Fig. 6

The motion of Al\(_2\)O\(_3\) particles is shown at a field strength of 4 kV/cm. a Particles move independently in the electric field. Their size is slightly enlarged for enhanced visibility here. b The particle position is shown over time. A perpetual motion between the lower grounded and upper high-voltage electrode occurs. For the charge characterization, the acceleration during the gap crossing (colored) is automatically quantified. The observed bouncing and resting do not influence the charge quantification (black) and are not considered by the tracking algorithm. The charge polarity is indicated by a plus and a minus.