scholarly journals Problem of the modeling the filaments after laser-induced breakdown the matter

2020 ◽  
pp. 16-27
Author(s):  
Petro P. Trokhimchuck
Keyword(s):  
Silicon Carbide ◽  
Laser Beam ◽  
Emission Spectrum ◽  
Detailed Analysis ◽  
Cherenkov Radiation ◽  
Spectral Composition ◽  
Critical Energy ◽  
Experimental Results ◽  
Physicochemical Models ◽  
Laser Induced Breakdown

The problems of the appearance of laser-induced filamets in the matter are discussed. A detailed analysis of the formation of such structures in various media: from air to silicon carbide, is represented. The influence of the spectral composition, the number of pulses and the duration of the irradiation and the medium on the geometric dimensions of the resulting structures and on their phase states is shown. In this case, the sizes of filaments vary from several hundred nanometers for silicon carbide to several hundred meters for air. The emission spectrum is continuous, and resembles the Cherenkov radiation. Therefore, the idea was developed that the radiation of filaments and the radiation of Cherenkov are of the same nature. The problems of the mechanisms of the formation of laser-induced destruction cascades in silicon carbide are discussed. To explain the experimental results, we used modified Rayleigh models (diffraction stratification of the laser beam and critical sizes of nanovoids), physicochemical models for determining critical energy values for the corresponding processes, and models for optically-induced Cherenkov radiation.

scholarly journals Detailed Analysis of the Timing Measurements in Optical Position Sensing Devices Based on Laser Beam Deflection

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Andreas Tortschanoff
Keyword(s):  
Laser Beam ◽  
Detailed Analysis ◽  
Cross Talk ◽  
Analytical Description ◽  
Experimental Results ◽  
Beam Deflection ◽  
Position Sensing ◽  
Optical Position

I present a detailed analysis of the timing signals observed, when measuring the oscillation of a Lissajous scanner by sending a reflected laser beam onto carefully placed trigger diodes. This technique was used in a device which we have developed recently for the measurement of resonant MEMS scanner mirrors. For 2D scanner mirrors, cross talk between the two axes is observed. This cross talk can be well understood theoretically. In this paper, a quantitative analytical description is presented, which is confirmed by experimental results.

Cutting Speed of Electric Discharge Machining for SiC Ingot

2012 ◽  
Vol 717-720 ◽  
pp. 861-864 ◽  
Author(s):  
Hideki Yamada ◽  
Satarou Yamaguchi ◽  
Norimasa Yamamoto ◽  
Tomohisa Kato
Keyword(s):  
Silicon Carbide ◽  
Electric Discharge ◽  
Cutting Speed ◽  
Experimental Results ◽  
New Method ◽  
Electric Discharge Machining ◽  
Hard Materials ◽  
Diameter Ingot ◽  
Diamond Saw

A new method based on electric discharge machining (EDM) was developed for cutting a silicon carbide (SiC) ingot. The EDM method is a very useful technique to cut hard materials like SiC. By cutting with the EDM method, kerf loss and roughness of sample are generally smaller than those obtained by cutting with a diamond saw. Moreover, the warpage is smaller than that by the diamond saw cutting, and the cutting speed can be 10 times faster than that of the diamond saw at the present time. We used wires of 50 mm and 100 mm diameters in the experiments, and the experimental results of the cutting speed and the kerf losses are presented. The kerf loss of the 50 mm wire is less than 100 mm, and the cutting speed is about 0.8 mm/min for the thickness of a 6 mm SiC ingot. If we can maintain the cutting speed, the slicing time of a 2 inches diameter ingot would be about seven hours.

scholarly journals Critical Stresses in Materials with Cracks

2019 ◽  
Vol 70 (7) ◽  
pp. 2442-2446
Author(s):  
Simona Eugenia Manea ◽  
Vali Ifigenia Nicolof ◽  
Teodor Sima
Keyword(s):  
Fracture Mechanics ◽  
Critical Stress ◽  
Crack Width ◽  
Crack Depth ◽  
Equivalent Stress ◽  
Critical Energy ◽  
Material Behavior ◽  
Experimental Results ◽  
Critical Stresses ◽  
Mechanics Concepts

The fracture mechanics concepts, as well as the concepts introduced on the basis of principle of critical energy, correlated with strength of materials with cracks is analysed. The equivalent stress method of strength was applied to cracked materials, by using the concept of local critical stress. This one depends on the material behavior and the deterioration due to crack. Experimental results have been obtained with specimens of OL304 steel with different cracks. The influence of crack depth and crack width is put into evidence.

scholarly journals CMOS Realization of All-Positive Pinched Hysteresis Loops

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
B. J. Maundy ◽  
A. S. Elwakil ◽  
C. Psychalinos
Keyword(s):  
Hysteresis Loop ◽  
Detailed Analysis ◽  
Hysteresis Loops ◽  
Nonlinear Circuits ◽  
Experimental Results ◽  
First Order ◽  
Pinched Hysteresis Loop ◽  
A Charge ◽  
Pinched Hysteresis ◽  
Nmos Transistors

Two novel nonlinear circuits that exhibit an all-positive pinched hysteresis loop are proposed. These circuits employ two NMOS transistors, one of which operates in its triode region, in addition to two first-order filter sections. We show the equivalency to a charge-controlled resistance (memristance) in a decremental state via detailed analysis. Simulation and experimental results verify the proposed theory.

