High Power Electromagnetic Pulse Research Articles

High Power Electromagnetic Pulse Damage Effect of a Low Noise Amplifier

Low noise amplifier (LNA) is the most sensitive component in the front end of a wireless communication system, which is very vulnerable to coupling attack of high-power electromagnetic pulse (HPEMP). This paper first analyzes the damage mechanism of a high-power electromagnetic pulse to a low noise amplifier, then designs the damage experiment of high-power electromagnetic pulse injection to the low noise amplifier, and verifies the damage mechanism and damage threshold of a certain radar low noise amplifier. The experimental results show that the LNA is not affected by the linear effect of high-power electromagnetic pulse. When the high-power electromagnetic pulse exceeds the damage threshold, thermal melting occurs between the FET grid sources in the device, causing permanent damage to the LNA and performance failure. This conclusion can provide data support for the high-power electromagnetic pulse protection design of this type of LNA.

Measurement of high-power transient electromagnetic pulse field with integrated photonic electric-field sensor

To satisfy certain special requirements for high-power transient electromagnetic pulse (EMP) field measurements, such as high electric field intensity, broad bandwidth, fast rise time, and compact size, here is described an integrated electro-optic sensor. The frequency response in the range from 100 kHz to 12 GHz and the time-domain input/output characteristics of a sub-nanosecond EMP field with an intensity from 5 to 100 kV/m were experimentally characterized. The sensor was demonstrated to measure the time-domain waveform of the ultrawideband EMP field signals with a rise time of 0.35 ns and bandwidth of 1 GHz. In addition, the minimal detectable electric field strength was 16 mV/m/Hz1/2 in the frequency domain, and an intense sub-nanosecond electromagnetic pulse with a peak amplitude of 100 kV/m was observed in the time domain. The reported sensor is expected to be broadly used for intense EMP measurements.

Research on electromagnetic coupling characteristics of UAV circuits in the Complex electromagnetic environment

The overall circuit model and Complex electromagnetic environment model of a typical UAV are built to explore the survivability of multirotor in the complex electromagnetic environment. The composite theoretical calculation model of the metal cavity aperture coupling and internal circuit coupling is constructed using the established UAV circuit model, which is based on the equivalent magnetic dipole algorithm and the FDTD algorithm. The terminal coupling voltage in the UAV circuit and the electromagnetic field distribution inside the metal cavity are estimated. CST software is used to simulate the response of UAV circuits in the same condition, and the correctness of the theoretical calculation model is confirmed. Then, the terminal coupling voltage of the PCB is used to create an electromagnetic coupling efficiency model. The findings reveal that the constructed composite theoretical model can accurately characterize the electromagnetic coupling characteristics of UAV circuits in the complex electromagnetic environment, with an error range of 1%~8%. When comparing the terminal coupling voltage of PCB in various complicated electromagnetic environments, the High-power microwave (HPM) has the maximum coupling efficiency. HPM initially causes the UAV circuits to attain the damage threshold under identical event conditions and target specifications. The findings could be used as a guide for multirotor circuit board protection in the complex electromagnetic environment, as well as for the development of high-power electromagnetic pulse weaponry.

Mechanism Analysis and Multi-Scale Protection Design of GaN HEMT Induced by High-Power Electromagnetic Pulse.

Currently, severe electromagnetic circumstances pose a serious threat to electronic systems. In this paper, the damage effects of a high-power electromagnetic pulse (EMP) on the GaN high-electron-mobility transistor (HEMT) were investigated in detail. The mechanism is presented by analyzing the variation in the internal distribution of multiple physical quantities in the device. The results reveal that the device damage was dominated by different thermal accumulation effects such as self-heating, avalanche breakdown and hot carrier emission during the action of the high-power EMP. Furthermore, a multi-scale protection design for the GaN HEMT against high-power electromagnetic interference (EMI) is presented and verified by a simulation study. The device structure optimization results demonstrate that the symmetrical structure, with the same distance from the gate to drain (Lgd) and gate to source (Lgs), possesses a higher damage threshold compared to the asymmetrical structure, and that a proper passivation layer, which enhances the breakdown characteristics, can improve the anti-EMI capability. The circuit optimization results present the influences of external components on the damage progress. The findings show that the resistive components which are in series at the source and gate will strengthen the capability of the device to withstand high-power EMP damage. All of the above conclusions are important for device reliability design using gallium nitride materials, especially when the device operates under severe electromagnetic circumstances.

