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The recent progress in plasma medicine as well as biomedical aspects of plasma physics over the last years have enhanced the need for experimental plasma devices which are capable of producing non‐thermal atmospheric pressure plasmas. These plasma sources are used for studying the effect of non‐thermal plasmas on biological samples of different nature. In this paper we present such an easy to build low cost apparatus that can be used for scientific as well as for educational purposes. Directions for the construction of the device are given and the basic plasma parameters are investigated. The characterisation of the experiment was done by electrical diagnostics for the measurements of the plasma potential in combination with optical emission spectroscopy. The latter is used for the determination of the excitation temperature of the plasma and the electron density. Furthermore the influence of the produced plasma on yeast cells is demonstrated. The produced plasma is characterised in different ways and it was found that the feeding gas has also a considerable impact on the radio frequency wave form of the source. It is also demonstrated that the constructed plasma source is capable of producing non‐thermal plasma that hinder cell growth of yeast colonies on a agar substrate. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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In this paper, we present systematic measurements of the basic plasma parameters of inverted fireballs (FBs) in a helium plasma for the first time. Inverted FBs in helium with a diameter of 10 cm are generated in a highly transparent hollow electrode via impact ionisation of accelerated electrons from an existing background plasma. The measured quantities are the plasma potential, the electron density and the electron temperature. The dependence of the plasma parameters on the discharge current was studied experimentally inside as well as outside the inverted FB. Furthermore, estimations of the neutral gas temperature inside the inverted FBs are made and possible explanations of the creation of macroscopic gas flows from the inverted FBs are given. It is shown in this paper that due to efficient thermalisation of electrons with neutrals the gas temperature inside the inverted FB can reach several thousand Kelvin, which also leads to a thermal equilibrium of ions and electrons inside this plasma structure.