A uniform description of the gas and plasma flow fields' refractive index

In this paper, a definition called the equivalent particle number density is introduced to describe and unify the refractive indexes of the gas and plasma flow fields. As a result, the uniform refractive index model can be described by three independent parameters—the specific composition, the probe wavelength and the equivalent particle number density. To verify whether the uniform description is feasible, the argon gas and argon arc plasma flow fields are chosen as two practical examples for experiment, while the refractive index measurements are achieved by moiré deflection tomography with the probe wavelength 635 nm. The distribution and the order of magnitude of the equivalent particle number density which is reconstructed via the new model, match well with the theoretically estimated results. This agreement implies that the uniform description is reasonable and effective.