Surface Plasmon Polaritons (SPP) dispersion and numeric port in COMSOL

In this video, I calculate the dispersion diagram for SPP at an air-plasma interface. The metal is described using Drude model. The dielectric is just air. The numeric port is used in COMSOL to launch the SPP mode at some frequency f0, sweeping this f0, we get the corresponding wave vector for the SPP and then draw the dispersion diagram for this mode.