Session RP1 - Poster Session VIII.
POSTER session, Thursday afternoon, October 30
Fran Hill Southeast Exhibit Hall, ACC
Real-time control of the plasma profiles (current, pressure and flows) is a key issue to sustain steady state discharges with internal transport barriers (ITB) and a large bootstrap current fraction. In order to simultaneously control the current and pressure profiles in JET ITB discharges, a multi-variable model-based technique has been proposed. It is based on a truncated singular value decomposition of an integral model operator and retains the distributed nature of the plasma parameter profiles. The related algorithms have been implemented in the JET control system, and applied to the control of the current profile in reversed shear plasmas using three actuators (neutral beam injection, ion cyclotron heating and lower hybrid current drive). Successful control of the q-profile has been achieved in quasi steady state conditions with a significant fraction of bootstrap current. In these experiments the strength of the ITB's was marginal during the control phase, due to the chosen q-profile setpoints and to the moderate heating power which was requested by the controller. Hence, further experiments aiming at the simultaneous control of the current profile and of the normalized ITB temperature gradient are being pursued and first results will be reported.