Tomographic reconstruction of 2D line radiation distribution in the JET MkIIGB divertor

Abstract A 2D-tomographic reconstruction of D α - and C III-emission distribution in L-mode, density limit discharge has been performed and compared with results from other diagnostics (KL2, KS3). The observed emission patterns in a poloidal plane show a strong in–out asymmetry, which depends on local plasma parameter in the divertor. It is shown that the major contribution to D α -emission, under the observed conditions, lies in excitation processes and that low-energy charge-exchange reactions with neutral deuterium can influence the ionisation balance of carbon and the recorded C III-emission line. The evolution of the intrinsic hydrogen and carbon impurity profiles has been analysed with respect to its dependence on the location of methane fuelling.