scholarly journals Analysis of C2 Swan Bands in Ablation-Dominated Arcs in CO2 Atmosphere

2019 ◽  
Vol 6 (1) ◽  
pp. 82-86
Author(s):  
R. Methling ◽  
St. Franke ◽  
N. Götte ◽  
S. Wetzeler ◽  
D. Uhrlandt
Keyword(s):  
High Speed ◽  
Circuit Breaker ◽  
Optical Emission ◽  
Active Phase ◽  
Video Camera ◽  
Nozzle Geometry ◽  
Optical Absorption Spectroscopy ◽  
Iccd Camera ◽  
Copper Electrodes ◽  
Current Zero

A model circuit breaker in a high-pressure chamber filled with CO<sub>2</sub> atmosphere is used to operate a wall-stabilized arc of several kilo-amperes between tungsten-copper electrodes surrounded by polytetrafluoroethylene nozzles. Optical emission spectroscopy (OES) is carried out via quartz plates inserted into the nozzles using a combination of an imaging spectrometer either with a high-speed video camera or with an ICCD camera. Depending on the nozzle geometry and the current, continuum from C<sub>2</sub> Swan bands was detected as absorption as well as emission pattern. After current zero, optical absorption spectroscopy (OAS) using a xenon flashlamp as broadband background radiator was applied. An absorption around 493 nm was detected and attributed to CuF molecules. The study proofs the existence of C<sub>2</sub> in the active phase and the formation of CuF near to current zero.

scholarly journals Ablation-Dominated Arcs in CO2 Atmosphere - Part II: Molecule Emission and Absorption

2020 ◽  
Author(s):  
Ralf Methling ◽  
Nicolas Götte ◽  
Dirk Uhrlandt
Keyword(s):  
Absorption Spectroscopy ◽  
High Speed ◽  
Broad Band ◽  
Imaging Spectroscopy ◽  
Circuit Breaker ◽  
Visible Spectral Range ◽  
Nozzle Geometry ◽  
Ambient Conditions ◽  
Band Absorption ◽  
Current Zero

Molecule radiation can be used as a tool to study colder regions in switching arc plasmas like arc fringes in contact to walls and ranges around current zero (CZ). This is demonstrated in the present study for the first time for the case of ablation-dominated high&ndash;current arcs as key elements of self&ndash;blast circuit breakers. The arc in a model circuit breaker (MCB) in CO2 with and an arc in a long nozzle under ambient conditions with peak currents between 5 and 10 kA were studied by emission and absorption spectroscopy in the visible spectral range. The nozzle material was polytetrafluoroethylene (PTFE) in both cases. Imaging spectroscopy was carried out either with high-speed cameras or with intensified CCD cameras. A pulsed high-intensity Xe lamp was applied as background radiator for the broad-band absorption spectroscopy. Emission of Swan bands from carbon dimers was observed at the edge of nozzles only or across the whole nozzle radius with highest intensity in the arc center, depending on current and nozzle geometry. Furthermore, absorption of C2 Swan bands and CuF bands were found with the arc plasma serving as background radiator. After CZ, only CuF was detected in absorption experiments.

scholarly journals Ablation-Dominated Arcs in CO2 Atmosphere—Part II: Molecule Emission and Absorption

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4720
Author(s):  
Ralf Methling ◽  
Nicolas Götte ◽  
Dirk Uhrlandt
Keyword(s):  
Absorption Spectroscopy ◽  
High Speed ◽  
Broad Band ◽  
Imaging Spectroscopy ◽  
Circuit Breaker ◽  
Visible Spectral Range ◽  
Nozzle Geometry ◽  
Ambient Conditions ◽  
Band Absorption ◽  
Current Zero

Molecule radiation can be used as a tool to study colder regions in switching arc plasmas like arc fringes in contact to walls and ranges around current zero (CZ). This is demonstrated in the present study for the first time for the case of ablation-dominated high-current arcs as key elements of self-blast circuit breakers. The arc in a model circuit breaker (MCB) in CO2 with and an arc in a long nozzle under ambient conditions with peak currents between 5 and 10 kA were studied by emission and absorption spectroscopy in the visible spectral range. The nozzle material was polytetrafluoroethylene (PTFE) in both cases. Imaging spectroscopy was carried out either with high-speed cameras or with intensified CCD cameras. A pulsed high-intensity Xe lamp was applied as a background radiator for the broad-band absorption spectroscopy. Emission of Swan bands from carbon dimers was observed at the edge of nozzles only or across the whole nozzle radius with highest intensity in the arc center, depending on current and nozzle geometry. Furthermore, absorption of C2 Swan bands and CuF bands were found with the arc plasma serving as background radiator. After CZ, only CuF was detected in absorption experiments.

