Lithium Divertor Targets and Walls for the ASTER Liquid Stellarator Reactor, Distributed Divertor

V. Queral; A. de Castro; J. Varela; S. Cabrera; I. Fernández; D. Spong; E. Rincón

doi:10.1007/s10894-025-00481-8

Lithium Divertor Targets and Walls for the ASTER Liquid Stellarator Reactor, Distributed Divertor

V. Queral, A. de Castro, J. Varela, S. Cabrera, I. Fernández, D. Spong, E. Rincón

Plasma Theory and Modeling

Research output: Contribution to journal › Article › peer-review

Abstract

Stellarators may have advantages for certain liquid metal options as Plasma Facing Components (PFC) for divertor targets and first walls due to the wide range of possible magnetic configurations, which additionally are free of disruptions and fast field variations. In a previous work (V. Queral et al., IEEE Trans. Plasma Sci. 52, 2024), a concept of stellarator reactor (ASTER-CP) based on swirling Li-molten salts and liquid lithium floating on the molten salt as PFC was presented. The divertor matters were not studied then and, thus, they are being studied and experimentally tested now. The ASTER-CP reactor concept, the initial liquid metal experiments and potential concepts for the ASTER-CP divertor and first wall are reported. Concerning the experiments, several small scale experiments of galinstan in a small rotating cylinder under magnetic field have been produced, including one experiment with high viscosity galinstan-mixture for increased thickness of layer. An experiment of floating lithium on the molten salt LiCl-PbCl₂ gave fast volatilization/decomposition of the molten salt. Particularly for divertors, the traditional free-flow, Capillary Porous Systems and ‘divertorlets’ have been studied for application to ASTER-CP. Surface waves (hot spots), lack of enough surface fluid turbulence and excessive fluid speed are the main issues found in fast free-flow. The perhaps original concept of Distributed Divertor and Equi-power Surface is tentatively proposed and studied, taking advantage of stellarator fields and low recycling regime.

Original language	English
Article number	15
Journal	Journal of Fusion Energy
Volume	44
Issue number	1
DOIs	https://doi.org/10.1007/s10894-025-00481-8
State	Published - Jun 2025

Funding

The authors are grateful to the HSX stellarator Team (University of Wisconsin\u2013Madison, USA) for granting the use of the HSX coil geometry for this publication, Francisco Saenz (PPPL, USA) for conversations on flowing lithium, Fernando R. Urgorri (liquids MHD) and Mar\u00EDa Gonzalez (ceramics) (CIEMAT), Jos\u00E9 Ferreira (CERN) and Daniel Alegre (CIEMAT) (comments on the Distributed Divertor) and Arnold Lumsdaine (ORNL, USA).The work is funded by the \u2018Agencia Estatal de Investigaci\u00F3n\u2019 (AEI), the \u2018Ministry of Science, Innovation and Universities\u2019, and by the \u2018Fondo Europeo de Desarrollo Regional\u2019 European Union (FEDER EU), under Grant n. PID2021-123616OB-I00, for the project \u201CStudy of improved stellarator assemblies consistent with proper in-vessel components for viable high-field stellarator reactors\u201D, and supported by the U.S. Department of Energy under Grant No. DEFG02-04ER54742.

Keywords

Distributed divertor
Galinstan
Lithium
Magnetic field
Molten-salt
Stellarator

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10.1007/s10894-025-00481-8

Cite this

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title = "Lithium Divertor Targets and Walls for the ASTER Liquid Stellarator Reactor, Distributed Divertor",

abstract = "Stellarators may have advantages for certain liquid metal options as Plasma Facing Components (PFC) for divertor targets and first walls due to the wide range of possible magnetic configurations, which additionally are free of disruptions and fast field variations. In a previous work (V. Queral et al., IEEE Trans. Plasma Sci. 52, 2024), a concept of stellarator reactor (ASTER-CP) based on swirling Li-molten salts and liquid lithium floating on the molten salt as PFC was presented. The divertor matters were not studied then and, thus, they are being studied and experimentally tested now. The ASTER-CP reactor concept, the initial liquid metal experiments and potential concepts for the ASTER-CP divertor and first wall are reported. Concerning the experiments, several small scale experiments of galinstan in a small rotating cylinder under magnetic field have been produced, including one experiment with high viscosity galinstan-mixture for increased thickness of layer. An experiment of floating lithium on the molten salt LiCl-PbCl2 gave fast volatilization/decomposition of the molten salt. Particularly for divertors, the traditional free-flow, Capillary Porous Systems and {\textquoteleft}divertorlets{\textquoteright} have been studied for application to ASTER-CP. Surface waves (hot spots), lack of enough surface fluid turbulence and excessive fluid speed are the main issues found in fast free-flow. The perhaps original concept of Distributed Divertor and Equi-power Surface is tentatively proposed and studied, taking advantage of stellarator fields and low recycling regime.",

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Lithium Divertor Targets and Walls for the ASTER Liquid Stellarator Reactor, Distributed Divertor

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