Observation of Doppler-shifted T(alpha) emission from TFTR tritium neutral beams

摘要

195 tritium ion source shots were injected into TFTR high power plasmas during December 1993--March 1994. In addition, four highly diagnosed pulses were fired into the calorimeter. Analysis of the Doppler-shifted T(alpha) emission of the beam in the neutralizer has revealed that the extracted ion composition for deuterium and tritium are indistinguishable: 0.72(plus minus)0.04 D(sup +), 0.22(plus minus)0.02 D(sub 2)(sup +), 0.07(plus minus)0.01 D(sub 3)(sup +) compared to 0.72(plus minus)0.04 T(sup +), 0.23(plus minus)0.02 T(sub 2)(sup +), 0.05(plus minus)0.01 T(sub 3)(sup +). The resultant tritium full-energy neutral fraction is higher than for deuterium due the increased neutralization efficiency at lower velocity. To conserve tritium, it was used only for injection and a few calorimeter test shots, never for ion source conditioning. When used, the gas species was switched to tritium only for the shot in question. This resulted in an approximately 2% deuterium contamination of the tritium beam and vice versa for the first deuterium pulse following tritium. Data from the calorimeter shots indicates that tritium contamination of the deuterium beam cleans up in 5--6 beam pulses, and is reduced to immeasurable quantities prior to deuterium beam injection.