Frequency and Time Domain Analysis of Influence of the Grounding Electrode Conductivity on Induced Current Distribution

The paper deals with an assessment of the influence of finite conductivity to the current induced along the horizontal grounding electrode. Analysis is performed in frequency and time domain, respectively. Current distribution along the grounding electrode buried in a lossy half-space is determined via analytical solution of the corresponding Pocklington equation in the frequency domain. The corresponding time domain response is obtained by means of Inverse Fast Fourier Transform (IFFT). The electrode is excited via an equivalent current source. Presence of the earth-air interface is taken into account via the simplified reflection coefficient arising from the Modified Image Theory (MIT). The electrode current is calculated for the case of perfectly conducting (PEC) electrode and for the electrodes made of copper and aluminum. Comparison of results shows no significant discrepancy between these electrodes, justifying the use of a PEC electrode approximation

EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

International audienceRecent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper

A comparison of finite-difference, finite-integration, and integral-equation methods in the time-domain for modelling ground penetrating radar antennas

Development of accurate models of GPR antennas is being driven by research into more accurate simulation of amplitude and phase information, improved antenna designs, and better-performing forward simulations for inversion procedures. Models of a simple dipole antenna, as well as more complex models similar to a GSSI 1.5GHz antenna and a MALA Geo-science 1.2GHz antenna were investigated in free space and over lossless and lossy dielectric half-spaces. We present comparisons of simulated data using the Finite-Integration Technique, the Finite-Difference Time-Domain method, and a Time-Domain Integral Equation approach, as well as measured data. For each scenario, phase, amplitude, and the shape of the waveform were compared. Generally we found very good agreement between the different simulation techniques, and good agreement between experimental and simulated data. Differences that were evident highlight the significance of understanding how features such as antenna feeding and material dispersion are modelled. This degree of match between experimental and simulated data cannot be attained by using just an infinitesimal dipole model in a simulation - a model including the structure of the antenna is required. This is important for the many GPR applications which operate in the near-field of the antenna, where the interaction between the antenna, the ground, and targets is important

A Stochastic Analysis of the Transient Current Induced along the Thin Wire Scatterer Buried in a Lossy Medium

The paper deals with the stochastic collocation analysis of a time domain response of a straight thin wire scatterer buried in a lossy half-space. The wire is excited either by a plane wave transmitted through the air-ground interface or by an equivalent current source representing direct lightning strike pulse. Transient current induced at the center of the wire, governed by corresponding Pocklington integrodifferential equation, is determined analytically. This antenna configuration suffers from uncertainties in various parameters, such as ground properties, wire dimensions, and position. The statistical processing of the results yields additional information, thus enabling more accurate and efficient analysis of buried wire configurations

Sensitivity analysis of the direct time domain analytical solution for transient impedance of the horizontal grounding electrode using ANOVA approach

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Comparison of Time-Domain Finite-Difference, Finite-Integration, and Integral-Equation Methods for Dipole Radiation in Half-Space Environments

In this paper we compare current implementations of commonly used numerical techniques - the Finite-Difference Time-Domain (FDTD) method, the Finite-Integration Technique (FIT), and Time-Domain Integral Equations (TDIE) - to solve the canonical problem of a horizontal dipole antenna radiating over lossless and lossy half-spaces. These types of environment are important starting points for simulating many Ground Penetrating Radar (GPR applications which operate in the near-field of the antenna, where the interaction among the antenna, the ground, and targets is important. We analysed the simulated current at the centre of the dipole antenna, as well as the electric field at different distances from the centre of the antenna inside the half-space. We observed that the results from the simulations using the FDTD and FIT methods agreed well with each other in all of the environments. Comparisons of the electric field showed that the TDIE technique agreed with the FDTD and FIT methods when observation distances were towards the far-field of the antenna but degraded closer to the antenna. These results provide evidence necessary to develop a hybridisation of current implementations of the FDTD and TDIE methods to capitalise on the strengths of each technique

Stochastic-deterministic and sensitivity analysis of the transient field generated by GPR dipole antenna and transmitted into a lossy ground

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Stochastic Collocation Applications in Computational Electromagnetics

The paper reviews the application of deterministic-stochastic models in some areas of computational electromagnetics. Namely, in certain problems there is an uncertainty in the input data set as some properties of a system are partly or entirely unknown. Thus, a simple stochastic collocation (SC) method is used to determine relevant statistics about given responses. The SC approach also provides the assessment of related confidence intervals in the set of calculated numerical results. The expansion of statistical output in terms of mean and variance over a polynomial basis, via SC method, is shown to be robust and efficient approach providing a satisfactory convergence rate. This review paper provides certain computational examples from the previous work by the authors illustrating successful application of SC technique in the areas of ground penetrating radar (GPR), human exposure to electromagnetic fields, and buried lines and grounding systems

Advanced analysis of the transient impedance of the horizontal grounding electrode: From statistics to sensitivity indices

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EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

International audienceRecent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper