Measurement of dust conversion factor for the JET carbon divertor phases

We compare the deposition of material on poloidal sets of divertor tiles that had been exposed in JET in 1998–2009 and 1998–2007. Post mortem analyses suggest toroidally integrated deposition being increased by 197.5cm3 during 2007–2009. The analysis of dust collected from the divertor indicates the amount accumulated during the same period to be 248.4g. Converting the weight of dust to volume, the fraction of material entering the divertor that was converted to dust and flakes is 43±10%. The size of most dust particles ranged from 10 to 100μm. The integrated amount of deposition on the “marker” tiles exposed in 2007–9 was found to be more than twice the amount expected from film growth on other tiles plus the dust because the plasma responds differently to the new tiles.