EFDA-JET-CP(04)03/39

Simultaneous Real-Time Control of the Current and Pressure Profiles in JET: Experiments and Modelling

Real-time control of the plasma profiles (current density, pressure and flow) is one of the major issues for sustaining Internal Transport Barriers (ITB) in a high performance plasma, with a large bootstrap current fraction. Indeed, the controllability of the proposed advanced scenarii must be demonstrated to envisage steady state operation in ITER, and the control of advanced discharges in JET is an essential part of this program. Past experiments focussed on the separate control of the maximum normalised electron temperature gradient r*Te, on one hand, or of the safety factor profile on the other hand, in different discharges. A major challenge still remains to control both the current and pressure profiles that are non-linearly coupled and therefore mix up the resistive and confinement time scales in a non-trivial way. We have recently investigated the experimental and numerical aspects of the simultaneous control of the current and pressure profiles in JET ITB discharges. The current density and the electron temperature were successfully controlled via the safety factor profile (or via its inverse the i-profile) and the r*Te profile, respectively. The results of these new studies will be presented here.
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