Study of RF Plasma Characteristics and Plasma Sterilization at the Atmospheric Pressure

Summary form only given. Plasma characteristics were studied through electrical and optical diagnostics for a volumetric (105 times 40 times 4 mm) RF plasma (MyPL; www.applasma.com) produced at the atmospheric pressure in the ambient air. The main discharge device has a conducting rod as a powered electrode, which is covered with a dielectric material and placed between two ground electrodes. A flow of the main supply gas is provided onto the conducting rod. The plasma length is extendable by having a longer rod. The plasma was produced at the peak to peak voltage of about 90 V with an ignition. The spatial uniformity of the visible emission was obtained through an image processing of the plasma image captured by a CCD camera. Varying the gas flow and the applied power, the uniformity along the length direction was maintained less than 10%. The gas temperature measured by a thermocouple and a fiber probe was between 300 and 400 K for the input power range of 40 and 100 W. The feasibility of plasma sterilization was also studied. An E-coli sample was treated with the plasma by varying treatment time, gas flow rate, treatment position etc. After the plasma treatment, the E-coli sample was cultured for 12 hours to study the plasma effects. So far, 30 s of treatment time is enough to kill every E-coli that there was none survived after the plasma treatment.