Yongjun Hong

Extremely Low Numerical Dispersion FDTD Method Based on H(2, 4) Scheme for Lossy Material

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.

Extremely Low Dispersion Higher Order (2,4) 2-D-FDTD Scheme for Maxwell-Boltzmann System

An extremely low dispersive algorithm based on two-dimensional higher-order (2,4) (H(2,4)) finite-difference time-domain method is developed for calculating a Maxwell-Boltzmann system. To minimize large numerical errors near the plasma frequency, a two-step process is proposed. In the first step, the weighted sum of the H(2,4) and Yee schemes is obtained, and correction of the electron density and collision frequency of weakly ionized plasma is implemented in the second step. With this process, the proposed scheme accurately estimates the electron density and collision frequency of weakly ionized plasma. Lastly, two plasma problems are solved to verify the validity of the proposed scheme.

Numerical investigation of 3-D radar cross section of dielectric barrier discharge plasma

Dielectric barrier discharge (DBD) actuator which is efficient as a flow controller unexpectedly changes the radar cross section (RCS) of a target. Because plasma generated by DBD can attenuates electromagnetic wave, numerical investigation of 3-D RCS is required to analyze the effect of the plasma actuator on flying vehicles. Simplified plasma modeling is utilized to describe inhomogeneous distribution of DBD plasma. The calculated RCS diagram shows good agreement with experiments. The effect of DBD in monostatic RCS is totally different as the observation plane is changed. It shows notable distortion in the plane which is perpendicular to electrode array while overall pattern is still obviously maintained in parallel plane. It is due to the asymmetry from the electrode arrangement of the actuators and inhomogeneous plasma distribution. 3-D analysis is essential to comprehend the effect of DBD plasma in RCS in order to analyze the dissimilar change in various observation planes.

Subcell Maxwell-Boltzmann FDTD Method for Analyzing Thin Plasma Layer

Analyzing electromagnetic properties in plasma medium, it is difficult to numerically solve electromagnetic problem with thin plasma. In this paper, subcell Maxwell-Boltzmann FDTD method was proposed which is combined with Maxwell-Boltzmann FDTD and subcell FDTD method for analyzing plasma and electrically thin materials, respectively. Calculations of reflection coefficient and absorption rate error were performed by using 1D FDTD method. Reflection coefficient computed by applying the proposed method is in agreement with analytic solution. Absorption rate error analyzed by employing the proposed method is 1/10 times less than one by using conventional method.

Optimized higher order 3-D (2,4) FDTD scheme for isotropic dispersion in plasma

In this paper, an optimized higher order (2,4) 3-dimensional finite-difference time-domain (FDTD) method is applied in plasma. The optimized scheme uses the scaling factors and weighted sum of the standard FDTD method (Yees scheme) and the standard (2,4) higher order FDTD method (H(2,4)) proposed by Fang. The proposed scheme improves performance of phase and attenuation constant error over propagation angle without additional computational complexity compared with H(2,4). The maximum phase constant error of the proposed scheme is reduced by 99.998% of the H(2,4)s error.

Electromagnetic Characteristics of Dielectric Barrier Discharge Plasma Based on Fluid Dynamical Modeling

In this paper, plasma modeling is achieved using fluid dynamics, thereby electron density is derived. The way proposes the key to overcoming the limitations of conventional researches which adopt simplified plasma model. The result is coupled with Maxwell-Boltzmann system in order to calculate scattering waves in various incident angle. The first part is dedicated to perform plasma modeling in dielectric barrier discharge(DBD) structure. Suzen-Huang model is adopted among various models due to the fact that it uses time independent variables to calculated potential and electron distribution in static system. The second part deals with finite difference time domain(FDTD) scheme which computes the scattered waves when the modulated Gaussian pulse is incident. Founded on it, radar cross section(RCS) is observed. Consequently, RCS is decreased by 1~2 dB with DBD plasma. The result is analogous to the RCS measurement in other researches.