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A microfabricated atmospheric-pressure microplasma source operating in air

2005; Institute of Physics; Volume: 38; Issue: 11 Linguagem: Inglês

10.1088/0022-3727/38/11/009

1361-6463

Jeffrey Hopwood, Felipe Iza, Stephen L. Coy, D. B. Fenner,

Electrohydrodynamics and Fluid Dynamics

An atmospheric-pressure air microplasma is ignited and sustained in a 25 µm wide discharge gap formed between two co-planar gold electrodes. These electrodes are the two ends of a microstrip transmission line that is microfabricated on an Al2O3 substrate in the shape of a split-ring resonator operating with a resonant frequency of 895 MHz. At resonance, the device creates a peak gap voltage of ∼390 V with an input power of 3 W, which is sufficient to initiate a plasma in atmospheric pressure air. Optical emission from the discharge is primarily in the ultraviolet region. In spite of an arc-like appearance, the discharge is not in thermal equilibrium as the N2 rotational temperature is 500–700 K. The intrinsic heating of the Al2O3 substrate (to 100°C) causes a downward shift in the resonant frequency of the device due to thermal expansion. The temperature rise also results in a slight decrease in the quality factor (142 > Q > 134) of the resonator. By decreasing the power supply frequency or using a heat sink, the microplasma is sustained in air. Microscopic inspection of the discharge gap shows no plasma-induced erosion after 50 h of use.