In this paper, we propose a study on the characterization, design and simulation of a THz sensor for applications in Structural Health Monitoring (SHM). The proposed sensor is assembled using two frequency selective surfaces (FSSs) based on metamaterial wire resonators. We present a theoretical model to describe its electromagnetics which is used not only to understand the physical principles underlying the functioning of the sensor but also to determine a set of optimized parameters for its operation in the THz window from 395 GHz to 455 GHz. We present our numerical simulations, involving both electromagnetic and mechanical simulation techniques, to determine the reflectance profile of the sensor as a function of applied force. In this study we considered the possibility of using two thermoplastic polymers as host materials: High-Density PolyEthylene (HDPE) and PolyTetraFluoroEthylene (PTFE). The two sensors have a good dynamic range and comparable characteristics. However, we found that with HDPE it is possible to construct a sensor with a more linear response, although not as sensitive as in the case of PTFE. With HDPE we are able to pass from a situation of full transparency to almost full opacity using only its linear operating zone.
We developed 1d3v Particle in Cell/Monte Carlo Collision (PIC/MCC) numerical code for the Radio-Frequency (RF) capacitive glow discharge. This method includes the solution of the Lorentz force equation for the motion of super particles and the Poisson equation for the electric field. Collisions between the particles are modeled with the Monte Carlo method. In this process, the elastic and charge exchange collisions between the ion-neutral pairs, as well as the elastic, excitation and ionization collisions between the electron-neutral pairs are taken into account. Test calculations were carried out for the plasma of RF discharge. Numerical code was validated by comparison with the published simulation results 1,2 . Parallelization of this code was performed and the efficiency in time was studied. This efficiency was also analyzed according to increasing number of cores in a cluster.
The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the code is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/ MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.
A parallel 1d3v Particle in Cell/Monte Carlo Collision (PIC/MCC) code was derived and applied for the investigation of the formation of photoplasma in sodium vapor. The effects of particle weighting and the Courant number on the computed plasma properties were examined, and the convergence of the numerical method with respect to these parameters was demonstrated. Simulations were carried out for the stepwise spatial profile of the resonant sodium atoms density. The basic plasma parameters (such as eedf, iedf, atomic and molecular ion and electron densities, and electric field and potential) were computed. The results of the PIC/MCC simulations were compared to those obtained from the fluid model. Simulations revealed a strong spatial non-uniformity in the electron density and the electric potential over the computational domain that provides evidence in favour of photovoltaic conversion of light energy into electrical energy.
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