A new miniature high-frequency (HF) plasma source intended for bio-medical applications is studied using nitrogen/oxygen mixture at atmospheric pressure. This plasma source can be used as an element of a plasma source array for applications in dermatology and surgery. Nitric oxide and ozone which are produced in this plasma source are well-known agents for proliferation of the cells, inhalation therapy for newborn infants, disinfection of wounds and blood ozonation.Using optical emission spectroscopy, microphotography and numerical simulation, the gas temperature in the active plasma region and plasma parameters (electron density and electron distribution function) are determined for varied nitrogen/oxygen flows. The influence of the gas flows on the plasma conditions is studied. Ozone and nitric oxide concentrations in the effluent of the plasma source are measured using absorption spectroscopy and electro-chemical NO-detector at variable gas flows. Correlations between plasma parameters and concentrations of the particles in the effluent of the plasma source are discussed. By varying the gas flows, the HF plasma source can be optimized for nitric oxide or ozone production. Maximum concentrations of 2750 ppm and 400 ppm of NO and O 3 , correspondingly, are generated.

We examine the applicability of the Langmuir-type of characterization for atmospheric pressure plasma jets generated in a millimeter-size cavity microwave resonator at 2.45 GHz. Wide range I-V characteristics of helium, argon, nitrogen, air and oxygen are presented for different gas fluxes, distances probe-resonator, and microwave powers. A detailed analysis is performed for the fine variation in the current around the floating potential. A simplified theory specially developed for this case is presented, considering the ionic and electronic saturation currents and the floating potential. Based on this theory, we conclude that, while the charge carrier density depends on gas flow, distance to plasma source, and microwave absorbed power, the electron temperature is quite independent of these parameters. The resulting plasma parameters for helium, argon, and nitrogen are presented.

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The Integrated Microwave Atmospheric Plasma Source (IMAPlaS) operating with a microwave resonator at 2.45 GHz driven by a solid-state transistor oscillator generates a core plasma of high temperature (T > 1000 K), therefore producing reactive species such as NO very effectively. The effluent of the plasma source is much colder, which enables direct treatment of thermolabile materials or even living tissue. In this study the source was operated with argon, helium and nitrogen with gas flow rates between 0.3 and 1.0 slm. Depending on working gas and distance, axial gas temperatures between 30 and 250 • C were determined in front of the nozzle. Reactive species were identified by emission spectroscopy in the spectral range from vacuum ultraviolet to near infrared. The irradiance in the ultraviolet range was also measured. Using B. atrophaeus spores to test antimicrobial efficiency, we determined log 10 -reduction rates of up to a factor of 4.