document: Our simulations confirm experimental observations that W net erosion represents only tiny fraction (in our simulation ∼1%) of the W gross erosion. The estimated upstream W fluxes, FWupstrem, are in good agreement with the experimentally observed values ⩽1019m-2s-1 [16]. Moreover, this value is not very sensitive to the divertor plasma temperature. For low temperatures the energy of D and C ions hitting to the divertor plates is too low to sputter sufficient amount of W. With increasing energy the W sputtering increases, but the potential drop in the divertor plasma increases too. As a result, most of the W atoms are ionized in the vicinity of the divertor and return back to the plates. There are two effects leading to the observed prompt redeposition of W ions: first is the “near-divertor” ionization of W due to low ionization potential −7.86eV (for comparison the ionization potentials for D and C are 13,6 and 10.6eV), second, W+n ions have large Larmor radius ∼2/nmm, so that they are redeposited within the distance of a Larmor radius. Important to note that a significant fraction of W ions escaping this prompt redeposition are returned back due to the friction with the main ions.
extractive_keyphrases: c d divertor estimated upstream w fluxes experimentally observed values friction with the main ions fwupstrem increasing energy ionization ionized large larmor radius observed prompt redeposition plates return simulations w
abstractive_keyphrases: d and c ions divertor plasma divertor plates hitting to the divertor plates near-divertor” ionization w atoms w fluxes w gross erosion w ions w net erosion w+n ions w sputtering