current measurement

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.

Modelling results obtained using an extended reaction kinetics model (RKM) suitable for the analysis of weakly ionised, non-thermal argon plasmas with gas temperatures around 300K at sub-atmospheric and atmospheric pressures are presented. Modelling was performed by means of a time- and space-dependent fluid model for two different dielectric barrier discharge configurations as well as for a micro-scaled atmospheric-pressure plasma jet setup. The results are also compared with measurements, as well as with modelling data obtained by use of a previously established 15-species RKM.

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 provided data describe the discharge current in DBD obtained by fluid modelling using different values of for the secondary electron emission coefficient γ and and the relative permittivity of the dielectric barrier εr in comparison with the measured current at a pressure of 100 mbar and an applied voltage amplitude of 1.8 kV. Furthermore, the dissipated power obtained by model calculations for different values of γ and εr together with the measured power in dependence on the pressure is given.

A time-dependent, spatially one-dimensional fluid-Poisson model has been applied to analyse the impact of small amounts of tetramethylsilane (TMS) on the discharge characteristics of an atmospheric-pressure dielectric barrier discharge (DBD) in argon. Based on an established argon kinetics, it includes a reaction kinetics for TMS, which has been validated by measurements of the ignition voltage at the frequency f = 86.2 kHz for TMS amounts of up to 200 ppm.

Recent research of gas metal arc welding (GMAW) has proven that the sheath voltage dominates the total voltage fall in the current circuit and delivers most of the energy, which is finally transferred to the wire and the weld pool. This data set provides the results for droplet temperatures and the energy delivered to the wire anode in comparison with the sheath voltages. These quantities have been studied experimentally for a typical pulsed GMAW process in the one drop per pulse mode for mild steel under Ar with 2.5% CO2 with different peak currents from 350 to 650 A.

The relation between the voltage and the arc length in gas metal arc welding (GMAW) is an important characteristic. It depends on a complex distribution of the electric conductivity along the current path and does not depend on the arc length only. Based on electric measurements and the arc length determination from high-speed arc images, a simplified electrical model is introduced for a pulsed GMAW process. It shows the relation of voltage, current, arc length and free wire length and considers also their temporal evolution during the process in particular during the high-current phase.