LLNL FESP Theory Highlights: November 2024

Technical Report · Tue Dec 03 00:00:00 EST 2024

DOI:https://doi.org/10.2172/2491430· OSTI ID:2491430

Dudson, Ben ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

This talk presented a refined understanding of plasma-facing thermionic emitter cathodes by examining the limitations of the conventional space charge-limited model, which overlooks ion trapping dynamics within the virtual cathode. While conventional theory distinguishes between temperature-limited and space charge-limited regimes based on electron current constraints, recent findings reveal that trapped ions can form a quasi-neutral "second plasma," expanding upstream and interacting with the primary plasma. These effects are amplified in non-planar geometries, such as cylindrical or spherical sheaths, where trapped ions create a positive feedback loop with the upstream plasma. To address these phenomena, a new "Aid-and-Compete" model was developed, offering insights into current enhancement and sheath mode transitions relevant for plasma devices, including emissive cathodes in electric propulsion, fusion applications, thin film deposition systems, and plasma diagnostics.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC52-07NA27344
• OSTI ID: 2491430
• Report Number(s): LLNL--TR-2001603
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Physics - Plasma physics