scholarly journals Mechanisms Responsible for Arc Cooling in Different Gases in Turbulent Nozzle Flow

2017 ◽  
Vol 4 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Y. Guo ◽  
H. Zhang ◽  
Y. Yao ◽  
Q. Zhang ◽  
J. D. Yan
Keyword(s):  
Material Properties ◽  
High Speed ◽  
Gas Flow ◽  
Ohmic Heating ◽  
Circuit Breaker ◽  
Fault Current ◽  
High Current ◽  
Physical Mechanisms ◽  
Current Zero ◽  
Different Gases

A high voltage gas blast circuit breaker relies on the high speed gas flow in a nozzle to remove the energy due to Ohmic heating at high current and to provide strong arc cooling during the current zero period to interrupt a fault current. The physical mechanisms that are responsible for the hugely different arc cooling capabilities of two gases (SF<sub>6</sub> and air) are studied in the present work and important gas material properties controlling the cooling strength identified.

scholarly journals Investigation of an Ablation-dominated Arc in a Model Chamber by Optical Emission Spectroscopy

2017 ◽  
Vol 4 (2) ◽  
pp. 153-156 ◽  
Author(s):  
R. Methling ◽  
A. Khakpour ◽  
S. Wetzeler ◽  
D. Uhrlandt
Keyword(s):  
Emission Spectroscopy ◽  
High Speed ◽  
Optical Emission Spectroscopy ◽  
Rotational Symmetry ◽  
Line Emission ◽  
Optical Emission ◽  
Ambient Air ◽  
Video Camera ◽  
Radial Temperature ◽  
Model Chamber

A switching arc in a model chamber is investigated by means of optical emission spectroscopy. Ignition wire is applied to initiate an arc of several kiloampere between tungsten−copper electrodes. Radiation emitted by the arc plasma is absorbed by a surrounding PTFE nozzle, leading to an ablation–dominated discharge. Video spectroscopy is carried out using an imaging spectrometer combined with a high–speed video camera. Carbon ion and fluorine atom line emission from the heating channel as well as copper, oxygen and nitrogen from ignition wire and ambient air are analyzed with focus on the low–current phases at the beginning of discharge and near current zero. Additionally, electrical parameters and total pressure are recorded while the general behavior of the discharge is observed by another video camera. Considering rotational symmetry of the arc the corresponding radial emission coefficients are determined. Finally, radial temperature profiles are calculated.

Roles of Hydrogen Atmospheres in Growth of Ultrananocrystalline Diamond by Pulsed Laser Deposition

2010 ◽  
Vol 638-642 ◽  
pp. 1685-1690
Author(s):  
Kenji Hanada ◽  
Takashi Nishiyama ◽  
Tsuyoshi Yoshitake ◽  
Kunihito Nagayama
Keyword(s):  
Pulsed Laser Deposition ◽  
High Speed ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Optical Emission ◽  
Hydrogen Atmosphere ◽  
Laser Deposition ◽  
Growth Time ◽  
Iccd Camera ◽  
Ultrananocrystalline Diamond

The growth of ultrananocrystalline diamond (UNCD) by pulsed laser deposition necessitates hydrogen atmospheres during the deposition. Optical emission spectroscopy was used to study the roles of the hydrogen atmosphere on the UNCD growth. Time-resolved images of a plume that expanded from a laser-irradiation spot toward a substrate were taken using a high-speed ICCD camera equipped with narrow-bandpass filters. While the plume disappeared at the longest within 1 s in vacuum, the emission from C+ lasted above the substrate surface for approximately 7 microseconds at a hydrogen pressure of 53.3 Pa. Since emission lifetimes of species are approximately 10 nanoseconds, this implies that C+ ions collided actively for such a long time. The hydrogen atmosphere has a role of forming a high number density of C+ ions. In addition, we believe that atomic hydrogen that might be generated by the collisions with carbon species contributes to the UNCD crystallite formation by their terminating the dangling bonds of carbon clusters as theoretically predicted in previous reports.

