Visualization of Tokamak Operational Spaces Through the Projection of Data Probability Distributions

ITER plasma scenario studies have shown that the optimisation of the flux consumption from the poloidal field coils requires control of the plasma inductance, used here li = li (3) [1]. This control was achieved in ITER demonstration discharges (at DIII-D, C-Mod, AUG and JET-C) using a combination of full bore start up with early X-point formation and current ramp-up in H-mode. H-mode during current decay down has been shown also instrumental to maintain low inductance in order to minimise flux consumption. Moreover variation of plasma inductance in ohmic discharges can be controlled, independently of the plasma current ramp-down rate, by varying the plasma elongation, as reported in [2]. An all-metal ITER-like wall (ILW), consisting of beryllium in the main chamber and tungsten surfaces in the divertor, has now been installed in JET. Its implementation has offered the opportunity to assess if the flux consumption and plasma inductance evolution is modified by Be-wall and W-divertor during the current rise and current decay (e.g. current profile evolution, plasma controllability issues as W accumulation in the transient phase, L-H transition, etc.). Details of the experimental results obtained in 2012 with the ILW and comparison with carbon-fibre reinforced carbon (CFC) wall (JET-C) will be given here. The CRONOS suite of codes has been used to interpret JET-ILW experimental results and make predictions for ITER.
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EFDC130317 772.73 Kb