How to make fusion chamber?

[Rob Pope]

Hi everyone, I'm new, and a scrounger, and was wondering what the best way to make a fusion chamber is.
I know stainless steel is the most common because it blocks the soft x-rays, but where is the best place to get stainless steel, and once I get it, should I just lathe it to the hemisphere shape I need?

Thanks!

[Chris Trent]

Welcome, Always good to see new folks here.

Last I checked most of us with stainless hemispheres ordered pre-formed hemisphere blanks and welded various fittings to them

You can find more info with a search. Just look for stainless hemisphere and you will get you far more information than I can possibly include in this post. People have written extensively about it in the past.

[David Geer]

Rob,

One of the things to look out for though is if you go with a fully pre-made hemisphere/sphere, you'll start looking at prices going well into the thousands and tens of thousands. Like Chris said, best bet is a plain hemisphere and custom fitting after you get it at a local machine shop or learn by doing (can be costly as well) with cutting/welding yourself.

The pre-formed Magedburg Sphere I want to get will cost me quite a bit ($8,000+) from http://www.kimballphysics.com but this comes with enough fittings and flanges/seals for view ports, laser/ion assemblies, HV node input and various other doodads I might consider adding in.

Good suggestion is to look around and start small. Kimball does have a good selection of chambers, electron/ion guns, cathodes/emitters, detectors and various hardware/software that can be used for fusors. BUT, scrounging for low-cost parts is always worth the time and effort.

[Steven Sesselmann]

Rob,

Keep in mind that the two hemisphere fusor is the stock standard model, but from all the fusors I have seen, there is no hard evidense that you need to do fusion in a sphere.

Many other shapes have been successful, so with a bit of imagination just about anything can become a fusor, as long as it will hold a vacuum.

Some nice work has been done in cylinders, and why not, so much easier to work with.

Have fun..

Steven

[Chris Bradley]

Rob, I think you could've done a little more searching before posting this question, but further to the other posts, personally speaking I would be interested to see more attempts with small, sub 3" fusors, which can be done with some of the larger standard 'connectors', rather than 'chambers'.

Like;

download_thread.php?site=fusor&bn=fusor ... 1300156177

Seems to me, as per my comment in that thread, that Paschen works against larger chambers. If you are starting out, how about trying a 2.75" CF cross, and use that as a chamber? I would speculate that the advantages are numerous;
a) easier to evacuate
b) less outgassing surfaces
c) higher fill concentration for given flow rate
d) less free-path electron cascading (viz.. Paschen breakdown higher with smaller distances), posibly higher reaction rate efficiency [which is the thing I'd like to see more evidence for, one way or the other]
e).... the biggie for amateurs.... cheap and plentiful!

Not that I am trying to get you to do an experiment for me (!) just that I would be very interested to see if yet another small fusor stamps up a solid neutron rate.

[Richard Hull]

Wagner sells hydroformed 304 SS hemispheres in 6" diameter for about $35.45 each so a full 6" fusor shell can be had in Stainless steel for a bit over $70.00. I have dealt with only Wagner since the 90's.

https://www.shopwagner.com/nxc/nxcli.nsf

Naturally you will need conflat flanges to be welded on and any ports you need will have to be bored and weldments made.

A complete fusor vessel can be built by a high schooler in metal shop for under $400.00!........ Less if his conflat attachments are purchased used off e-bay or from our trading post. My first 6-inch diameter, neutron producing, fusing, fusor body cost me about $100.

Yes, if you order from Kurt Lesker & Co., a precise stainless fusor shell with windows, flanges, HV insulator, ports, SS hosing, valves, etc., which is fully vacuum tested, electropolished and ready to go, you will need about $3,000-$5,000.

Your choice;....... less than $400..... or more than $4,000. Same end result, just not as pretty or as gleeming professional.

Richard Hull

[Chris Bradley]

Or you could try a new CF tee for $100:

http://cgi.ebay.co.uk/290460626816

Feedthrough in one hole, vac out the other, viewport in the third. Job done!

[Richard Hull]

That appears to be a 2.75 CF Tee with 1.5" interior and way over priced based on stuff currently in our own trading post. A bit small, too. A larger Tee would be better but would have a hefty price on it. It all falls back on what the builder visually expects when done in a trade off against costs, performance, expandability and future research capabilities, etc.

I would say that about 60-75% of the fusors that have been successful were spherical types. The rest are a mish-mash of SS bell jars, cylinders, tanks, CF crosses and Tees. I think everyone here, from Joe th' pipe fitter to the perfection riden purist, knows you just need a sealed, metal, vacuum vessel to do fusion.

Noobs can see the vast number of designs in Image du jour, but they still tend to like the presentation and image of the spherical system. Only a person on a very limited or low budget and fixed on just becoming a fusioneer and then abandoning the effort might opt for the less frequented, yet successful designs.

I would personally say that a CF, 6" or larger, 5 or 6 way cross might present as the ideal research chamber, While a simple 6-8-inch cylinder CF stub or extension might be the cheapest and easiest CF solution. The sphere is sort of in the middle in both expense and difficulty of assembly and experiment. It remains the king of eye-candy and for many, that is a big part of their ultimate goal.

