Advances in predictive thermo-mechanical modelling for the JET divertor experimental interpretation, improved protection, and reliable operation

Advances in predictive thermo-mechanical modelling for the JET divertor experimental interpretation, improved protection, and reliable operation

Advances in predictive thermo-mechanical modelling for the JET divertor experimental interpretation, improved protection, and reliable operation 150 150 UKAEA Opendata
UKAEA-CCFE-PR(20)64

Advances in predictive thermo-mechanical modelling for the JET divertor experimental interpretation, improved protection, and reliable operation

The JET outboard divertor targets are the in-vessel components which receive the largest heat flux density. Surface delamination, radial cracks, and tie rod failures have been observed in the outboard tungsten-coated CFC tiles, while bulk tungsten special lamellas were intentionally melted in dedicated experiments. These different types of damage were not reproducible using existing models and tools. Several analysis and development activities have been completed during the last campaigns for improving the tools used for prediction of the plasma parallel heat flux density and the thermo-mechanical behaviour of the tiles. Experimental thermography measurements at different impinging angles, interpreted with new algorithms including a correction to the optical projection have led to a reduction of the peak parallel heat flux density of 1/3 compared to the previously estimated value. Integrity assessments are performed using the engineering footprint concept, which averages ELM and inter-ELM plasma load. Improvements on the ELM profiles result in a fall-off length for this engineering footprint of one order of magnitude larger than that inferred from the inter-ELM scaling laws. All these advances have been implemented in integrated analysis tools which can quickly predict the behaviour of the divertor tiles in an automated and power consistent manner. This development carried out at JET supports the experimental understanding, enhances the real-time protection systems, improves the evaluation of the operating instructions, and is also transferable to ITER.

Collection:
Journals
Journal:
Nuclear Fusion
Publisher:
IOP (Institute of Physics)