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This paper presents the polarization characteristics of electrochemical oxygen pumps (EOPs) during transfer oxygen from/to liquid lead-bismuth eutectic (LBE). A thick-walled (1.5 mm) one-end closed tube of yttria partially stabilized zirconia was used as a solid electrolyte. Three different electrode of air/LSM (lanthanum strontiummanganite), air/LSCF (lanthanum strontium cobalt ferrite) and LBE/PbO were compared. The polarization characteristics were obtained by linear sweep voltammetry in LBE at 450°C at various dissolved oxygen concentrations in LBE. The EOP with LBE/PbO electrode showed negligible activation polarization compared to EOPs with other electrodes. However, with the LBE/PbO electrode a significant concentration polarization occurred at low current density, limiting its capacity for oxygen transfer from EOP to LBE. The oxygen transfer from LBE to EOP is limited by oxygen mass transfer from the LBE bulk to the solid electrolyte surface of EOPs, especially under low dissolved oxygen condition. [ABSTRACT FROM AUTHOR]

Parallel transport associated with type I edge localized model (ELM) filaments in the scrape-off layer (SOL) is studied by means of three computational approaches--fluid, Vlasov and particle-in-cell (PIC). These techniques are benchmarked for convective transients by analysing power fluxes at the target. In spite of kinetic effects due to fast electrons which are not captured in the fluid code, the overall agreement between the codes is satisfactory. In addition, the collisionless Vlasov model agrees well with an analytic free-streaming model. The total peak energy flux at the target is comparable between the models, but the individual fractions of the flux carried by ion and electron components are determined by kinetic effects and processes in the sheath and the energy source in the fluid code is redistributed between electrons and ions in order to obtain the best match with the PIC model. From results for convective ELMs, approximate expressions for the energy fluence and the peak energy flux at the target are derived. Additionally, conductive ELMs are studied. [ABSTRACT FROM AUTHOR]