Material Deposition on Inner Divertor Quartz Microbalance Systems during ITERLike Wall Operation in JET
The migration of beryllium, tungsten and carbon to remote areas of the inner divertor of JET-ILW and the accompanying co-deposition of deuterium has been investigated using post mortem analysis of the housings of quartz micro balances and their quartz crystals. The data show that the deposition rate of beryllium atoms is significantly reduced compared to the deposition rate of carbon during the carbon wall conditions of JET-C at the locations of the QMBs. A reduction factor of 50 was found at the entrance gap to the cryo pumps while it was 14 under the load bearing tile LBT (tile5). The deposits have atom ratios C/Be of typically 0.1­0.5 showing an enrichment of carbon in remote areas. The deuterium retention fraction is between 0.3 and unity.