Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum

• Published in: Nuclear materials and energy Vol. 18; pp. 118 - 124
• Main Authors: Huber, A., Brezinsek, S., Kirschner, A., Ström, P., Sergienko, G., Huber, V., Borodkina, I., Douai, D., Jachmich, S., Linsmeier, C.h., Lomanowski, B., Matthews, G.F., Mertens, P.h.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2019; Elsevier
• Subjects: Fysik; JET-ILW; PFC; Physics; PSI; PSI PFC; Tungsten erosion; Tungsten imaging spectroscopy; W Divertor; W Divertor; JET-ILW; Tungsten imaging spectroscopy; PFC; Tungsten erosion; PSI
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2018.12.009

•A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion.•The identification of the tungsten atom sources and the measurement of their radiation profiles in front of all plasma-facing components has been performed in JET.•The resultant intra-ELM sputtering was of about 7 × 1018 atoms/ELM in H-mode pulses with an input power of PIN = 21.5 MW.•It was observed that intra-ELM sputtering dominated by a factor of 7 over inter-ELM sputtering.
The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional view, equipped with interference filters of different bandwidths centred on the W I (400.88 nm) emission line. A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion even in the inner divertor region where the strong recombination emission is dominating over the tungsten emission. Analysis of W sputtering and W redistribution in the divertor by video imaging spectroscopy with high spatial resolution for three different magnetic configurations was performed. A strong variation of the emission of the neutral tungsten in toroidal direction and corresponding W erosion has been observed. It correlates strongly with the wetted area with a maximal W erosion at the edge of the divertor tile.