Optimal size for a fusor (embedment)

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Richard Hull
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Optimal size for a fusor (embedment)

Post by Richard Hull » Fri Jul 08, 2016 7:08 pm

A serious discussion needs to be made for embedment boosted fusion in a fusor. Check out this post for details not to be covered here.

viewtopic.php?f=6&t=10831&p=71599#p71599

If bedment boosted fusion is a given, is there a limit to this boosting process? I feel there is. It may well be related to fusor size. and operational gas pressure at a given size.

Embedment boosts by deuteron production near the shell as deuterons are "popped out" of the shell as ions due to electron bombardment and localized shell heating due to same. This is much in the manner of an inefficient ion source over a large surface area. We wind up with deuterons created near the ideal point, (the shell), which can undergo maximum acceleration towards the grid. In the case of non-IEC fusion, we still wind up with faster deuterons for the now known gas volume fusion process...deuteron-fast neutral fusion. As pressure and voltage increase, the mean free path varies in a complicated but calculable fashion.

Could a fusor be made so large that the mean free path is such that no IEC fusion might take place, or a grossly reduced amount? IEC fusion typically means fusion occurs within the central grid focus volume. What fusion might take place would be velocity space fusion in the gas volume due to the long path radius of a large fusor. Would this resultant velocity space fusion still be great enough to offset the IEC losses due to size? The U of W and U of I fusion teams announced that most of the fusion in their very large fusion chambers were found within the gas volume and not in the grid focus region.

The counter argument might be posited that smaller is better due to the possibility of shorter mean free path for embeded detuerium at higher pressures. However there would always be high voltage issues in very small systems due to arcing.

This is an area for amateur research but means several fusor must be built to investigate the premise.

Richard Hull
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Re: Optimal size for a fusor (embedment)

Post by Steven Sesselmann » Tue Jul 12, 2016 5:44 am

Richard,

I find it quite fascinating that we have been doing this for so many years and still don't have a clue what's going on inside the kettle. The basic framework is quite simple, we have a kettle with a bunch of gas molecules moving in all directions with a range of velocities. Before we turn on the power the gas is at room temperature and a Maxwell-Bolzman distribution of velocites, but once we turn on the power everything changes and we basically don't have a clue.

We can say with some certainty how the ions will move, but for some reason particles take on the familiar star formation and chaos becomes organised, ions move along closed paths and randomly collide with neutrals exchanging electrons along the way, so we end up with ions of varying potential and speeds.

I am firmly of the opinion that fast moving ions don't fuse (unless they are travelling in the same direction), my logic is the same as for a craft wanting to land on the moon, if it's going too fast it just won't happen, the spacecraft and the moon have to be moving in the same direction and at the same speed for the landing to be successful. It is quite possible that star mode causes ions to move in harmony and therefore get close enough to each other to fuse, if this is the case then it makes sense for fusion to take place anywhere within the fusor and not just inside the grid.

Let us imagine a couple sitting next to eachother on two swings, they can only hold hands a) when the swings are standing still or b) when the the swings are swinging in harmony.

A fusor goes into harmonic star mode because it is a favourable mode for increasing the entropy of the system.

My approach has been more like a) above where the swings don't swing much at all so the ions are standing relatively still and being allowed to fuse that way.

Either way, it doesnt matter if you are Richard Hull, ITER or the University of Wisconsin, we are all up against the same problem, fusion is a self extinguishing process. The heat produced by the fusion reaction increases particle velocity and in turn reduces the likelyhood of fusion. I don't know any workaround for that problem.

Steven
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Re: Optimal size for a fusor (embedment)

Post by Richard Hull » Tue Jul 12, 2016 5:12 pm

You note that "The heat produced by the fusion reaction increases particle velocity and in turn reduces the likelyhood of fusion.

The "heat" from fusion in a fusor is a success story! The particles released, (fusion ash), are wall bound to a dead stop. (T, 3He, P). There are not enough of these to affect the bulk gas as the fusion rate is a microscopic, imperceptable fraction of the gas molecules in the chamber. The "heat", as you call it, is the KE of the three wall bound particles and the escaping neutron. They do not heat the gas in the chamber as the probability of interaction in the short distance to the wall is ultra low of an already microscopic fusion debris flow.

