One more cube fusor

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Finn Hammer
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One more cube fusor

Post by Finn Hammer »

I am trying to design my fusor.

And boy, do I wish that Joe Gayo lab tour would become accessible somehow.

It may be remembered that I welded this monstrosity a couple of years ago:
IMG_20210207_120945.jpg
That stainless ball is destined into the future, and that may well be the landfill, I'm not sure about that.

With a power supply well within reach:

Already functional 30kV 50mA prototype:
IMG_20210207_124244.jpg
And still waiting for potting material to fill the 50kV version:
IMG_20210119_110242.jpg
I am working on the design of an aluminum cube which is inspired by Jon Rosenstiels well documented cube.

I am thinking about 2 different iterations, one with a Coulter-style grid:
coulter.JPG
And one with a Rosenstiel grid:
rosenstiel.JPG
The difference lies in the endplugs, where the first one forms a cylindrical shape to acomodate the cylindrical grid.
The viewport is on the cube face opposing the feedthrough.

I admit, this one is mainly so that I can make a nice star picture.

The other one has shallower endplugs, with spherical surfaces, to mimic a sphere along the plasma beam axix.
Such a small internal volume must surely save big on the Deuterium consumption.
Any wisdom about the needed clearance from grid to wall is invited.
Is any alloy usable, or must I use 6061?

It was an eye opener how a cube is just a cross internally, but at least it will be easier to cool, a function I have not yet put into the design.

Cheers, Finn Hammer
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Richard Hull
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Re: One more cube fusor

Post by Richard Hull »

Nice design Finn, as we know cooling is critical and internal clearances are also very important with no significant high field points allowed until the central grid or cylinder. I like a minimum 2" in vacuo clearance from any high field points, but this, as in all cases, depends on you highest planned high voltage.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Mark Rowley
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Re: One more cube fusor

Post by Mark Rowley »

Excellent plan Finn.
I can’t say enough good about cubes and the cylinder version I made last year. Aside from the ease of water cooling, the versatility of my recent cube for the BoT will make conversion to a dual gunned fusor fairly easy.

The ability to bore one axis larger than the rest results in excellent operational stability. A factor that the small 2.75” crosses can’t provide.

I’ll be interested to see if adding concave plugs makes for any remarkable differences in stability or neutron output.

Mark Rowley
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Richard Hull
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Re: One more cube fusor

Post by Richard Hull »

In my early 2.75 cross setup, before I abandoned it as being worthless for my purposes, tungsten needles in the center of the target conflats were posited by me here. Such a simple addition would make for high field electron emitters/ionizers for deuterium accelerators to the central region of the system.

How much of our fusion is neutral wall implanted deuterium, beam on target fusion via fast neutrals?? If wall related, the more wall area the better, assuming very little pure deuteron-deuteron fusion in our systems. Militating for the spherical system. Will we ever know for sure in the multi-functional, fusion level mess, in our simple systems?

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: One more cube fusor

Post by Finn Hammer »

Mark,
I know nothing about plasma in a vacuum, but a bit about breakdown in atmospheric pressure. I assume that the same rules apply with regard to field control.Therefore, the plugs in the squirrel cage grid version, I drew them that way, because I wanted the cylindrical grid axially aligned in an approximation of a cylinder, instead of what resembles a swiss cheese. Try to eliminate some of the discontinuities. I know that an arc starts with a corona, which is initiated where the electrical field is too high. Rounding corners, smoothing things out, and keep a distance is a good thing in high voltage work, perhaps also inside a fusor, that is the route I intend to follow, anyway. ( Arh, well, perhaps not so much keep the distance in this tiny chamber)

Richard,
Will we ever know?, Certainly not me, I just came back, now everybody are talking beam on target, I don't know what it is.
My son-in-law's brother works on a project for ITER, related to measuring the speed of particles. I offered him my understanding of fusion, and he replied: Finn, you cannot understand these things on an intuitive level, you have to look at the math in it. If you want to know where a particle is, you cannot know it's speed, and you can know it's speed, but then you won't know where the particle is.
I hope the proces of getting the fusor up and running will enlighten me somehow.
I have had a very productive week, at the local tech. college, where I am allowed to use the machine shop.
DIN 55027 spindle nose parts for my Boxford, a fusor cube, drill templates for the fastners, and a little indexing aid for squirrel cage grid construction, in my home shop that doesn't include a milling machine, shame on me.


