Fast Electromagnetic Research Articles

EMSim: A Fast Layout Level Electromagnetic Emanation Simulation Framework for High Accuracy Pre-Silicon Verification

Electromagnetic (EM) emanation measurement and evaluation is one important testing for modern integrated circuits (ICs). Severe electromagnetic interference may degrade the performance of electronic devices or even cause system crashes. As a result, modern ICs need to follow strict electromagnetic compatibility (EMC) requirements. Moreover, EM emanations offer a covert channel for adversaries to steal secret information from fabricated ICs, causing side channel attacks. Due to the lack of fast and high-accuracy EM simulation tools, existing EM measurements often happen at the post-silicon stage. Any identification of side channel vulnerability or EM incompatibility may lead to high cost and delay the time-to-market. As a result, design-time EM simulation tools with fast simulation speed and high accuracy for pre-silicon designs are urgently needed. To this end, we propose EMSIM, a layout-level EM simulation framework that significantly speeds up the EM simulation process while maintaining high accuracy of the simulated EM emanations. To achieve this goal, we provide the theoretical explanation for the root cause of EM emanations from ICs. Guiding by this, EMSIM leverages techniques of parasitic network reduction and device model approximation to reduce the computation complexities while still ensuring high simulation accuracy. EMSIM further leverages Graphics Processing Unit (GPU) resources to solve equations for EM simulation. The efficiency and effectiveness of EMSIM are validated by showing the consistency between simulation results and physical measurements obtained from fabricated circuit designs.

Coupled plasma transport and electromagnetic wave simulation of an ECR thruster

An electron-cyclotron resonance thruster (ECRT) prototype is simulated numerically, using two coupled models: a hybrid particle-in-cell/fluid model for the integration of the plasma transport and a frequency-domain full-wave finite-element model for the computation of the fast electromagnetic (EM) fields. The quasi-stationary plasma response, fast EM fields, power deposition, particle and energy fluxes to the walls, and thruster performance figures at the nominal operating point are discussed, showing good agreement with the available experimental data. The ECRT plasma discharge contains multiple EM field propagation/evanescence regimes that depend on the plasma density and applied magnetic field that determine the flow and absorption of power in the device. The power absorption is found to be mainly driven by radial fast electric fields at the electron-cyclotron resonance region, and specifically close to the inner rod. Large cross-field electron temperature gradients are observed, with maxima close to the inner rod. This, in turn, results in large localized particle and energy fluxes to this component.

Solving Combined Field Integral Equation With Deep Neural Network for 2-D Conducting Object

Solving the combined field integral equation (CFIE) for the large-scale scattering problem is computationally expensive. In this letter, we investigate the feasibility of applying deep learning to solve the CFIE for 2-D perfect electrically conducting objects. Inspired by the conjugate gradient method, an iterative deep neural network is designed to learn the manner of solving the surface current density from the CFIE, with the input being the coefficient matrix of the equation. This process involves physics through surface integration and need less iterations than the conventional iterative equation solver. In numerical tests, we evaluate the network's performance by comparing the predicted surface current density and bistatic scattering cross section with the solutions rigorously computed. This method provides an insight into applying machine learning techniques together with electromagnetic (EM) physics to fast EM computation with the same level of accuracy as traditional method.

A Moving Target Deception Jamming Method Based on Fast Azimuth-Domain Block EM Calculation Against SAR-GMTI

This paper presents a novel moving target deception jamming method against synthetic aperture radar (SAR)-ground moving target indication (GMTI) based on fast azimuth-domain block EM calculation. In this method, a fast electromagnetic(EM) calculation based on equivalent bistatic scattered fields is used to simulate the scattering characteristics of moving false target, which greatly improves the computational efficiency. With the azimuth-domain block implementation, the jammer’s frequency response (JFR) can be calculated by fast searching and interpolating with EM database, and the computation load is further reduced. The implementation and the performance of the proposed method are discussed. Comparing with the traditional methods based on a point model, the proposed method is able to generate more verisimilar moving false targets for different attitudes and resolutions. The simulation experiments are provided to demonstrate the validity of the proposed method.

