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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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Active Tailoring of the Electron Energy Distribution in an Atmospheric-Pressure Dual-Frequency Argon Jet

Poster 22
Presenter: Daehee Wi (Korea Advanced Institute of Science and Technology (KAIST))
Authors: jiwon CHOI (Korea Advanced Institute of Science and Technology (KAIST)), Hyeondo Cho (Korea Advanced Institute of Science and Technology (KAIST)), Sanghoo Park (Korean Advanced Institute of Science and Technology (KAIST))

The electron-energy distribution function (EEDF) is the primary determinant of processes in low-temperature plasmas. In conventional glow RF discharges at atmospheric pressure, frequent electron–neutral collisions rapidly force the EEDF toward a single Maxwellian, constraining both physical and chemical controls. Here, we overcome this barrier with a dual-frequency atmospheric-pressure argon plasma jet; a sinusoidal 5 MHz power is supplied to the main pin electrode, while a low frequency power applies 50-kHz bipolar square voltage to the counter electrode. Nanosecond-resolved laser Thomson scattering captures the phase-resolved EEDF, along with electron temperature (Te) and density (ne). Analysis of the scattered spectra with super-Gaussian fitting and Bayesian inference provides phase-dependent deviations from a Maxwellian EEDF. The EEDFs respond dynamically to the time derivative of the voltage applied to the counter electrode; a high-energy tail emerges during a falling phase of the 50 kHz voltage, whereas low-energy electrons are preferentially populated during a rising phase, sharpening the low-energy part of distribution. These µs-scale modulations of the EEDF are accompanied by corresponding oscillations in ne (up to 2.2×1019 m⁻³) and Te (0.85–1.0 eV). These findings suggest that dual-frequency excitation provides a practical µs-scale lever for tailoring the EEDF and, in turn, tuning plasma chemistry in atmospheric-pressure plasma jets.

Funding acknowledgement

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. RS-2024-00432328)

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