Electric-Shock-Free Coupling of Double Atmospheric-Plasma Jets

The electrical potential of a plasma column is investigated, and the potential of a plasma plume exiting through the open end of the glass tube is measured for a pair of two plasma jets coupled by the operation voltage polarity. When the double plasma jet devices are operated by high voltages in the opposite polarities of ac voltage with a few kilovolts at both ends of a glass tube, the ejected plasma jets are attractive to each other at the intersection, merging and having the plasma potential of a several tens of volts. Therefore, electric shock would not be any problem when the merged plumes are exposed to biosubstrates. In contrast to the attractive coupling of different voltage polarities, if the two plasma jets are operated by the same voltage polarity of repulsive coupling, the ejected plasma jets are repulsive to each other at the intersection, having the plasma potential of a several hundreds of volts and causing an electrical shock.