Measurement and numerical modeling of the scattering and broadband absorption of microwaves by an arc plasma column

Measurements of scattering and absorption of microwave by an arc plasma column were obtained using a calibrating vector network analyzer with time domain option. An attempt to explain the measurement by modeling the plasma column as an infinite length lossy dielectric cylinder was also made. Two approaches are taken for the theoretical modeling: 1) the method of moments (MoM) and, 2) expansion in eigenfunctions. The MoM approach allows the inclusion of the density inhomogeneity in the plasma column but is the more computationally time-consuming of the two in obtaining solutions. It is shown that the eigenfunction approach obtains the solution rapidly for the near field while the MoM approach is more suitable when the desired observation point is many wavelengths away from the scattering plasma column. Comparisons of the calculated results with measurements lead to physical parameters for the plasma such as density and collision frequency and serve to validate the theoretical model.