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Electron Density Estimation and Fiber Fuse Simulation in Laser-Irradiated Bulk Glass
Issue:
Volume 10, Issue 1, February 2022
Pages:
1-9
Received:
26 December 2021
Accepted:
11 January 2022
Published:
18 January 2022
Abstract: To clarify the formation mechanism of periodic nanometer-size cavity structure of a borosilicate glass sample, the free electron density around the exit surface was investigated when it exposed to intense femtosecond laser radiation. The electron density near the edge of the crack on the surface was estimated to be 1020-1022 cm-3. From this result, the temperature of the irradiated heating area near the edge of the crack was estimated to reach at least about 6,000 K, which was sufficient for the initiation and propagation of the fiber fuse. In this way, periodic nanosized cavities could be formed by fiber fuse propagation starting near the edge of the crack on the exit surface. Next, fiber fuse propagation in the modified zone formed by continuous-wave laser irradiation in a silica glass sample was investigated theoretically by the explicit finite-difference method using the thermochemical SiOx production model. In the calculation, we assumed the glass to be in an atmosphere and that part (40 mm in length) of the modified zone was heated to a temperature of 2,923 K. The calculated velocities of fiber fuse propagation in the modified zone were in fair agreement with the experimental values observed at 0.514 and 1.064 mm.
Abstract: To clarify the formation mechanism of periodic nanometer-size cavity structure of a borosilicate glass sample, the free electron density around the exit surface was investigated when it exposed to intense femtosecond laser radiation. The electron density near the edge of the crack on the surface was estimated to be 1020-1022 cm-3. From this result,...
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Integrated Transformer with Buried Windings in Ferrite Core
Mahamat Ahmat Taha,
Mahamat Hassan Bechir,
Ouzer Nabil Adam,
Arafat Ousman Bechir,
Boukhari Mahamat Issa,
Yaya Dagal Dari,
David Pietroy,
Jean Jacques Rousseau
Issue:
Volume 10, Issue 1, February 2022
Pages:
10-17
Received:
15 January 2022
Accepted:
27 January 2022
Published:
9 February 2022
Abstract: In the field of electronics, one of the objectives of current research is to integrate numerous components in increasingly smaller volumes. Reducing the cost of manufacturing components requires integration and collective manufacturing. This paper mainly focuses on the design and the main steps of the micro-fabrication of a transformer with magnetic layers. Windings have been buried in a ferrite core by using Femtosecond Laser Micromachining. Such a burying of windings avoids air gap and greatly increases primary and secondary inductances. Different technological steps from copper deposition to the realization of the grooves in the magnetic material (in the case of the buried transformer) through etching, gilding, lapping, sawing, polishing and gluing have been described. We also used a negative photoresist (SU-8) as an insulating layer and as a support for the fabrication of an air bridge to connect the center pad of the coils to the ground plane. The micro-transformer was characterized with a Vector Network Analyzer and the bandwidth was observed from 20 kHz to 7 MHz. The gain in the bandwidth is equal to 0,86. The buried conductors allow to increase the magnetizing inductance of the transformer and the shift of 45° between the primary and secondary windings allows to decrease the capacitive coupling.
Abstract: In the field of electronics, one of the objectives of current research is to integrate numerous components in increasingly smaller volumes. Reducing the cost of manufacturing components requires integration and collective manufacturing. This paper mainly focuses on the design and the main steps of the micro-fabrication of a transformer with magneti...
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Statistical Investigation of the Disturbances Affecting the Power Distribution Networks (HTB/HTA) of a Few Source Substations in South-Benin
Oswald Gbètondji Acclassato,
Mathias Adjimon Houékpohéha,
Irénée Vianou Madogni,
Hagninou Elagnon Venance Donnou,
Etienne Houngninou,
Basile Bruno Kounouhéwa
Issue:
Volume 10, Issue 1, February 2022
Pages:
18-30
Received:
15 October 2021
Accepted:
13 November 2021
Published:
16 February 2022
Abstract: Power quality is a significant issue that has become increasingly important to both electric power utilities and their customers because of financial losses caused by insufficient. In this work, the Fourier transform (FT) has been exploited for the statistical investigation of the disturbances affecting the electrical distribution networks (HTA) in South-Benin. The data coming from the overhead line disturbances and underground cables, especially from the source substations of MARIA-GLETA, VEDOKO, AKPAKPA, GBEGAMEY and SEME have been treated. These data have been collected and made in our disposal by the Beninese Electricity Energy Company (SBEE) over the period from 2010 to 2017. Harmonic Distortion Rate (TDH) and the Disturbance Rate (DR) have been used to evaluate the variation coefficient of the different disturbances registered at the each source substation, in order to characterize the harmonic pollution and the reactive power consumption. According to the EN 50160 N standard, the results obtained show that VEDOKO registered 500 to 2000 interruptions of duration between 0.4x105 and 1.8x105 minutes, between 2013 and 2016 especially due to a very critical load shedding. The dominance of the disturbances observed has been due exclusively to the incidents setting off and the load shedding incidents in 2017. 2013 and 2015 have been characterized by the frequent blackouts of long living, and occasion considerable damages, and consequently slow down the economic activities, social and cultural life of consumers.
Abstract: Power quality is a significant issue that has become increasingly important to both electric power utilities and their customers because of financial losses caused by insufficient. In this work, the Fourier transform (FT) has been exploited for the statistical investigation of the disturbances affecting the electrical distribution networks (HTA) in...
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Fiber Fuse Simulation in Double-Clad Fibers for High-Power Fiber Lasers
Issue:
Volume 10, Issue 1, February 2022
Pages:
31-38
Received:
25 January 2022
Accepted:
9 February 2022
Published:
16 February 2022
Abstract: Rare-earth-doped optical fibers are one of the most promising solid-state lasers. In these fiber lasers, a cladding-pumping scheme using double-clad fibers is utilized to increase the overall conversion efficiency of pumping light. To maintain acceptable beam quality, the low-numerical aperture large-mode-area fibers is effective for the double-clad fibers because the effects of stimulated Raman scattering can be reduced via the corresponding reduction in the power density in the large fiber core. For the large-mode-area double-clad fibers, fiber fuse propagation was investigated theoretically by the explicit finite-difference method using the thermochemical SiOx production model. In the calculation, we assumed the fiber to be in an atmosphere and that part (40 μm in length) of the core was heated to a temperature of 2,923 K. The threshold power for the double-clad fiber with the core radius of 10 μm was 1.6 W at 1.080 μm and it was close to the experimental value. The power dependence of the velocity of fiber fuse propagation was calculated for the double-clad fibers with the core radius of 10 and 15 μm. The calculated velocities were in fair agreement with the experimental values observed in the input power range from 1 kW to 3.5 kW at 1.080 μm.
Abstract: Rare-earth-doped optical fibers are one of the most promising solid-state lasers. In these fiber lasers, a cladding-pumping scheme using double-clad fibers is utilized to increase the overall conversion efficiency of pumping light. To maintain acceptable beam quality, the low-numerical aperture large-mode-area fibers is effective for the double-cla...
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