Coherent x-ray radiation induced by high-current breakdown on a ferrite surface

For the first time observed that at the initial stage of a high-current discharge, a low-divergence short (<2 ns) electromagnetic pulse is formed over a ferrite surface. The 50% part of the energy spectrum of this pulse lies in the region of sufficiently hard x-ray radiation (hν > 1 keV) with an energy of 0.6 mJ and an average power of 0.3 MW. The radiation propagates parallel to the surface in the anode direction with the angle divergence <2°. The high directionality of the radiation in absence of the aperture-limiting devices for the radiation beam and the quadratic dependence of the spatial radiation energy flux density on the length of working part of the ferrite prism points to the coherent nature of the observed radiation. A possible generation mechanism of the radiation is proposed. It is based on the short-lived magnetization of the ferrite plots by a high-power electromagnetic pulse and the subsequent coherent interference of unit waves irradiated by these plots.

Influence of gate voltage dependent piezoelectric polarization on damage effect of GaN HEMT induced by high power electromagnetic pulse

In this paper, the influence of gate voltage dependent piezoelectric polarization on the damage effect of GaN HEMT induced by high power electromagnetic pulse was investigated in detail. Firstly, the necessity of considering gate voltage dependent piezoelectric polarization charge is stated theoretically. Secondly, by adding the polarization vector of z-axis PZPE, the modified polarization model is constructed. Then series of gate injection experiments were carried out with the help of TCAD simulation software to analysis the damage effect and the influence of gate voltage dependent piezoelectric polarization on the damage threshold of GaN HEMT caused by high power EMP. The results show that the threshold power and threshold energy of the device are reduced due to the temperature rise of the device becoming steeper at the same injected power and the damage time of the device shorter when considering the gate voltage dependent piezoelectric polarization. This conclusion is very important for device design using GaN materials especially when the device operates under high voltage conditions.

High-Power Electromagnetic Pulse Exposure of Healthy Mice: Assessment of Effects on Mice Cognitions, Neuronal Activities, and Hippocampal Structures.

Electromagnetic pulse (EMP) is a high-energy pulse with an extremely rapid rise time and a broad bandwidth. The brain is a target organ sensitive to electromagnetic radiation (EMR), the biological effects and related mechanisms of EMPs on the brain remain unclear. The objectives of the study were to assess the effects of EMP exposure on mouse cognitions, and the neuronal calcium activities in vivo under different cases of real-time exposure and post exposure. EMP-treated animal model was established by exposing male adult C57BL/6N mice to 300 kV/m EMPs. First, the effects of EMPs on the cognitions, including the spatial learning and memory, avoidance learning and memory, novelty-seeking behavior, and anxiety, were assessed by multiple behavioral experiments. Then, the changes in the neuronal activities of the hippocampal CA1 area in vivo were detected by fiber photometry in both cases of during real-time EMP radiation and post-exposure. Finally, the structures of neurons in hippocampi were observed by optical microscope and transmission electron microscope. We found that EMPs under this condition caused a decline in the spatial learning and memory ability in mice, but no effects on the avoidance learning and memory, novelty-seeking behavior, and anxiety. The neuron activities of hippocampal CA1 were disturbed by EMP exposure, which were inhibited during EMP exposure, but activated immediately after exposure end. Additionally, the CA1 neuron activities, when mice entered the central area in an Open field (OF) test or explored the novelty in a Novel object exploration (NOE) test, were inhibited on day 1 and day 7 after radiation. Besides, damaged structures in hippocampal neurons were observed after EMP radiation. In conclusion, EMP radiation impaired the spatial learning and memory ability and disturbed the neuronal activities in hippocampal CA1 in mice.

