This paper deals with magnetic source characterization in time domain. The basic idea is to solve the inverse problem using the measured near field radiation cartography. In order to ensure the identification procedure, the Time Reversal (TR) technique is used. This procedure allows both the spatial and temporal focusing determination by forcing waves to virtually converge to their initial source. The originality of the proposed methodology is to present a full time domain study of a magnetic source reconstruction. Indeed, this approach is particularly suitable for structures that emit non-sinusoidal radiations such as power electronic systems. First, the Electromagnetic Time Reversal (EMTR) basis are introduced. Then a simulation case study is discussed. Finally, results from an experiment test are presented to verify the proposed methodology. The measured results are in good agreement with the calculated electromagnetic fields. The experimental validation shows that compared to other identification techniques, especially those developed in the frequency domain, the proposed approach is more efficient and simple.
This paper presents a study on the characterization of electromagnetic near field radiation in the time domain. The proposed methodology affords a radiation model based on the electromagnetic inverse method using analytical expressions of the equivalent dipoles. The identification procedure is conducted by the Time Reversal technique (TR). The advantage of this process is focusing a field in both time and space. The main goal of this paper is to investigate the use of the Electromagnetic Time Reversal (EMTR) method in the time domain. First, the EMTR principle is presented. The characterization of the time domain magnetic field distribution is then developed. The radiating source localization and the excitation signal's shape were successfully defined. In addition, the calculated distribution cartography of the magnetic field is compared to the reconstructed cartography. The obtained results show the effectiveness of the proposed approach.
This paper presents a comparative study between two different methods used in modeling electromagnetic transient disturbances of power electronic systems. The first method is the Electromagnetic Time Reversal (EMTR) technique based on time domain analysis. The second one is the frequency inverse method based on Genetic Algorithms (GA). The two methods are using the near field scanning technique. Moreover, both algorithms are established on the resolution of an inverse problem and they employ magnitude-only data. The obtained equivalent radiation models are compared with initial pattern for both simulation and experimental test cases. The frequency-time evaluation is discussed. The comparison between the two proposed methods shows that the EMTD method is more suitable for studying power electronics radiation and that it can provide an accurate equivalent model in a reduced time.
The MIP Timing Detector will provide additional timing capabilities for detection of minimum ionizing particles (MIPs) at CMS during the High Luminosity LHC era, improving event reconstruction and pileup rejection. The central portion of the detector, the Barrel Timing Layer (BTL), will be instrumented with LYSO:Ce crystals and Silicon Photomultipliers (SiPMs) providing a time resolution of about 30 ps at the beginning of operation, and degrading to 50-60 ps at the end of the detector lifetime as a result of radiation damage. In this work, we present the results obtained using a 120 GeV proton beam at the Fermilab Test Beam Facility to measure the time resolution of unirradiated sensors. A proof-of-concept of the sensor layout proposed for the barrel region of the MTD, consisting of elongated crystal bars with dimensions of about 3 × 3 × 57 mm 3 and with double-ended SiPM readout, is demonstrated. This design provides a robust time measurement independent of the impact point of the MIP along the crystal bar. We tested LYSO:Ce bars of different thickness (2, 3, 4 mm) with a geometry close to the reference design and coupled to SiPMs manufactured by Hamamatsu and Fondazione Bruno Kessler. The various aspects influencing the timing performance such as the crystal thickness, properties of the SiPMs (e.g. photon detection efficiency), and impact angle of the MIP are studied. A time resolution of about 28 ps is measured for MIPs crossing a 3 mm thick crystal bar, corresponding to a most probable value (MPV) of energy deposition of 2.6 MeV, and of 22 ps for the 4.2 MeV MPV energy deposition expected in the BTL, matching the detector performance target for unirradiated devices.
In the present paper, the electromagnetic time reversal technique (EMTR) is studied in the electromagnetic compatibility (EMC) context. The main issue addressed by this approach is to deal with EM radiating sources identification. This paper is intended to provide a time domain (TD) study of EMTR in the near field (NF) and prove its efficiency in characterizing transient disturbances in power electronics. The reconstruction of EM emissions is based on two stages. First, modeling process relies on the use of TD analytical expressions. Second, signal processing is referring to time reversal (TR) technique, which defines an inverse problem resolution. The method proposes to identify a set of equivalent dipoles. The validation is carried out experimentally using a TD measurement bench. The main purposes of this method is to extract the dipoles locations, moments and orientation. The magnetic field maps calculated at each time step using obtained equivalent sources are compared to measured distributions. Adequate agreement is achieved, which confirms the efficiency of the proposed method. In addition, for validation purposes, the equivalent model is compared to that obtained by a frequency domain (FD) method based on the standard genetic algorithms. Unlike FD, TD investigations allow characterizing transient disturbances in power electronic systems that emit strong EM interferences, by finding a sufficient equivalent model valid on a wide frequency band at once.
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