Comparison of plasma performance with beryllium and carbon divertor targets in JET

Single null X-point discharges having exactly the same main plasma parameters were performed on the C and on the Be target tiles in order to compare the two materials under similar conditions. Low power L-mode, H-mode and hot-ion H-mode pulses were used in this comparison. The impurity production when using a Be target is a factor of 3 higher than at the C target under similar plasma conditions. The power handling capability of Be is approximately a factor of 1.5 lower than that of C. In radiative divertor (gas target) experiments, however, Be seems to be superior to C. This may be due to the fact that the maximum Be radiation occurs at a plasma temperature of 1.5 eV compared with 7 eV in the case of C. (author). 17 refs, 5 figs