The Experts below are selected from a list of 2889 Experts worldwide ranked by ideXlab platform
Navendu Goswami - One of the best experts on this subject based on the ideXlab platform.
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structural magnetic and dielectric study of fe2o3 nanoparticles obtained through Exploding Wire technique
Current Applied Physics, 2021Co-Authors: Surendra Singh, Navendu GoswamiAbstract:Abstract We propose an Exploding Wire technique based facile approach to prepare Fe2O3 nanoparticles in ambient conditions. TG-DSC analysis of the prepared precursor (Fe(OH)3) nanoparticles were done. The phase, lattice parameter and the average crystallite size were evaluated through X-ray diffraction analysis. The morphology of prepared nanoparticles was studied by scanning electron microscopy and Transmission electron microscope. The functional group formation of Fe2O3 nanoparticles and intrinsic stretching vibration bands of Fe–O were estimated through FTIR analysis. The direct band gap of Fe2O3 nanoparticles occurring in conjunction with indirect band gaps was established via Tauc plot. The magnetic parameters were studied through Mossbauer spectroscopy, ESR, M-H and M-T plot analysis. The attributes of dielectric behaviour like dielectric constant (e′), loss tangent (tan δ), dielectric loss (e″) and alternating current (AC) conductivity (σAC) were measured at various temperatures in the frequency range of 10 Hz-106 KHz.
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dielectric and electrical study of zinc copper ferrite nanoparticles prepared by Exploding Wire technique
Applied Physics A, 2019Co-Authors: Surendra Singh, S C Katyal, Navendu GoswamiAbstract:The experimental investigation of electrical and dielectric characteristics of spinel Zn–Cu ferrite (ZCFO) nanoparticles, synthesized adopting an Exploding Wire technique (EWT)-based approach, is reported in this paper. The direct current (DC) electrical parameters of prepared nanoparticles were studied by two-probe method in the range of 300 K (RT) to 423 K. The activation energy for hopping of charge carriers, drift mobility and charge concentration was determined through DC analysis. The attributes of dielectric behavior like dielectric constant (e′), loss tangent (tan δ), dielectric loss (e″) and alternating current (AC) conductivity (σAC) were measured at various temperatures in the frequency range of 10 Hz–10 MHz. The increase in AC conductivity with frequency, observed in our study, represented the normal behavior of spinel ferrite. The two-layer model based on space charge polarization could satisfactorily elucidate variation in dielectric constant with frequency. The dielectric parameters at different frequencies were also determined in temperature range of 300–673 K. The decrease in DC resistivity as well as the increase in AC conductivity, with rise in temperature, affirms the semiconducting nature of prepared nanoferrite with the band gap energy of 3.16 eV, as calculated through UV–visible analysis. The capacitance of thin grain boundary region (Cgb), grain boundary resistance (Rgb) and relaxation time (τg) of zinc–copper nanoferrite were estimated through Cole–Cole plot analysis.
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impedance spectroscopic study of nanoscale zn cu ferrite prepared by Exploding Wire technique
DAE SOLID STATE PHYSICS SYMPOSIUM 2018, 2019Co-Authors: Surendra Singh, S C Katyal, Navendu GoswamiAbstract:In this article, the complex impedance spectra and electric modulus are analyzed to determine the electrical properties of nanoscale Zinc Copper ferrite (ZCFO), synthesized by Exploding Wire technique (EWT). The real part of complex impedance and electric modulus are analyzed as function of frequency at specified temperatures. The frequency dependence of imaginary part of electric modulus at specified temperatures is studied. The contribution of electrode polarization is estimated via impedance and electric modulus analysis. Single semicircular arc is obtained in M″ versus M′ plot indicates that grains have negligible role in electrical property of the sample. The grain boundary resistance (Rgb) and grain boundary capacitance (Cgb) are found in the order of KΩ and nF respectively. The relaxation time is estimated to be as few micro seconds. The various processes involved in the electrical conductivity of prepared nanoferrite have been revealed through the present studies.
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structural vibrational and electronic properties of cuo nanoparticles synthesized via Exploding Wire technique
Ceramics International, 2018Co-Authors: Anshuman Sahai, Navendu Goswami, Monu Mishra, Govind GuptaAbstract:Abstract The study of mixed phase Cu/Cu2O/CuO nanoparticles synthesized by Exploding Wire Technique has been recently reported by us. Aiming to achieve single phase CuO nanoparticles, the mixed phase Cu/Cu2O/CuO nanoparticles were subjected to annealing at different temperature and time durations in oxygen environment. In this article, we discussed two samples; two phase Cu2O/CuO and single phase pure CuO nanoparticles obtained by annealing at 500 °C and 900 °C for 10 h. Rietveld refinement and Williamson-Hall analyses revealed formation of pure phase of CuO at 900 °C with an average crsytallite size of 27.6 nm. Irregular shape of nanoparticles with average size of ~8 nm was observed by Transmission Electron Microscopy. Selected Area Electron Diffraction pattern matches with standard interplanar distance of CuO. Fourier Transform Infrared and Micro-Raman (µR) spectra exhibit broadening of vibrational modes; indicative of pure phase CuO at 900 °C. Extensive X-ray Photoelectron Spectroscopy analysis revealed that the percentage contributions of Cu1+ and oxygen vacancy (VO) decreases whereas; Cu2+ and interstitial oxygen (Oi) enhances on increasing the annealing temperature from 500 °C to 900 °C and thus, resulting the pure phase formation of CuO nanoparticles. Notably, through our analyses we propose an electronic band structure diagram on the basis of valance band maximum, as obtained by XPS and the band gap energy as estimated via UV–visible spectroscopy for mixed phase of Cu2O/CuO (1.6 ± 0.02 eV) and pure phase of CuO (1.3 ± 0.02 eV) nanoparticles.
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cu cu 2 o cuo nanoparticles novel synthesis by Exploding Wire technique and extensive characterization
Applied Surface Science, 2016Co-Authors: Anshuman Sahai, Navendu Goswami, S D Kaushik, Shilpa TripathiAbstract:Abstract In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and Wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu2O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu2O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu2-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu2O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu2O/CuO nanoparticles are reflected through UV–vis (UV–vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes occurring therein. Iterative X-ray photoelectron spectroscopy (XPS) fitting of core level spectra of Cu (2p3/2) and O (1s), divulges presence of Cu2+ and Cu+ in the lattice with an interesting evidence of O deficiency in the lattice structure and surface adsorption. Magnetic analysis illustrates that the prepared nanomaterial demonstrates ferromagnetic behaviour at room temperature.
Rowan Sinton - One of the best experts on this subject based on the ideXlab platform.
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A Marx Generator for Exploding Wire Experiments
2011 Asia-Pacific Power and Energy Engineering Conference, 2011Co-Authors: Rowan Sinton, Ryan Van Herel, W. Enright, Pat BodgerAbstract:A two-stage Marx generator was designed, constructed and tested for the purpose of investigating long distance Exploding Wire experiments. The voltage and energy requirements for the experiments are unique; up to 180 kV and 40 kj is required. Capacitor banks, earthing switches, spark gaps and resistors were purpose-built. Using the completed setup, conductive plasma paths up to 36 m long have been investigated.
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design and construction of a triggered spark gap for long distance Exploding Wire experiments
Australasian Universities Power Engineering Conference, 2010Co-Authors: Rowan Sinton, Ryan Van Herel, W. Enright, P S BodgerAbstract:This paper gives the technical information required to build a triggered spark gap (TSG) for igniting Exploding Wire experiments. The TSG, which uses a concentric three-electrode configuration, reliably triggers on test voltages between 10 and 60 kVdc from a 21 μF capacitor bank discharge source. A description of the electronic triggering circuit, operating region and a set of experimental results obtained using the TSG are also given.
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Investigating Long-Distance Exploding-Wire Restrike
IEEE Transactions on Plasma Science, 2010Co-Authors: Rowan Sinton, Ryan Van Herel, Wade Enright, Pat BodgerAbstract:An experimental setup was built using commonly available high-voltage laboratory equipment to investigate the creation of Exploding-Wire restrikes up to 9 m long. Sets of voltage traces are presented with varying applied average electric fields. Restrikes (formation of plasma paths) have been found to occur in a region of average electric field between 5.6 and 15 kV/m. The average electric field of this region of restrikes is relatively low and will assist in investigation of novel plasma conductor configurations.
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Observations of the long distance Exploding Wire restrike mechanism
Journal of Applied Physics, 2010Co-Authors: Rowan Sinton, Ryan Van Herel, W. Enright, Pat BodgerAbstract:An Exploding Wire restrike mechanism is applied to create plasma paths up to 9 m in length. The mechanism uses enameled copper Wires in a 5 to 10 kV/m region of average electric field (AEF). This relatively low AEF restrike mechanism appears to be linked to the formation of plasma beads along the Wire’s length. Voltage traces, measurement of relative emitted light intensity and photographs are presented at AEFs below, inside and above the identified restrike region.
