Is There an Optimal Size for Magrid Casings?

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

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tombo
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Post by tombo »

Sphere = vacuum chamber shell?
no the theoretical sphere centered on the center of the device passing through all the coils. ie. the sphere defined by the coils. The vacuum chamber is neither here nor there at this point.
By "outward" do you mean tending to open up the "v"s?
No. Outward from the center of the machine.
If so, I think I disagree. There may be the attempt by one magnet to open it up, but the magnet next to it is pushing the other way on each of the segments. Net cross beam load, nil. There WILL be a load pointing radially outward from the center of the MaGrid.
That is exactly what I was trying to point out.
Those are taken up easily by my design.
What is your design? I would like to see a picture, even if it is just a scan of a sketch.
But the SC wire probably won't take that kind of strain. Anything more than ~0.2% and you start losing capacity fast. Some toughened wires go to 0.4%!
They will be inside a coolant channel that should isolate it from the bending forces. In any case it must bend enough to coil or it is useless for our purposes.
The multiple parallel sc wires will need to be loose enough in the channel to slide past each other as the outer layers are bent. The ends are free so they can move. This will also allow them to adjust their positions independently during operation without stressing themselves.
How bout the "union" idea? Anyway, for a first try, can you just make the pipes rectangular cross section, 1" radial for each 4" transverse, and the duplicate it 3 times at the appropriate extended radius? This would result in the square cross setion SC core that folk are bandying about.
Possible but a lot of work especially if the rectangular cross sections don't want to line up across the various regions.
The corners are going to look like a highway interchange.
or electrons in the plasma?
plasma are the only ones that RE-circulate.
Actually, it makes for quad REAL magnets and NO nubbins (nubbins being defined as those little cross pipes in the middle of the funny cusps that carry little or no current and just get in the way!)
Right
True. He anticipated it, they're called "funny" cusps and he didn't seem to care. He just made a mistake by putting the nubbins in the middle of them.
That though true is not what I meant. Look at the details. You have one pass at, say, 2 m radius then another at 2.1 m radius then another at 2.2 and another at 2.3 . The field line wrap around each of them, and they are parallel therefore there will be field nulls between each pair of them.
Also what is the field in the little square hole?
Do you mean to have the whole thing in 1 casing or do you envision 4 separate casings?
Please answer this, it will help me understand.

Are you trying for something like this: http://www.justodians.org/SphericalMagn ... agPic1.htm
viewtopic.php?p=11900&highlight=#11900
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

MSimon
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Post by MSimon »

KitemanSA wrote:Looks a lot different than the last set of #s I recall. But I don't recall the going in assumptions, just that they made sense at the time.

This is why we need a wiki so that intermediate product is saved at the top level, not in posts in some poorly named topic somewhere.

Does anyone know how to set up a wiki?

Is anyone else interested?
In the great Polywell information burst in the summer of 2007 a wiki was set up. It didn't get any trade.

There were three sites that lasted from that burst. This site. IEC Fusion Technology blog. And a Yahoo News Group which mostly serves as an announcement list these days. There is hardly any posting on NASA Spaceflight these days. And the NASA site was where it all began.
Engineering is the art of making what you want from what you can get at a profit.

MSimon
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Post by MSimon »

There must be no matter where the field goes to zero.

There must be no matter where the field gradient is radial.
Engineering is the art of making what you want from what you can get at a profit.

Billy Catringer
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Post by Billy Catringer »

Here's another picture of the shells nested together without the SC Core in the way.

http://www.flickr.com/photos/36049122@N ... 6/sizes/o/

Volume of LHe: 3,063L or 809 US gal. Weight of He = 383kg. (This will go down some after I add supports.)

Volume of LN2: 2,143 Liters or 563 US gal. Weight of LN2 = 1,724kg.

Volume of the Cool Water Jacket: 3,247L or 858 US gal. Weight of CW = 3,241kg.

Volume of Hot Water: 3,673L or 971 US Gal. Weight of HW = 3,666kg.

Chief Simon? I'd like to abandon the legs-on-the-edge, or "lollipop" support for three legs in the magrid shadow for each magnet if the physics will permit it. Going that route would greatly simplify the plumbing and might even let us reduce the thickness of the Cool Water jacket.

If we could use aluminum bronze for the Hot Water jacket we could save a lot of weight. Aluminum bronze is about 1.36g/cm^2 lighter than pure copper. It hold up better to corrosion and might even be a little stronger. I am still researching the matter.

KitemanSA
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Post by KitemanSA »

MSimon wrote: ... There is hardly any posting on NASA Spaceflight these days. And the NASA site was where it all began.
Yeah, I read that several months ago. Downloaded all multi-hundred pages and took several days of spare time to wade thru it.

Where was the wiki? Does it still exist?

KitemanSA
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Post by KitemanSA »

MSimon wrote:There must be no matter where the field goes to zero.
There must be no matter where the field gradient is radial.
Got it. There shouldn't be on mine, but we'll have to see.

