scholarly journals Generation of super-short avalanche electron beams in SF6

2014 ◽  
Vol 32 (2) ◽  
pp. 331-341 ◽  
Author(s):  
Cheng Zhang ◽  
Victor F. Tarasenko ◽  
Tao Shao ◽  
Dmitry V. Beloplotov ◽  
Mikhail I. Lomaev ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electric Field ◽  
Wave Front ◽  
Electron Beams ◽  
Negative Polarity ◽  
Ionization Wave ◽  
Curvature Radius ◽  
Positive Polarity ◽  
Inhomogeneous Electric Field ◽  
Diffuse Discharge

AbstractIn this work, the generation of a super-short avalanche electron beam (SAEB) in SF6 in an inhomogeneous electric field is studied on two generators with pulse rise times of 0.5 and 2 ns, respectively. The SAEB parameters in SF6 are compared with those obtained in other gases (air, nitrogen, argon, and krypton). It is shown that the SAEB amplitude in SF6 at pressures ranging from 0.05 to 0.2 MPa is commensurable with that in krypton and is much lower than that in air and nitrogen. It is also found that in SF6, SF6 mixture with 2.5% of nitrogen, and other gases, a diffuse discharge is ignited not only at negative polarity but also at positive polarity of the electrode with small curvature radius. Furthermore, the velocity of the ionization wave front in SF6 in an inhomogeneous electric field is studied. Experimental results show that the velocity of the ionization wave front in SF6 is lower than that in air and nitrogen as well as such velocity decreases when the pressure increases from 0.05 to 0.3 MPa in all gases.

Study on Effect of Pulse Electric Field on Solidification Process of Fe-C-S Alloy Melt

2011 ◽  
Vol 284-286 ◽  
pp. 1137-1142
Author(s):  
Zhi You Liao ◽  
Hai Chuan Wang ◽  
Peng Hong ◽  
Xin Li ◽  
Shi Jun Wang ◽  
...  
Keyword(s):  
Electric Field ◽  
Pulse Electric Field ◽  
Boundary Segregation ◽  
Solidification Process ◽  
Negative Polarity ◽  
Solidification Microstructure ◽  
Grain Boundary Segregation ◽  
Positive Polarity ◽  
Pulse Electric ◽  
Migration Law

It can reduce the grain boundary segregation effectively, and improve the solidification microstructure, as well as cause the migration and redistribution of elements by adding the pulse electric field during the solidification process of the Fe-C-S alloy melt. Where, the element S migrates from the positive polarity to the negative polarity, while the migration law of the element C is reverse to that of the element S. The principal ingredient of the inclusion in solidification microstructure after treatment is FeS and a small amount of MnS, while FeS is distributed at the edge and in the centre area of the whole sample spherically.

scholarly journals On the formation of a bead structure of spark channels during a discharge in air at atmospheric pressure

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Victor Tarasenko ◽  
Dmitry Beloplotov ◽  
Alexander Burachenko ◽  
Evgenii Baksht
Keyword(s):  
Electric Field ◽  
Rise Time ◽  
Atmospheric Pressure ◽  
Negative Polarity ◽  
Inhomogeneous Electric Field ◽  
Iccd Camera ◽  
Voltage Pulses

The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied. Voltage pulses with an amplitude of up to 150 kV and a rise time of ≈1.5 µs were applied across a 45-mm point-to-plane gap. Under these conditions, spark channels consisting of bright and dim regions (bead structure) were observed. It is shown that when current is limited, an increase in the rise time and the gap length does not affect the formation of the bead structure. It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads. The appearance of the bead structure is more likely at negative polarity of the pointed electrode. The formation of spark channels was studied with a four-channel ICCD camera. 

scholarly journals Corona at Large Coated Electrodes

2018 ◽  
Author(s):  
Mats Larsson ◽  
Olof Hjortstam ◽  
Håkan Faleke ◽  
Liliana Arevalo ◽  
Dong Wu ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Negative Polarity ◽  
Electrode Geometry ◽  
Positive Polarity ◽  
Electrical Fields ◽  
Insulating Material ◽  
Air Gaps ◽  
High Electric Fields ◽  
Coated Electrodes

