Study of lithium vapor flow in a detached divertor using DSMC code. (May 2019)

• Record Type: Journal Article
• Authors: Emdee, E.D.; Goldston, R.J.; Schwartz, J.A.; Rensink, M.E.; Rognlien, T.D.
• Is Part Of: Nuclear materials and energy. Volume 19(2019)
• Page Start: 244
• Page End: 249
• Publication Date: 2019-05
• Subjects: Divertor -- Lithium -- DSMC -- Detachment; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2019.01.032
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: The lithium vapor box divertor localizes dense lithium vapor to cause stable detachment. This localization is formed by local evaporation and nearby condensation. Lithium vapor flow in a lithium vapor box design was simulated. We find the lithium exits the baffles for this configuration at a rate of ∼ 4 g/s. This should be acceptable since ionization of ∼ 60 g/s of lithium is taking place to cause detachment. Changes in detachment front position over 19 cm can cause a factor of 18 increase in lithium ionization rate Unbaffled results are more modest, but nonetheless promising. Abstract: A detached divertor is predicted to be necessary to handle the heat fluxes of a demonstration fusion power plant. The lithium vapor box divertor localizes dense lithium vapor to cause stable detachment. This localization is formed by local evaporation and nearby condensation. We provide a simulation of lithium vapor flow using the SPARTA Direct Simulation Monte Carlo (DSMC) code. Simulations of a baffled vapor box divertor's lithium mass flow are within a factor of two of an ideal-gas choked nozzle flow calculation. Lithium flow and density within each chamber are given for a 200 MW power input Demo-scaled vapor-box example configuration. We find the lithium exits the baffles of this configuration at a rate of ∼ 4 g/s. This should be acceptable since ionization of ∼ 60 g/s of lithium is taking place to cause detachment [3]. A simple model of the Fusion National Science Facility (FNSF) divertor plasma is also explored. We compare our simulations using SPARTA to a similar UEDGE simulation, showing the lithium ionizations rates can be emulated to a reasonable degree. The addition of baffles causes a decrease in far SOL ionization by a factor of eight. Changes in detachment front position over a range of 19cm can cause more than a factor of 18 increase in ionization rate, indicating detachment location is highly stable to variations in heatflux. Unbaffled results are more modest, but nonetheless promising with a factor of six change in ionization over the same region.