The electric strength of highly compressed gases

Cohen, Eyal

doi:10.1049/pi-a.1956.0055

Cited by 11 publications

(4 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This rarefaction and sudden recompression have important consequences for breakdown processes. According to Paschen's Law, the maximum electric field, E b , that can be sustained between two charged surfaces, separated by some distance d, before the intervening gas undergoes electrical breakdown is roughly inversely proportional to pressure (for pressures of up to 13-20 atmospheres; Cohen, 1956;Paschen, 1889). Quantitatively, such relationship can be expressed as…”

Section: Modelmentioning

confidence: 99%

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Harper

Cimarelli

Dufek

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

Observations at numerous volcanoes reveal that eruptions are often accompanied by continual radio frequency (CRF) emissions. The source of this radiation, however, has remained elusive until now. Through experiments and the analysis of field data, we show that CRF originates from proximal discharges driven by the compressible fluid dynamics associated with individual volcanic explosions. Blasts produce flows that expand supersonically, generating regions of weakened dielectric strength in close proximity to the vent. As erupted material—charged through fragmentation, friction, or other electrification process—transits through such a region, pyroclasts remove charge from their surfaces in the form of small interparticle spark discharges or corona discharge. Discharge is maintained as long as overpressured conditions at the vent remain. Beyond describing the mechanism underlying CRF, we demonstrate that the magnitude of the overpressure at the vent as well as the structure of the supersonic jet can be inferred in real time by detecting and locating CRF sources.

show abstract

Section: Modelmentioning

confidence: 99%

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Harper

Cimarelli

Dufek

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…In previous studies, the ratio of BDV of SF 6 to that of air for the same gap length and pressure is commonly calculated as reference of comparison. Different researchers presented various values from 1.5 to 2.7 under different experimental conditions 20, 21. All of the values are at power frequency.…”

Section: Discussionmentioning

confidence: 99%

Breakdown voltage of compressed SF₆ at very low frequency/low frequency (VLF/LF)

Han

Gorur

Hansen

2010

Int Trans Elec Energy Syst

View full text Add to dashboard Cite

SUMMARY The breakdown voltage (BDV) of compressed sulfur hexafluoride (SF6) in the pressure range of 1–5 atm at 30 kHz, the frequency used by Navy for communications with vessels, is presented. Experiments were conducted in both uniform field (plane–plane gap) and non‐uniform field (rod–plane gap). The impact of pressure on the BDV is quantitatively analyzed. The pressure correction factors for calculating the BDV of SF6 at 30 kHz have been developed from knowledge of breakdown characteristics of air and from regression models. Copyright © 2010 John Wiley & Sons, Ltd.

show abstract

“…According to Flagan 34 this is, for two concentric cylinder electrodes, one third of the field strength given by Paschen's Law for concentric DMA. We did not apply Paschen's Law but used one third of the experimental values from Cohen 35 at pressures between p = 1 bar (lower end) and p = 60 bar (upper end) instead. Below the breakdown voltage the electric conductivity of air is so low that temperature rise due to Joule heating is negligible.…”

Section: Methodsmentioning

confidence: 99%

Aerosol classification by dielectrophoresis: a theoretical study on spherical particles

Lorenz

Weber

Baune

et al. 2020

Sci Rep

View full text Add to dashboard Cite

The possibilities and limitations using dielectrophoresis (DEP) for the dry classification of spherical aerosol particles was evaluated at low concentrations in a theoretical study. For an instrument with the geometry of concentric cylinders (similar to cylindrical DMA), the dependencies of target particle diameter d * P , resolution, and yield of the DEP classification on residence time, applied electric field strength, and pressure of the carrier gas were investigated. Further, the diffusion influence on the classification was considered. It was found that d * P scales with the mean gas flow velocity u gas , classifier length L, and electric field strength E as d * P ∝ (u gas /L) 0.5 E −1. The resolution of the classification depends on the particle diameter and scales proportionally to d * P 1.3. It is constrained by the flow ratio β (i.e., sheath gas to aerosol flow), electrode diameters, and applied electric field strength. The classification yield increases with the ratio of the width of the extended outlet slit s e to the diffusion induced broadening σ z. As expected, resolution and yield exhibit opposite dependencies on s e /σ z. Our simulations show that DEP classification can principally cover a highly interesting particle size range from 100 nm to 10 µm while being directly particle size-selective and particle charge independent. The dry classification of particles with diameters below 10 µm is key to obtain high-value powders with narrow size distributions. These fine particles find application in a variety of high-value products such as coatings 1 , printing products 2 , porous functional structures 3 , particle-reinforced polymers 4 and electrodes in electro-chemical energy storage 5. Many established classification technologies suffer from insufficient selectivity or throughput in this size range. For instance sieving, which is a common tool in industrial separation, comes only close to this size range when performed as wet technique 6. When starting from a dry powder, wet sieving could lead to agglomeration and material property changes and would additionally require an uneconomical drying step following the classification. Deflection wheel classifiers exhibit a significant loss in sharpness of cut and throughput in this particle size range 7. Electrophoretic mobility classification relies on the defined charging of the particles, and thus particle-size-dependent charge probability distributions. Hence, particle size is not directly measured but merely the electrophoretic mobility distribution of the particles. A standard inversion procedure exists to back-calculate size distribution from electrophoretic mobility measurements. Nevertheless, exact particle size classification is not possible with this technique because particles of different size may have the same electrophoretic mobility due to their charge. A comprehensive survey concerning charging of airborne particles is given for example by Friedlander 8 , chapter 2. In this manuscript we outline the behaviour of a particle-charge-independent...

show abstract

The electric strength of highly compressed gases

Cited by 11 publications

References 1 publication

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Breakdown voltage of compressed SF₆ at very low frequency/low frequency (VLF/LF)

Aerosol classification by dielectrophoresis: a theoretical study on spherical particles

Contact Info

Product

Resources

About

The electric strength of highly compressed gases

Cited by 11 publications

References 1 publication

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Breakdown voltage of compressed SF6 at very low frequency/low frequency (VLF/LF)

Aerosol classification by dielectrophoresis: a theoretical study on spherical particles

Contact Info

Product

Resources

About

Breakdown voltage of compressed SF₆ at very low frequency/low frequency (VLF/LF)