Simulations of a high-density, highly-radiating lithium divertor. (January 2019)

• Record Type: Journal Article
• Authors: Rognlien, T.D.; Rensink, M.E.; Emdee, E.; Goldston, R.J.; Schwartz, J.; Stotler, D.P.
• Is Part Of: Nuclear materials and energy. Volume 18(2019)
• Page Start: 233
• Page End: 238
• Publication Date: 2019-01
• Subjects: Divertor modeling -- Lithium -- Plasma detachment -- UEDGE -- FNSF; 00-01 -- 99-00; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2018.12.030
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Existence of a stable, high density lithium divertor is demonstrated by 2D edge-plasma transport simulations. Greater than 90% of the core exhaust power can be radiated by the high-density lithium divertor. The upstream lithium concentration adjacent to the core plasma boundary ranges from 0.054 to 0.15, depending on assumptions of thermal force coefficients. Abstract: Results are presented for one- and two-dimensional (2D) edge plasma transport simulations for strong injection of lithium (Li) in the divertor region of a tokamak. The model includes the scrape-off layer and divertor regions, and, for 2D, a small region inside the magnetic separtrix. Equations are solved for the density and momentum of a deuterium/tritium (DT) species and all three charge states of Li, in addition to separate ion and electron energy equations via the UEDGE code. Equations are also included for the DT and Li gas species. Lithium gas is injected from the side walls or divertor plate, implying that these surfaces are evaporating liquid Li. For a range of Li gas input, steady-state, detached-plasma solutions are shown where greater than 90% of the exhaust power is radiated by Li, resulting in peak surface heat fluxes ∼ 2 MW/m 2 on the divertor plate, outer wall, and private-flux wall. While Li ions dominate in the divertor leg, their density is in the range of 10% of the DT density at the midplane. The collisional parallel thermal force plays a key role in determining the midplane ion Li density, and sensitivity of results to different model assumptions are discussed. Here the key issue is possible dilution of the core DT fuel. A brief comparison of the Li neutral solution is made with that from the Direct Simulation Monte-Carlo (DSMC) SPARTA code.