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The effects of the position of the current probe on electrical measurements as well as those of typical materials on the current of a He plasma jet during the interaction of the plasma jet with surface materials were investigated using a dielectric barrier discharge reactor, in which the two electrodes were isolated from ambient air by electrical insulating oil. Here, we demonstrate accurate discharge power measurement obtained by positioning the current probe between the two electrodes rather than on the ground wire. The emission current of the plasma jet increased sharply upon the interaction with a ground-connected metal surface, because in this case, the surface functioned as a second ground electrode. Similarly, important is that the average velocity of a plasma bullet can be estimated from the phase shift of the current waveforms at different positions. The phase shift can be monitored by an oscilloscope using a cursor tool during the plasma discharge process. The average velocity of the plasma bullets in this paper ranged from 56 to 266 km/s. [ABSTRACT FROM AUTHOR]

This work presents the effects of the insulation of ground electrode and operating parameters on CO 2 reforming of CH 4 to syngas in a coaxial-cylindrical dielectric barrier discharge (DBD) plasma reactor coupled with Ni/α-Al 2 O 3 catalyst. For the conventional plasma reactor, abnormal outside discharge inevitably ignites and develops from the ground electrode, giving rise to the formation of harmful substances (e.g. , NO x) and the waste of energy. The power dissipation for the conventional reactor therefore includes both that used for the dry reforming reactions and the loss of energy due to the air discharge. The new finding of this work is that by covering the ground electrode with an insulating oil jacket, not only the NO x formation is prevented but also the conversion rates, product selectivity and energy efficiency are largely enhanced by roughly 30, 10 and 100% at a specific energy input of about 47 kJ, respectively. The results are associated with the extinguishment of the discharge occurring outside the reactor, which is usually neglected when designing DBD reactors. Image 1 • Avoiding outside discharges by immersing the ground electrode in insulating oil. • Improvement of plasma-assisted catalytic dry reforming of CH 4 by oil immersion. • Increasing conversion rates, selectivity and energy efficiency by oil immersion. • Eliminating NO x emission using a plasma reactor with oil-immersed ground electrode. • An advanced dielectric barrier discharge reactor proposed for CO 2 reforming of CH 4. [ABSTRACT FROM AUTHOR]