Electric Field Optimization of 1MV DC-GIL Spacer with Surface Conductivity Gradient for ITER NBI

2021 ◽  
pp. 1-1
Author(s):  
Xiaolin Li ◽  
Yun Chen ◽  
Jin Li
Keyword(s):  
Electric Field ◽  
Surface Conductivity ◽  
Conductivity Gradient

scholarly journals Empirical Conductivity Equation for the Simulation of the Stationary Space Charge Distribution in Polymeric HVDC Cable Insulations

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3018 ◽  
Author(s):  
Christoph Jörgens ◽  
Markus Clemens
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Charge Distribution ◽  
Euler Method ◽  
Accurate Description ◽  
Conductivity Equation ◽  
Transient Model ◽  
Space Charges ◽  
Sigmoid Functions ◽  
Conductivity Gradient

Many processes are involved in the accumulation of space charges within the insulation materials of high voltage direct current (HVDC) cables, e.g., the local electric field, a conductivity gradient inside the insulation, and the injection of charges at both electrodes. An accurate description of the time dependent charge distribution needs to include these effects. Furthermore, using an explicit Euler method for the time integration of a suitably formulated transient model, low time steps are used to resolve fast charge dynamics and to satisfy the Courant–Friedrichs–Lewy (CFL) stability condition. The long lifetime of power cables makes the use of a final stationary charge distribution necessary to assess the reliability of the cable insulations. For an accurate description of the stationary space charge and electric field distribution, an empirical conductivity equation is developed. The bulk conductivity, found in literature, is extended with two sigmoid functions to represent a conductivity gradient near the electrodes. With this extended conductivity equation, accumulated bulk space charges and hetero charges are simulated. New introduced constants to specify the sigmoid functions are determined by space charge measurements, taken from the literature. The measurements indicate accumulated hetero charges in about one quarter of the insulation thickness in the vicinity of both electrodes. The simulation results conform well to published measurements and show an improvement to previously published models, i.e., the developed model shows a good approximation to simulate the stationary bulk and hetero charge distribution.

scholarly journals Rapid AC Electrokinetic Micromixer with Electrically Conductive Sidewalls

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 34
Author(s):  
Fang Yang ◽  
Wei Zhao ◽  
Cuifang Kuang ◽  
Guiren Wang
Keyword(s):  
Electric Field ◽  
Transverse Direction ◽  
Flow Direction ◽  
Conductivity Ratio ◽  
Mixing Length ◽  
Electrically Conductive ◽  
Electrokinetic Phenomena ◽  
Two Fluids ◽  
Conductivity Gradient ◽  
Lower Voltage

We report a quasi T-channel electrokinetics-based micromixer with electrically conductive sidewalls, where the electric field is in the transverse direction of the flow and parallel to the conductivity gradient at the interface between two fluids to be mixed. Mixing results are first compared with another widely studied micromixer configuration, where electrodes are located at the inlet and outlet of the channel with electric field parallel to bulk flow direction but orthogonal to the conductivity gradient at the interface between the two fluids to be mixed. Faster mixing is achieved in the micromixer with conductive sidewalls. Effects of Re numbers, applied AC voltage and frequency, and conductivity ratio of the two fluids to be mixed on mixing results were investigated. The results reveal that the mixing length becomes shorter with low Re number and mixing with increased voltage and decreased frequency. Higher conductivity ratio leads to stronger mixing result. It was also found that, under low conductivity ratio, compared with the case where electrodes are located at the end of the channel, the conductive sidewalls can generate fast mixing at much lower voltage, higher frequency, and lower conductivity ratio. The study of this micromixer could broaden our understanding of electrokinetic phenomena and provide new tools for sample preparation in applications such as organ-on-a-chip where fast mixing is required.

scholarly journals Influence of Surface-conductivity Nonuniformity on Charge Accumulation Phenomena of GIS Insulator under DC Electric Field