MSimon
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Post by MSimon »

Billy Catringer wrote:Here's another picture of the shells nested together without the SC Core in the way.

http://www.flickr.com/photos/36049122@N ... 6/sizes/o/

Volume of LHe: 3,063L or 809 US gal. Weight of He = 383kg. (This will go down some after I add supports.)

Volume of LN2: 2,143 Liters or 563 US gal. Weight of LN2 = 1,724kg.

Volume of the Cool Water Jacket: 3,247L or 858 US gal. Weight of CW = 3,241kg.

Volume of Hot Water: 3,673L or 971 US Gal. Weight of HW = 3,666kg.

Chief Simon? I'd like to abandon the legs-on-the-edge, or "lollipop" support for three legs in the magrid shadow for each magnet if the physics will permit it. Going that route would greatly simplify the plumbing and might even let us reduce the thickness of the Cool Water jacket.

If we could use aluminum bronze for the Hot Water jacket we could save a lot of weight. Aluminum bronze is about 1.36g/cm^2 lighter than pure copper. It hold up better to corrosion and might even be a little stronger. I am still researching the matter.
Explore away. We are not committed to bashing metal. Yet.
Engineering is the art of making what you want from what you can get at a profit.

MSimon
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Post by MSimon »

KitemanSA wrote:
MSimon wrote: ... There is hardly any posting on NASA Spaceflight these days. And the NASA site was where it all began.
Yeah, I read that several months ago. Downloaded all multi-hundred pages and took several days of spare time to wade thru it.

Where was the wiki? Does it still exist?
Probably. I don't have the link anymore. A few pages were developed and then it died.

One of the problems was that the size was limited.
Engineering is the art of making what you want from what you can get at a profit.

KitemanSA
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Post by KitemanSA »

tombo wrote: {{Several exchanges leading to}} That is exactly what I was trying to point out.
Good, then we are synoptic here
tombo wrote:
Those are taken up easily by my design.
What is your design? I would like to see a picture, even if it is just a scan of a sketch..
I think you have a pretty good mental image of it. Make the MPG in 4 layers then slide each layer 90 degrees sideways till they line up again. At that point each intersection will have magnets on all sides. As you say, the core would look like a freeway intersection, but no it is NOT like the item shown in that picture. That layup shouldn't work.
tombo wrote:
But the SC wire probably won't take that kind of strain. Anything more than ~0.2% and you start losing capacity fast. Some toughened wires go to 0.4%!
They will be inside a coolant channel that should isolate it from the bending forces. In any case it must bend enough to coil or it is useless for our purposes.
The multiple parallel sc wires will need to be loose enough in the channel to slide past each other as the outer layers are bent. The ends are free so they can move. This will also allow them to adjust their positions independently during operation without stressing themselves..
I don't see how that would work, though I can't say it won't. I just don't think it necessary. It seems doable to just lay the unit up directly.
tombo wrote:
How bout the "union" idea? Anyway, for a first try, can you just make the pipes rectangular cross section, 1" radial for each 4" transverse, and the duplicate it 3 times at the appropriate extended radius? This would result in the square cross setion SC core that folk are bandying about.
Possible but a lot of work especially if the rectangular cross sections don't want to line up across the various regions.
The corners are going to look like a highway interchange..
If you just lay them up, one on top of the other, you would start with your MPG, but square in cross section. If your rendition is precise, then simply rotating each layer 90 degrees around the sphere's north pole should get all the bowed runs to lie exactly on top of each other again. As the 4 layers (strata) approach an intersection, two of the layers will go one way and two the other.
Imagine using real bowed square magnets and real bowed triangular magnets all arranged side by side, not real/virtual but real/real. That is what this provides with the single pass MPG concept. (Actually, it really should be two loops per layer rather than one to balance ALL the intersections.
I've just signed up with Photobucket so I hope these come out ok.
ImageThis shows the intent of what the final arrangement would be, magnets all around the funny cusp. Strength members inside the pipe and carrying all the radial load in membrane stress, the most efficient kind of structure. I believe the magnets may need to be moved back some more, but I can’t be sure until it is analyzed.
Image This shows your north polar view (great!) with some labels. If you look at all the “corners” on the black circle (the equator), you will see that half are curved toward the squares and half toward the triangles. The same can be said for all the other latitudes except at 45 degrees latitude and 0 longitude where the pattern is broken. Indeed, the MPG could be split there and have two pairs of I/Os which would keep the plumbing simple but would shorten the coolant run by half. It would also make the item completely symmetrical and assure that when the 4 strata are overlaid, each corner has two and exactly two strata running thru it. This will assure a significant degree of magnetic protection for the corneres which are the “cross-connects”.
tombo wrote:
or electrons in the plasma?
plasma are the only ones that RE-circulate..
Ok, then I have no idea what your concern is so I can't answer you. The overall look from the outside would be as I described earlier, your graphic except Magnets all around.
tombo wrote:
True. He anticipated it, they're called "funny" cusps and he didn't seem to care. He just made a mistake by putting the nubbins in the middle of them.
That though true is not what I meant. Look at the details. You have one pass at, say, 2 m radius then another at 2.1 m radius then another at 2.2 and another at 2.3 . The field line wrap around each of them, and they are parallel therefore there will be field nulls between each pair of them.
The intent is to have the 4 strata bound and cased together as one stretch of coil. Only at the intersections where you have open corners meeting would there be a difference.
tombo wrote:Also what is the field in the little square hole?.
The “funny cusp”. Near the two “square” corners, the field goes out (using the convention of the round/square coils pointing “in”; and near the two “triangle” corners, the field points in. In the exact center is a singularity known as the “funny” cusp.
tombo wrote:
Do you mean to have the whole thing in 1 casing or do you envision 4 separate casings?
Please answer this, it will help me understand..
IBID.
No.

