Haiyan Xie

Theoretical and Experimental Study of Effective Coupling Length for Transmission Lines Illuminated by HEMP

This paper presents theoretical and experimental study of effective coupling length (ECL) for transmission lines illuminated by a high-altitude electromagnetic pulse (HEMP). Based on the transmission line theory, the ECL of transmission lines is analyzed theoretically and numerically first, then the ECL is applied to simply the analysis of nonuniform fields coupling with a power line, and some conclusions are validated experimentally. The impacts of the incident angles, the line height, and the ground conductivity on the ECL are given. The results show that the ECL for transmission lines illuminated by the HEMP defined by the IEC standard can range from tens of meters to hundreds of meters. The results also imply that the coupled current of a load is mainly determined by the field coupling with the line section, which adjoin the load and has the same length as the ECL. This conclusion is also validated by the experiment. This study can be useful to simply the solution of HEMP or nonuniform fields coupling with long lines or large-scale networks, which may be rather tricky when computing the problem directly.

Analysis and Efficient Estimation of Random Wire Bundles Excited by Plane-Wave Fields

The random wire bundle is an important factor resulting in the randomness of the interferences. This paper studies the efiect of random wire positions due to the bundle rotation on the coupling with external flelds and presents an e-cient method to estimate the averages and standard deviations of the voltages and powers induced on the loads. Three conflgurations of a four-wire bundle under external flelds are investigated by using the Baum-Liu-Tesche equation in the frequency domain and together with the inverse Fourier transform in the time domain, and the results show that the induced voltages and powers change as sine functions when the bundle rotates. The proposed method can estimate the averages and standard deviations of the induced voltages and powers quickly, just by three times repeated analysis, and the results agree well with those obtained statistically.

INFLUENCE ANALYSIS OF STOCHASTIC TRANSLATION OF TRANSMISSION LINES OVER GROUND

This paper proposes a method for the quick estimation of the average voltages at terminal loads when the transmission line translate randomly and analyzes the sensitivities of the loads’ voltages to the translation. Because nonuniform transmission lines can be approximated as n-cascaded uniform lines, the study of uniform lines is the basis. Based on the transmission-line equations, the equations are derived to estimate the average voltages, the voltage variations, and the sensitivity of the voltage to the random translation when transmission lines have random translation in their cross sections. With these equations, the average voltages at the loads, the probability distributions of the voltage variations, and the sensitivity of the voltage to the random translation can be obtained quickly. A two-wire line over the ground is studied by using the proposed method. The average voltages and the voltage variations’ probability distributions agree well with those via the Monte Carlo (MC) method and the proposed method is more efficient. The results show that the sensitivities of the voltages at the loads to the random height increase with the terminal sources but decrease with the height.

Supplements to “Theoretical and Experimental Study of Effective Coupling Length for Transmission Lines Illuminated by HEMP”

A previous paper studied the effective coupling length (ECL) for transmission lines illuminated by high-altitude electromagnetic pulse (HEMP) theoretically and experimentally. However it did not consider the effect of the relative dielectric constant of the ground on the ECL. This paper studies the effect of the relative dielectric constant.

Empirical Formula of Effective Coupling Length for Transmission Lines Illuminated by E1 HEMP

This paper presents empirical formulas of the effective coupling length (ECL) for the transmission lines illuminated by the horizontally or vertically polarized E1 HEMP, which is defined by the IEC standard. Based on the analysis and the numerical data of the ECL, the empirical formulas are developed through fitting first. Then, the empirical formulas are inspected and the results show that the empirical formulas can cover the range of the numerical values of the ECL well. At last, the empirical formulas are adopted to simplify the analysis of the HEMP coupling with a transmission line network. The results show that the ECL can greatly simplify the computation of the HEMP coupling with large transmission line networks but is not suitable for the line which the E1 HEMP coupling with is weak.

Verification of FDTD code using the method of exact solutions

Verification & Validation (V&V) attract more and more interests now and are extensively used in computational electromagnetics. In this paper, the method of exact solutions (MES) which is important in code verification is introduced by explaining the flow chartand the important glossaries and concepts of this method are explicated too. The process of global error evaluating by the approach of L2 norm of the numerical simulation is commentated. Finite-difference time-domain (FDTD) arithmetic is chosen for the application of code verification by MES and the convergence rate and order-of-accuracy of FDTD are analyzed. The exact solution is selected and code verification using MES is given by comparing the observed order-of-accuracy of the numerical simulation result with the theoretical analysis result. This verification method would be useful in FDTD software development.

Simulation method of charge collection mechanism in CVD diamond detector

Mechanism of charge collection is an important factor for improving the performance of diamond particle detector. With semiconductor device simulation software GSRES, numerical simulations of transport properties of carriers in diamond are carried out. The important material properties, for instance, energy gap and ionization energies, which affect in simulation are set same to pure CVD diamond with no impurity. The physical processes of transport of carriers is numerically researched by the drift-diffusion model, and the SRH recombination mechanism in semiconductor material is the main cause of the loss of charge as simulation results show. Other parameters, as electric field intensity, incident depth and lifetime of carrier, which influences the charge collection rate is studied. The simulation results are compared to theoretically analysis, and show well agreement. This numerical research method would be useful in CVD diamond detector development and improvement.

Electro-thermal characteristics of PIN diode under HPEMP

Electrothermal characteristics of PIN diode under the injection of two types of high power electromagnetic pulse signals are numerically simulated by a self-developed semiconductor device simulation GSRES. The curves of burn out time and amplitude of injection electromagnetic pulse (EMP) and high power microwave (HPM) signals are calculated. Response of carriers in diode is numerical simulated. As simulation results show, under the injections of EMP signals, the charge is concentrated in the PN junction, and the peak value of electric field and the hot-dot of device is in the same position; While under the injections of HPM signals, the charge is concentrated in middle part of device, and the peak value of electric field and the hot-dot of device is in the same position. Temperature in the diode rises slower when the frequency of the HPM signals are increasing. These results can be used in radiation hardening for PIN diode limiter.

Thermal study of MOSFET under HEMP

A simulator based on drift-diffusion physics model is used in this paper to study the electro-thermal response of MOSFET under HEMP by setting induced voltage signals to the electrode of the device. The temperature of the MOSFET rises if the amplitude of forward-biased induced signal is greater than threshold of the device and falls down either the induce signal is less than threshold or it is forward-biased. In heating process, heat generated by electro-thermal effect is concentrated in one end of the channel that close to drain electrode and makes it to be a hot-dot, while in cooling or heat conduction process, the distribution of temperature tends to be uniformity in the middle of the channel. The intense and acutely varying electric field in the hot-dot leads to the generation of Joule heat as numerical result shows and begets this position the vulnerability of MOSFET under HEMP interference. Simulation result can be applied in damage mechanism analysis and harden design of MOSFET against the HEMP.

Efficient Evaluation of Multiconductor Transmission Lines With Random Translation Over Ground Under a Plane Wave

This paper presents an efficient evaluation method for multiconductor transmission lines with random translation over an infinite and perfectly conducting ground under a plane wave. Based on the assumption of small translation quantity, the equations for the estimation of average induced voltage, induced voltage variation, and the probability distribution of the voltage variation are derived. The average induced voltages and the probability distribution of the voltage variation estimated by the proposed method are in a good agreement with those via the Monte Carlo method but the proposed method is more efficient. The relative sensitivity of the induced voltage to the height approximately equals the inverse of the line height, which can be applied to evaluate the influence induced by the random translation of the line quickly, especially in the low frequency range.