Electrical potential measurement in plasma columns of atmospheric plasma jets

The electrical potential of plasma generated from an atmospheric plasma jet device with Ar or He gas is measured with a high voltage probe in a plasma column inside a tube as well as in the plasma ejected through the open end of the tube. When the double plasma jet devices with Ar-gas are operated by the opposite polarities of an ac voltage with a few kV at both ends of a glass tube, the electrical potential of plasma column is high at both ends of the column, while the electrical potential in the middle of the plasma column is a few tens of volts. When the plasma column is formulated with the double plasma jets of a high voltage electrode at one end of the glass tube and a grounded electrode at the other end of the tube, the plasma column potential decreases linearly from a high voltage to a very low value, as the measurement position moves from the side of high voltage to the grounded location. In the double plasma jets of He-gas operated by high voltages in opposite polarities, the ejected plasma jets are attractive to each other at the intersection, merging together and having the electrical potential of a few tens of volts. On the other hand, if the two plasma jet columns are operated by high voltages of same polarity the ejected plasma jets are repulsive to each other at the intersection, having the electrical potential of a few hundreds of volts and causing an electrical shock. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4766756]