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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Moderator: Markus Zahn

The Massachusetts Institute of Technology

Department of Electrical Engineering and Computer Science

Laboratory for Electromagnetic and Electronic Systems

Session: Electromagnetic Design and Modeling

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

1. Nonlinear magnetic fluid behavior in dc, ac, androtating magnetic fields for MRI applications

2. Dielectrometry sensors to measure moisturediffusion processes

3. High voltage streamer initiation and propagationin electrical breakdown events

M. Zahn COMSOL Research Applications

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Dielectrometry SensorsCapacitive sensor for measuring

material properties.

3 Sensor 6 Channel Sensor

periodic zperiodic

Measurement determines C12

and G12.

Use Laplaces equation to find theoreticalfield solution.

Study more complex cases with Multiphysics.

Planar

periodiczperiodic

G Ground, D Drive, S SenseSensors Conforms to various geometries

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Moisture Diffusion

Sensors can be used to measuredielectric properties as temperaturea moisture content change.

Moisture Diffusion Experiments

Estimated Moisture Profiles

Black,

Expe

riment

Red,

Theory

Do = 1.3 x 10-8 m2/sec.

Analysis of more sophisticated diffusion

experiments made possible by Multiphysics

Moisture enters end of rod.6 channel zperiodic sensor used.

Response determined by MC.Estimate diffusion from experiment.

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Video Clip: Concentration Diffusion

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

High Voltage Streamer Initiation and

Propagation in Electrical Breakdown EventsNeedle-Sphere

Electrode Structure Electrical streamers are

highly conductive structures

that form in dielectric liquidsprior to the formation of anarc.

Much of this research onstreamers has been

empirical in nature and theredoes not exist a universallyaccepted breakdown theory,which describes the initiationand growth of streamers in

dielectric liquids. Using COMSOL, an electro

and thermo dynamic modelwhich describes the

development of such ageneral theory has beenvalidated

Geometry Modeland Meshing

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

25mm 25mm 25mm

t 20 s=t 10 s=t 2 s=

Surface Plots of Electric FieldPresented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Video Clip: Electric Field

Surface Distribution

Presented at the COMSOL Users Conference 2007 Boston

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Electromagnetic Design and ModelingElectromagnetic Design and Modeling

Video Clip: Surface and Contour Plots

of Charge Density Concentration

Presented at the COMSOL Users Conference 2007 Boston