More and more plasma-assisted processes are finding their way into technological applications and thus into various areas of our lives. Examples include surface treatment in joining technology or, more recently, applications in the health sector. However, the plasma-chemical or plasma-physical effects that occur in such processes are complex and have not yet been fully clarified, which means that empirical investigations are required. Therefore, a detailed diagnostic investigation of the plasmas used is indispensable for a better understanding of the processes as a whole. One of the most industrially used principle for plasma generation is a pulsed low-current high-voltage discharge with a power between 0.3 kW and 1 kW. Nevertheless, no previous work could yet be found in which the relevant plasma parameters, or more specific the electron number density and electron temperature, for such discharge were determined purely experimentally. Thus, the main objective of this work is to characterise a pulsed low-current high-voltage discharge under atmospheric pressure as holistically as possible by combining quantitative and qualitative diagnostic methods. In particular, the electron parameters should be determined experimentally by means of laser scattering. The scattering results show that, depending on the operating frequency, an electron density between 1.7E21 m^(-3) and 2.0E21 m^(-3) with electron temperatures in the range of 40000 K can be expected for a pulsed nitrogen discharge of this type at atmospheric pressure. A heavy particle temperature of about 6000 K is reached in the core of the discharge channel at nozzle exit, and drops downstream in the axis of the emerging plasma jet from 4000 K at 10 mm to 2000 K at 15 mm from the outlet. Due to the complex nature of the excitation processes of nitrogen, relatively slow electron recombination rates are observed so that the discharge channel, once ionised, does not extinguish between successive pulses but transitions from a glow discharge to a spark discharge with each pulse. Furthermore, the behaviour of the discharge was visualised with additional camera-based diagnostics. In summary, the results obtained in this work contribute significantly to the understanding of pulsed low-current high-voltage discharges at atmospheric pressure. The quantitative results can facilitate the validation and development of existing and new computational models to achieve a more accurate spatial composition of the plasma. This knowledge, extended by the findings of qualitative diagnostics, can be used to better adapt such discharges to specific applications in industrial or experimental environments.    «

More and more plasma-assisted processes are finding their way into technological applications and thus into various areas of our lives. Examples include surface treatment in joining technology or, more recently, applications in the health sector. However, the plasma-chemical or plasma-physical effects that occur in such processes are complex and have not yet been fully clarified, which means that empirical investigations are required. Therefore, a detailed diagnostic investigation of the plasmas...    »