Fast full‐wave calculation of electromagnetic fields based on weak‐form volume integral equation for MRI applications

High-field magnetic resonance imaging (MRI) scans have safety problems because energy is not homogeneously distributed in the human body. A prescan where energy and temperature distributions are calculated for input energy budgeting can significantly lower the risk. Therefore, fast and accurate calculations of the electromagnetic (EM) fields of an MRI system with a subject under scan are needed. Here, the authors present a fast EM solver based on a weak-form volume integral equation (VIE) for solving this problem. The proposed approach calculates the EM field inside the human body at a high speed without sacrificing accuracy. In the proposed approach, the VIE formulation for an inhomogeneous dielectric object is employed for near-field calculations. The operation on a dense matrix resulted by the VIE is accelerated by fast Fourier transform (FFT) in conjunction with the latest efficient iterative method. Numerical experiments are presented to show the speed and accuracy of the proposed EM solver.

EM zooming procedure in ANSYS Maxwell 3D

The severity of electromagnetic (EM) loads produced by plasma disruptions is one of the most concerning issues for the ITER in-vessel components design. To investigate the effects of fast EM transients on plasma surrounding structures during a disruption the Secondary Excitations (SE) method is used. This is an interface procedure to couple 2D plasma equilibrium codes with Finite Elements (FE) software. The Zooming Approach (ZA) used for the analyses presented here is a particular implementation of the SE method. The aim of this work is the demonstration that the ZA can be effectively applied in case of ANSYS Maxwell 3D analyses combining the ease of use of the Maxwell code with the computational efficiency of the ZA. The work has been carried out evaluating the EM loads acting on the ITER Diagnostic Equatorial Port Plug (EPP) during major disruptions scenario and comparing these loads with those obtained in previous analyses. Additional analyses have been performed to study the effect of ferromagnetic materials on EM loads in order to investigate ANSYS Maxwell capabilities in simulating non-linear magnetic properties.

Bilateral sparse transform for fast solving EM scattering problems by compressed sensing

Rapid and accurate calculation of electromagnetic (EM) scattering problems over a wide incident angle range is always a difficult task which requires repeated numerical computation as the incident angle changes. Aiming at this subject, a solution that introduces compressed sensing into traditional method of moments is described, and the bilateral sparse transform method is first proposed to form a new scheme, in which the effectiveness is improved greatly since the total number of measurements required is reduced drastically as compared with the traditional unilateral sparse transform method. The basic principle is analysed in detail and the high effectiveness of bilateral sparse transform is verified by numerical results.

The instability in the radially non-uniform electron beam-ion channel system

The instability caused by the interaction among the electron beam, plasma, and electromagnetic (EM) waves in a radially non-uniform ion channel is studied. The dispersion relation of the interaction is derived in this paper. The study shows that the EM instability can be induced nearby the center of the beam through the coupling between the fast plasma wave and forward EM wave. On the other hand, the beam mode instability is found in the region relatively far from the center, which means the beam mode can couple with the slow plasma wave so that the electron beam can provide energy to the plasma wave. The distributions of the instability with radius and plasma density are given, respectively, by the numerical simulation, and the result shows that the instability frequency is increased exponentially with the increase of the plasma density. When the plasma density reaches 1×1024m−3, the scale of the frequency can be 10 THz, which provides a theoretical basis for developing the new kind of high-power terahertz radiation sources. Besides, the related physics mechanisms of the instability are also discussed.