Only failed deutrons which accelerate, do not fuse, but instead are recombined, create fast neutrals. This is really the bulk of the reactions in any fusor, as the idea of recirculating deuterons, on an efficient scale, has been shown not to be the case. No particle, save for the rare fusion ash, can ever have a KE greater than 2 times the applied KEV.

The idea that two particles can only fuse when moving in the same direction with zero relative KE to one another is rather hard to swallow. Certainly this has not been shown to be the case. A great test of this would be a small highly pressurized chamber of T and D or of just D allowed to cool in a bath of liquid helium and check for fusion from the chamber so immersed. Eventually, the bulk of the gas molecules, would reach near zero KE and some would ultimately move in the same direction and fuse if your thoughts are correct. No high voltage would be needed.

Richard Hull
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Re: Optimal size for a fusor (embedment)

Post by Steven Sesselmann » Tue Jul 12, 2016 10:14 pm

Richard Hull wrote:You note that "The heat produced by the fusion reaction increases particle velocity and in turn reduces the likelyhood of fusion. The "heat" from fusion in a fusor is a success story! The particles released, (fusion ash), are wall bound to a dead stop. (T, 3He, P). There are not enough of these to affect the bulk gas as the fusion rate is a microscopic, imperceptable fraction of the gas molecules in the chamber. The "heat", as you call it, is the KE of the three wall bound particles and the escaping neutron. They do not heat the gas in the chamber as the probability of interaction in the short distance to the wall is ultra low of an already microscopic fusion debris flow.
Ricard, I concede and agree that the fusion products in a fusor are wall bound, at best they might ionise a few molecules on the way out, in a larger reactor like jet or ITER they might contribute more to the heating and ultimately make the plasma unstable.
Richard Hull wrote:Only failed deutrons which accelerate, do not fuse, but instead are recombined, create fast neutrals.
If you mean an accelerated deuteron which didn't fuse and ends up recombining, then the resulting neutral should on average have half the accelerated velocity (conservation of momentum)
Richard Hull wrote: This is really the bulk of the reactions in any fusor, as the idea of recirculating deuterons, on an efficient scale, has been shown not to be the case. No particle, save for the rare fusion ash, can ever have a KE greater than 2 times the applied KEV.
Yes, I take it you mean no neutral particle, because if you remove the electron from a deuteron at ground potential the nucleus instantly takes on a tremendous speed, equal to the difference between it's surface potential and ground potential divided by the proton potential times the speed of light. let's do the math;

Deuteron mass in eV = 1876 MeV/c^2
Mass per nucleon = 938.2 MeV/c^2
Surface potential of deuteron nucleus = 938.2 million volts
Surface potential of proton = 938.7 million volts
Ground potential = 930 million volts
∆U = 8.2 million volts

Velocity or speed in this case is always calculated relative to the observer at ground potential, therefore ∆v = c (8.2 MV/938.7 MV) = 0.00873c = 2617 km/s

At first glance it might seem impossible for a nucleus to take off at 2617 km/s from a standing start, but in reality the nucleus inside an atom is not standing still it is in a mutual orbit with the electron, and jiggles with this velocity inside the atom, so when the electron looses it's grip, it takes off on a tangential path at an incredible 2617 km/s.

At this tremendous speed there is no way two deuterons can combine, not even if there was a most unlikely head on collision, because there simply is nowhere for the kinetic energy to go. Most of the ions will hit the walls, bounce off other nuclei and recapture an electron. If I understand my own theory correctly, these super fast deuterons won't heat the chamber in any way, because they are simply moving at this speed because they are so small and obey Avogadro's ideal gas laws. It is the natural velocity a deuteron obtains when colliding with the heavier Fe nucleus in the shell at room temperature.
The idea that two particles can only fuse when moving in the same direction with zero relative KE to one another is rather hard to swallow. Certainly this has not been shown to be the case. A great test of this would be a small highly pressurized chamber of T and D or of just D allowed to cool in a bath of liquid helium and check for fusion from the chamber so immersed. Eventually, the bulk of the gas molecules, would reach near zero KE and some would ultimately move in the same direction and fuse if your thoughts are correct. No high voltage would be needed.
In an experiment as you describe above, the atoms are not ionised and due to the Pauli exclusion principle the electrons prevent nuclei getting close enough together to fuse. But as I have described earlier, there is a better way, and it's relatively easy, just pick off the electron at low potential. The equation I wrote above looks totally different when you ionise the deuteron at -62 kV instead of ground potential.