M. Milanese - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of a shock wave with time dependent energy release generated by an Exploding Wire in air
Physics of Plasmas, 2018Co-Authors: Gonzalo Rodriguez Prieto, Luis Bilbao, M. MilaneseAbstract:When there is a fast release of energy in any suitable fluid, a shock wave is produced. One of the ways to create shock waves in a laboratory environment is the use of an Exploding Wire system; a metallic Wire transformed into plasma due to the action of a strong, above kiloamperes, and fast, under tens of microseconds, electrical current. Therefore, it has been used in many experiments to study shock waves with an energy release that can be considered instantaneous with respect to the shock wave evolution time. On the contrary, this work presents experimental results for the dynamics of a shock wave created by an Exploding Wire with an energy release dependent on time.When there is a fast release of energy in any suitable fluid, a shock wave is produced. One of the ways to create shock waves in a laboratory environment is the use of an Exploding Wire system; a metallic Wire transformed into plasma due to the action of a strong, above kiloamperes, and fast, under tens of microseconds, electrical current. Therefore, it has been used in many experiments to study shock waves with an energy release that can be considered instantaneous with respect to the shock wave evolution time. On the contrary, this work presents experimental results for the dynamics of a shock wave created by an Exploding Wire with an energy release dependent on time.
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Exploding Wire energy absorption dynamics at slow current rates
Laser and Particle Beams, 2016Co-Authors: G. Rodriguez Prieto, Luis Bilbao, M. MilaneseAbstract:AbstractAbsorption of electrical energy provided to a metal Wire in an Exploding Wire system is thought to be terminated or greatly diminished when the plasma is formed, after the joule heating of the metallic Wire by the electrical current. Accordingly, it is common to account for the electrical energy delivered to the Wire that the integration of current and voltage signals is halted when the voltage peak changes its slope. Usually, this moment is synchronized with the plasma appearance, as detected by optical sensors. In this work, experimental evidence of a two-step electrical energy absorption in an Exploding Wire surrounded by atmospheric air is presented. During the first step of the energy absorption the plasma is not formed, indicating that the delivered energy is not enough for ionizing the Wire, giving place to a dark pause that lasts until a second energy absorption produces a plasma. The delay between the two steps can reach ≈2.2 µs for copper Wires of 50 µm diameter charged at an initial voltage of 10 kV. Experimental investigation of variation of the delay between the two steps with different metals, charging voltages, and Wire diameters are presented. A relation of the current density with the initial kinetic energy of the plasma and the electrical current rate is devised as a possible explanation of the observed phenomena.
Omri Ram - One of the best experts on this subject based on the ideXlab platform.
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small scale blast wave experiments by means of an Exploding Wire
2018Co-Authors: O Sadot, Omri Ram, Eliram Nof, Eytan Kochavi, G BendorAbstract:The effort invested in improving our understanding of the physics of high energy explosion events has tremendously increased in the past few decades. Moreover, the dramatic increase in computer capabilities over the last two decades made the numerical simulation approach the dominant tool for investigating blast wave related phenomena and their effects. However, both large- and small-scale field tests are still in use. In the following, we present an experimental tool capable of better resolving and studying the blast–structure interaction phenomenon. In addition, this experimental tool can assist in validating numerical simulations of these phenomena prior to applying them to simulate large-scale events. The experimental tool uses an Exploding Wire technique to generate small-scale cylindrical and spherical blast waves. This approach permits safe operation, high repeatability, and usage of advanced diagnostic systems that cannot be used in large-scale field experiments. The system was calibrated using an analytical model, an empirical model, and a numerical simulation. To ensure that spherical blast geometry was achieved, a set of free air blast experiments in which high-speed photography was used to monitor the blast wave structure was conducted. Furthermore, by using similitude analysis the results obtained from small-scale experiments can be applied to full-scale problems. It has been clearly shown that an Exploding Wire system offers an inexpensive, repeatable, safe, easy to operate, and effective experimental tool for studying phenomena involving blast–structure interactions.
