Comparative diagnostics of Ar and He surfatron generated plasma by means of optical emission spectroscopy and probe measurements
Résumé
Plasma applications in technology, medicine and biomedicine are already known for a longer time. Our work is focused on diagnostics and applications of a microwave plasma source in these areas. The diagnosed microwave-driven plasma source consists of a surfatron powered by a microwave magnetron generator, working at 2.45 GHz in the output power range 0-300 W, which creates plasma from the flowing working gas in a quartz nozzle. The gas flow rate is kept typically constant at 600 sccm but ratio of carrier gas and reactive gas is varied. The working gas handling system enables to make a defined mixture of up to three gases. The article is focused on comparative diagnostics of plasmas where Ar and He are used as carrier gases and N_2 and O_2 are used as reactive gases. The quartz nozzle ends in a vacuum chamber pumped out by a large oil backing pump. The pressure inside the chamber as well as the flow rate of the working gases are independently variable. We present results of diagnostic of generated plasma at nozzle exit as well as in the nozzle at different experimental conditions: variable absorbed power, total chamber pressure etc. The diagnostics of plasma column was performed by means of double probe measurement (mainly electron temperature is calculated from measured data) and by optical emission spectroscopy (rotational and vibrational temperatures are determined; overview of spectra serves for estimation of plasma composition).
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