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–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 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 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 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.

A Background Emission Correction System for Atomic Absorption Spectrometry

1981 ◽  
Vol 35 (2) ◽  
pp. 176-181 ◽  
Author(s):  
Frederic G. Dewalt ◽  
John R. Amend ◽  
Ray Woodriff
Keyword(s):  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Broad Band ◽  
Absorption Spectrometry ◽  
Broad Band Emission ◽  
Band Emission ◽  
Band Absorption ◽  
Correction System

A simple system which corrects for both broad band absorption and broad band emission in thermally atomized atomic absorption spectroscopy is presented in this article.

scholarly journals High sensitivity ultra-broad-band absorption spectroscopy of inductively coupled chlorine plasma

2016 ◽  
Vol 25 (3) ◽  
pp. 035019 ◽  
Author(s):  
Daniil Marinov ◽  
Mickaël Foucher ◽  
Ewen Campbell ◽  
Mark Brouard ◽  
Pascal Chabert ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Broad Band ◽  
High Sensitivity ◽  
Inductively Coupled ◽  
Band Absorption

A High Speed Method of Continuous Background Correction in Atomic Absorption Spectrometry

1975 ◽  
Vol 29 (2) ◽  
pp. 154-158 ◽  
Author(s):  
T. H. Donnelly ◽  
A. J. Eccleston
Keyword(s):  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
High Speed ◽  
Broad Band ◽  
Absorption Spectrometry ◽  
Point Of View ◽  
Background Correction ◽  
Continuum Source ◽  
Continuous Background ◽  
Band Absorption

The need for background correction in atomic absorption spectrometry (AAS), particularly when graphite furnaces are used to generate the atomic vapor, is discussed. It is shown that a Beckman hydrogen arc lamp is suitable as a continuum source from the point of view of noise, extent of its useful broad band absorption, and light intensity for background-corrected absorption (BCA) measurements over the wavelength range examined (200 to 460 nm). The standard method of determining tin present in rock samples as cassiterite, by extraction as the volatile tin iodide, was examined by flameless AAS with BCA. The method corrects for the large nonatomic absorption present, it is rapid, and it enables easier examination of solutions containing low concentrations of tin (detection limit for a 1 g starting sample is ∼1 jug tin).

scholarly journals Ablation-Dominated Arcs in CO2 Atmosphere - Part I: Temperature Determination near Current Zero

2020 ◽  
Author(s):  
Ralf Methling ◽  
Alireza Khakpour ◽  
Nicolas Götte ◽  
Dirk Uhrlandt
Keyword(s):  
High Speed ◽  
Wall Material ◽  
Maximum Temperature ◽  
Single Shot ◽  
Temperature Profiles ◽  
Optical Investigation ◽  
Ambient Conditions ◽  
Radial Temperature ◽  
Zero Crossing ◽  
Current Zero

Wall&ndash;stabilized arcs dominated by nozzle&ndash;ablation are key elements of self&ndash;blast circuit breakers. In the present study, high&ndash;current arcs were investigated using a model circuit breaker (MCB) in CO2 as gas alternative to SF6 and in addition a long polytetrafluoroethylene nozzle under ambient conditions for stronger ablation. The assets of different methods for optical investigation were demonstrated, e.g. high-speed imaging with channel filters and optical emission spectroscopy. Particularly the phase near current zero (CZ) crossing was studied in two steps. In the first step using high-speed cameras, radial temperature profiles have been determined until 0.4 ms before CZ in the nozzle. Broad temperature profiles with a maximum of 9400 K have been obtained from analysis of fluorine lines. In the second step, the spectroscopic sensitivity was increased using an intensified CCD camera, allowing single-shot measurements until few microseconds before CZ in the MCB. Ionic carbon and atomic oxygen emission were analyzed using absolute intensities and normal maximum. The arc was constricted and the maximum temperature decreased from &amp;gt;18000 K at 0.3 ms to about 11000 K at 0.010 ms before CZ. The arc plasma needs about 0.5-1.0 ms after both the ignition phase and the current zero crossing to be completely dominated by the ablated wall material.

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