ASDEX Upgrade , 2007, 2007 IEEE 34th International Conference on Plasma Science (ICOPS).

[8]  D. A. Humphreys,et al.  Requirements for alignment of electron cyclotron current drive for neoclassical tearing mode stabilization in ITER , 2008 .

[9]  William Bin,et al.  Low power tests on the new front steering EC launcher for FTU , 2011 .

[10]  William Bin,et al.  Design of a new ECRH launcher for FTU tokamak , 2009 .

[11]  William Bin,et al.  A New Launcher for Real-Time ECRH Experiments on FTU , 2009 .

[12]  C. Sozzi,et al.  ECRH antenna at 140 GHz on FTU Tokamak , 2001 .

[13]  R. J. La Haye,et al.  Prospects for stabilization of neoclassical tearing modes by electron cyclotron current drive in ITER , 2009 .

[14]  Gilles Berger-By,et al.  The ECRH/ECCD system on Tore Supra, a major step towards continuous operation , 2003 .

[15]  Hermes Giberti,et al.  A model predictive protection system for actuators placed in hostile environments , 2010, 2010 IEEE Instrumentation & Measurement Technology Conference Proceedings.

[16]  D. A. Humphreys,et al.  Stabilization and prevention of the 2/1 neoclassical tearing mode for improved performance in DIII-D , 2007 .