Speaker
Dr
Matej Mayer
(Max-Planck-Institut für Plasmaphysik)
Description
During JET operation with all carbon walls prior to 2010 (JET-C) massive re-deposition of previously eroded carbon was observed in the divertor and in remote divertor areas. This massive carbon re-deposition was accompanied by a high retention of hydrogen isotopes trapped by co-deposition. Extrapolations of these results to ITER predicted very high potential tritium retention, resulting in the decision to remove carbon from the ITER divertor.
One aim of the JET ITER-like wall (JET-ILW) project was to study plasma-surface interactions in a carbon-free beryllium/tungsten environment comparable to the ITER material configuration. All divertor tiles were manufactured either from tungsten coated carbon-fibre composite (CFC) material or from bulk tungsten. Erosion and deposition in the JET divertor were studied during the campaigns JET-ILW1 (2011-2012), ILW-2 (2013-2014) and ILW-3 (2015-2016) by using specially prepared divertor marker tiles using W/Mo marker layers, which were analysed before and after the campaign using elastic backscattering of 3 and 4.5 MeV incident protons and nuclear reaction analysis using 0.8 to 4.5 MeV $^3$He ions.
The erosion/deposition pattern observed with the JET-ILW configuration shows partly drastic changes compared to the pattern observed with JET-C: The total material deposition rate in the divertor decreased by a factor of 4–9 compared to the deposition rate of carbon in JET-C. This decrease of material deposition in the divertor is accompanied by a decrease of total deuterium retention inside the JET vessel by a factor of about 20.
The erosion/deposition pattern observed during JET ILW-2 was qualitatively comparable to JET ILW-1, the observed D inventory was roughly comparable to the inventory observed during JET ILW-1. The results obtained during JET ILW-2 therefore confirm the positive results observed in JET ILW-1. Early results from JET ILW-3 also indicate agreement; more details will become available in summer 2018.
| Country or International Organization | Germany |
|---|---|
| Paper Number | EX/P1-15 |
Primary author
Dr
Matej Mayer
(Max-Planck-Institut für Plasmaphysik)
Co-authors
Dr
Alexandra Baron-Wiechec
(Culham Centre for Fusion Energy,Culham Science Centre)
Dr
Anna Widdowson
(UKAEA)
Dr
Cristian Ruset
(National Institute for Laser, Plasma and Radiation Physics)
Dr
Ionet Jepu
(National Institute for Laser, Plasma and Radiation Physics)
Dr
Jari Likonen
(VTT Technical Research Centre of Finland)
Dr
Kalle Heinola
(University of Helsinki)
Dr
Paul Coad
(Culham Centre for Fusion Energy,Culham Science Centre)
Dr
Per Petersson
(Fusion Plasma Physics, Royal Institute of Technology)
Dr
Sebastijan Brezinsek
(Forschungszentrum Jülich)
Dr
Stepan Krat
(National Research Nuclear University MEPhI)
Dr
Yury Gasparyan
(National Research Nuclear University MEPhI)
