The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Frede Blaabjerg - One of the best experts on this subject based on the ideXlab platform.
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Asymmetrical $\Gamma$-Source Inverters
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Wei Mo, Frede BlaabjergAbstract:Impedance-Source inverters are inverters with voltage-buck-boost capability that cannot be achieved by the traditional inverters. Their boost capability is introduced by shorting their phase legs without causing damages. Impedance-Source inverters are therefore less prone to false triggering caused by electromagnetic interference. Present impedance-Source inverters are, however, burdened by their low modulation ratio at high input-to-output gain. Such low modulation usually leads to high-voltage stresses across the components and poor spectral performance at the inverter output. To avoid these problems, inverters with coupled transformers have been introduced, but they usually lead to high turns ratio, and hence many winding turns, at high gain. An alternative would then be the asymmetrical Γ-Source inverters proposed in this paper, whose gain is raised by lowering their turns ratio toward unity. The input current drawn by the proposed inverters is smoother and, hence, more adaptable by the Source. Theories and experimental results have been presented in this paper for validating the concepts proposed.
Gérald Rimpault - One of the best experts on this subject based on the ideXlab platform.
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Analysis and optimization of minor actinides transmutation blankets with regards to neutron and Gamma Sources
EPJ Nuclear Sciences & Technologies, 2020Co-Authors: Timothée Kooyman, L. Buiron, Gérald RimpaultAbstract:Heterogeneous loading of minor actinides in radial blankets is a potential solution to implement minor actinides transmutation in fast reactors. However, to compensate for the lower flux level experienced by the blankets, the fraction of minor actinides to be loaded in the blankets must be increased to maintain acceptable performances. This severely increases the decay heat and neutron Source of the blanket assemblies, both before and after irradiation, by more than an order of magnitude in the case of neutron Source for instance. We propose here to implement an optimization methodology of the blankets design with regards to various parameters such as the local spectrum or the mass to be loaded, with the objective of minimizing the final neutron Source of the spent assembly while maximizing the transmutation performances of the blankets. In a first stage, an analysis of the various contributors to long- and short-term neutron and Gamma Source is carried out whereas in a second stage, relevant estimators are designed for use in the effective optimization process, which is done in the last step. A comparison with core calculations is finally done for completeness and validation purposes. It is found that the use of a moderated spectrum in the blankets can be beneficial in terms of final neutron and Gamma Source without impacting minor actinides transmutation performances compared to more energetic spectrum that could be achieved using metallic fuel for instance. It is also confirmed that, if possible, the use of hydrides as moderating material in the blankets is a promising option to limit the total minor actinides inventory in the fuel cycle. If not, it appears that focus should be put upon an increased residence time for the blankets rather than an increase in the acceptable neutron Source for handling and reprocessing.
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Analysis and optimization of minor actinides transmutation blankets with regards to neutron and Gamma Sources
EPJ Web of Conferences, 2020Co-Authors: Timothée Kooymana, L. Buiron, Gérald RimpaultAbstract:Heterogeneous loading of minor actinides in radial blankets is a potential solution to implement minor actinides transmutation in fast reactors. However, to compensate for the lower flux level experienced by the blankets, the fraction of minor actinides to be loaded in the blankets must be increased to maintain acceptable performances. This severely increases the decay heat and neutron Source of the blanket assemblies, both before and after irradiation, by more than an order of magnitude in the case of neutron Source for instance.We propose here to implement an optimization methodology of the blankets design with regards to various parameters such as the local spectrum or the mass to be loaded, with the objective of minimizing the final neutron Source of the spent assembly while maximizing the transmutation performances of the blankets. In a first stage, an analysis of the various contributors to long and short term neutron and Gamma Source is carried out while in a second stage, relevant estimators are designed for use in the effective optimization process, which is done in the last step. A comparison with core calculations is finally done for completeness and validation purposes. It is found that the use of a moderated spectrum in the blankets can be beneficial in terms of final neutron and Gamma Source without impacting minor actinides transmutation performances compared to more energetic spectrum that could be achieved using metallic fuel for instance. It is also confirmed that, if possible, the use of hydrides as moderating material in the blankets is a promising option to limit the total minor actinides inventory in the fuel cycle. If not, it appears that focus should be put upon an increased residence time for the blankets rather than an increase in the acceptable neutron Source for handling and reprocessing.
Wei Mo - One of the best experts on this subject based on the ideXlab platform.
