i'm trying to build a dodecahedron polywell reactor

[KitemanSA]

you need to get it dipped and baked. You could try to wrap it by hand, but you will end up with no turns. No turns means you would have to slam it with current to get any kind of field.

What the gentleman is pointing out is that to get a significant magnetic field (fairly necessary for a Polywell) you need an high number of "amp-turns". With copper tubing, you will have fewer turns than with thin copper wire. Therefore, you will need to feed in more amps. But the copper tubings will allow higher amperage. The benefit (in my opinion, but I've never built one so it is just an opinion) is that the tubing will allow a MUCH easier job of cooling, expecially cryo-cooling, so the ability to cram more amps in becomes easier still.

Various writings (no, I can't point one out but they are there) have indicated that the MPG design of coil manufacture would be very amenable to this kind of MaGrid design.

I am not sure what his problem with hand wrapping tubing is. If you go wire, I would agree with him. But tubing should be reasonably simple to hand wrap. Again, an opinion.

My suspicion is that the hardest part will be getting a nice smooth "can" for the coils that will allow a high MaGrid charge without arcing.

Thoughts anyone?

[vnbt4]

i understand that not only does copper tubing make cooling easier, it also can carry a greater amperage. What happens to the inside of the tube can't arcing happen across the water if the inside of the tube is not insulated?

[ladajo]

You would want to use de-ionized water. It would be safer.

As for dip & bake. I was thinking that if you went with square tube, you could go for multiple turns, this would be enhanced if you took the multiturn coil to a motor shop, where they could clean it, then dip in varnish and bake it like a normal winding. If you did this, you would be able to get more turns in the Magrid can, than if you hand wrapped the tubing.

Or....you could do like Kite is saying and go for a single tube coil or just a couple of turns per coil but run it at a higher current to get some magnetic field that means something.

I also agree with him about the casing, it is not easy to make.

[ladajo]

I applaud your desire to do this, and encourage you to try if you have the resources. However, I am getting the distinct feeling that the build is a little beyond your experience level. But that does not mean you can;t learn on the fly. It just means it will take more time, and money (as Famulus is finding out).

[vnbt4]

your right I'm not experienced with this level of construction and the math involved probably more so. That's why i started this topic and joined Talk-Polywell to get a new perspective on some the problems i have yet to solve.



thank you for posting

[ladajo]

I fully encourage you to have at it within reason. Some of the things your are going to play with can easily kill you. Especially if you are completely oblivious to the risks.

Just be careful, and if you think it could be dangerous, it probably is, and it is time to ask someone (preferably in person with a show and tell) that actually knows about it to give you some advice.

Good luck!

[ladajo]

By the way, you would be amazed at what you can do without the math. The math really just saves you time and money in the bigger picture.

[vnbt4]

I think I will use a both copper wire and tubing

[mvanwink5]

For electric utility generators copper with interstitial cooling tubes are used for H2 gas cooled coils. For liquid (water) cooled coils each conductor in the coil bundle is a tube. One thing to watch out for in copper tubes is that there is a maximum velocity that when exceeded causes impingement damage and the water will drill right through the coil wall, springing a leak. I believe 7 to 8 ft/sec velocities are near the maximum, but that is just my memory.
Best regards

PS Why not get a good large motor shop to design and build the coils. For a project like this you might find someone whose interest you will peak. Some of these guys are known to have formidable skills at that sort of work. Just a thought. An example of an issue that might come up is if transposing of conductors from the coil inside to the outside is needed. If this was pure DC, maybe not, but for plasma, who knows?

[ladajo]

PS Why not get a good large motor shop to design and build the coils. For a project like this you might find someone whose interest you will peak.

Very good point. I know of at least two shops here in the North-East that would more than likely jump in for free as a hobby project. The larger the shop however, the less likely they will want to play. I would look for a small to medium shop, say 10 to 20 employees, and privately owned by a "hands-on" owner.

If you are lucky, they may even help with materials. Shops, especially older ones, tend to have a stash of stuff they have accumulated over the years.

[vnbt4]

when you say motor shop could you be more specific?

[ladajo]

Electric Motor Rewinding and Repair shop.

[stevethetinker]

Where would a person get tubing made of electrical grade copper? Is it readily available? Normal tubing for plumbing (soft tubing is the purest) has enough contaminants to raise its resistive heating quite a bit compared to electrical grade, especially at high currents. Remember, power = current squared times resistance.

Someone mentioned that the velocity of the coolant through the tube is limited by the potential for erosion. This is made worse by an unevenly-bent tube. I don't know how evenly it has to be bent to reduce the erosion problem to the minimum, but it's got to be quite a trick.

[WizWom]

A quick google for "high purity copper tubing":
http://www.hptinc.com/copper.html

[KitemanSA]

This appears to be "surface" purity, not electric vs mechanical chemical purity.