High-Power Electromagnetic Pulse Effect Prediction for Vehicles Based on Convolutional Neural Network

This study presents a prediction model for high-power electromagnetic pulse (HPEMP) effects on aboveground vehicles based on convolutional neural networks (CNNs). Since a vehicle is often located aboveground and is close to the air-ground–half-space interface, the electromagnetic energy coupled into the vehicle by the ground reflected waves cannot be ignored. Consequently, the analysis of the vehicle’s HPEMP effect is a composite electromagnetic scattering problem of the half-space and the vehicles above it, which is often analyzed using different half-space numerical methods. However, traditional numerical methods are often limited by the complexity of the actual half-space models and the high computational demands of complex targets. In this study, a prediction method is proposed based on a CNN, which can analyze the electric field and energy density under different incident conditions and half-space environments. Compared with the half-space finite-difference time-domain (FDTD) method, the accuracy of the prediction results was above 98% after completing the training of the CNN network, which proves the correctness and effectiveness of the method. In summary, the CNN prediction model in this study can provide a reference for evaluating the HPEMP effect on the target over a complex half-space medium.

Improved FDTD Method for Coupling Analysis of a Dielectric-Coated Wire Above Rough Soil Surface Under HPEM Pulse

An improved finite difference time domain (FDTD) method is proposed to calculate the transient coupling of a dielectric-coated wire above the rough soil surface under the high power electromagnetic (HPEM) pulse. The improved method is based on the domain decomposition technique, in which the dielectric-coated wire and the rough surface are allocated into the target subdomain and the rough surface subdomain, respectively. The reflected waveform from the rough surface is computed by applying the FDTD method combined with the time-domain Huygen's technique. The incident field on the target subdomain is calculated through the superposition of the excitation fields generated with the directly incident wave and the reflected wave from the rough surface. The near-field distribution and the energy-flux density (EFD) inside the dielectric-coated wire are simulated by running the FDTD in the target subdomain. The accuracy and high efficiency of the improved method are validated and demonstrated by comparing with the conventional FDTD method. Finally, the influences of some parameters related to the rough soil surface and dielectric-coated wire on the EFD are analyzed through the typical examples.

Generation of high-power electromagnetic pulses and its application to radiation effect research: A review

<p indent=0mm>This study reviews the research progress of high-power electromagnetic pulse generation. It introduces the physical model, different technologies, and the experimental generation of ultrafast, ultrashort, and ultra-high-power electromagnetic pulses. Progress on the radiation effects of electromagnetic pulses and the measured damage thresholds of microcontroller and photo-electronic devices are also discussed. Finally, future research prospects in this field are suggested.

Design of Compact Solid-State Modulator for High-Power Electromagnetic Pulse Generation

The proposed compact solid-state modulator for the generation of high-power electromagnetic (HPEM) pulses uses a lithium polymer battery as the input power source and is capable of achieving a 100-Hz pulse discharge rate with a peak voltage of 400 kV for 2 min. The developed pulse generator consists of two charging units. The primary charging unit is designed to work with 200-A battery current, which increases switching losses and temperature increments at the main switch. To compensate the problems, a half-bridge three-phase structure is connected to transformers via the proposed delta-star connection that decreases the turns ratio of the three-phase transformer effectively. Furthermore, the resonant components are intentionally placed on the secondary side of the three-phase transformer, which is characterized by low current and high voltage conditions. The secondary charging unit uses the resonance between the two capacitors, and the inductor must protect not only the controller, which is susceptible to HPEM pulse effects, but also the output rectifying diodes of the primary charging unit from the peak 20-kA pulse discharging effect. The design procedures and analysis are verified with simulations for each charging unit. The experimental results using various loads, including the actual tesla transformer, validate the system performance and confirm a 94% power efficiency with a peak power density of 431 W/L.

