electrical measurements

Anode activity in high current vacuum arcs leads to the formation of various high current modes and transitions between them. Intense material evaporation during the anode spot mode and formation of a neutral vapour cloud during the anode plume mode modify the arc plasma properties and, hence, can have a crucial impact in applications, like e.g. reduction of interruption performance of switching devices.

Low direct current arcs generated between Cu electrodes in atmospheric pressure air are investigated in relation to low-voltage switching. Electrical and optical measurements and high-speed imaging give insight into the dynamics of the arc. Side-on spectroscopy with a grating spectrometer and suitable optical imaging delivers spatially resolved spectral emission coefficients of three emission lines of the Cu atom. The experimental findings are compared with results from modelling.

The dataset provides the data related to the modelling of microdischarges in metal vapour of cadmium. Such microdischarges occur in a testing equipment for the safety assessment of electric devices for explosion protection. A one-dimensional unified non-equilibrium model that resolves the entire discharge gap is employed and simulations are conducted for a constant current of 60mA with gap lengths varying between 20 μm and 160 μm. These conditions match the experiment and enable a comparison with measured data.

A pre-study of free burning arcs between carbon electrodes for potential use in gasification processes is presented. Free-burning arcs offer the potential to be used without additional gas feed or significant changes to gas flows in established gasification systems as well as with minimal cooling requirements for improved energy efficiency. Direct current (DC) arcs with currents up to 200 A and power levels up to 40 kW have been operated in molecular gas mixtures of H2, CO and CO2.

The effects of nitrous oxide (N2O) in nitrogen (N2) on the development and morphology of sine-driven dielectric barrier discharges in a single-filament arrangement were studied. Detailed insight in the characteristics of the discharge and its development were obtained from electrical measurements combined with ICCD and streak camera recordings as well as numerical modelling. A miniaturised atmospheric pressure Townsend discharge (APTD) could be generated for admixtures up to 5vol% N2O in N2 although N2O is an efficient collisional quencher of metastable nitrogen molecules.

A study on the scalability of discharge characteristics of a single-filament dielectric barrier discharge (DBD) to a spatially one-dimensional multi-filament arrangement driven by the same high-voltage (HV) pulses was performed for a gas mixture of 0.1 vol% O2 in N2 at 1 bar. Both arrangements feature a 1 mm gap with dielectric-covered electrodes featuring two hemispherical alumina caps for the single-filament and two parallel alumina-tubes for the multi-filament arrangement.

Presented data was obtained from the analysis of the impact of the electrode proximity on the streamer breakdown and development of pulsed-driven dielectric barrier discharges (DBDs) in a singlefilament arrangement in a gas mixture of 0.1 vol% O2 in N2 at 0.6 bar and 1.0 bar. The gap distance was varied from 0.5 mm to 1.5 mm, and the applied voltage was adapted correspondingly to create comparable breakdown conditions in the gap. Fast electrical measurements provided insight into discharge characteristics such as the transferred charge and consumed energy.

The data set is related to a two-dimensional and stationary magneto-hydrodynamic model of a plasma spray torch operated with argon, which is developed to predict the plasma properties in a steady operating mode. The model couples a submodel of a refractory cathode and its non-equilibrium boundary layer to a submodel of the plasma in local thermodynamic equilibrium in a self-consistent manner. The Navier-Stokes equations for a laminar and compressible flow are solved in terms of low- and high-Mach number numerical approaches.

In this work we present for the first time a unified model of a low-current short-length arc between copper electrodes. The model employs one-dimensional fluid description of the plasma in argon and copper vapour at atmospheric pressure and the heat transfer in the electrodes made of copper. The solution of the particle and energy conservation of electrons and heavy particles is coupled with the solution of the Poisson equation, from which the self-consistent electric field is obtained. The operation of the non-refractory cathode is based on thermo-field emission.