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In this study, we constructed a gliding arc to investigate the treatment of microorganisms in vegetables and fruits at atmospheric pressure using the microorganism Erwinia carotovora subsp. carotovora. The gliding arc was driven by direct current (DC) voltage between two knife-shaped electrodes. The treatment of potatoes using this method was effective against this pathogen. The disinfection duration was a few seconds, which is rather fast, with no overheating. The use of a thermal image sensor enabled us to determine the percentage of the concentration of individual temperatures in the arc region. Using this method, we were able to identify thermal and nonthermal regions of the arc. The temperature increase of the potatoes during plasma treatment by gliding arc at atmospheric pressure was only few degrees above room temperature, assuring a mild treatment of biomaterials.

To examine the effect of humidity on the operation of dielectric barrier dis-tween two parallel plates covered by dielectric in water mist. With increasing relative humidity (RH) levels, the signal current indicated different behaviors of the discharge. The discharge began as a multipeak Townsend discharge at low humidity levels. After increasing RH of the injected mist, the width and amplitude of current microdischarges decreased until they reached a diffuse discharge free from microdischarges. With discharge current gradually decreasing with increasing humidity, discharge power began to decrease but then increased continually of bacteria found in serum plasma.

We apply different cold atmospheric plasma (CAP) configurations to treat wheat seeds using (1) a direct atmospheric plasma jet (APJ) in the dry form, (2) indirect plasma-activated water (PAW) in the soaked form, and (3) plasma-activated mist (PAMI) in the wet form. Wheat seedling germination parameters including germination potential, germination index, vigor index, and shoot and root lengths are measured for different plasma treatment-time intervals. Seed germination and seedling growth of wheat specimens are enhanced compared to those of untreated controls. Indirect wet PAW and PAMI show higher wheat germination compared to that of dry direct APJ. During plasma treatment, a rise in hydrophilization of seed surface coat is accompanied by increased water uptake of treated seeds. Ozone generated by plasma shows an increase in all discharge conditions, but this increase is reduced for higher relative humidity values in the PAMI mode. During treatment, OH radicals that are generated by APJ increase largely near seed surfaces. Regarding seed germination, PAW shows a larger impact than PAMI. However, PAMI can be considered to be the more practical technique for treating large numbers of seeds at an industrial scale.

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