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In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented. [ABSTRACT FROM AUTHOR]

In this paper, a database of L-mode plasmas with Greenwald density fractions smaller than 0.8 is used to analyse the parametric dependences of the radiative power and the effective charge Zeff . It is found that the radiative power has a linear dependence on the total power and a linear fit is derived. In order to understand this parametric dependence, the changes in the radial extension of the radiation are studied with the help of bolometry measurements and it is found that the increase in Prad with Ptot can be explained by an increase in the neutral source of impurities (basically carbon erosion) during additional heating. A comparison of deuterium and helium plasmas shows that they radiate the same amount at the same total power. Significant positive deviations from the fit of the radiative power are observed for high ratios of Cu XIX/(ne). Zeff is also found to depend roughly linearly on the total power. The link found between Zeff and Prad is compatible with that of multimachine scaling (Matthews et al 1997 J. Nucl. Mater. 241-243 450). These results are obtained in a limiter machine, running in L-mode in the case where carbon is the dominant impurity. [ABSTRACT FROM AUTHOR]

Observations of lower hybrid (LH) radio frequency heating effects on toroidal plasma rotation in L-mode Tore Supra plasmas are reported. A database of more than 50 plasma discharges has been analysed. Core rotation is found to increment in co- or counter-current direction depending on the plasma current (Ip). At low plasma current, the induced rotation is up to +15 km s−1 in the co-current direction, the rotation profile being affected over the whole plasma minor radius. At higher plasma current, an opposite trend is observed, the core plasma rotation incrementing up to −15 km s−1 in the counter-current direction, the profile being affected up to r/a < 0.6 only. At the zero crossing point, which is defined when the plasma rotation profile is not affected by LH power injection, Ip ∼ 0.95 MA. In both low and high Ip cases, rotation increments are found to increase with the injected power. Several mechanisms in competition which can induce co- or counter-current rotation in Tore Supra LHCD plasmas are investigated and typical order of magnitude are discussed. How those effects evolve with plasma parameters and how they compete are important issues addressed in this paper. Rotation increment increase with Ip at fixed LH power is consistent with a dominant standard momentum confinement mechanism related to Ip increase. The co-current change in rotation is consistent with a fast electron ripple loss mechanism, while thermal ripple induced neoclassical friction and absorbed LH wave momentum from resonant electrons are expected to influence the rotation in the counter-current direction. Finally, the numerical simulations show that the radial turbulent momentum transport does impact the rotation behaviour inducing increment in co- or counter-current directions, depending on the plasma current amplitude. [ABSTRACT FROM AUTHOR]