Kron's Model for the Radiated Immunity and Signal Integrity Analysis of Multi-Conductor Shielded Cable

This article develops an innovative model of shielded cable illuminated by high power electromagnetic pulse based on the tensorial analysis of network. The succinct model under study is competent in quick analysis of the radiated immunity (RI) and signal integrity (SI) considering skew, unbalanced impedance, and other nonideal factors for high-speed application. A Kron's topology graph describing coupling relation among ports of shielded cable is established. The Kron–Branin (KB) general metric of the unbalanced multiconductor cable RI and SI problem is formulated afterward. A 2 m twinax cable over a ground plane is calculated using KB model and the results agree well with the SPICE model and the simulation of CST. Skew, mixed-mode S-parameters variation, and radiation immunity with respect to various typical unbalanced factors are analyzed. The computational efficiency of KB model is compared with the SPICE model and CST. This inventive model provides system designers with a fast calculation tool in frequency domain for performance evaluation of long cable in a harsh electromagnetic environment.

Research on the damage mechanism of the PIN limiter diode SMP1330 under EMP

Overheating is the cause of PIN limiter diode damage under a high-power electromagnetic pulse, but the physical mechanism for overheating has not previously been clarified and thus is studied in this paper through measurements and simulations. The damage process of the PIN limiter diode SMP1330 is measured first, where a drastic voltage drop is observed. The mechanism causing the voltage drop is analyzed by using semiconductor device simulation. It is found a negative differential resistance is formed by the avalanche process after the first breakdown. This causes current filamentation and local overheating at the filament position, which overheats and, therefore, damages the diode.

Coupling of Wideband Radiated IEMI to Cables Above Ground

In this paper, transmission-line (TL) theory is applied to formulate a worst-case analysis for the assessment of wideband intentional electromagnetic interference radiated onto a cable harness (with terminal units) above ground. Given the bandwidth and the energy density of the high-power electromagnetic pulse impinging on the cable, the pulse spectrum maximizing the peak value of the common-mode voltage waveform induced at a cable end is obtained. Unlike in a full-wave solution to the problem, the proposed TL model allows for, first, deriving closed-form expressions in the special case of a cable terminated in a matched load at the opposite end; second, computationally efficient evaluation of the spectrum for any other loading conditions. The obtained results clearly unveil the impact of the system parameters (cable length, height, terminal loads, and pulse bandwidth) on the statistics of the worst-case voltage peak for the random direction of incidence and polarization.

Predicting the Effects of HPEM Radiation on a Transmission Line Terminated With Linear/Nonlinear Load in Perforated Metallic Enclosure Using FDDM/VF

High-power electromagnetic (HPEM) pulse affects electronic devices that have linear/nonlinear characteristics. To protect the electronic circuit board, the use of metallic enclosure as an electromagnetic shield is one of the best methods. Apertures and slots in the body of metallic enclosure is the path of coupling HPEM fields to electronic board and equipment. In this article, we are following to evaluate the effect of HPEM fields on the microstrip line with nonlinear load that is enclosed by perforated metallic enclosure. For this purpose, a method has been proposed that uses the benefits of the time domain analysis and frequency domain analysis. The whole electromagnetic system of the problem is decomposed into linear and nonlinear subsystems. Thevenin’s equivalent circuit of the linear subsystem from the connection point to nonlinear load has been evaluated by using finite difference delay modeling (FDDM) in the frequency domain. By vector fitting method and by using rational functions, Thevenin’s equivalent circuit is converted to circuits with RLC elements and the time domain voltage source. This circuit can be analyzed in Spice. Results obtained from this model are well adopted with those that are calculated by CST-Microwave studio for linear and nonlinear load and have better time efficiency.