Low-latency data analysis for the spherical detector Mario Schenberg

The confrontation of gravitational waves (GWs) with their electromagnetic (EM) counterparts will be rich with information about astrophysical events. Initially, this confrontation will corroborate GW detections; afterwards, when GW detections become more recurrent, it will allow astrophysics to combine information from different channels (GW, EM and also neutrinos). A low-latency data analysis which provides the direction of an incoming GW candidate is required to confront it with fast follow-up EM observations. Until now, no low-latency data analysis has been developed for spherical detectors. One spherical detector alone is capable of determining both the GW direction and polarization. By using this capability, we have developed a low-latency data analysis pipeline for the Mario Schenberg detector. This pipeline is able to retrieve the direction of GW triggers with an average angular resolution from δs ∼ 8° at SNR ∼ 12 to δs ∼ 1° at SNR ∼ 80, in a timespan of a 4 s for 32 s of data being analyzed. We apply a veto which reduces fake events up to 90% when maintaining the GW efficiency above 90% for high SNRs. We provide here a description of the method and its efficiency: resolution on the direction, false alarm rate and computational time.

Fast EM Modeling Exploiting Shape-Preserving Response Prediction and Space Mapping

We present a low-cost modeling methodology for microwave structures exploiting low/high-fidelity electromagnetic (EM) simulations, shape-preserving response prediction (SPRP)/generalized shape-preserving response prediction (GSPRP), and space mapping (SM). Our approach is a two-step process. In step 1, a coarse model is constructed from low-fidelity (coarse discretization) EM simulation data by means of a recently developed SPRP/GSPRP technique. A comparison between the SPRP and GSPRP methods is described. In step 2, the coarse model is enhanced by SM using a fine model (high-fidelity EM simulations). We summarize the substeps in each step of the proposed algorithm and illustrate them graphically. We compare our proposed method with relevant benchmark techniques. Our approach is demonstrated by using two microstrip filter examples. The results and efficiency of our approach are compared with the benchmark techniques, indicating substantial accuracy improvement for comparable training set size. Applications for design optimization are also discussed.

Compressional and EM wave velocity anisotropy in a temperate glacier due to basal crevasses, and implications for water content estimation

AbstractWe have conducted a series of experiments designed to investigate elastic and electromagnetic (EM) velocity anisotropy associated with a preferentially aligned fracture system on a temperate valley glacier in south-central Alaska, USA. Measurements include a three-dimensional compressional wave (P-wave) seismic reflection survey conducted over a 300 m x 300 m survey patch, with uniform source grid and static checkerboard receiver pattern. Additionally, we acquired a multi-azimuth, multi-offset, polarimetric ground-penetrating radar (GPR) reflection experiment in a wagon-wheel geometry with 94° of azimuthal coverage. Results show azimuthal variation in the P-wave normal-moveout velocity of >3% (3765 and 3630 m s–1 in the fast and slow directions respectively) and difference of nearly 5% between the fast (0.164 m ns–1) and slow (0.156 m ns–1) EM velocities. Fracture orientations estimated from the GPR and seismic velocity data are consistent and indicate a preferred fracture orientation that is 30-45° oblique to glacier flow; these measurements agree with borehole observations. Anisotropic analysis of the polarimetric data gives a single volumetric water content estimate of 0.73 ±0.11%. We conclude that meaningful estimates of physical properties in glaciers based on EM or seismic velocity measurements require collecting data such that the presence of anisotropy can be evaluated and an anisotropic analysis employed when necessary.

Investigation of range profiles from buried 3-D object based on the EM simulation

The 1-D range profiles are suitable features for target identification and target discrimination because they provide discriminative information on the geometry of the target. To resolve features of the buried target, the contribution from individual scattering centers of the buried target in the range profiles need to be identified. Thus, the study of complex scattering mechanisms from which the range profiles are produced is of great importance. In order to clearly establish the relationship between the range profile characteristics and the complicated electromagnetic (EM) scattering mechanisms, such as reflections and diffractions, a buried cuboid possessing straight edges is chosen as the buried target in this paper. By performing an inverse discrete Fourier transform (IDFT) on the wideband backscattered field data computed with an accurate and fast EM method, the 1-D range profiles of the buried cuboid is successfully simulated. The simulated range profiles provide information about the position and scattering strength of the cuboid's scattering centers along the range direction. Meanwhile, a predicted distribution of the scattering centers is quantitatively calculated for the buried cuboid based on the ray path computation. Good agreement has been found between simulated and predicted locations of the range profiles. Validation for amplitudes of the range profiles is further provided in the research. Both the peak amplitudes and locations of the range profiles could be understood and analyzed based on the knowledge of the scattering mechanisms. The formation of the 1-D range profiles has been revealed clearly from the full analysis of the scattering mechanisms and contributions. The problem has been solved for both near and far field regions. Finally, the buried depth and the characteristic size of the object are reasonably deduced from the simulated range profiles.

