Comments on "Electric current and electric field induced in the human body when exposed to an incident electric field near the resonant frequency" and "Electric fields induced in cells in the bodies of amateur radio operators by their transmitting antennas" [with reply]

2001 ◽  
Vol 49 (4) ◽  
pp. 734-736
Author(s):  
G.D. Lapin ◽  
A.W. Guy ◽  
R.W.P. King
Keyword(s):  
Electric Field ◽  
Resonant Frequency ◽  
Electric Current ◽  
Electric Fields ◽  
Human Body ◽  
Incident Electric Field ◽  
Amateur Radio ◽  
In Cells

The Experimental Study on the Influence of Human Body to Measurement of High Voltage Power Frequency Electric Field

2013 ◽  
Vol 303-306 ◽  
pp. 482-488
Author(s):  
Kai Mao ◽  
Jin Gang Wang ◽  
Xu Dong Deng ◽  
Wei He ◽  
Zuo Peng Zhang
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
High Voltage ◽  
Human Body ◽  
Enhancement Factor ◽  
Electric Field Distribution ◽  
Field Distortion ◽  
Power Frequency ◽  
Frequency Electric Field

Based on the basic theory of electromagnetic field, the Electric Field Distortion (EFD) in power frequency electric field caused by induced current of human body has been analyzed. The enhancement factor of the electric field distortion is introduced to reduce the influences caused by human body in the measurement of high voltage electric fields. The Ansoft Maxwell is used to simulate and calculate the electric field distribution under the influence of the human body to have the value of enhancement factor. In addition, the enhancement factor has been corrected by experiment with the electromagnetic field analyzer EFA300. With the enhancement factor introduced in this paper, the measurement error can be reduced.

Electric currents in the ionosphere - Ionization drift due to winds and electric fields

1953 ◽  
Vol 246 (913) ◽  
pp. 306-320 ◽  
Keyword(s):  
Electric Field ◽  
Electric Current ◽  
Electric Fields ◽  
Body Force ◽  
Surrounding Medium ◽  
The Other ◽  
Electric Currents ◽  
Vertical Drift ◽  
Meteor Trails ◽  
Current Flows

An analysis is made of the drift velocity of the (neutral) ionization in a uniform ionosphere under the influences of an electric field and/or atmospheric wind. It is shown that this drift of ionization produces the Ampere body force on the medium; the electric current flows perpendicular to the drift. The motion of a cylinder of ionization, of density differing from the surrounding medium, is then studied. It is found that the motion is electrodynamically stable, but unstable hydrodynamically, if Hall conductivity is appreciable. In the latter event there is rapid accretion of (neutral) ionization on one side of the cylinder, depletion on the other. It is suggested that this is the origin of sporadic E ( E 5 )ionization, and is likely to be an important factor in the production of the long-enduring meteor trails detected by radio methods. Formulae are derived for the horizontal and vertical drift of ionization at all latitudes in a thin ionosphere in which vertical electric currents are prohibited by polarization. Graphs are given which permit derivation of the true wind or field in a given region of the ionosphere from experimental observations of the drift velocities.

scholarly journals Characterization of Chaotic Electroconvection near Flat Inert Electrodes under Oscillatory Voltages

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 161 ◽  
Author(s):  
Jeonglae Kim ◽  
Scott Davidson ◽  
Ali Mani
Keyword(s):  
Electric Field ◽  
Electric Current ◽  
Electric Fields ◽  
Oscillation Frequency ◽  
Stokes Equations ◽  
Convective Transport ◽  
Constant Frequency ◽  
Wide Range ◽  
Oscillation Frequencies ◽  
Electroconvective Instability

