A Symbolic-Numeric Approach to an Electric Field Problem

2007 ◽  
pp. 349-359 ◽  
Author(s):  
David J. Jeffrey ◽  
Silvana Ilie ◽  
James M. Gardiner ◽  
Steven W. Campbell
Keyword(s):  
Electric Field ◽  
Field Problem

A Wavelet Transform Boundary Element Method for Electric Field Problem Inside Substations

2012 ◽  
Vol 54 (1) ◽  
pp. 193-197 ◽  
Author(s):  
Jun Deng ◽  
Yanpeng Hao ◽  
He Chen ◽  
Licheng Li ◽  
Jun Wang ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Boundary Element Method ◽  
Electric Field ◽  
Boundary Element ◽  
Field Problem ◽  
Transform Boundary ◽  
Element Method

Investigation of heat effects in pulse electric field treatment of cellular materials

2020 ◽  
pp. 1-18
Author(s):  
Ilona Iatcheva ◽  
Ilonka Saykova
Keyword(s):  
Electric Field ◽  
Pulse Electric Field ◽  
Cellular Materials ◽  
Field Analysis ◽  
Field Problem ◽  
Modeling And Analysis ◽  
Electric Pulses ◽  
Heat Effects ◽  
Before And After ◽  
Electric Field Treatment

The paper deals with modeling and analysis of coupled electro-thermal processes during the pulsed electric field treatment of cellular materials for extraction of bioactive compounds. Subject of consideration is evaluation of heat effects: appearance of local thermal spots and high temperature gradients in the treated tissue. The presence of these phenomena is important for the processing: it aids the process of electroporation and thereby is useful for the extraction, but also could cause overheating and deterioration of the product quality. The analysis is provided using the finite element method, applied to the coupled time-dependent electric and transient thermal field problem. The mechanisms of heat transfer are studied by numerical simulations corresponding to the parameters (type and duration of electric pulses) of experimental examination of the processes of extraction of substances from vegetable seeds. Two steps are considered in the modeling: before and after electroporation. The field analysis after electroporation is carried out for correspondingly changed size and properties of the contact area between the cells. The obtained results can be used for adjustment of the process parameters in order to improve the yield of the extracted substances, without risk of overheating and degrading the quality of extracted product.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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