KitemanSA
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Post by KitemanSA »

MSimon wrote:
KitemanSA wrote: Where was the wiki? Does it still exist?
Probably. I don't have the link anymore. A few pages were developed and then it died.
One of the problems was that the size was limited.
Do you remember who set it up?

MSimon
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Post by MSimon »

KitemanSA wrote:
MSimon wrote:
KitemanSA wrote: Where was the wiki? Does it still exist?
Probably. I don't have the link anymore. A few pages were developed and then it died.
One of the problems was that the size was limited.
Do you remember who set it up?
No. Had it been what I consider useful it would have gotten a link on my fusion sidebar. If you want to start one "Wiki Spaces" is what you want.

I found a link:

http://iecfusion.wikispaces.com/IEC+Fus ... ganization

BTW I see unsupported "V"s in your dwg. If you intend to support them with struts going to the walls you should make that clearer.

And the piping can not be stepped. It will cause high electrical field gradients.
Engineering is the art of making what you want from what you can get at a profit.

tombo
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Post by tombo »

Kiteman,
Zoom in on the funny cusp region and look closer at the current directions and fields.
Using the picture you just posted:
(BTW What program did you use to mark up my drawing? It looks useful.)
BEFORE adding the cross connects sketch in the current directions.
The field above and below the cross connect points (say) into the sphere and
the field left and right of the cross connect points out of the sphere.
In the area that will be cross connected the field points out of the sphere just like it does in the connected regions left and right. All fields change continuously and there are no field nulls.
AFTER adding the cross connects sketch the currents in the cross connects.
Now look at the field within the small cross-connected square.
Some fields point into the sphere and some point out of the sphere.
That means there are field nulls in that region. Actually it looks to me like one "X" shaped one. And, of course we all know that field nulls are like a short circuit for the plasma.

Yes, it does support the the V's very nicely, but the price in field nulls is too high.
Dr Mike has pointed this type of problem out to me several times when I had what I thought was a good idea. Welcome to the club.

Another way to look at it is that you have traded an even vertex (per Dr B) with four odd vertices (not per Dr B).

The funny cusp area does not mean field nulls. In fact those are the highest fields in the device.
The funny cusp comes from its similarity to 1/4 of the circumference of the cusp machine field geometry.


Billy,
You seem to be showing MSimon some pictures off line.
I would like to see them too.
Hey, I posted mine so you could throw pies at them. :) Fair is fair.

I would rather fight the problems of bending a multilayer stackup than to try to cram in the multilayer Y's & T's and sew it all up by hand. Yours is of course the obvious design path.
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

MSimon
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Post by MSimon »

The funny cusp area does not mean field nulls.
Yes it does. The fields have to null (or at the very least change from axial to radial) in the funny cusp region. Go back and look at Indrek's field simulations again.

It took me almost a year to get comfortable with those ideas. You can see how my thinking evolved on NASA Spaceflight.

Getting so you have Fingerspitzengefühl on this design takes a lot of time.
Engineering is the art of making what you want from what you can get at a profit.

Billy Catringer
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Post by Billy Catringer »

tombo wrote:I would rather fight the problems of bending a multilayer stackup than to try to cram in the multilayer Y's & T's and sew it all up by hand. Yours is of course the obvious design path.

What? You mean the links I posted didn't work? Lemme see can I bring 'em here.

Image

This one is based on a 1 meter radius with the cool water jacket thick enough to hold up without tension supports.

Here is the same thing, but with a 2 meter radius:

Image

This is the two radius beast without the core so that you can get a better look at how the shells nest. This one also has the Hot Water jacket in place.

Image

I working on changes to this because it is going to be mounted differently from the way I originally thought it would have to be mounted. That will translate into a thinner Cool Water jacket. I think I have found us a material that will let us get away with a much thinner Hot Water jacket.

Forgive the bad rendering. Blender can do a better job of rendering pictures, I just don't know how to tell it do that yet. I am trying to learn the software and build the models we need at one and the same time.

Okay, so what did I do wrong?

Betruger
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Post by Betruger »

n/t
Last edited by Betruger on Mon Mar 09, 2009 2:16 am, edited 1 time in total.

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