Objectives and prospects of using Thomson scattering technique to diagnosethe divertor of fusion reactor ITER

ITER divertor operation is dominated by the necessity to exhaust around 200 MW power via the scrape-off layer. A large fraction of the input power must be irradiated by the impurities either intrinsic or seeded. It is importan t that the radiation source be well distributed over the entire divertor pl asma. The plasma detachment at the divertor target should be precisely adju sted as to enable a partially attached operating that is detached near the separatrix strike point and attached further out in the scrape-off layer. T o provide information on key fenomena which may limit the divertor performa nce is the challenging task for diagnostics in ITER. The reliable T-e, n(e) profile measurements in the divertor upstream (near X-point) and downstream (divertor bottom) regions address the highly promis ing Thomson scattering diagnostics. The high resolution time-of-flight LIDA R Thomson scattering for the X-point and the conventional Thomson scatterin g technique for the divertor leg fit the reference divertor configuration w ith minimal impact on ITER design.