Dusty plasma containing active spores of a micro-organism

Spores of a micro-organism (Bacillus subtilis var. natto) were injected into a plasma, which was generated by applying 13.56 MHz radio frequency power between parallel-plate electrodes in a chamber filled with Ar gas. A cloud of the spores was observed in the gas phase of the plasma. During levitation of the spores in the plasma, they were charged and irradiated by electrons and ions. A flux of massive ions caused significant physical damage to the surface of the spores. The flux was characterized by the orbit-motion-limit (OML) theory. The spores levitated in the gas phase tended to be inactivated more than those treated on the surface of the electrode covered with a Bohm sheath. This resulted from the flux calculated by the OML theory, which is few times greater than that in the Bohm sheath. Furthermore, the x-ray photoelectron spectroscopy made it clear that chemical bond components were changed by the flux.