COMSOL simulation of a FUSOR?

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
Daniel Fajardo
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Re: COMSOL simulation of a FUSOR?

Post by Daniel Fajardo » Wed Sep 27, 2017 12:22 am

Hello Werner,

Its funny you asked this question just now. I'm about to finish my demo fusor and want to start working on a simulation in COMSOL.

I'm thinking about simulating the electric field and particle tracing. I'm not quite sure how to make the grid geometry, though.

Please let me know if you have worked on something. I would love to share ideas with you.

Daniel Fajardo

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Re: COMSOL simulation of a FUSOR?

Post by ian_krase » Wed Sep 27, 2017 5:03 am

Thomas Rapp's beam-on-target machine (he actually built two) doesn't use the 20kV to do the fusion. Rather, that is just used to drive his canal-ray ion source.

He is also ballasting the living daylights out of this (100 megaohms!) so likely he isn't even getting near 20 kV in operation. Not sure why he didn't just use an NST.

In any case, the small test-tube-looking appendage is the ion source. The pipe tee is at ground potential, and the terminal on the end of the ion source is at +20 kV. D2 is piped into it and the glow discharge ionizes it. The E-field extracts D+ ions into and through the pipe tee and into the long, large glass column, which is at a much better vacuum.

His initial tests just had the resulting canal beam hitting the end of the column which cannot have been easy on the glass. Later on, he replaced the end of the column with a target holder and secondary electron suppressor, and applied -100 kV directly to this target holder, with the glass column serving as an insulator).

Why do you have your ion source at high potential?

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Samuel Low
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Re: COMSOL simulation of a FUSOR?

Post by Samuel Low » Tue Dec 18, 2018 8:40 am

I don't think COMSOL has a module to do particle tracing unlike SIMION. I know for sure you can definitely run an electrostatic simulation to see the spherical E-field patterns - the usefulness of it would really then be the ability to just see the E-field patterns for different CAD models of inner grids. It would be very interesting to see the effects of various inner grid geometries, I would love to see some screenshots with the colour bar scale if you ever get to doing the experiments! Good luck! :)
"Physicists are made of atoms." - Michio Kaku

Andrew Seltzman
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Re: COMSOL simulation of a FUSOR?

Post by Andrew Seltzman » Wed Dec 19, 2018 4:50 am

I believe comsol does have a particle tracking module, but it has to be licensed and installed separately and is not part of the basic package.
Andrew Seltzman

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