Microwave plasma generation by the fast rotation and slow pulsation of resonant fields in a cylindrical cavity
| Autor: | Kobayashi Satoru, Dima Lubomirsky, Keiji Nakamura, Yuichi Hasegawa, Soonam Park, Hideo Sugai |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Materials science Angular frequency Physics and Astronomy (miscellaneous) Oscillation business.industry General Engineering General Physics and Astronomy 02 engineering and technology Plasma Low frequency 021001 nanoscience & nanotechnology Rotation 01 natural sciences Optics 0103 physical sciences 0210 nano-technology business Frequency modulation Microwave Microwave cavity |
| Zdroj: | Japanese Journal of Applied Physics. 56:046203 |
| ISSN: | 1347-4065 0021-4922 |
| Popis: | A digitally controlled solid-state microwave generator allowing variable frequency operation and precise phase control is adopted for plasma generation. In this study, a resonant cylindrical cavity is used as a microwave applicator in place of conventional waveguides. In order to improve the plasma uniformity, the TE111 mode is agitated by injecting microwaves into the cavity from two spatially orthogonal directions, with a temporal phase difference . Theoretical analyses and finite-difference time-domain simulations derive the following effects of the phase control. In the case of = ±π/2, fast rotation of the cavity field takes place with a rotational frequency of ω/2π (= 2.4–2.5 GHz), where ω denotes the microwave angular frequency. On the other hand, when is linearly modulated in time with a low frequency of Ω/2π (= 0.1–1000 Hz), slow pulsation takes place, in which the cavity field alternately excites a circular rotation and a standing oscillation at the modulation frequency. These effects are experimentally confirmed in microwave discharges in argon at 0.1–20 Torr with total injection powers from 50 to 800 W. Two-dimensional images of the optical emission from the generated plasma show that both the fast rotation and slow pulsation improve azimuthal plasma uniformity. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|