New 6" 5 way cross- $850, 6 way- $1,150 blanks $202 each total $1860 or $2362
New 6" full nipple- $225 + end plates (blanks) $202 each total $629.00
New 8" flanges (6"hole) $335 each thus full 6-inch sphere new $70.00 total $740
Cylinder slightly cheaper than sphere but research cross, very expensive.
None of this pricing allows for scounging, super deals on or off e-bay.

Richard Hull

[Chris Bradley]

(Sorry... thought it was the next size up...)

Just a thought, and 'options for the future'; maybe it would be constructive to have a thread in which interesting minor variations could be tried by newcomers, thus giving them an option of aiming for an experiment that might add and expand on the current quantity of 'like-experiments'. So in this case, I'm suggesting it might be interesting for a new-builder to go for a smaller device, to add to the currently limited set of data on such a configuration.

Other suggestions for focussed attention on certain aspects of fusors could then be more readily picked up by new comers and they might feel they can add to the range of experiments, rather than reproducing a standard - if they were so inclined to aim slightly 'off-centre', so to speak.

A bit like a fresh post-grad student coming along to see his Doctorate tutor for the first time. The forum [the tutor] could have a set of ready-made experimental suggestions in keeping with the previous [student's] research, that the new student might use as a guide-line to consider, research, and develop for himself.

[Rob Pope]

Thanks everyone for the input, I've done some research (yea, could have done more ), but I wanted to get the opinion of the more experienced members. As time goes on I will probably post in pretty much every forum section.

Chris, actually, one of the things I had been thinking about was how to make this something that is undeniably my own rather than repeating what someone else has done. Because of this and price, I think I will go with a smaller fusor (along with electrolysis to obtain deuterium). Should be easier to pick up neutrons too since I can get a detector closer to the source.
I will gladly contribute to the proposed kind of thread.

Since I'm chronically broke, a large fitting or connector seems to be the way to go. I will ask a friend's dad who works at steel dynamics, see if I can swing anything there... if not theres my friends dad who works in construction, or my dads friend who practically owns a machine shop.
Or I guess I COULD buy one... I'm trying to stretch my $100 as far as possible to get to the plasma stage.
Then theres the $50 for heavy water (It does look fun to play with though, ice that sinks

[Jeroen Vriesman]

I got some big stainless steel hemispheres (about 30 cm inside) from a scrap metal dump, didn't cost much but takes a lot of work to make it into a vacuum chamber. They came from an oil storage company (vopak), originally big rotary vanes.
So if you can find friends at an oil storage/refinery.
You can see the pictures on nuclearfusionreactor.blogspot.com

[Chris Bradley]

Jeroen, maybe you can improve on E-6 with a balzers 330 (is that what you have?) pumping against nothing for 4 hours. Good enough vac for fusion, I guess, but if you find the pressure goes up between runs then it may be drawing in atm and contaminating the chamber for your next run. Best see how it looks once the chamber is on, you might improve the vac with a re-seal against the pump.

[Jeroen Vriesman]

It was just a test run for testing the cooling water pump.

I'm not building a standard fusor and I need much better than E-6 mbar.
The pump is a THP270, and I will (eventually... it's a lot of work) do bakeout at 180 C.

[Rob Pope]

Hello again,
I was thinking, and looking around my garage, and I realized I have an old engine block sitting in a corner.
It's an old in line 4, and I was wondering what your guys's thoughts are about using it as a possible fusion chamber?
I was thinking I could seal off one cylinder, it's already designed for HV feedthrough with the spark plug, where the head was would be an excellent place to place a gasket and a view window, and there are only a couple other holes to seal, one of which could be used for duterium feed, another for the vacuum pump.

What are your thoughts on the idea?

[David Geer]

Why not use the fuel injection port for the deuterium feed unless you want the feed further from the HV feedthrough. The chamber will definitely take the pressure but you'll have to do some rigging to fully seal the area. Maybe flash weld the cylinder head in-place near the bottom of the chamber.

[Chris Bradley]

There's a 'novelty' factor, to be sure, but 'novelty' tends to go along with 'not being very serious'.

I don't see how you would get a good seal - at either end. The metallurgy of the cylinder bore may not be suitable for the vaccum required, plus the surfaces are honed so I don't see how you'd get a seal, at least at the crankshaft end. I expect you'd get a reasonable plasma out of it, so maybe it is a good start for that experience, but anticipate that you would need to move on to 'serious' if you wanted more than just a glow plasma.

One thing is for sure - 'shell heating' will be the least of your problems!

[David Geer]

That's why I suggested flash welding a cylinder head at the crankshaft end (straight-through weld of the contact surfaces) to provide a very solid seal and leaving only the header as the point of weakness.

This can easily become a serious project if he's wanting to use spare materials that are just lying around. Nothing stating it's gotta be done in a pyrex tub/jar or SS sphere. Might even get better pressures since the block is already tested to withstand massive punishment.

Another thought would be to try dense D2 mixture like you would gasoline but a mechanical control arm to maintain an increased atmosphere pressure within the chamber with HV input. Test to see if fusion is possible in a high density environment like what would be found in the sun.

