Special materials for the (ma)gnetically shielded (grid)?

[MrE]

Last weekend I read almost every post on this forum, forgive me if I overlooked what I am about to ask.

I am curious about the construction of WB models. It is called the "magrid"?

From pictures I have seen it looks like metal is used to encapsulate the coils of wire. The wire is then energized to expand a magnetic field in order to deflect electrons from being grounded(striking) the magrid. The magrid is somehow depleted of electrons, made to be positively charged. I am still uncertain if there is a grounding going on or because there are simply more electrons swirling around the magnetic field lines that the metal encapsulation appears positively charged.

My question is: Has there been discussion about what materials are best to satisfy what is required of the magrid or has it been assumed "some type of metal"?

I am hoping the font of knowledgeable internet personalities(You) would outline what the magrid must be able to satisfy. Pretty please with sugar on top.

Am I correct in assuming that the material:

1) Must be electrically conductive.

2) Must withstand possibly 'high' temperatures.

3) Must not block the magnetic field from the coils.

What else must it do?

This is my first post of hopefully many more to come.
My name is Eric and I am from the central coast of California.
I do architectural CAD drafting for a design firm.
I am 26.

[MSimon]

Must minimize nuclear activation if used in a neutron producing reactor.

http://iecfusiontech.blogspot.com/2008/ ... oling.html

http://iecfusiontech.blogspot.com/2008/ ... oblem.html

http://iecfusiontech.blogspot.com/2007/ ... ances.html

http://iecfusiontech.blogspot.com/2007/ ... -book.html

I discuss some of the issues at the above links.

[drmike]

Last weekend I read almost every post on this forum, forgive me if I overlooked what I am about to ask.

That's pretty impressive! You will soon find we all have questions.

I am curious about the construction of WB models. It is called the "magrid"?

MaGrid = Magnetic Grid. It is a combination of the Farnsworth-Hirsh fusor grid and
a magnetic bottle.

From pictures I have seen it looks like metal is used to encapsulate the coils of wire. The wire is then energized to expand a magnetic field in order to deflect electrons from being grounded(striking) the magrid. The magrid is somehow depleted of electrons, made to be positively charged. I am still uncertain if there is a grounding going on or because there are simply more electrons swirling around the magnetic field lines that the metal encapsulation appears positively charged.

My question is: Has there been discussion about what materials are best to satisfy what is required of the magrid or has it been assumed "some type of metal"?

Not too much here, but the outer shield has to be non-magnetic and be a reasonably good conductor, work well in vacuum and be easy to machine. Aluminum seems like
a good candidate, but I bet there are many other choices.

I am hoping the font of knowledgeable internet personalities(You) would outline what the magrid must be able to satisfy. Pretty please with sugar on top.

Am I correct in assuming that the material:

1) Must be electrically conductive.

yes

2) Must withstand possibly 'high' temperatures.

Not so much high temps as high nuclear impacts from MeV class alphas and
gammas. Hopefull the thermal plasma won't be touching it at all.

3) Must not block the magnetic field from the coils.

Right - otherwise the magnetic bottle is blocked from forming.

What else must it do?

It can't outgas in the vacuum, unless it does it on purpose to add fuel.
That is something that has been discussed here. It might be useful to
have the grid add some oscillations for stability or beam forming, so being
able to stand off high voltage differentials between coils may be something
to look at. Nobody knows yet - that's what makes this all so much fun!

This is my first post of hopefully many more to come.
My name is Eric and I am from the central coast of California.
I do architectural CAD drafting for a design firm.
I am 26.

I'm in Madison Wisconsin (usa), I build medical electronics and I'm 54.
I think it's going to be a fun summer!

[TallDave]

We might think about focusing on neutron impacts for the moment. We're almost certainly going to have to get a D-D/D-T reactor working before we start seriously considering something at p-B11 energies.

[TallDave]

I have a show stopper. Each neutron absorbed produces 2.8 MeV. In a D-D reactor there is no way to carry the heat away without adding more water layers. At best a very thin layer might buy us some operational time for a test reactor. The advantage may go to using a B11 superconductor even with its lower Tc. That still only gets us months of operation. Probably good enough for experimental work.

BTW the neutron flux in a D-D reactor with a coil radius of 2 m at the coil radius is on the order of 3E14 neutrons a second at 100 MW fusion output.

That worries me a lot.

In a p-B11 reducing the intercept area is going to be important, because of course we want our alphas efficently converting to electricity rather than heating our coils. I wonder, though -- in a D-D/D/T, is it possible we could make huge coils cooled with borated water and use that cooling for primary power generation?

I'm not sure if the geometry works out right on that.

[MrE]

We might think about focusing on neutron impacts for the moment. We're almost certainly going to have to get a D-D/D-T reactor working before we start seriously considering something at p-B11 energies.

The first part of a quest(journey) involves one foot in front of another. I agree with what you say.

My mind is focused on controlling electrons as my interest is in power electronics and materials engineering. I am building right now a 500W RF source @ ~4MHz that has self tuning circuitry via a feedback antenna sampling the resonator. Basically it is a mini tesla coil. I intend on using this RF power source, in combination with a crystal growth chamber I have designed, to manufacture ultra capacitors and unique materials through PVD.

That is where my mind is focused on right now. The polywell device seems like an excellent opportunity for me to make a miniature version in order to burn stuff.(non nuclear) The goal being to control the electron cloud and find unique ways to reduce loss. I figure that the control circuitry and data can be used towards the homebrew-garage WB.

[MSimon]

Dave,

Borated water is not much help when you want to reduce neutron flux 10 orders of magnitude.

What works is moderation (light water is very good - about 2" to 4" thick) followed by a layer of B10. I'd have to go back over my numbers but I think 1" of B10 at the indicated flux would last 100 years.

The residual flux is totally dependent on the efficiency of the moderator. The B10 sucks up all the slow neutrons.

[drmike]

MrE - that sounds like a really fun project! Dangerous toys are always the most fun.

[MrE]

I am still a bit gun shy after a capacitor exploded on me a little while ago. Luckily no aluminum shards hit me and I was wearing a face shield so the electrolyte just sprayed on it and my clothes. Afterwards, my clothes developed holes in them. :) It was a stupid mistake, I forgot to put a resistor to slow the charge of the caps and it overheated and went critical. Yesterday, Saturday, I ordered the last salvo of parts. $45 US. Jameco is my candy shop. I did an cost breakdown on each 500watt RF unit: $56.291. That is down the each resistor and heatsink. I did not include a breadboard as I have lots of them in inventory. Same for solder and hookup wire. I have enough parts to make 5 RF units. I also made a PCB with pad2pad.com's service and am ready to order it once I make sure it actually works. I squeezed all parts of the circuit onto a 4"x3", minus the 150V amplification. The 150V amplification can easily be done by hand and I prefer to separate the higher voltages from the frequency control parts.
I call this project "B.A.R.R.I.S." after a good friend of mine. "Borated radio reflecting injection system"
Once I get first corona I will record some video and post it on youtube. I slapped down for a usb oscilloscope and I have yet to actually use it.
A Velleman pcsu1000.