Laser-based and thermal methods for fuel removal and cleaning of plasma-facing components

摘要

The efficiency of two methods for in situ fuel removal has been tested on carbon and tungsten limiters retrieved from the TEXTOR and Tore Supra tokamaks: laser-induced ablation of co-deposits and annealing in vacuum at elevated temperature. The analyses of gas phase and surfaces performed with thermal desorption spectrometry, optical spectroscopy, ion beam analysis, surface profilometry and microscopy methods have shown: (i) the ablation leads to the generation of dust particles of 50 nm - 2 μm; (ii) volatile products of ablation undergo condensation on surrounding surfaces; (iii) D/C ratio in such condensate is in the range 0.02-0.03; (iv) long-term annealing of 623 K for 70 h results in release of not more than ～10% of deuterium accumulated in plasma-facing components; (v) effective removal is reached by heating to 900-1300 K.