Direct optimization of neoclassical ion transport in stellarator reactors

Lee, B. F.; Lazerson, S. A.; Smith, H. M.; Beidler, C. D.; Pablant, N. A.

doi:10.1088/1741-4326/ad75a6

Title: Direct optimization of neoclassical ion transport in stellarator reactors

Journal Article · 09 September 2024 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/ad75a6 · OSTI ID:2440299

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; Smith, H. M.;

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Abstract We directly optimize stellarator neoclassical ion transport while holding neoclassical electron transport at a moderate level, creating a scenario favorable for impurity expulsion and retaining good ion confinement. Traditional neoclassical stellarator optimization has focused on minimizing $ϵ_{eff}$ , the geometric factor that characterizes the amount of radial transport due to particles in the $1 / ν$ regime. Under expected reactor-relevant conditions, core electrons will be in the $1 / ν$ regime and core fuel ions will be in the $\sqrt{ν}$ regime. Traditional optimizations thus minimize electron transport and rely on the radial electric field ( E _r ) that develops to confine the ions. This often results in an inward-pointing E _r that drives high- Z impurities into the core, which may be troublesome in future reactors. In this work, we increase the ratio of the thermal transport coefficients $L_{11}^{e} / L_{11}^{i}$ , which previous research has shown can create an outward-pointing E _r . This effect is very beneficial for impurity expulsion. We obtain self-consistent density, temperature, and E _r profiles at reactor-relevant conditions for an optimized equilibrium. This equilibrium is expected to enjoy significantly improved impurity transport properties.

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Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: European Union (EU); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)

Grant/Contract Number:: AC02-09CH11466; SC0024386

OSTI ID:: 2440299

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 10 Vol. 64; ISSN 0029-5515

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: IAEA

Language:: English

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY
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Title: Direct optimization of neoclassical ion transport in stellarator reactors

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