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How do I model space charge by charged particles

Posted 2 sept. 2010, 06:58 UTC−4 1 Reply

Joohwa Lee
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Hello!

I am trying to simulate trajectories of charged particles under electric field.
As charged particles travel in the space, they leave space charge density.
This space charge density alters electric field (or potential) and therefore the motion of charged particles is affected.

I can compute electric field (or potential) by solving Poisson's equation.
The trajectories can be obtained in Particle Tracing at Postprocessor.
However, these trajectories do not make space charge...
How can I feedback the space charge into Poisson's equation and do particle tracing?

Thanks,

Starry
1 Reply Last Post 3 sept. 2010, 10:01 UTC−4
Per Sundqvist
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Posted: 1 decade ago 3 sept. 2010, 10:01 UTC−4
Its a diffusion equation you have to add.

rho=e*n in Poisson

and diffusion

dn/dt=div(kB*T*grad(n)-e*grad(V)*n)/mu

Un fortunately it can be overdamped so convergence gets bad... (kB*T*grad(n)<<<<e*grad(V)*n)

Otherwise it is a MonteCarlo simulation you need and take rho=sum of all particles...

Best,
Per
Its a diffusion equation you have to add. rho=e*n in Poisson and diffusion dn/dt=div(kB*T*grad(n)-e*grad(V)*n)/mu Un fortunately it can be overdamped so convergence gets bad... (kB*T*grad(n)

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