Plasma structures observed in gas breakdown using a 1.5 MW, 110 GHz pulsed gyrotron
- 12 March 2009
- journal article
- Published by AIP Publishing in Physics of Plasmas
- Vol. 16 (5)
- https://doi.org/10.1063/1.3083218
Abstract
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/ cm2. 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, SF6, 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/ cm2 was found to be of the order of 10 km/s.open322Keywords
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