Assessing material migration through 13C injection experiments

摘要

To mimic a localized impurity source for materials migration studies, ~(13)CH_4 has been injected into AUG, DIII-D, JET, JT-60U and TEXTOR at a single location into repeat, well-characterized plasmas, making for much more interpretable data than campaign-integrated erosion and deposition. Such studies have shown convincingly that for single null configurations, material is likely to migrate from the wall to the inner divertor creating tritiated co-deposits there. It has also indicated that for an unbalanced double-null configuration similar to ITER's the sputtered wall material is likely to create co-deposits on the blanket wall rather than the divertor; this has implications for ITER tritium retention in Be co-deposits since the wall can only be baked to 240 °C. The location and magnitude of tritium co-deposition in the 1997 JET DTE was not as expected from the 1991 PTE. It is recommended that ~(13)C or other tracer experiments be performed in ITER as early as possible.