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exploration of methods in the Exploding Wire technique for simulating large blasts
2017Co-Authors: Eliram Nof, Omri Ram, Eytan Kochavi, G Bendor, O SadotAbstract:Small-scale modeling of explosive events has become an important tool in the investigation of blast wave-structure interactions. In this approach, a full-scale model is miniaturized and subjected to “gram-scale” explosions from detonated micro-charges. While offering a cheaper, faster, and ultimately more manageable alternative to full-scale field tests, small-scale testing also offers better reliability and accuracy in more complex scenarios where numerical simulations become limited. Nevertheless, small-scale experiments introduce other difficulties due to the reliance on the well-known Cranz-Hopkinson “cube-root” scaling law. This scaling relationship is suitable for self-similar open-field experiments but does not necessarily apply to urban scenarios. Additionally, chemical explosive charges of such small quantities might be susceptible to changes in parameters such as the explosive compound compression strength, the humidity of the explosive and of the surrounding atmosphere, the method of ignition, etc. Logistically, the handling and preparing of the experimental setup with these small chemical explosives requires specially trained personnel and permits. To overcome these challenges, the Exploding Wire (EW) technique offers an elegant substitute to using small chemical charges in scaled-down modeling.
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Mitigation of Exploding-Wire-generated blast-waves by aqueous foam
Physics of Fluids, 2015Co-Authors: M. Liverts, Omri Ram, Oren Sadot, Nicholas Apazidis, Gabi Ben-dorAbstract:In this work, we implement an Exploding Wire technique to generate small-scale cylindrical blast waves in aqueous foam. The Exploding Wire system offers an easy to operate and effective tool for studying blast-wave/foam interaction related phenomena in real explosion scenarios. The mitigation of blast waves as a function of the thickness of the foam barrier is discussed and quantified. A fluid mixture pseudo-gas based numerical approach with the aid of the point explosion theory is used to separate the mitigation mechanisms into the near- and the far-field related groups and to analyze the contribution of each group to the overall losses of the blast wave energy.
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implementation of the Exploding Wire technique to study blast wave structure interaction
Experiments in Fluids, 2012Co-Authors: Omri Ram, O SadotAbstract:The effort invested in improving our understanding of the physics of high-energy explosion events has been steadily increasing since the latter part of the twentieth century. Moreover, the dramatic increase in computer power over the last two decades has made the numerical simulation approach the dominant tool for investigating blast phenomena and their effects. However, field tests, on both large and small scales, are still in use. In the current paper, we present an experimental tool to better resolve and study the blast–structure interaction phenomenon and to help validate the numerical simulations of the same. The experimental tool uses an Exploding Wire technique to generate small-scale cylindrical and spherical blast waves. This approach permits safe operation, high repeatability, and the use of advanced diagnostic systems. The system was calibrated using an analytical model, an empirical model, and numerical simulation. To insure that spherical blast geometry was achieved, a set of free air blast experiments was done in which high-speed photography was used to monitor the blast structure. A scenario in which an explosion occurred in the vicinity of a structure demonstrated the system’s capabilities. Using this simple but not trivial configuration showed unequivocally the effectiveness of this tool. From this comparison, it was found that at early times of blast–structure interaction, the agreement between the two sets of results was very good, but at later times incongruences appeared. Effort has been made to interpret this observation. Furthermore, by using similitude analysis, the results obtained from the small-scale experiments can be applied to the full-scale problem. We have shown that an Exploding Wire system offers an inexpensive, safe, easy to operate, and effective tool for studying phenomena related to blast-wave–structure interactions.
O Sadot - One of the best experts on this subject based on the ideXlab platform.
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small scale blast wave experiments by means of an Exploding Wire
2018Co-Authors: O Sadot, Omri Ram, Eliram Nof, Eytan Kochavi, G BendorAbstract:The effort invested in improving our understanding of the physics of high energy explosion events has tremendously increased in the past few decades. Moreover, the dramatic increase in computer capabilities over the last two decades made the numerical simulation approach the dominant tool for investigating blast wave related phenomena and their effects. However, both large- and small-scale field tests are still in use. In the following, we present an experimental tool capable of better resolving and studying the blast–structure interaction phenomenon. In addition, this experimental tool can assist in validating numerical simulations of these phenomena prior to applying them to simulate large-scale events. The experimental tool uses an Exploding Wire technique to generate small-scale cylindrical and spherical blast waves. This approach permits safe operation, high repeatability, and usage of advanced diagnostic systems that cannot be used in large-scale field experiments. The system was calibrated using an analytical model, an empirical model, and a numerical simulation. To ensure that spherical blast geometry was achieved, a set of free air blast experiments in which high-speed photography was used to monitor the blast wave structure was conducted. Furthermore, by using similitude analysis the results obtained from small-scale experiments can be applied to full-scale problems. It has been clearly shown that an Exploding Wire system offers an inexpensive, repeatable, safe, easy to operate, and effective experimental tool for studying phenomena involving blast–structure interactions.
