Digital plasma control system and Alcasim simulation code for Alcator C-Mod

Abstract

Abstract The Alcator C-Mod control system was upgraded to digital architecture DPCS (Digital Plasma Control System). The main features of the digital system are the high flexibility, robustness and maintainability. The hardware consists of low-latency digitizers, a single processor Xeon server and DAC output cards. The software is a set of IDL routines. In the current version of the software, DPCS is emulating the PID controller of the previous control system Hybrid, but some advanced and adaptive features have already been implemented, for example the compensation of the input offsets. DPCS has been operating successfully since the beginning of the 2004-2005 experimental campaign. One of the advantages of a digital control system is that a simulator can be embedded in the system. We programmed a Matlab-Simulink simulator Alcasim for Alcator C-Mod. The simulator is a versatile tool to model the tokamak and the plasma, to interface with the database of the real experiments and to test new control algorithms, while running open loop and closed loop simulations. The powerful block-diagram language of Simulink allows to easily update the various components of the feedback loop, should the need arise. Preliminary results from the simulations of real shots are presented and discussed.