Integration of a Radiative Divertor for Heat Load Control into JET Operational Scenarios

The ITER-like Wall project in JET is replacing its Plasma Facing Components (PFCs) currently made of Carbon-Fibre Composite (CFC) with bulk beryllium main-chamber limiters and full tungsten divertor. Experiments on JET have prepared to explore the domain of moderate exhaust for acceptable impact upon plasma performance on standard high d ELMy H-mode discharges. Systematic studies were carried out on the individual effects of deuterium fuelling and seeding with two extrinsic impurities, as well as their interplay. An operational domain was achieved where this baseline scenario suffers less than 10% decrease in the pedestal stored energy and is both compatible with the ILW engineering limits and in the domain of low W sputtering. Nitrogen (N2) may be preferable as an extrinsic radiator to neon (Ne) as it mostly affects the divertor radiation without significantly increasing core radiation. In the non-carbon machine, deuterium fuelling alone is unlikely to reach this operational domain as it is just able to reach it in the present machine, hence extrinsic impurities would then have to be used.
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