Cheers, Finn Hammer
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Richard Hull
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Re: One more cube fusor

Post by Richard Hull »

Finn,
There is no possibility of any form of precision measurement of particles in a fusing fusor. There is one thing we know for sure and has been covered in past posts. There are many possible modalities to do fusion in a fusor. They are all undoubtedly in play. This makes a crude mess of activity within a fusor. The best we can hope for is to experiment with forms within the device to increase production of fusions. We are not looking for efficiency of production as that is just a chance thing. I would rather produce an upper limit in a device of 10e8 fusions per second at 3,000 watts out of the wall outlet than peak out at 10e6 at 200 watts.

We will never break even or approach it to within 6 orders of magnitude! The power company is willing to sell us all the power we need. As such, efficiency is nice for the nit-picker, but for me and many here who want the neutrons we are willing to accept gross inefficiency if the numbers are there and can be had at any expense.

Efficiency is a bragging right if that is your goal. Sheer fusion and neutron numbers are a bragging right if that is your goal.

Beam on target fusion can have two meanings.

One in the purely scientific sense as is normally done..... A pre-loaded, hydrogen absorptive metal target of deuterium or tritium created via chemical of other processes is bombarded by a fast, (high energy), beam of deuterons and a lot of fusion takes place at the pre-loaded "target". Note: This requires very high acceleration voltages to be useful to a professional or an amateur.... 100 KV is low energy

The other is more related to our amateur efforts......An unloaded metal wall that is capable of some limited hydrogen loading is bombarded by deuterons beamed or un-beamed in our fusors. Ultimately some absorption occurs. As deuteron bombardment continues, provided the deuteron energies are there, some "effective" beam on target fusion will take place. Fusion is very easy to do and there are many ways to do it, provided you throw efficiency of production out of any form of mindset. That is what makes fusion easy. Fusion is a probabilistic, quantum tunneling effect. (specific and detailed FAQ exists on this topic). Fusion is a casting of the dice. Good practice in any fusion system can load those dice to make snake eyes "fusion" take place more often than other throws. Being a chance affair, is why there are no fusion power plants and why there may never be any.

If one goes for the professional beam on target fusion, a lot of special metals and operations are involved well beyond the need for ultra high voltages.

The amateur method is very crude and the cube fusors are pretty much trying to do fusion this way, but all the other processes we know of are also involved. Regardless, the cube fusor is still a very crude and simplistic fusion reactor and subject to all the processes found in any amateur fusor, as is the cross and spherical versions.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: One more cube fusor

Post by ian_krase »

Can you elaborate a bit on the difficulties of beam on target work? At least two people have done it. Certainly it's more substantial than a fusor.

I hope you won't landfill that chamber - I am sure that it could find much use even if not as originally intended.
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Mark Rowley
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Re: One more cube fusor

Post by Mark Rowley »

The cube looks great Finn. You're making some fast progress!

Ian,
Fwiw my BoT2021 has already made neuts and I'm currently finishing a 150kV supply to get the numbers well within the range of activation work. I will say though, it's more involved than building a fusor as it requires 4 separate power supplies and a host of other gadgets. Well within reach of any hobbyist with a small machine shop.

Carl Willis, Robert Tubbs, and I believe two others have built operational BOTs.

This is my current work:
viewtopic.php?f=12&t=13769

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Finn Hammer
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Re: One more cube fusor

Post by Finn Hammer »

A bit more work on the cube.

The inside of it was given the fillets, and the polish, quite a wavy surface despite the shine.
IMG_20210212_200052.jpg

I decided to put helicoil in the mounting holes, since the thing probably has to come apart again and over.


IMG_20210213_143530.jpg

I spent a lot of time drawing it in 3d, and this was necessary, in order to figure out how to configure the cooling system, here is a view of the cube now, quite a swiss cheese:
cool.JPG

If you look closely, you will see how the main tunnel of the fusor is circomferented on 3 sides by two runs of Ø10mm holes, for coolant, but there is more cooling, the endcaps get their share too:
I could not stand the thought of 8 hoses exiting the thing, so, a litle extra work on the manifold.
Udklip.JPG

I tend to think I should have been a mechanic, because every time I get into making these things, they start to look like an engine:
fusor.JPG


I am starting to think there is a touch of steampunk over it, Steampunk Dragon?
IMG_20210218_131536.jpg
Anyway, parts are coming along nicely.

edit:

I just got the last render of the total system, Quite nice I think:

Untitled.JPG
Cheers, Finn Hammer
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Richard Hull
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Re: One more cube fusor

