PMI Laboratory Experiments

1. PMI Laboratory Experiments • R. Doerner “Mixed Interactions of W, Be, C, D & He” • Pure He plasmas exhibit strong temperature dependence of W surface morphology and reduced tungsten sputtering (W fuzz) • D-He plasmas show reduced D retention in W (~35x) and Be; not observed in C • Presently studying D retention in Be codeposits and fluence-material matrix of D-implanted C/Be/W mixed materials (both by TDS) • D. Nishijima “Observations of suppressed retention and blistering for W exposed to D+He mixture plasmas” • D-He plasmas suppress blisters in SR-W & RC-W; TFG W-TiC shows no blisters in D or D-He plasmas and much lower D retention (x100) • D-He plasmas show high density of near-surface nano-size bubbles (D barrier) • G. Oehrlein “Influence of Tungsten/Carbon Interactions On Carbon Erosion Behavior In D2 Plasma” • Using ellipsometry to monitor a-C:H film evolution in a ICP reactor • Monolayer of W coverage reduces film erosion (~8x) and increases roughness • XPS indicates W removal is slow • R. Ochoukov “Study of radio frequency sheath rectification in Alcator C-Mod” • Katsumada plasma potential probe is being developed to study RF sheath rectification in Alcator C-Mod (benchmarked against emissive probe) • M. Shimada “First result of tritium experiment from TPE at INL” • Depth profiles on Mo & W show T reaching mm past the surface (amount?) • Mo & W deuterium retention are similar to previous measurements

2. PMI Laboratory Experiments • R. Kolasinski “Characterization of W and C surfaces exposed to low energy plasmas and ion beams” • Blister formation on W in D plasmas shows strong T dependence; correlation with WC • Strong dependence of D retention on BET surface area observed in CFCs • LEIS measurements and simulations being used to study H binding to W surface • Gas driven permeation being measured (< 500 ºC); new system being built (< 1000 º C) • C. Taylor “Complex chemical interactions of lithium, deuterium, and oxygen on lithium-coated graphite PFC surfaces” • XPS of controlled surfaces and NSTX tiles are being used to understand bonding • Li bonding with C and O; all play a role in D retention • V. Surla “Recent Results from IIAX: Sputtering and Thermal Evaporation Studies of Lithiated Graphite” • Suppressed Li evaporation observed from ATJ graphite surfaces (10X); D further reduces • Li sputtering of Li-C surface similar to Li surface (suppressed compared with C surface); D does not reduce • M. Jaworski “Observations of Thermo-Electric MHD Driven Flows in the SLiDE Apparatus” • First results from SLiDE demonstrating Qp = 0.7 MW/m2 (Q = 180 MW/m2 m) • TEMHD flows dominate over TCMHD; give rise to azimuthal flow and heat spreading • D. Hillis “Research opportunities provided by a high flux linear plasma device for Plasma-Surface Interaction Studies” • US fleet of PMI tools is in need of an upgrade; ORNL is studying helicon source design