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RESEARCH PRODUCT

Spectrometric analysis of inner divertor materials of JET carbon and ITER-like walls

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Abstract One of main reasons of the Joint European torus (JET) transformation from the carbon (JET-C) to ITER-like (JET-ILW) wall was high tritium retention of carbon. In order to compare the tritium retention, samples of analogous positions of the plasma-facing side of vertical tiles No. 3 of two campaigns: JET-C (2008–2009) and JET-ILW (2011–2012) were cut out. Temperature-programmed tritium desorption spectrometry in He + 0.1% H2 gas flow showed that JET-C sample without a tungsten coating had by a factor of >20 higher surface concentration of tritium than JET-ILW tungsten-coated sample: 4.9 × 1013 and 1.7–2.2 × 1012 T atoms/cm2 respectively. Installation of metallic plasma facing wall in the JET was a unique possibility to collect from the vacuum vessel the first wall erosion products (EP) – dust and flakes. Selected EP were investigated by means of energy dispersion X-ray (EDX), electron spin resonance (ESR), infrared and Raman spectrometry. EDX analysis shows presence of metallic impurities and carbon as a main component. Investigations with ESR spectrometry allows to estimate presence of two main paramagnetic centres – g = 2.002 and g = 2.12. Infrared spectra show presence of inorganic oxides. The obtained results supplement the information about composition of the EP from fusion devices.