The onset of electroconvective instability in an aqueous binary electrolyte under external oscillatory electric fields at a single constant frequency is investigated in a 2D parallel flat electrode setup. Direct numerical simulations (DNS) of the Poisson–Nernst–Planck equations coupled with the Navier–Stokes equations at a low Reynolds number are carried out. Previous studies show that direct current (DC) electric field can create electroconvection near ion-selecting membranes in microfluidic devices. In this study, we show that electroconvection can be generated near flat inert electrodes when the applied electric field is oscillatory in time. A range of applied voltage, the oscillation frequency and the ratio of ionic diffusivities is examined to characterize the regime in which electroconvection takes place. Similar to electroconvection under DC voltages, AC electroconvection occurs at sufficiently high applied voltages in units of thermal volts and is characterized by transverse instabilities, physically manifested by an array of counter-rotating vortices near the electrode surfaces. The oscillating external electric field periodically generate and destroy such unsteady vortical structures. As the oscillation frequency is reduced to O ( 10 − 1 ) of the intrinsic resistor–capacitor (RC) frequency of electrolyte, electroconvective instability is considerably amplified. This is accompanied by severe depletion of ionic species outside the thin electric double layer and by vigorous convective transport involving a wide range of scales including those comparable to the distance L between the parallel electrodes. The underlying mechanisms are distinctly nonlinear and multi-dimensional. However, at higher frequencies of order of the RC frequency, the electrolyte response becomes linear, and the present DNS prediction closely resembles those explained by 1D asymptotic studies. Electroconvective instability supports increased electric current across the system. Increasing anion diffusivity results in stronger amplification of electroconvection over all oscillation frequencies examined in this study. Such asymmetry in ionic diffusivity, however, does not yield consistent changes in statistics and energy spectrum at all wall-normal locations and frequencies, implying more complex dynamics and different scaling for electrolytes with unequal diffusivities. Electric current is substantially amplified beyond the ohmic current at high oscillation frequencies. Also, it is found that anion diffusivity higher than cation has stronger impact on smaller-scale motions (≲ 0.1 L).

Influence of Electric Fields and Surface Chemistry on Ice Nucleation Kinetics

2015 ◽  
Author(s):  
Katherine Carpenter ◽  
Vaibhav Bahadur
Keyword(s):  
Electric Field ◽  
Electric Current ◽  
Electric Fields ◽  
Dielectric Layer ◽  
Supercooled Water ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Crystal Nucleation ◽  
Nucleation Kinetics ◽  
Bubble Generation

The majority of studies on ice formation have attempted to prevent or reduce ice build-up; very few studies have focused on promoting ice nucleation which would have applications in appliances, cryopreservation, and pharmaceutical freeze-drying. Such studies are also relevant to the synthesis of methane hydrates for natural gas transportation. This paper details a fundamental study on the influence of interfacial electric fields on ice nucleation promotion. Electrofreezing, i.e. applying an electric field has been shown to electrically induce nucleation of supercooled water. The freezing temperatures of supercooled water can thus be increased via electrofreezing. However, the mechanisms responsible for elevating the freezing temperature are unclear. Typically, bare electrodes are submerged in water, which creates a volumetric electric field in water. With this type of electric field, the application of a voltage can result in multiple phenomena such as current flows, chemical reactions and gas bubble formation or growth. It is unclear whether electrofreezing is the result of the electric field or the current flow-related secondary phenomena. In the present work, the role of electric fields and surface charge on electrofreezing is isolated by studying electrofreezing of water droplets on a dielectric layer. This dielectric layer blocks current and creates an interfacial electric field with a build-up of electric charge at the solid-fluid interface. Ultra-high electric fields of up to 80 V/μm were applied, which is one order of magnitude higher than in previous studies. Infrared (IR) thermography was used to capture ice nucleation and determine the electrofreezing temperature. The results show that the electric fields alone can elevate the freezing temperature of water by as much as 15 °C; however, this effect saturates at electric fields of approximately 20–40 V/μm. Also, the electrofreezing effect was found to be polarity independent. Therefore, it is hypothesized that the mechanism underlying electrofreezing is a reduction in the Gibbs free energy for ice crystal nucleation. Furthermore, by intentionally creating pinholes in the dielectric layer, which creates current paths, the influence of electric current on electrofreezing was also studied. It was observed that electric currents and/or other secondary effects, such as bubble generation, further increased the electrofreezing temperatures. Overall, this work fills many existing gaps in the current understanding of electrofreezing. It is seen that both the electric field and electric current influence electrofreezing; however, the physical mechanisms are different.

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