A study of genuine pion correlations and fluctuations in relativistic nucleus–nucleus collisions

2021 ◽  
Author(s):  
Imtiyaz A. Najar ◽  
W. Bari
Keyword(s):  
Experimental Data ◽  
Detailed Analysis ◽  
Experimental Results ◽  
Relativistic Nucleus ◽  
Particle Correlations ◽  
Projectile Nucleus ◽  
Urqmd Model

In this study, we have performed a detailed analysis of genuine pion correlations and fluctuations in terms of the normalized factorial comulant moments of second and third orders, [Formula: see text] and [Formula: see text], in case of [Formula: see text]O–AgBr interactions at [Formula: see text][Formula: see text]A and [Formula: see text][Formula: see text]A GeV/c. The experimental results are compared with the predictions of AMPT and UrQMD model simulated events. The UrQMD model reproduces the trends in experimental results but the strength of correlation is much smaller. However, the AMPT model does not also replicate all features of the experimental data. The genuine two-particle and three-particle correlations are found to become weaker with the increase in momentum of the projectile nucleus.

An 8kW LLC resonant converter in plasma power supply based on SiC power devices for efficiency improvement

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 181-188
Author(s):  
Zhenmin Wang ◽  
Wenyan Fan ◽  
Fangxiang Xie ◽  
Chunxian Ye
Keyword(s):  
Silicon Carbide ◽  
Power Supply ◽  
High Frequency ◽  
Experimental Results ◽  
Switching Frequency ◽  
Resonant Converter ◽  
Plasma Power ◽  
Power Devices ◽  
Content Type ◽  
Llc Resonant Converter

Purpose This paper aims to present an 8 kW LLC resonant converter designed for plasma power supply with higher efficiency and lighter structure. It presents how to solve the problems of large volume and weight, low performance and low efficiency of traditional plasma power supply. Design/methodology/approach At present, conventional silicon (Si) power devices’ switching performance is close to the theoretical limit determined by its material properties; the next-generation silicon carbide (SiC) power devices with outstanding advantages can be used to optimal design. This 8 kW LLC resonant converter prototype with silicon carbide (SiC) power devices with a modulated switching frequency ranges from 100  to 400 kHz. Findings The experimental results show that the topology, switching loss, rectifier loss, transformer loss and drive circuit of the full-bridge LLC silicon carbide (SiC) plasma power supply can be optimized. Research limitations/implications Due to the selected research object (plasma power supply), this study may have limited universality. The authors encourage the study of high frequency resonant converters for other applications such as argon arc welding. Practical implications This study provides a practical application for users to improve the quality of plasma welding. Originality/value The experimental results show that the full-bridge LLC silicon carbide (SiC) plasma power supply is preferred in operation under conditions of high frequency and high voltage. And its efficiency can reach 98%, making it lighter, more compact and more efficient than previous designs.

Vibration Analysis of Tapered Pole Linear Switched Reluctance Machine

2017 ◽  
Vol 8 (2) ◽  
pp. 957
Author(s):  
Lenin N C ◽  
Arvind S V
Keyword(s):  
Detailed Analysis ◽  
Vibration Analysis ◽  
Experimental Results ◽  
Switched Reluctance Machine ◽  
Switched Reluctance Motors ◽  
Two Phase ◽  
Switched Reluctance ◽  
Reluctance Machine

The Vibration is one of the major problem in linear switched reluctance motors (LSRMs). This paper present a detailed analysis of vibration in a two phase LSRM and proposes a new structure to reduce the effect. The experimental results of this paper prove that the proposed structure is well suited for conveyor application.

scholarly journals The analysis of friction properties after laser texturizing of the silicon carbide surface layer

2018 ◽  
Vol 183 ◽  
pp. 02010
Author(s):  
Norbert Radek ◽  
Agnieszka Szczotok ◽  
Renata Dwornicka
Keyword(s):  
Silicon Carbide ◽  
Surface Layer ◽  
Statistical Analysis ◽  
Design Of Experiments ◽  
Laser Beam ◽  
High Reliability ◽  
Laser Beam Machining ◽  
Before And After ◽  
High Roughness ◽  
Modification Of The Surface

The modification of the surface properties is a desired technological procedure. One of the possible method is the electro-spark deposition (ESD). Unfortunately, ESD process produces a surface with high roughness. The laser beam machining (LBM) has been involved to lower roughness of the coating made by ESD. The elements coated by ESD have been tested to determine tribological properties and they were compared before and after LBM. To achieve high reliability of the results, the test has been conducted in accordance with design of experiments methodology and the results which were obtained have been processed by a statistical analysis. The description of such an experiment performed for a silicon carbide SiC coating, the obtained results and the conclusions are included in this paper.

scholarly journals Theory of Cherenkov radiation in periodic dielectric media: Emission spectrum

2009 ◽  
Vol 79 (1) ◽  
Author(s):  
Christian Kremers ◽  
Dmitry N. Chigrin ◽  
Johann Kroha
Keyword(s):  
Emission Spectrum ◽  
Cherenkov Radiation ◽  
Dielectric Media
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