Should never dismiss anything that hasn't been fully tested out before.

[Rob Pope]

Thanks for the input, I just realized it's a VW beetle flat four, not an inline, if that makes any difference to you.
I also had the thought of using the existing fuel injection port to enter the duterium, but I'll have to look into whether or not it will hold up under a vacuum.
Then again, the pressure on the other side would also be low... I'll look into it.

If I start this, which I think I will, I intend for it to be a serious project. My goal is to build a fusor that produces neutrons for less than $100. I think I have everything figured out except the neutron detection.
(old AC unit for the vacuum, flyback for the HV, electrolysis for the duterium)
Of course I'll probably end up spending more than $100 in parts, but I'd like a final budget that's fairly low.

[Chris Bradley]

Rob Pope wrote:
> I also had the thought of using the existing fuel injection port to enter the duterium, but I'll have to look into whether or not it will hold up under a vacuum.
> If I start this, which I think I will, I intend for it to be a serious project. My goal is to build a fusor that produces neutrons for less than $100. I think I have everything figured out except the neutron detection.
So this block has a direct fuel injection port? On the block? Eh!?

And a project, with deuterium, all for $100? I don't think I'm hearing the beginnings of 'a serious project' just yet!


David Geer wrote:
> Another thought would be to try dense D2 mixture like you would gasoline but a mechanical control arm to maintain an increased atmosphere pressure within the chamber with HV input. Test to see if fusion is possible in a high density environment like what would be found in the sun.
> Should never dismiss anything that hasn't been fully tested out before.
Au contraire. Compressing D2 in a combustion engine piston to get fusion? There are some things you really CAN dismiss before fully testing them! That's surely one of them.

[Rob Pope]

Chris Bradley wrote:
>So this block has a direct fuel injection port? On the block? Eh!?

>And a project, with deuterium, all for $100? I don't think I'm hearing the beginnings of 'a serious project' just yet!

Not direct fuel injection, but however old cars got fuel into the piston. There is an opening of some sort. The internal combustion engine isn't exactly my forte.

And heavy water is pretty cheap. I don't expect to actually spend less than $100, but it should be possible to point at every part on the completed thing, total up their costs, and have it be less than a C note.


>Au contraire. Compressing D2 in a combustion engine piston to get fusion? There are some things you really CAN dismiss before fully testing them! That's surely one of them.

If you guys mean compressing the duterium with the piston in the cylinder in order to achieve fusion, that sounds a bit ridiculous, and inefficient, and Promethean. If you mean simply finding the effects of different pressures on the system, then it sounds like it might be a decent way to change the pressure after fusion has been established without introducing massive amounts of duterium or other unwanted gases.

[David Geer]

Chris,

Rob got part of the idea I was aiming at but even with the combustability of D2, an engine block would be able to contain the destructiveness. Once you have a vacuum pressure, a control arm could slide the piston head to quickly adjust pressure both positively and negatively. Only constraint would be a tighter seal or completely sealing the intake/exhaust ports. Maybe a computer controlled mechanical armature to float the pressure with an interface to the atmospheric gauge(s). Possible to help reduce outgassing by auto-adjustment of containment area.

Changing the old school fuel intake port to a control feed/mist(er) system would work for supplying deuterium into the chamber.

Whether is be vacuum with IEC forced gas density or the same with added compression/expansion of a vacuum area. Fusion should still be possible, as long as, the atmosphere to deuterium ratios are correct and you have the HV static field. For those who have already achieved fusion/neutron club status. What's not worth trying different variables to get different results? You've already succeeded in the hardest step so why not try to improve upon it?

Said enough for now so I'll let folks take what they will from this snippet and provide feedback.

[Chris Bradley]

David Geer wrote:
> Fusion should still be possible, as long as, the atmosphere to deuterium ratios are correct
eh? The 'correct' ratio is 'zero' [as close as practical]. (Sounds like a Ronald Richter plan!)


> Once you have a vacuum pressure, a control arm could slide the piston head to quickly adjust pressure both positively and negatively. Only constraint would be a tighter seal or completely sealing the intake/exhaust ports.
Just a tighter seal!?

Piston rings aren't designed to be 'seals' at all. They can compress a charge because the compressing chamber gas can't escape past the wettened rings at any comparable rate to the speed of the piston. Take away the oil and you can press 'blow by' gas past the rings when you push a piston in. (That's why you need crankcase ventilation - because there is always some blow-by gas). Typical injectors inject just above the intake valve. The stem of the valve is not usually that good a seal either (if your car smokes when you take your foot off the gas then an excess of oil is likely being sucked down the stems).

So you would have to seal up the valve stems of the valves as well as the intake ports, and completely modify the way a piston sits in a bore. And all this is cheaper and easier than buying a CF cross!? QRT.

[David Geer]

OK, so apparently I'm not that knowledgable with engine mechanicals.

[Rob Pope]

Well, it may not matter if I can't convince me parents to let me.
I mentioned radiation and my mom flipped, and my dad just doesn't see the point and thinks it's a waste of time.