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Plasma diagnostics for the therapeutic applications
Kletzander, Lukáš ; Slavíček, Pavel (referee) ; Krčma, František (advisor)
Plasma, an ionized gas, is often regarded as the fourth state of matter. It has many useful applications, from arc welding to plasma displays. An emerging application of low-temperature plasma is in medicine, too. Reactive species generated in plasma discharges are the source of its usefulness in sterilization and supporting would healing. The detailed characterization of plasma is a key point before its real application in medicine. Thus, this is the main goal of this thesis. The subject of this thesis was the characterization of three new experimental applicators generating microwave plasma at 2,45 GHz in argon. The angle of argon flow into the applicator was the differentiating factor, the three versions have had angles of 0, 15 and 30 degrees. This angle affected the spatial distribution of the generated reactive species, as well as the discharge length and its stability. The reactive species, which included nitric oxide, oxygen radical and hydroxyl radical, were analyzed using optical emission spectroscopy. The diagnostic was done along the discharge axis for different mass flows of argon and at different power. In addition, photos of the discharges at selected powers and argon flows were taken. The lengths of the discharges were measured from the images. It was found out that the intensity of spectral transitions of the reactive species is dependent on the aforementioned parameters – mass flow of argon and supplied power. The intensity of these particles’ radiation related to their concentrations generally increased as more power was supplied to the applicator. The intensity subsequently decreased with increasing gas flow. The active region of the discharge also decreased as gas flow was increased. The length of the discharges was also dependent on supplied power and gas flow. The three versions of the applicators have shown differences – a maximum and a subsequent decrease in length with increasing gas flow were observed, the rate of the decrease being different for the three versions. The average length of the discharge was also different for the three applicators.
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