Uncertainty Quantification of Electromagnetic Wave Propagation in Plasma Slabs Using Polynomial Chaos Expansion

When a hypersonic reentry vehicle travels through the dense atmosphere, the air surrounding it is partially ionized to generate a plasma sheath. The key plasma parameters, however, are rarely deterministic, and their stochastic effects may significantly alter the reflection properties. To more efficiently predict wave-plasma interactions, they are considered a necessary component in the analysis. Therefore, this article investigates the impact of parametric uncertainties on electromagnetic wave propagation through nonmagnetized, cold collisional plasma slabs. The plasma is modeled through its complex permittivity, and the wave interaction is formulated using the transmission matrix method for transverse electric (TE) and transverse magnetic (TM) polarization modes under oblique incidence. Uncertainty in the electron density, plasma thickness, electron collision frequency, and incidence angle is represented through random variables, and the resulting variability in wave reflectance is quantified using polynomial chaos expansion (PCE). Both regression-based and spectral projection formulations are considered and compared against Monte Carlo (MC) simulations. Numerical results show that PCE achieves accurate estimation of statistical moments of the reflectance at a fraction of the computational cost of MC sampling, in both the GHz and THz regions. The spectral projection method achieved at best a speed-up factor of over 200 compared to the MC method. The proposed framework enables efficient and interpretable uncertainty quantification (UQ) for high-frequency plasma-wave interactions relevant to hypersonic vehicle communication blackout and electromagnetic stealth applications.