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Nonthermal gas discharges at atmospheric pressure, such as dielectric barrier discharges are currently investigated for low-temperature packaging sterilization in order to reach the conditions required for aseptic food packaging. In particular, understanding the basic sterilization mechanisms and the enhancement of the main bacterial reduction pathways are the goals of our investigations. For this purpose, germ reduction experiments were carried out with Bacillus Subtilis and Aspergillus Niger spores using different gas mixtures and plasma conditions with the direct and the indirect influence of barrier discharges. In order to analyze the contribution of UV radiation during plasma germ deactivation, experiments with different excimer UV lamps, also driven by barrier discharges in special UV-emitting gas mixtures, have been carried out. Results of germ reduction experiments using barrier discharges and prospects for atmospheric discharge systems, suitable for industrial packaging sterilization, are presented in this paper

We present a so-called cascaded dielectric barrier discharge (CDBD) set-up. Compared to standard single-gap discharge set-ups, the cascaded arrangement uses an additional UV-transparent dielectric to form two separated discharge gaps. These can interact electrically and by transmission of UV light. Investigation of plasma properties is done by emission spectroscopy and by measurement of the single filament charge transfer. Clear differences in CDBDs compared to single-gap discharge arrangements are demonstrated. The CDBD set-up shows a smaller single filament charge transfer if a UV-transparent dielectric is used and-for both gaps-we obtain a higher conversion efficiency in the UV range than for a single-gap discharge.

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Summary form only given, as follows. Environmental and economical needs for food or health care packaging require the development of new efficient low-temperature sterilisation techniques. We investigate the application of non-thermal, atmospheric pressure plasmas for sterilisation of thermolabile plastic packaging materials like polyethylene terephthalate (PET). The investigation resulted in UV radiation as one main inactivation pathway but also plasmachemical effects occur. In order to enhance the UV irradiance on the sample a new stacked setup combining planar UV emission (e.g. from excimer light sources) with dielectric barrier discharge (DBD) plasma has been built. Experimental results that show a significant increase of sterilisation efficiency for spores of bacillus subtilis compared with standard DBD setups are presented. Almost sterile packaging can be reached now within a few seconds with the described setup

The paper presents the results of an investigation into the thermal and optical characteristics of alpha-type dual-mirror grazing incidence collectors for Extreme Ultra-violet Lithography integrated into a tin-fueled discharge produced plasma source. The performance of the system is assessed at various power levels and temperature conditions. The thermal and the optical data, in particular images at extra-focal planes behind the intermediate focus, are compared to the predictions of the thermo-optical model of the system. The data we present provide verification of the models used to design the collector and validation of the thermo-optical modeling approach for design of future generations of collectors.