What is the kinetic energy of a deuteron with respect to the observer at ground potential when you accelerate it to -62 keV?

ke = 1/2mv^2

If I am not mistaken it's about -2600 km/s, yes minus because it's moving away from you!

So we start off with a nucleus which has an intrinsic velocity of +2600 km/s and accelerate it to -2600 km/s and voila it stands still, and when you create a bunch of these they start fusing.

Richard, there is NO Coulomb force, and I came to that conclusion all thanks to you and the other guys here on fusor.net.

Steven

PS: On the subjecty of embedment, I think embedment in the grid itself is more likely to be a contributing factor to fusion, because these embedded deuterons come out of the grid at grid potential when the grid heats up, and if they ionise down there they will stand a good chance of finding a mate at the same speed and fuse.
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Re: Optimal size for a fusor (embedment)

Post by Richard Hull » Wed Jul 13, 2016 7:38 am

As you do not believe in the coulomb force's existence and I value it as one of the two main universal, macroscopic, pondermotive potential energy exchange forces that keep the universe active and in motion to "stir the soup, of the universe, I think we are at logger-heads on our physics. I tend towards the conventional proven physics that I see functioning as predicted.

Fusion is not easy as there is no ready "cocked energy gun" waiting for a low energy trigger pull to let any energy out. Good thing too because, fortunately, nature can't even do it well either. (volumetrically)

Cocked energy guns....very easy trigger pulls...(wood, paper, coal, gun powder, water on a mountain, U235)...Vast amounts of energy out related to trigger pull input energy and effort. Completely self consuming once started in simple environments

Non ready to use, very high energy trigger elements (H, D, T, He, B, etc.) volumetrically low return for energy input in all man made situations. Non-self sustaining, (actually, self quenching), rather complex environmental conditions demanded for paltry energy output.

All of this whether there is, or is not, a coulomb force. It's the way the physics of fusion works and how the cookie crumbles in doing it to advantage on earth.

Richard Hull
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Re: Optimal size for a fusor (embedment)

Post by Steven Sesselmann » Wed Jul 13, 2016 10:05 am

Richard,

One can never be at logger-heads about physics, either your understanding is further advanced than mine or my understanding is further advanced than yours.

In this business opinions and beliefs don't count for much which is why I am skeptical of anything invisible and intangible with a strange name, and the Coulomb Force is just one of them.The problem arises when such unicorns have been around for as long as the Coloumb force, people start accepting them as real.

Steven
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Re: Optimal size for a fusor (embedment)

Post by Scott Moroch » Fri Jul 15, 2016 6:38 pm

I think the initial premise of the post is an important one, which is to gain a better understanding of how the fusor does fusion. With a larger fusor I think it can be suggested that large amount of fusion is due to beam on target or beam to background reaction. I think further investigations will have to be done with the optimal size of a fusor for embedment by gathering data from fusors of all sizes.

Jack and I were very interested in gaining a better understanding of how much beam on target fusion contributes to the total amount of fusion. In addition, one part of the fusor that has never been tested extensively is to observe if different metals on the chamber wall will yield a greater amount of fusion. We believe we have devised a controlled experiment that will test both of these and we hope to be conducting it in the next couple of weeks. We are in the process of doing extensive research in hydrogen absorption in different metals as well as running calculations for the probability of recombination in a fusor. We hope that our experiment will not only provide insight to how the fusor operates, but also how others can optimize their systems. In other words, the rate of absorption of hydrogen in a metal such as titanium may be higher than stainless steel which can allow fusors to reach maximum neutron rates in a shorter period of time.

