Effect of impurities on the thermo-oxidative removal of codeposits from DIII-D and JET divertor tiles

Results are presented for the thermo-oxidative removal of codeposits from DIII-D and JET divertor tiles. The DIII-D codeposits are relatively thin (1-2 $\mu $m) and contain B impurities (0-45{\%}), while the JET codeposits are thick (up to $\sim $250 $\mu $m) and contain up to $\sim $75{\%} Be. Erosion rates, D-removal rates and the remaining D content in the codeposits were measured as a function of (i) pressure (2.1-79 kPa), (ii) temperature (523-673 K), and (iii) oxidation time (15 min to 8 h). The DIII-D results show that for C-D codeposits with less than a few percent B, it is possible to remove $>$95{\%} of the D content in the codeposit in 15 minutes. The D-removal rate decreases with higher levels of B concentration. Our first results for the `thick' Be-containing JET codeposits suggest that the initial rate of D removal is much higher for these thicker codeposits than for the previously studied relatively `thin' (1-2 $\mu $m) DIII-D and JET deposits. This is despite the large Be concentration. Implications for ITER will be discussed.