Spectroscopy for impurity control in ITER

Bremsstrahlung losses from the common low Z impurities play a much larger role in ITER than in present tokamaks due to the larger plasma dimensions and relatively better energy confinement of ITER. Control of the level of medium and high Z impurities inside the main plasma is also of utmost importance for achieving ignition in ITER. The need is outlined for spectroscopic diagnostics not only covering the main plasma but also the radiation mantle, the scrapeoff layer (SOL) and the divertor. (author)