Worst-Case Wideband Radiated IEMI for Unshielded and Shielded Cables: A Statistical Analysis of the Main Influencing Parameters

This study deals with intentional electromagnetic interference and presents statistical analysis of common-mode and differential-mode disturbances induced in unshielded or shielded cables by a radiated, wideband, high-power electromagnetic (HPEM) pulse. The quantity of interest is the worst-case (i.e., maximum) peak in the time-domain waveform of the voltage that can be induced in a terminal interface of the harness by an HPEM pulse with specified bandwidth and energy density. Statistics is required to account for the lack of knowledge on the direction of incidence and polarization of the impinging plane-wave field, which are treated as random variables. Consequently, the worst-case induced-voltage peak is characterized by a cumulative distribution function (cdf). The analysis puts into evidence the different properties of the cdf for unshielded and shielded cables, with reference to the influence exerted by the main system parameters, including the cable length, the height above ground, and terminal impedances.

Measurement of the electric field strength generated in the experimental chamber by 10 TW femtosecond laser pulse interaction with a solid target

Results are reported on a direct measurement of the electric field of a strong electromagnetic pulse generated through laser interaction with a thick solid target inside an experimental chamber of a 10 TW femtosecond laser. Two Prodyn FD5C conductive D-dot probes were used to demonstrate that the signal-to-noise ratio in this arrangement is 10:1 and that probes are sensitive to the component of the electric field parallel to their axis. Maximum value of the electric field on the order of 18 kV/m was obtained for a 50 fs laser pulse with 270 mJ energy on target. To ascertain a correct estimate of the recorded electric fields a comparative study was performed in an anechoic chamber with two other D-dot probes, involving electromagnetic pulses emitted by a tube antenna and the high-power broadband electromagnetic pulse generator. Some frequency dependence in the FD5C equivalent area was found below 1 GHz.

Scattering by an Electrically Large Slot in a Rectangular Cavity

This paper presents a new approach to describe the scattering of an electrically large slot aperture between half-space and a rectangular cavity. The developed method generalizes known theories for the scattering of electrically small apertures and presents a general and understandable formalism for correctly calculating the induced scattering moments. The theory is first developed and validated for the electrically long thin wire in free space. Then, it is applied to describe the scattering of an electrically large thin slot in an infinite screen and backed by a rectangular cavity. The results can be used to determine the effects of external excitation, e.g., a high-power and wideband electromagnetic pulse, on the internal and external fields caused by the scattering slot. The external fields can also be analyzed for the internal resonances of the cavity.

强电磁脉冲辐照屏蔽舱结构电子系统的效应仿真

强电磁脉冲辐照屏蔽舱结构电子系统的效应仿真

Electric Field Sensor for Electromagnetic Pulse Measurement

A high-power electromagnetic (HPEM) pulse blast of few kV/m with a sharp rise-time in the order of nanoseconds and even picoseconds levels may be generated in many ways using a flux compression generator (FCG) or wideband pulse generator that may operate on varying frequencies from 1 to 100 GHz and their accurate detection is a necessity for efficient research and development of the HPEM systems. A simple dipole antenna may not be used for this purpose due to their extreme deficiency in capturing the abrupt rise-time. In spite of that, there is a need for an array of the sensor for measurement with the wideband HPEM system, which enhances overall measurement system cost. An electric field (or D-dot) sensor is the most suitable choice for accurate detection of such electromagnetic pulse owing to their sharp rise-time. In this paper, a new conceptual design of the ground-plane D-dot sensor, followed by the design philosophy is discussed. Two types of optimized prototypes of the wideband D-dot sensor with a different combination of matters has been designed using a thorough analytical investigation with FEM analysis and verification by VNA and 5 kVA pulse source. The developed D-dot sensor has a bandwidth range of, but not limited to 10.50 to 11.19 GHz, which minimize multi-sensor requirement with wideband EMP or HPEM systems development.