Sputtering and Thermal Evaporation Studies of Lithiated ATJ Graphite

Sputtering yields and thermal evaporation fluxes of lithium and lithiated ATJ graphite are studied. Sputtering yields are measured for the ATJ graphite by lithium ion bombardment at 45° incidence, with 700-2000 eV accelerations. Typically, 4 × 10
¹³
ions/(cm
²
· s) flux of Li ion beam is obtained from LiCl powder in a Colutron ion source. Sputtered particles are collected by a quartz crystal microbalance to determine sputtering yields. The experiment is repeated after Li is evaporated onto the ATJ graphite target. Suppressed amounts of sputtered particles are observed after Li treatment. Deuterium (D) saturation treatment for lithiated graphite is also done to simulate actual divertor conditions. The sputtering yield after D saturation does not show distinct difference with nonsaturated samples. In addition, thermal evaporation fluxes of Li on stainless steel (SS) and intercalated Li in the ATJ graphite are measured. An interesting finding is that Li in graphite shows a magnitudeless evaporation flux than Li on SS for surface temperatures ranging from 250°C to 500°C.