Modeling of Plasma Formation During High-Power Microwave Breakdown in Air Using the Discontinuous Galerkin Time-Domain Method

Abstract

Rapid plasma formation and evolution during highpower microwave (HPM) air breakdown in an HPM device produce a macroscopic plasma shield to the microwave transmission, which can severely limit the performance of the device. In this paper, the electromagnetic (EM)-plasma interaction and the HPM breakdown in air are modeled by a nonlinearly coupled full-wave Maxwell and plasma fluid system under conditions of high pressure and high collision frequency. The resulting multiphysics and multiscale system is solved by a nodal discontinuous Galerkin timedomain (DGTD) method, which is uniformly high order in both space and time. To demonstrate the capability of the DGTD method in the modeling of the HPM breakdown problems, the air breakdown and plasma formation in a metallic aperture are simulated, from which the underlining physical process can be interpreted and better understood.Index Terms-Air breakdown, discontinuous Galerkin time domain (DGTD), high-power microwave (HPM), nonlinear modeling, plasma fluid model, plasma formation, plasma shielding.

An enhanced transient solver with dynamic p‐adaptation and multirate time integration for electromagnetic and multiphysics simulations

“…For pure EM problems, the numerical solution of Maxwell's equations is concerned. For multiphysics problems, the multiphysics interaction between EM waves and plasma fluids is used as an example, which is governed by the following coupled EM‐plasma equations: where μ and ϵ stand for permeability and permittivity of the medium, respectively, q e , m e , n , and stand for the electron charge, mass, number density, and velocity, respectively, and E inc stands for the incident electric field. In and , E and H are the secondary electric and magnetic fields radiated by the electron current J e =− q e n u .…”

“…The transport coefficients, including the electron–neutral collision ( ν m ) frequency, the electron diffusion ( D eff ), ionization ( ν i ), and attachment ( ν a ) frequencies, and the recombination ( r ei ) coefficient, are all nonlinear functions of the reduced effective electric field intensity E eff / p with p as the ambient air pressure and E rms the root‐mean‐square (RMS) value of the local total electric field ( E inc + E ) over one period of the EM operation at angular frequency ω . The detailed expressions of the transport coefficients can be found in the previous studies . It should be pointed out that other plasma models can also be used if other physical mechanism dominates .…”

“…It is noted that other choice of flux is also possible. For example, the local discontinuous Galerkin flux described in the study of Yan and Jin can be used where an artificial “wind" direction is specified.…”

“…For pure EM problems, the numerical solution of Maxwell's equations is concerned. For multiphysics problems, the multiphysics interaction between EM waves and plasma fluids is used as an example, which is governed by the following coupled EM-plasma equations [29][30][31] :…”

“…The detailed expressions of the transport coefficients can be found in the previous studies. [29][30][31] It should be pointed out that other plasma models can also be used if other physical mechanism dominates. 32 To enforce the two Gauss's laws and maintain the current continuity, divergence-cleaning and continuity preserving techniques can be further applied.…”