Compact 3-D Envelope ADI-FDTD Algorithm for Simulations of Coherent Radiation Sources

A modified complex-envelope (CE) alternating-direction-implicit (ADI) finite-difference time-domain solver for electromagnetic (EM) fields is presented. Like the conventional ADI scheme, the modified scheme is based on splitting the time step into two halves. In each substep, Maxwell's equations are solved implicitly in one direction and explicitly in the perpendicular direction. The new scheme is a combination of the conventional CE-ADI scheme and the leapfrog ADI scheme that was recently reported. The main features are a more compact form of the tridiagonal equations and greater flexibility in the application of boundary conditions. The boundary conditions on the six faces of the solution box are general and can be specified either as perfect conductor, symmetry boundary conditions, cavity modes, or arbitrary external specification. The new compact CE-ADI scheme is unconditionally stable; thus, the time step can be larger than the one imposed by the Courant-Friedrichs-Lewy (CFL) condition. Fast stable EM simulations of a planar slow-wave structure are demonstrated, with time steps exceeding the CFL limit by two orders of magnitude.

Excitation of coupled ion lattice-streaming carrier modes in high mobility semiconductors

Interaction between streaming carrier plasmons and lattice vibrations in ultrahigh mobility materials generates novel, hybrid, lattice-streaming carrier modes. The Boltzmann kinetic equation for a collisionless carrier response is employed to obtain a dispersion relation including the effects of thermal velocity spreads. The resulting slow electrostatic (ES) modes involve plasmon-phonon (PP) coupling, while the fast electromagnetic (EM) modes involve plasmon-photon-phonon coupling. There is an unstable parameter regime leading to spontaneous growth of slow ES PP modes from noise. Thermal spreads reduce but do not eliminate the growth rate. The fast EM modes are found to be stable and slightly damped over the parameter regime. Spontaneous growth of ES modes carries implications for terahertz generation in high mobility materials.

Planetary electromagnetic waves in the ionospheric E-layer

The linear theory for the large-scale (λ>10 3 km) electromagnetic (EM) waves in the middle-latitude ionospheric E-layer is developed. The general dispersion relation for these waves is derived. It is shown that the latitudinal inhomogeneity of the geomagnetic field and the angular velocity of the Earth's rotation can lead to the appearance of wave modes in the form of slow and fast EM planetary waves. The slow mode is produced by the dynamo electric field and it represents a generalization of the ordinary Rossby type waves in a rotating atmosphere when the Hall effect in the E-layer is included. The fast mode is a new mode, which is associated with the oscillations of the ionospheric electrons frozen in the geomagnetic field. It represents the variation of the vortical electric field and it arises solely due to the latitudinal gradient of the external magnetic field. The basic characteristics of the wave modes, such as the wavelength, the frequency and the Rayleigh friction, are estimated. Other types of waves, termed slow magnetohydrodynamic (MHD) waves, which are insensitive to the spatial inhomogeneity of the Coriolis and Ampére forces are also reviewed. It is shown that they appear as an admixture of slow Alfvén (SA) and whistler type waves. Such waves can generate variations in the magnetic field from a few tenth to a few hundreds nT. It is stressed that the basic features of the considered waves agree with the general properties of the magnetic perturbations observed at the world network of magnetic and ionospheric stations.