Analysis of tritium implanted in an edge probe in TFTR

Tritium analysis has carried out for the 4D C-C composite deposition probe exposed to the edge of D-D plasma several times in Tokamak Fusion (TFTR) at Princeton University. It is expected that a non-negligible amount of tritium would be captured in it. The samples for the tritium measurement were small thin slices taken from different parts of the probe and powder yielded. The amount of tritium was measured in two different ways. One was the conventional combustion and scintillation counting of trapped water for the sliced samples, and the other a direct counting method of the powder suspended in the scintillator. The burning method gave 87 to 398 kBq/g, depending on the part of probe areas. The data indicate that the ion drift side contains more tritium than the electron drift side, which is consistent with earlier surface measurements for deuterium and lithium. On the other hand, the direct counting method resulted in 61 kBq/g. The smaller activity by the direct method indicates that tritium was distributed beyond the escape depth of the beta rays from the surface. Nevertheless, the direct counting appears to be applicable to for the estimation of tritium inventory in the carbon first wall as a rapid technique and should be convenient for carbon debris of considerably small particle sizes. (author)