Characterization of a kHz atmospheric pressure plasma jet: Comparison of discharge propagation parameters in experiments and simulations without target

This paper quantitatively characterizes a kHz atmospheric pressure He plasma jet without target powered by a pulse of positive applied voltage. It focuses on a quantitative comparison between experimental measurements and numerical results of a two-dimensional fluid model using the same configuration, for different values of magnitude and width of pulsed applied voltage. Excellent agreement is obtained between experiments and simulations on the gas mixture distribution, the length and velocity of discharge propagation and the electric field in the discharge front. For the first time in the same jet, the experimentally measured increase of the electric field in the plume is confirmed by the simulations. The electron density and temperature, measured behind the high field front, are found to agree qualitatively. Moreover, the comparison with simulations shows that discharge propagation stops when the potential in the discharge head is lower than a critical value. Hence, pulse width and magnitude allow to control propagation length. For long pulses, the potential in the discharge front reaches this critical value during the pulse. For shorter pulses, propagation is determined by the pulse shape, as the critical value is reached around 90-130 ns after the fall of the pulse. The results suggest that the magnitude of this critical value is defined by the gas mixture at the position of the front.