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exploration of methods in the Exploding Wire technique for simulating large blasts
2017Co-Authors: Eliram Nof, Omri Ram, Eytan Kochavi, G Bendor, O SadotAbstract:Small-scale modeling of explosive events has become an important tool in the investigation of blast wave-structure interactions. In this approach, a full-scale model is miniaturized and subjected to “gram-scale” explosions from detonated micro-charges. While offering a cheaper, faster, and ultimately more manageable alternative to full-scale field tests, small-scale testing also offers better reliability and accuracy in more complex scenarios where numerical simulations become limited. Nevertheless, small-scale experiments introduce other difficulties due to the reliance on the well-known Cranz-Hopkinson “cube-root” scaling law. This scaling relationship is suitable for self-similar open-field experiments but does not necessarily apply to urban scenarios. Additionally, chemical explosive charges of such small quantities might be susceptible to changes in parameters such as the explosive compound compression strength, the humidity of the explosive and of the surrounding atmosphere, the method of ignition, etc. Logistically, the handling and preparing of the experimental setup with these small chemical explosives requires specially trained personnel and permits. To overcome these challenges, the Exploding Wire (EW) technique offers an elegant substitute to using small chemical charges in scaled-down modeling.
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Implementation of the Exploding Wire technique to study blast-wave–structure interaction
Experiments in Fluids, 2012Co-Authors: O. Ram, O SadotAbstract:The effort invested in improving our understanding of the physics of high-energy explosion events has been steadily increasing since the latter part of the twentieth century. Moreover, the dramatic increase in computer power over the last two decades has made the numerical simulation approach the dominant tool for investigating blast phenomena and their effects. However, field tests, on both large and small scales, are still in use. In the current paper, we present an experimental tool to better resolve and study the blast–structure interaction phenomenon and to help validate the numerical simulations of the same. The experimental tool uses an Exploding Wire technique to generate small-scale cylindrical and spherical blast waves. This approach permits safe operation, high repeatability, and the use of advanced diagnostic systems. The system was calibrated using an analytical model, an empirical model, and numerical simulation. To insure that spherical blast geometry was achieved, a set of free air blast experiments was done in which high-speed photography was used to monitor the blast structure. A scenario in which an explosion occurred in the vicinity of a structure demonstrated the system’s capabilities. Using this simple but not trivial configuration showed unequivocally the effectiveness of this tool. From this comparison, it was found that at early times of blast–structure interaction, the agreement between the two sets of results was very good, but at later times incongruences appeared. Effort has been made to interpret this observation. Furthermore, by using similitude analysis, the results obtained from the small-scale experiments can be applied to the full-scale problem. We have shown that an Exploding Wire system offers an inexpensive, safe, easy to operate, and effective tool for studying phenomena related to blast-wave–structure interactions.
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implementation of the Exploding Wire technique to study blast wave structure interaction
Experiments in Fluids, 2012Co-Authors: Omri Ram, O SadotAbstract:The effort invested in improving our understanding of the physics of high-energy explosion events has been steadily increasing since the latter part of the twentieth century. Moreover, the dramatic increase in computer power over the last two decades has made the numerical simulation approach the dominant tool for investigating blast phenomena and their effects. However, field tests, on both large and small scales, are still in use. In the current paper, we present an experimental tool to better resolve and study the blast–structure interaction phenomenon and to help validate the numerical simulations of the same. The experimental tool uses an Exploding Wire technique to generate small-scale cylindrical and spherical blast waves. This approach permits safe operation, high repeatability, and the use of advanced diagnostic systems. The system was calibrated using an analytical model, an empirical model, and numerical simulation. To insure that spherical blast geometry was achieved, a set of free air blast experiments was done in which high-speed photography was used to monitor the blast structure. A scenario in which an explosion occurred in the vicinity of a structure demonstrated the system’s capabilities. Using this simple but not trivial configuration showed unequivocally the effectiveness of this tool. From this comparison, it was found that at early times of blast–structure interaction, the agreement between the two sets of results was very good, but at later times incongruences appeared. Effort has been made to interpret this observation. Furthermore, by using similitude analysis, the results obtained from the small-scale experiments can be applied to the full-scale problem. We have shown that an Exploding Wire system offers an inexpensive, safe, easy to operate, and effective tool for studying phenomena related to blast-wave–structure interactions.
