  The free-streaming plus recycling model (FSRM) has recently been developed to
understand and predict tungsten gross erosion rates from the divertor during
edge localized modes (ELMs). In this work, the FSRM was tested against
experimental measurements of W sputtering during ELMs, conducted via fast WI
spectroscopy. Good agreement is observed using a variety of controlling
techniques, including gas puffing, neutral beam heating, and plasma shaping to
modify the pedestal stability boundary and thus the ELM behavior. ELM
mitigation by pellet pacing was observed to strongly reduce W sputtering by
flushing C impurities from the pedestal and reducing the divertor target
electron temperature. No reduction of W sputtering was observed during the
application of resonant magnetic perturbations (RMPs), in contrast to the
prediction of the FSRM. Potential sources of this discrepancy are discussed.
Finally, the framework of the FSRM is utilized to predict intra-ELM W
sputtering rates in ITER. It is concluded that W erosion during ELMs in ITER
will be caused mainly by free-streaming fuel ions, but free-streaming seeded
impurities (N or Ne) may increase the erosion rate significantly if present in
the pedestal at even the 1% level. Impurity recycling is not expected to cause
significant W erosion in ITER due to the very low target electron temperature.
