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Poster Session II

4:30 pm – 6:30 pm, Wednesday October 15 Session DW5 COEX, Lobby E
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Microwave-driven Plasma for Low-power Microsatellite Propulsion

Poster 83
Presenter: Kyungtae Kim (POSTECH(Pohang university of science and technology))
Authors: Kil-Byoung Chai (Korea Atomic Energy Research Institute), Gunsu Yun (Pohang University of Science and Technology)

Microwave-driven Coaxial Transmission Line Resonator (μ-CTLR) is a compact plasma source operable for a wide pressure range—from atmospheric pressure down to a few mTorr—owing to the high electric field intensity at the open end of its resonant electrode. Under low-pressure conditions, the μ-CTLR generates a small-volume, high-density plasma plume (~1020m⁻³) with less than 10 W input power, making it a promising candidate for miniature space propulsion systems that demand compact size, stable operation, and low power consumption [1]. In our previous study, a μ-CTLR operating at 900 MHz and 8 W with an argon mass flow rate of 100 SCCM (3 mg/s) showed a thrust of 3.4 mN, specific impulse of 116 s, total efficiency of 24 %, and a thrust-to-power ratio of 425 mN/kW [1]. In this study, we investigate the performance of a μ-CTLR integrated with a magnetic nozzle (MN) composed of annular permanent magnets to enhance specific impulse and efficiency. The system operates stably with argon gas flow rates below 2.5 SCCM (0.075 mg/s), producing a visibly expanding plasma plume under vacuum conditions (operating pressure ~ 10-4 Torr; base pressure ~10-7 Torr). The MN configuration provides a maximum axial magnetic field strength of approximately 200 G near the nozzle throat, contributing to plasma confinement and acceleration. Near the open end of the electrode, the electron density reaches ~5 × 1019 m-3, increasing significantly as the mass flow rate decreases. Moreover, ion energy measurements using a Retarding Potential Analyzer (RPA) indicate fast ion populations with energies up to ~50 eV. Our results propose the μ-CTLR with a magnetic nozzle as a highly efficient mN-class thruster for miniature satellites, with performance comparable to or exceeding other plasma thrusters [2–3].

[1] Kim K. et al., Plasma Sources Sci. Tech., 33(8), 085003, (2024)

[2] Takahashi T., et al., Journal of Applied Physics, 125(8), 083301, (2019)

[3] Zolotukhin, D. B., et al., Science Advances, 8(36), eadc9850, (2022)

Funding acknowledgement

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (RS-2023-00273696, RS-2022-00155950, and RS-2023-00281272) and the BK21+ program of NRF, the 2025 POSTECH Next Generation Convergence Research Pioneer Program.

POSTERS (88)