scholarly journals Properties of Vacuum Arcs Generated by Switching RMF Contacts at Different Ignition Positions

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5596
Author(s):  
Sergey Gortschakow ◽  
Steffen Franke ◽  
Ralf Methling ◽  
Diego Gonzalez ◽  
Andreas Lawall ◽  
...  
Keyword(s):  
High Speed ◽  
Near Infrared ◽  
Active Phase ◽  
Optical Filters ◽  
Green Energy ◽  
Anode Surface ◽  
Optical Absorption Spectroscopy ◽  
Design Development ◽  
Ignition Point ◽  
Zero Crossing

The influence of initiation behavior of the drawn arc on the arc motion, on arc characteristics during the active phase, as well as on the post-arc parameters, was studied. The study was focused on arc dynamics, determination of the anode surface temperature after current interruption, and diagnostics of metal vapor density after current zero crossing. Different optical diagnostics, namely high-speed camera video enhanced by narrow-band optical filters, near infrared spectroscopy, and optical absorption spectroscopy was applied. The initiation behavior of the drawn arc had a clear influence on arc parameters. Higher local electrode temperature occurs in case of the electrodes with ignition point near the outer electrode boundary. This further causes an enhanced density of chromium vapor, even in cases with lower arc duration. The results of this study are important for design development of switching RMF contacts for future green energy applications.

Enhancing the Aggressive Intensity of a Cavitating Jet by Introducing Water Flow Holes and a Long Guide Pipe

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Hirokazu Kamisaka ◽  
Hitoshi Soyama
Keyword(s):  
Mass Loss ◽  
Water Flow ◽  
High Speed ◽  
Pure Aluminum ◽  
Video Camera ◽  
Nozzle Geometry ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Erosion Area ◽  
Cavitating Jet

Abstract It is known that the geometry of the nozzle has a great effect on the aggressive intensity of a cavitating jet. In previous reports, various nozzle geometries were proposed, and improvements made to the aggressive intensity were reported. However, no detailed description of the reasons why the aggressive intensity is improved by these various geometries was given. In this study, we conducted erosion tests on pure aluminum Japanese Industrial Standards JIS A1050P using 11 different nozzles with different geometries downstream from the throat outlet in order to understand the effects of the nozzle geometry on the aggressive intensity. In addition, in order to investigate the characteristics of the cavitating jet produced by each nozzle, measurements of the erosion areas, images of the cavitating jet using a high-speed video camera, and measurements of the impingement pressure of the cavitating jet were taken, and correlations between the parameters were obtained. It was found that the nozzle with the largest mass loss was a nozzle with water flow holes near to the throat outlet and a long guide pipe (LGP). The mass loss was 2.5 times that of the previously reported optimum geometry nozzle. Very high correlations were obtained between the mass loss, the inner diameter of the annular erosion area, the impingement pressure measured at the same standoff distance and the cavitation cloud lifetime. Based on these results and the images of the cavitating jets taken with the high-speed video camera, a new cavitating jet progression process is proposed.

scholarly journals Detonation effects of shallow buried explosive in sandy soil on target plate acceleration in a small-scale blast test

2018 ◽  
Vol 192 ◽  
pp. 02028
Author(s):  
Hassan Zulkifli Abu ◽  
Ibrahim Aniza ◽  
Mohamad Nor Norazman
Keyword(s):  
Sandy Soil ◽  
High Speed ◽  
Early Stage ◽  
Time History ◽  
Video Camera ◽  
Small Scale ◽  
Target Plate ◽  
Air Blast ◽  
High Speed Video Camera ◽  
The Impact

Small-scale blast tests were carried out to observe and measure the influence of sandy soil towards explosive blast intensity. The tests were to simulate blast impact imparted by anti-vehicular landmine to a lightweight armoured vehicle (LAV). Time of occurrence of the three phases of detonation phase in soil with respect to upward translation time of the test apparatus were recorded using high-speed video camera. At the same time the target plate acceleration was measured using shock accelerometer. It was observed that target plate deformation took place at early stage of the detonation phase before the apparatus moved vertically upwards. Previous data of acceleration-time history and velocity-time history from air blast detonation were compared. It was observed that effects of soil funnelling on blast wave together with the impact from soil ejecta may have contributed to higher blast intensity that characterized detonation in soil, where detonation in soil demonstrated higher plate velocity compared to what occurred in air blast detonation.

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