Numerical Study on the Effect of Electric Field Non-uniformity on the Pulse Characteristics of Positive Corona Discharge in SF6/N2 Gas Mixtures

2021 ◽  
Vol 28 (6) ◽  
pp. 1949-1956
Author(s):  
Yanliang He ◽  
Wei Ding ◽  
Anbang Sun ◽  
Guanjun Zhang
AIP Advances ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 055027 ◽  
Author(s):  
Yanliang He ◽  
Anbang Sun ◽  
Jianyi Xue ◽  
Zhiwei Shen ◽  
Xing Zhang ◽  
...  

2017 ◽  
Vol 27 (10) ◽  
pp. 2268-2288 ◽  
Author(s):  
Qiang Ma ◽  
Zhenqian Chen

Purpose The paper aims to discuss the mass transfer of gas mixtures under the influence of electrohydrodynamic (EHD) flow induced by direct current (DC) corona discharge of wire-to-plane electrode, using a coupled numerical model. Design/methodology/approach A coupled numerical method is developed in this paper. Lattice Boltzmann model of binary gas mixtures coupled with the Coulomb force as an external force is introduced to predict the gas flow and species transport affected by EHD flow. Meanwhile, the distributions of electric field and space charge density during DC corona discharge are obtained using the finite difference method and the method of characteristics. Findings The numerical results of mass transfer effected by EHD flow reveal that the high electric field intensity is observed near the surface of corona wire, which causes the higher Coulomb force to form the EHD flow pattern of anticlockwise vortex. The EHD vortex flow plays a considerable role in the mass transport enhancement of gas species emit from the plane electrode, and the significant difference of the local Sherwood number is presented along the direction parallel to plane electrode. In addition, the enhance effectiveness with the different applied voltage is assessed, and the influencing mechanism of enhancement is investigated in this work. Originality/value The proposed numerical model will be useful in the study of mass transfer and fluid flow effected by EHD.


2019 ◽  
Vol 187 ◽  
pp. 114-128
Author(s):  
Matheus F. Grings ◽  
Rejane de C. Oliveski ◽  
Ligia D.F. Marczak

Author(s):  
Yingxia Wei ◽  
Yaoxiang Liu ◽  
Tie-Jun Wang ◽  
Na Chen ◽  
Jingjing Ju ◽  
...  

We report on a systematic experimental study on the fluorescence spectra produced from a femtosecond laser filament in air under a high electric field. The electric field alone was strong enough to create corona discharge (CD). Fluorescence spectra from neutral and ionic air molecules were measured and compared with pure high-voltage CD and pure laser filamentation (FIL). Among them, high electric field assisted laser FIL produced nitrogen fluorescence more efficiently than either pure CD or pure FIL processes. The nonlinear enhancement of fluorescence from the interaction of the laser filament and corona discharging electric field resulted in a more efficient ionization along the laser filament zone, which was confirmed by the spectroscopic measurement of both ionization-induced fluorescence and plasma-scattered 800 nm laser pulses. This is believed to be the key precursor process for filament-guided discharge.


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
José Alvim Berkenbrock ◽  
Rafaela Grecco Machado ◽  
Daniela Ota Hisayasu Suzuki

Electrochemotherapy is an anticancer treatment based on applying electric field pulses that reduce cell membrane selectivity, allowing chemotherapy drugs to enter the cells. In parallel to electrochemotherapy clinical tests, in silico experiments have helped scientists and clinicians to understand the electric field distribution through anatomically complex regions of the body. In particular, these in silico experiments allow clinicians to predict problems that may arise in treatment effectiveness. The current work presents a metastatic case of a mast cell tumor in a dog. In this specific treatment planning study, we show that using needle electrodes has a possible pitfall. The macroscopic consequence of the electroporation was assessed through a mathematical model of tissue electrical conductivity. Considering the electrical and geometrical characteristics of the case under study, we modeled an ellipsoidal tumor. Initial simulations were based on the European Standard Operating Procedures for electrochemotherapy suggestions, and then different electrodes’ arrangements were evaluated. To avoid blind spots, multiple applications are usually required for large tumors, demanding electrode repositioning. An effective treatment electroporates all the tumor cells. Partially and slightly overlapping the areas increases the session’s duration but also likely increases the treatment’s effectiveness. It is worth noting that for a single application, the needles should not be placed close to the tumor’s borders because effectiveness is highly likely to be lost.


Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 333
Author(s):  
Pedro Llovera-Segovia ◽  
Gustavo Ortega-Braña ◽  
Vicente Fuster-Roig ◽  
Alfredo Quijano-López

Piezoelectric polymer cellular films have been developed and improved in the past decades. These piezoelectric materials are based on the polarization of the internal cells by means of induced discharges in the gas inside the cells. Internal discharges are driven by an external applied electric field. With this polarization method, cellular polypropylene (PP) polymers exhibit a high piezoelectric coefficient d33 and have been investigated because of their low dielectric polarization, high resistivity, and flexibility. Charging polymers foams is normally obtained by applying a corona discharge to the surface with a single tip electrode-plane arrangement or a triode electrode, which consists of a tip electrode-plane structure with a controlled potential intermediate mesh. Corona charging allows the surface potential of the sample to rise without breakdown or surface flashover. A charging method has been developed without corona discharge, and this has provided good results. In our work, a method has been developed to polarize polypropylene foams by applying an insulated high-voltage electrode on the surface of the sample. The dielectric layer in series with the sample allows for a high internal electric field to be reached in the sample but avoids dielectric breakdown of the sample. The distribution of the electric field between the sample and the dielectric barrier has been calculated. Experimental results with three different electrodes present good outcome in agreement with the calculations. High d33 constants of about 880 pC/N have been obtained. Mapping of the d33 constant on the surface has also been carried out showing good homogeneity on the area under the electrode.


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