Plasma Shape Control at TCV
A thorough description of the TCV is beyond the scope of this work. The interested reader is referred to . Hereafter we will outline only those aspects that are relevant to control. The main parameters of the TCV tokamak are given in Table 8.1. The TCV was originally constructed to explore the effect of the shape on plasma performance. Figure 8.1 shows a poloidal view of the tokamak. The vessel has an almost rectangular section with a height/width ratio of 3. The TCV is equipped with 16 independently powered shaping coils (E1–E8; F1– F8) distributed around the vessel; this gives the possibility of obtaining a wide range of plasmas: limiter or diverted; centred or up-down asymmetric; circular or elongated. Besides the poloidal field (PF) coils, there are two ohmic heating (OH) coils, whose main aim is to induce the plasma toroidal current. The high number of PF coils which can be used to generate the magnetic field needed to control the plasma, makes the TCV an ideal plant for control purposes. This, together with the growing interest in more sophisticated control algorithms, motivates the replacement of a hybrid analogue–digital system with a PID structure with an entirely new digital plasma control system (DPCS).
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