29th Symposium on Fusion Technology (SOFT 2016)

P1.108 Influence of divertor material modifications on the inventory of tritium in the divertor region

5 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 108

Poster F. Plasma Facing Components P1 Poster session

Speaker

Mihails Halitovs (University of Latvia)

Description

Fusion device materials have been modified over the years for the main aim of using optimal materials in ITER fusion device. Post-mortem analysis of materials used in JET provides valuable information for further material development and improvements required. One of key fusion device elements is the divertor. It minimizes plasma contamination and draws a big part of thermal and neutron load in the fusion device. Over the years it was proven that CFC material itself is not an outstanding divertor material. It has high tritium affinity and plasma erosion rate. Therefore W coatings have been applied to test the efficiency of W in reducing tritium accumulation in the fusion device divertor region. In the research various divertor tiles from JET 2007-2009 and 2010-2012 campaigns with W coating have been analysed for tritium accumulation depth profiling. A comparison to profiles of tritium accumulation in uncoated tiles of comparable divertor positions was also done. The results show gradual decrease in tritium activity on the surface of divertor tiles when W coatings are applied (approximately 10⁵5 Bq·g^-1-1 for W-coated samples compared to 10⁶6-10⁸8 Bq·g^-1-1 for various uncoated samples). Though efficiency of W coatings in reducing the amount of accumulated tritium varies considerably and does not depend strictly on W coating itself. Samples of tiles 7 and 8 that are not in constant direct interaction with plasma show smaller difference between surface activity (~10⁵5 Bq·g^-1-1) and bulk activity (5·10⁴4 Bq·g^-1-1) than samples of tiles closer to Louvre (10⁶6 Bq·g^-1-1 on the surface, 10⁴4 Bq·g^-1-1 in the bulk).As it can be concluded, the W coating is efficient in reducing inventory of tritium in divertor region, though it varies strongly on the tile position and plasma interaction.