Post by Richard Hull »

Lots of nice pre-assembly fitting design. All of these latter-day fusors require a lot more special design forethought than the old spherical systems. This is due solely to the quest for higher numbers in the fusion arena. This goal is a great one as this site matures with more experimentation. While break even is and will forever be impossible, We find that at least one order of magnitude improvement over the simple D-D spherical system is just about within reach, provided the "in it to win it" mindset is cast off. I am seeing less and less wild eyed high schoolers here of late and far more attempts at new, more advanced and, thereby, expensive and complex fusor systems develop. This started with the wall loading concept year ago and this lead to a fusor system based on loading that mimes the BOT process in small system design. Great work!

Such efforts leaves the low to zero funded youth out of this high end game, for the most part. The cost of suitable instrumentation and special machining, water cooling, etc, not only demands verve, but funds and a rather full grasp of all of the technologies to a high degree based on experience and not the quick rinse seen years ago to just get fusion done at any cost.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: One more cube fusor

Post by Jon Rosenstiel »

Wow! Very nice Finn, love what you've done with your cooling system. More than once I've sat staring at my cube trying to visualize how to configure cooling water passages similar to what you have done. Good, and very neat, work. Steampunk-ish indeed.

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Finn Hammer
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Re: One more cube fusor

Post by Finn Hammer »

A litle update on the Steampunk Dragon.

Some brass and alluminum discs arrived:
Materials for the endplugs and the manifold. Also shown are the jigs I use to drill the associated holes
Materials for the endplugs and the manifold. Also shown are the jigs I use to drill the associated holes

These materials were run across the lathe, soldered and cleaned up. Endplugs in particular need more polishing.

The manifold parts are now complete, and the endplugs just need polish.
The manifold parts are now complete, and the endplugs just need polish.

This manifold is a bit complicated to make, and I have full understanding if an 8-arm octopus style cooling arrangement will be the weapon of choice in the future.


There are now 52 helicoil inserts in the assembly:
With the work invested, I do not want to suffer the grief of a pulled out thread.
With the work invested, I do not want to suffer the grief of a pulled out thread.

So anyway, here it is, in the first test assembly:
The Steampunk Dragon first test assembly.
The Steampunk Dragon first test assembly.
That's it for now, still a long way to go before first plasma, however, I have just now taken delivery of a rod of EDM carbon stock for the Coulter style lens.

Cheers, Finn Hammer
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Jim Kovalchick
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Re: One more cube fusor

Post by Jim Kovalchick »

Just premier work!
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Mark Rowley
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Re: One more cube fusor

Post by Mark Rowley »

Beautiful work Finn.

In more ways than one, yours will be the coolest fusor around!

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Richard Hull
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Re: One more cube fusor

Post by Richard Hull »

Just wow!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: One more cube fusor

Post by Finn Hammer »

Just an update on progress.

Drawings are needed to support the image of the Fusor assembly, that I have in my brain. They start with scribblings, like this one here, where the main lines are lay'd out, believe me, even though it may not be at all obvious.


Scribbled attempt to hold on to a vision.
Scribbled attempt to hold on to a vision.

And it is also my own problems reading the drawing, and the tedium of redrawing it over and over to put more parts into it that
at this point I finally realised, that there is only one way, lad. And that is CAD.

The challenge of drawing the individual components looked overwhelming to start, but soon the resulting view into what becomes a clean and simple layout, proves that the effort is well spent. The occation to learn more techniques within the CAD package is an added bonus, I got better at mating parts, and the bent bellow tube is my pride. And a part drawn in CAD can be used over and over.....


Nice clean view of components.
Nice clean view of components.

Cad rocks!
Cad rocks!

The core structure is a 901P monitoring the foreline, just before the Pfeiffer TMH 071 P turbo. This one gets throttled into KF25 (the joy of having a lathe, now) and routed to a MKS bellows throttle/isolating valve and enters a cross which feeds into the fusor, a 50 micron Baratron and a 999 Quattro pressure transducer, which both are thus kept out of the line of plasma, and the transducers and the fusor are equally distanced to the center of the cross, which ought to facilitate accurate measurements. The Quattro can measure higher vacuums than the Baratron, so that one is for determining base pressure before filling with Deuterium,(and for zeroing the Baratron) monitoring of plasma pressure is reserved for the Baratron.
The Deuterium flow will be controlled by a 10 CCM mass flow controller, preceded by a Sigma Aldrich pressure gas regulator. Ahead of that is the precious lecture bottle, not yet shown.

