Implications of the TORE-SUPRA WEST-project on radio frequency additional heating systems

This year, TORE-SUPRA celebrated 25 years of operation. During this time, a number of technologies have been developed. First of all, it was mandatory to develop reliable superconducting magnets at ∼1.8 K, with superfluid helium as an efficient coolant. For the production of steady-state discharge, three types of radio-frequency (RF) additional heating systems have been developed: lower hybrid current drive, ions and electrons cyclotron resonance heating. To cope with long-lasting discharges (up to 380 s ×,2.8 MW) and large RF additional heating power (12.3 MW ×3 s), actively cooled (AC) plasma facing components were deployed in TORE-SUPRA for the first time in a tokamak environment. TORE-SUPRA is now being modified into a D-shaped axisymmetric tokamak with AC main chamber walls and an AC tungsten divertor, the W-for tungsten-Environment in Steady-state tokamak (WEST). This new facility has the objective to offer ITER a test bed for validating the relevant AC metallic technologies in D-shaped H-mode plasmas. In contrast to other metallic devices such as JET and ASDEX upgrade, WEST will rely only on RF additional power systems. A set of plasma scenarios have been identified, ranging from a high total RF power scenario up to 15 MW-30 s, to a high fluence scenario of 1000 s with up to 10 MW of injected RF power. These scenarios are able to reproduce ITER-relevant conditions of steady-state heat loads of 10-20 MWm², to test tungsten AC divertor technologies with relevant power heat fluxes and particle fluence.