Udo Krohmann

Microwave-based characterization of an atmospheric pressure microwave-driven plasma source for surface treatment

A plasma source operating at atmospheric pressure by continuous or pulsed microwave at 2.45 GHz with a maximum power of 1.7 kW is developed for surface treatment applications. The microwave power is coupled into a cylindrical cavity used as a process chamber. The device characteristics are studied in detail using a simple network analysis and finite integration technique simulations. Experimental results are compared with the outcome of the model. The TM01 mode in the process chamber is found to be appropriate for surface treatment. The results obtained are used to optimize and simplify the device performance and operation. It has been found that the electric field strength, responsible for plasma ignition, and the microwave power coupling into the plasma demonstrate a contradictory course—a maximum field corresponds to a minimum power in-coupled. A set of parameters representing a compromise between stable plasma ignitions and proper plasma treatment has been found.

Antimicrobial Treatment of Heat Sensitive Products by Atmospheric Pressure Plasma Sources

The technological potential of non-thermal plasmas for the antimicrobial treatment of heat sensitive materials is well known. Despite a multitude of scientific activities with considerable progress within the last years the realization of industrial plasma-based decontamination or sterilization technology remains a great challenge. The aim of the work presented in this contribution is to demonstrate the applicability of plasma-based processes for the antimicrobial treatment on selected, heat sensitive products. The idea is to use modular and selective plasma sources. These plasma sources are driven at atmospheric pressure due to its technological advantages (avoidance of vacuum devices and batch processing). According to the specific requirements given by the product different plasma sources, namely rf-driven plasma jets, microwave-driven air plasmas are used.