Great satisfaction at the CAD package is had!

I ordered a lead glass viewport from Lesker, and there will also be sacrifical quartz glass disks inside the fusor, probably also a screen.

Speaking of Quartz glass, a week ago I did not know anything about it, now I am in love! Fantastic stuff, I have ordered lengths of it in 19/25 dia and in lengths of 100, 150, 200, 250, 300 mm. It is my intension to do a piece of research into the needed length of tubing in the do-it-yourself feedthroughs that I see, originating from Coultier, Selzman, David. I will apply field controll to the best of my knowledge, but that is for the second iteration.

Getting to know about new materials and new techniques is the core of the Fusor effort satisfaction

Cheers, Finn Hammer
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Re: One more cube fusor

Post by Richard Hull »

I have always pushed for proper predesign setup planning on fusor systems, especially as relates to spaces being too tight for easy servicing or even convenient initial assembly and subsequence disassembly in repair or replacement situations. Try and get a wrench to tighten or loosen a conflat bolt with an ill designed work space around it. Try and fight putting on a KF fitting clamp that can't easily fit around the couplings that are against a wall or a plate. It is a design challenge and jungle out there in an attempt to think of everything that seems so simply mechanical until you screw up having worked so well on keeping it all compact, neat and tidy..

Nice that you are noodling it all out before hand.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Finn Hammer
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Re: One more cube fusor

Post by Finn Hammer »

Things are starting to come together, and I need to ask a question about mounting the turbo.
latestcube.JPG
Sideways, and with the inlet pointing down (since I am using a rotary vane pump) is as recommended in the manual, but there seems to be some reservations on the side of Pfeiffer, regarding the rigid mounting of the pump on the far side of it. Far side being opposite of the inlet.

Pfeiffer seems to favour mounting the pump from the high vacuum side, by attaching the big flange to the chamber, and they have some limits to the forces that can be excerted to the pump.

My approach is to fix the bottom of the pump, and be gentle with it on the high vacuum side, by using a bellows pipe right next to it.
mockup.jpg
I am asking if this looks right, since now is the last chance to change it.


Cheers, Finn Hammer
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Re: One more cube fusor

Post by Jim Kovalchick »

Finn,
My turbo experience is with a Leybold not Pfeiffer, but mine is a similar size. I started using a horizontal alignment recently after always using vertical in the past. I use a bellows right angle valve before the turbo. So, there is a right angle. I also have a KF 40 sized instrument pipe before that. It's not optimum but it works.
As far as vibration, your mount is more important than your incoming line. My biggest source of vibration is the roughing pump. I use a flexible steel bellows pipe on that side. I use a foam pad beneath the turbo to muffle the vibes.
My experience is also that the smaller turbos are fairly tolerant of abuse.

Good luck.

Jim K
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Finn Hammer
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Re: One more cube fusor

Post by Finn Hammer »

Thanks, Jim

On second thought, the frame as it is, is awfully wiggly. I probably better finish it up as a full "aquarium" frame, and add corner gussets, to make it rigid and stiff.
perhaps also double that corner post up on the other side of the turbo, to support the bracket on both sides of the turbo.

Speculating about which way to mount the turbo, I visionalised these two alternatives:
turbowiggle.jpg
If these modes of wiggle hold water, then sure, it would be better to mount it by the throat. The turbo end of the pump is mounted in a magnetic bearing, which allows the rotor to find and rotate around its own center of gravity, which may not be the same as the shaft centerline. I have a feeling that too much wiggle there could cause a crash. But if the mount is rigid enough, then mounting it at the bottom should work as well. Actually, there should not be much vibration at all.
Time to order more extrusions.

Cheers, Finn Hammer
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Re: One more cube fusor

Post by Richard Hull »

I had no direct experience with turbos until Fusor V, but do have experience with gyroscopes of some size. I bolted the living hell out of my little turbo to the rigid fusor table which is bolted to the wall of the building with the side wall bolted into the concrete floor with poured molten lead anchor bolts. Certainly over kill, but I don't worry about the turbo torqueing around.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: One more cube fusor

Post by Finn Hammer »

All,

After I realized that the frame had to be closed on all sides, and a additional post for the other side of the turbo, everything got rock solid, and the turbo spins up without any problems.
firstlook.jpg
I will move over to Images du Jour from now on, since things are getting very basic.

Cheers, Finn Hammer
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