<p>In geometries relevant form HVDC applications where large electrodes and large air gaps are utilized, the observed corona can be quite different from geometries studied in the literature where needles or wires are used as high voltage electrodes. Corona discharges at large electrodes often initiates when the electric field on the electrode surface appears lower than the critical electric field strength, 2.4 kV/mm. Surface contamination of the electrode has been pointed out as the reason for such discharge events. Our experimental results indicate that one possible way to prevent such corona is to coat the electrode with an insulating material, such as epoxy or oxide layers. It seems that the layer separates any corona inducing particle from the electrode, which in turn hinders the corona to form. However, as the layer breaks down and gets punctured, the corona preventing propertied disappears and corona forms easily. We conclude that as long as the layer doesn’t get punctured, coating electrodes with insulating material is preventing corona to initiate at electrical fields below the critical electric field, as given by the electrode geometry. In contrast to positive polarity, for negative polarity the epoxy coating could withstand high electric fields without breaking down.</p>

scholarly journals The Study of EHD Flow:Velocity and electrical power

2018 ◽  
Vol 156 ◽  
pp. 02016
Author(s):  
Sumariyah ◽  
Kusminarto ◽  
Arief Hermanto ◽  
Pekik Nuswantoro
Keyword(s):  
Electric Field ◽  
Corona Discharge ◽  
High Voltage ◽  
Electrical Power ◽  
Negative Polarity ◽  
Ring Electrode ◽  
Positive Polarity ◽  
Concentric Ring ◽  
Single Ring ◽  
Gas Medium

Electrohydrodynamics (EHD) flow is the yield of the corona discharge. Corona discharge characterized by electrical phenomena that occur together in a gas medium under the influence of an electric field. In corona discharge, the electric field is not homogeneous due to the geometry of the electrode configuration. In this study, a pin-multi concentric ring electrode (P-MRE) and pin-single ring electrode (P-SRE) has been used as electrodes configuration. The objective of this research is to get the velocity of EHD flow and determining the electrical power of the EHD flow. EHD flow generated by a DC high voltage (up to 5 kV). The pin electrode was connected to a positive polarity and electrode ring/multi-concentric rings to negative polarity. Based on our result, we make a comparison of two types of corona configurations. The results were obtained that, EHD flow velocities with the P-MRE was greater than the P-SRE for the same distance and voltage. We found that u-P characteristics of EHD flow with the P-MRE and P-SRE follow relationship as u ∞ P1/3.

scholarly journals Soot and Fullerenes Formation in the Premixed Benzene-Oxygen Mixture in Electric Field at Low Pressure

2011 ◽  
Vol 14 (1) ◽  
pp. 13
Author(s):  
Z.A. Mansurov ◽  
N.G. Prikhodko ◽  
B.T. Lesbayev ◽  
M. Auyelkhankyzy
Keyword(s):  
Electric Field ◽  
Electric Current ◽  
Negative Polarity ◽  
Oxygen Mixture ◽  
Positive Polarity ◽  
Direct Electric Current ◽  
Yield Parameters ◽  
Intensity Range ◽  
Maximum Decrease ◽  
Electrode Systems

<p>Influence of the direct electric current of different polarity on flame forms, soot yield, parameters of soot samples micro crystals (Lа, Lc and d<sub>002</sub>) and soot particles sizes in intensity range from 0.5 to 20 kV at electrode systems «needle-plane» at combustion of benzene-oxygen mixture at the ratio С/О = 1.0 with addition of 10% volume of argon at pressure 40 Torr was investigated. It was found that at positive polarity action of electric field rises to such a degree that at U ≥ 10 kV it leads to flame extinction. It is shown that maximum decrease in soot yield is observed at negative polarity. It was found that intensity range of electric field in which soot yield was 10% more soot yield without applying electric field. It was shown that parameters of soot micro crystals on average remain constant irrespective of intensity and polarity. Fullerenes С<sub>60</sub>, С<sub>70</sub> and PAH were identified in the extracts of soot samples by the method of IRspectroscopy.</p>

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

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