Modeling and simulation of electromagnetically-interacting low-temperature plasma discharges for actively controlled metamaterials
In this work, we present a framework for computational modeling of microwave-induced nonthermal plasma discharges interacting with dielectric and conducting structures, with applications to actively-controlled metamaterials and photonic crystals. The discharge model is based on a low-temperature quasi-neutral description of the plasma with lumped chemistry for ionization, attachment and recombination. The first part of this work details the development of a local time-stepping strategy for the finite-difference time- domain method on an adaptive mesh. The algorithm is implemented on a quad/octree mesh in order to demonstrate its computational efficiency for plasma-metamaterial problems. In the second part of this work we study how dense low-temperature plasmas are generated by metamaterial and photonic crystal systems, as well as how they modify the system behavior. We show that the existence of a plasma in the vicinity of a metamaterial can be used to shift the characteristic resonance frequency of the system and reduce over- all system transmission due to absorption in the plasma. We demonstrate that in some instances, the presence of a plasma permits a surface plasmon polariton propagating mode with a corresponding low-frequency pass band. The final part of this work focuses on the development of an extended fluid model which accounts for nonlinear electron dynamics in the presence of strong electromagnetic fields. The influences of nonlinear electron dynamics on the plasma response are found to be dominated by the electron inertial effects and wave-induced magnetization. These effects are shown to lead to efficient harmonic generation in plasmas with spatial extent smaller than the wave skin depth and plasma frequency exceeding the wave frequency. Furthermore, magnetized electron gyration effects are shown to lead to an electromagnetic Hall drift, modified electron mean energy, and modified transport coefficients for cross-field diffusion and mobility.