Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotron
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, 167 Albany St., Cambridge, Massachusetts 02139 (United States)
- Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering and Physics, Texas Tech University, MS 43102, Lubbock, Texas 79409 (United States)
- Naka Fusion Research Institute, Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0196 (Japan)
Regular two-dimensional plasma filamentary arrays have been observed in gas breakdown experiments using a pulsed 1.5 MW, 110 GHz gyrotron. The gyrotron Gaussian output beam is focused to an intensity of up to 4 MW/cm{sup 2}. The plasma filaments develop in an array with a spacing of about one quarter wavelength, elongated in the electric field direction. The array was imaged using photodiodes, a slow camera, which captures the entire breakdown event, and a fast camera with a 6 ns window. These diagnostics demonstrate the sequential development of the array propagating back toward the source. Gases studied included air, nitrogen, SF{sub 6}, and helium at various pressures. A discrete plasma array structure is observed at high pressure, while a diffuse plasma is observed at lower pressure. The propagation speed of the ionization front for air and nitrogen at atmospheric pressure for 3 MW/cm{sup 2} was found to be of the order of 10 km/s.
- OSTI ID:
- 21277139
- Journal Information:
- Physics of Plasmas, Vol. 16, Issue 5; Other Information: DOI: 10.1063/1.3083218; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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