The COMPASS Tokamak Plasma Control Software Performance

The COMPASS tokamak has began operation at the IPP Prague in December 2008. A new control system has been built using an ATCA-based real-time system developed at IST Lisbon. The control software is implemented on top of the MARTe real-time framework attaining control cycles as short as 50 μs, with a jitter of less than 1 μs. The controlled parameters, important for the plasma performance, are the plasma current, position of the plasma current center, boundary shape and horizontal and vertical velocities. These are divided in two control cycles: slow at 500 μs and fast at 50 μs. The project has two phases. First, the software implements a digital controller, similar to the analog one used during the COMPASS-D operation in Culham. In the slow cycle, the plasma current and position are measured and controlled with PID and feedforward controllers, respectively, the shaping magnetic field is preprogrammed. The vertical instability and horizontal equilibrium are controlled with the faster 50-μs cycle PID controllers. The second phase will implement a plasma-shape reconstruction algorithm and controller, aiming at optimized plasma performance. The system was designed to be as modular as possible by breaking the functional requirements of the control system into several independent and specialized modules. This splitting enabled tuning the execution of each system part and to use the modules in a variety of applications with different time constraints. This paper presents the design and overall performance of the COMPASS control software.

[1]  Vitalii D. Shafranov,et al.  Plasma equilibrium in a Tokamak , 1971 .

[2]  Filippo Sartori,et al.  The PCU JET Plasma Vertical Stabilization control system , 2010 .

[3]  Parag Vyas,et al.  Plasma vertical position control in the COMPASS–D tokamak , 1996 .

[4]  C.A.F. Varandas,et al.  Fast feedback control for plasma positioning with a PCI hybrid DSP/FPGA board , 2005, IEEE Transactions on Nuclear Science.

[5]  J. Lingertat,et al.  Local expansion method for fast plasma boundary identification in JET , 1993 .

[6]  Beatriz Carvalho,et al.  Real-time software for the COMPASS tokamak plasma control , 2010 .

[7]  Alfredo Portone,et al.  The JET PCU project: An international plasma control project , 2008 .

[8]  Filippo Sartori,et al.  A new approach to the solution of the vacuum magnetic problem in fusion machines , 2007 .

[9]  G. Ambrosino,et al.  Magnetic control of plasma current, position, and shape in Tokamaks: a survey or modeling and control approaches , 2005, IEEE Control Systems.

[10]  J. B. Lister.  The evolution of feedback control in tokamaks , 2003 .

[11]  R. Albanese,et al.  Current, position, and shape control of tokamak plasmas: a literature review , 2000, Proceedings of the 2000. IEEE International Conference on Control Applications. Conference Proceedings (Cat. No.00CH37162).

[12]  Antonio Barbalace,et al.  MARTe: A Multiplatform Real-Time Framework , 2010, IEEE Transactions on Nuclear Science.

[13]  C.A.F. Varandas,et al.  ATCA digital controller hardware for vertical stabilization of plasmas in tokamaks , 2006 .

[14]  B. P. Duval,et al.  Real-time data transfer in the TCV advanced plasma control system , 2006 .

[15]  J. B. Lister,et al.  Control of the vertical instability in tokamaks , 1990 .

[16]  J. B. Lister,et al.  The Control of Tokamak Configuration Variable Plasmas , 1997 .

[17]  L. L. Lao,et al.  Real time equilibrium reconstruction for tokamak discharge control , 1998 .

[18]  Miguel Correia,et al.  An ATCA Embedded Data Acquisition and Control System for the Compass tokamak , 2009 .

[19]  W. Press,et al.  Numerical Recipes in C++: The Art of Scientific Computing (2nd edn)1 Numerical Recipes Example Book (C++) (2nd edn)2 Numerical Recipes Multi-Language Code CD ROM with LINUX or UNIX Single-Screen License Revised Version3 , 2003 .

[20]  B. G. Penaflor,et al.  Current status of the upgraded DIII-D real-time digital plasma control system , 2004 .

[21]  R. Aymar,et al.  The ITER design , 2002 .

[22]  M. Valovic,et al.  The H-mode in COMPASS-D , 1996 .

[23]  J. Stöckel,et al.  Reinstallation of the COMPASS-D tokamak in IPP ASCR , 2006 .