To return back to your initial statement about mean free path, I certainly think further investigation on fusor size is something that needs to be done. Perhaps we will see an influx of data from smaller fusors as it seems to be a more common route these days for financial reasons. When we operated our small fusor we had issues with large temperature increases on the wall due to the star mode beams. Therefore, even if the smaller fusor does foster beam-beam fusion, the beam-target fusion on the walls may be limited due to the inability to store deuterium.

Scott Moroch
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Re: Optimal size for a fusor (embedment)

Post by Richard Hull » Sat Jul 16, 2016 3:54 am

Complete data is already available on hydrogen in numerous metals. Among the highest absorbers are Paladium, titanium, nickel and Thorium. Google search will yield charts and graphs. The methodology of absorption and ejection play a key role. Stainless steel is not a good absorber, technically. However all metals absorb hydrogen and the number of deuterium neutrals of both high and low speed are in far greater abundance at any point over the deuteron number in our fusors. Thus, the walls see a constant shower of deuterium neutrals of vastly varied KE. Burying is taking place. Ejection is taking place via electron bombardment.

Electrons, no matter where they are produced in the fusor, are all wall bound due to simple coulombic attraction. Some will ionize deuterium neutrals on their accelerated way to the wall, most will not. These will smash into the wall and possibly pop out a deuteron.

The heating of a fusing fusor's shell is solely due to electron bombardment and KE transfer from shell bombarding neutral deuterium atoms. This represents the final resting place of 99.99999% of the applied energy input to the fusor and is a net loss. A tiny fraction of this seeming loss results in deuteron production via pop out deuterons from the lattice and chance ionization of neutrals by in falling fast electrons before hitting the shell walls. (a benefit in disguise hiding amongst a loss that gives us the interesting number of fusions taking place, not related to IEC.)

The best data on loading metals can be found in the scientific work done in cold fusion as many respected papers came out of that work. All such loadings were done electrochemically as they were looking at max lattice loadings (gentle with no ejection) All the metals noted above were loaded and studied save Thorium.

Our loading is much more rough and tumble, but I imagine often buried very deep in the lattice at the high KE of some of the neutrals.

It is great to do the research here. I wish I had the money to get identical Titanium and Nickel chambers made or line a SS chamber with Pd foil. Much could be gleaned for this effort. I would start at 6" hemispheres.

Richard Hull

Good luck to all experimenters.

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Re: Optimal size for a fusor (embedment)

Post by Steven Sesselmann » Sat Jul 16, 2016 11:19 pm

One Australian startup company attempted to make a sealed neutron source which used a commercial getter to store the deuterium, the pressure in the fusor was adjusted by heating the getter element, which in turn released some of the deuterium and reabsorbed it again when it cooled down. The getter system worked fine, but the device never got off the ground because of various other predictable issues for a sealed source without a vacuum pump.

Richard, what is your thoughts on hydrogen absorption in the grit itself ?

During operation the grid gets red hot and as it cools down after a run you would expect it to suck up quite a bit of deuterium from the chamber, which would come out again when the fusor is run the second time.

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Re: Optimal size for a fusor (embedment)

Post by Richard Hull » Mon Jul 18, 2016 4:35 am

There is little doubt that the grid does absorb and re-emit deuterium and deuterons. Heating alone will force out trapped hydrogen/deuterium from any metal. The grid is a metallic entity and acts as a conductive cathode to positive deuterons. The heating of the grid is partially due to ion bombarment, but at some point, due to electronic field emission. This can and does cause a current runaway at certain applied potentials and gas pressures.

Many functional, field emission vacuum diodes have be made and used in old hipot-testers. These used hair fine tungsten wires as the cathode. At high rectifying potentials the tips of these "hairs" glow white hot via field emission. The plate is a form of silvered aquadag hemisphere. The wires are electron emitters in this type of rectifier.

The fusor has no great vacuum but typical potentials and currents within its gas volume can cause the grid to heat via both ion bombardment and field electron emission.

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
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