- #1

- 184

- 0

Thanks,

Sean

- Thread starter seang
- Start date

- #1

- 184

- 0

Thanks,

Sean

- #2

NoTime

Science Advisor

Homework Helper

- 1,568

- 0

I'm not sure of what you mean by geometric.

Why won't the spice models work for you?

Why won't the spice models work for you?

- #3

- 174

- 0

- #4

- 184

- 0

I need a geometric simulation. I'm trying to model a spark plug kind of thing, you know?

I need to be able to say: If I apply a voltage at one end of the spark plug, what will the voltage be on the other side? How will the charge be distributed across the tip of the spark plug?

The Analog Kid:

You're right, but I don't think I have the skill level to build a dielectric breakdown model in matlab (3d, mind you). I'll check if one already exists.

Is there much formulae for dielectric breakdown? In my classes, we just heard things like If there's a lot of voltage, you can break a capacitor, etc. If there are formulae which model dielectric breakdown on a geometric basis, I'd sure like to know about it.

- #5

f95toli

Science Advisor

Gold Member

- 3,059

- 556

However, full FEM solvers tend to be pretty complicated, you need to know what you are doing and preferably understand at least the basics of how FEM solvers work.

That said, Comsol itself is actually quite user friendly, so the user interface etc will not cause any problems.

If 2D is enough (axial symmetry?) the PDE toolbox in Matlab might also work. I know there are also some free 2D FEM solvers that can handle EM problems, but I have never used any of them.

- #6

- 184

- 0

Thanks alot, that should help out quite a bit. Yeah, a 2D simulator is what I had in mind at first (that's what Sonnet is)...

However, full FEM solvers tend to be pretty complicated, you need to know what you are doing and preferably understand at least the basics of how FEM solvers work.

That said, Comsol itself is actually quite user friendly, so the user interface etc will not cause any problems.

If 2D is enough (axial symmetry?) the PDE toolbox in Matlab might also work. I know there are also some free 2D FEM solvers that can handle EM problems, but I have never used any of them.

The thing I've having problems with is, once dielectric breakdown occurs, you can't really apply the rules of electrostatics/dynamics, can you? I mean planar simulators assume that the energy is moving from trace to trace via electromagnetic waves (maxwell's equations and stuff.), don't they?

In other words, you'd probably have to write out the PDE which governs wave propagation (in COMSOL, or similar) in order to be able to solve the problems. But I'm having trouble finding equations which govern arc behavior, which is what I'd need, I think.

Last edited:

- #7

NoTime

Science Advisor

Homework Helper

- 1,568

- 0

Zero? I suppose you could use other reference systems, but that just makes things more complex. If your measurement device needs to be remote rather than connected to the electrode you may need to contend with IR losses.No Time:

I need a geometric simulation. I'm trying to model a spark plug kind of thing, you know?

I need to be able to say: If I apply a voltage at one end of the spark plug, what will the voltage be on the other side?

Generally evenly, but there is going to be concentrations at surface imperfections in the tip where breakdown eventually initiates.How will the charge be distributed across the tip of the spark plug?

The big determinant of the breakdown characteristics is the gas mixture between the electrodes.

Unless you are modeling very short time intervals your parameters are

Breakdown voltage

Breakdown resistance

Quench voltage

A small neon bulb might be easier to study than something like a car sparkplug due to the low voltages involved. Plus by controlling currents you can get a visual on breakdown initiation and propagation.

- #8

- 1

- 0

Hi Sean,

Thanks,

Sean

I am right working on the same thing, and I would be so grateful if we can share the ideas.

thanks,

- #9

- 17

- 0

field distribution in high voltage conductors but I don't think it will determine the

breakdown, just the field strength. I doubt a simulation would be very accurate anyway as the breakdown mechanism is fairly complex with many factors (temperature/pressure/humidity/ion collision factor) Do a search for Townsend breakdown .

- #10

- 17

- 0

- #11

- 1

- 0

- Replies
- 2

- Views
- 682

- Last Post

- Replies
- 4

- Views
- 2K

- Replies
- 5

- Views
- 2K

- Replies
- 2

- Views
- 359

- Replies
- 2

- Views
- 493

- Replies
- 3

- Views
- 7K

- Replies
- 3

- Views
- 2K

- Replies
- 7

- Views
- 927

- Last Post

- Replies
- 22

- Views
- 42K

- Replies
- 1

- Views
- 583