Multiphysics Analysis of Plasma-Based Tunable Absorber for High-Power Microwave Applications

Power handling capability of a tunable plasma-based multilayer absorber is studied using multiphysics analysis, then validated by experimental data. The proposed two-pole absorber is based on conductor-backed thickness customizable high-order bandpass frequency-selective surfaces (FSSs). Such technique allows simple integration of the tuning elements, while simultaneously providing the option to realize FSSs (including absorbers) with specific/desired thicknesses and transfer responses. Lossy magnetodielectric slabs, used to absorb electromagnetic (EM) energy in the $C$ -band, are added between the metallic layers. The lossy slabs are perforated to host discrete, electrically tunable, ceramic gas-encapsulating chambers (plasma-shells), enabling dynamic control of the absorption spectral band. To study the power handling capability of the proposed multilayered tunable absorber, dielectric and air breakdowns within the device are numerically emulated using EM simulation by quantifying the maximum field enhancement factor (MFEF). Furthermore, a comprehensive thermal analysis using a simulation method that couples EMs and heat transfer is performed for the absorber under high-power continuous microwave excitations. Since the heat generated within the absorber is a primary concern, the steady state as well as transient state temperature distributions have been evaluated for various incident power densities. The performance of the proposed absorber is validated for a prototype having a finite size of $13\times13$ cm2.