Characterization of an atmospheric pressure plasma generated by a plasma torch array

Based on a capacitively coupled electrical discharge scheme, it is demonstrated that an array of plasma torches can be lit up simultaneously to form a dense plasma layer in the open air by a single ac power source. The number of torches is only limited by the power handling capability of the source. The measured nu - i characteristic of the discharge indicates that the torch is operating in the diffuse arc mode. Experiments have been performed to explore the effect of the plasma torches on the propagation of microwaves in an X-band rectangular waveguide by passing the plasma of the torches through holes in the top and bottom walls of the waveguide. The results show that the plasma torches can effectively attenuate microwaves. The wave-plasma interaction process is also analyzed numerically. The plasma parameters deduced from the theoretical model, by matching the numerical results with those of experiments, are shown to agree well with the experimental measurements. (C) 1998 American Institute of Physics. [S1070-664X(98)04310-9].