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Asymmetrical $\Gamma$-Source Inverters
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Wei Mo, Frede BlaabjergAbstract:Impedance-Source inverters are inverters with voltage-buck-boost capability that cannot be achieved by the traditional inverters. Their boost capability is introduced by shorting their phase legs without causing damages. Impedance-Source inverters are therefore less prone to false triggering caused by electromagnetic interference. Present impedance-Source inverters are, however, burdened by their low modulation ratio at high input-to-output gain. Such low modulation usually leads to high-voltage stresses across the components and poor spectral performance at the inverter output. To avoid these problems, inverters with coupled transformers have been introduced, but they usually lead to high turns ratio, and hence many winding turns, at high gain. An alternative would then be the asymmetrical Γ-Source inverters proposed in this paper, whose gain is raised by lowering their turns ratio toward unity. The input current drawn by the proposed inverters is smoother and, hence, more adaptable by the Source. Theories and experimental results have been presented in this paper for validating the concepts proposed.
N.m. Badiger - One of the best experts on this subject based on the ideXlab platform.
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Determination of K to L shell total vacancy transfer probabilities using a weak Gamma Source: An alternative method
Journal of Quantitative Spectroscopy & Radiative Transfer, 2010Co-Authors: A.s. Bennal, K.m. Niranjan, N.m. BadigerAbstract:Abstract The K–L total vacancy transfer probabilities (ηKL) of selected elements in the atomic range 42≤Z≤82 have been determined using a weak Gamma Source. The targets are excited by 123.6 keV Gamma photons from a weak 57Co Source and K X-ray photons are measured by an ORTEC type GMX-10P HPGe detector coupled to 8 K multichannel analyzer. By measuring the K X-ray intensity ratio and K shell fluorescence yield, the K to L total vacancy transfer probabilities have been determined. Measured values have been compared with theoretical and other experimental values.
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Determination of rest mass energy of the electron—an undergraduate laboratory experiment
European Journal of Physics, 2007Co-Authors: S B Hosur, N.m. BadigerAbstract:We present a simple Compton scattering experiment to determine the rest mass energy of the electron which is unique for graduate and undergraduate laboratories. In the present experiment, we have measured the energies of the backscattered Gamma photons with an NaI(Tl) Gamma ray spectrometer coupled to a 1 K multichannel analyser. In order to enhance the backscattered Gamma photons, a thick aluminium target is placed over the radioactive Gamma Source. The rest mass energy of the electron is determined by using 203Hg, 137Cs, 54Mn and 60Co radioactive Gamma Sources. The measured values are found to agree with the standard value.
Konstantin Y. Platonov - One of the best experts on this subject based on the ideXlab platform.
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Laser-excited Gamma Source with high spectral brightness
High-power lasers and applications, 2000Co-Authors: Alexander A. Andreev, Yuri V. Rozhdestvenskii, Konstantin Y. PlatonovAbstract:Abstract This paper considers various channels of y-quantum generation via an ultra-short high-power laser pulseinteraction with different targets.We analyse the possibilities to create a pulsed y - radiation Source usinglaser triggering of some nuclear reactions and isomer targets. It is shown that 0.2 MeV monochromaticshort pulse ofy - radiation can be obtained with pulse energy sub-mJ level from isomer atoms localizedin a magnetic trap. For nuclear reaction channel in light- atom materials, it is shown that 100-TW laserpulse gives rise to formation of about io6 photons near 5 MeV energy. 1. Introduction To date, many physical problems call for using a Sources of'y -radiation and vast scope of theseproblems ranging from non destructive Gamma flaw detection to medical examinations[1I. It should benoted that, presently, the intensity of ordinary radioactive Sources cannot be higher than 10-100 GBk,whereas much higher intensity is necessary for many investigations.Commonly, synchrotron radiation is used as a high-intensity y -Source, its activity being about PBk.However, significant success notwithstanding, the use ofthe synchrotron radiation as a y -Sourcefeatures some essential drawbacks. First, it is impossible to obtain the high intensity 'y -radiation in verynarrow frequency range, because the synchrotron radiation spectrum is continuous. Hence narrow-frequency-band experiments with a high-power y -Source appear to be impossible, because the power of
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Extremely intensive Gamma Source with high spectral brightness
Laser Optics '98: Superstrong Laser Fields and Applications, 1998Co-Authors: Alexander A. Andreev, Yuri V. Rozhdestvenskii, Konstantin Y. PlatonovAbstract:In this work we consider a possibility of pulse (Gamma) - Source creation for atoms of nuclear isomers localized in a magnetic trap. It was shown, that in this case we can obtain a (Gamma) -radiation pulse duration of 102-103 picosecond with a pulse energy about 10-3.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