2011 ◽  
Vol 131 (7) ◽  
pp. 584-590 ◽  
Author(s):  
Taiki Donen ◽  
Hiroyuki Iwabuchi ◽  
Shigeyasu Matsuoka ◽  
Akiko Kumada ◽  
Kunihiko Hidaka ◽  
...  
Keyword(s):  
Electric Field ◽  
Surface Conductivity ◽  
Charge Accumulation ◽  
Dc Electric Field

Unsteady electrophoretic motion of a non-spherical colloidal particle in an oscillating electric field

1994 ◽  
Vol 278 ◽  
pp. 149-174 ◽  
Author(s):  
Michael Loewenberg
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Colloidal Particle ◽  
Volume Fraction ◽  
Added Mass ◽  
Surface Conductivity ◽  
Spherical Particles ◽  
Oscillating Electric Field ◽  
Dilute Suspension ◽  
Spherical Colloidal Particle

The oscillatory motion of an electrically charged non-spherical colloidal particle in an oscillating electric field is investigated. The particle is immersed in an incompressible viscous fluid and assumed to have a thin electric double layer. For moderate-aspect-ration spheroids and cylinders, a simple algebraic expression is derived that accurately describes oscillatory electrophoretic particle motion in terms of the steady Stokes resistance, added mass, and Basset force. The effects of double-layer conduction and displacement currents within dielectric particles are included. The results indicate that electroacoustic measurements may be able to determine the ζ-potential, dielectric constant, surface conductivity (and microstructural information contained therein), size, density, volume fraction, and possibly shape of non-spherical particles in a dilute suspension. A simple formula is obtained for the high-frequency electrical conductivity of a dilute suspension of colloidal spheroids with arbitrary charge and dielectric constant; only the added mass and Basset force are required and the requisite parameters are given. The result is needed for electroacoustic measurements but it may also be independently useful for determining the dielectric constant, surface conductivity, volume fraction, and possibly the shape of non-spherical particles in a dilute suspension. Electroacoustic energy dissipation is described for a dilute colloidal suspension. It is shown that resistive electrical heating and viscous dissipation occur independently. Electrical and viscous dissipation coefficients that characterize the order volume fraction contributions of the suspended particles are calculated; the electrical dissipation coefficient is O(1) for all oscillation frequencies, whereas the latter vanishes at low- and high-frequencies. The fluid motion is shown to be a superposition of unsteady, viscous and potential flows past an oscillating particle with no applied electric field. The electro-osmotic flow field is insensitive to particle geometry and qualitatively different from the flow past an oscillating particle with no applied field.

Electrokinetic Dispersion in Field Amplified Sample Stacking

2018 ◽  
Author(s):  
Kaushlendra Dubey ◽  
Amit Gupta ◽  
Supreet Singh Bahga
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Body Force ◽  
Vital Role ◽  
Scaling Analysis ◽  
Unstable Flow ◽  
Sample Stacking ◽  
Concentration Enhancement ◽  
High Electric Fields ◽  
Conductivity Gradient

In this work, we performed an experimental study of electrohydrodynamic effects on the dispersion of sample ions in field amplified sample stacking (FASS). A typical FASS experiment involves a streamwise electrical conductivity gradient collinear to the applied electric field to enhance the sample stacking. Earlier studies on FASS have focused on how the conductivity gradient sets a non-uniform electro-osmotic flow which causes the dispersion. However, the coupling of the electric field with conductivity gradient leads to a destabilizing electric body force and generates unstable flow. This work demonstrates that generated body force influences the dynamics of FASS. We present a scaling analysis to show that at high fields, electrohydrodynamic effects play a vital role in sample dispersion. To justify our scaling arguments, we performed experiments at varied electric fields which shows that at high electric fields maximum concentration enhancement is lowered significantly. To ensure the EHD effects on the dynamics of FASS, we have also performed experiments with suppressed EOF conditions.

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