Fusor Computer Modeling - Call for Contributions

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Frank Sanns
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Fusor Computer Modeling - Call for Contributions

Post by Frank Sanns » Thu Mar 24, 2016 3:34 am

The subject of computer modeling comes up from time to time but we have never had a group thread of contributions to treat the subject rigorously. Simple field lines does not do it.

Some questions that would be constructive to answer and illustrative for the newcomers:

1. What is the optimum ratio of inner and out grids.
2. Does having an outer grid and leaving a relatively large distance to the chamber wall gain recirculation time or energy?
3. How do ions seemingly have more energy than they started with when they pass right by the outer grid after passing through the inner grid?
4. If potential is relative, why does it matter the inner grid is negative or the outer grid is positive (large space from the chamber wall or insulated)?
5 Why is there "star" mode?
6. Why is there an upper limit of neutrons at a given current despite the voltage?
7. Why are point electrodes or plasma electrodes as effective or more than grids?
8. Is it really recirculation fusion in the bulk fusor volume, in the inner grid, or beam on target fusion of the grid or the walls?

There are more but I just wanted to get some starting thoughts down. I have seen some papers but I have not seen any that could answer several of these questions.

I think this is a good thread started for this advanced area. I hope you computer people step up to this one and give the group a jump start on these issues. Many of us with experience can answer some of them but to take fusion to the next step we really need a comprehensive understanding of all of the above and then some.

Let the discussions and contributions begin.

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Re: Fusor Computer Modeling - Call for Contributions

Post by benbartlett » Tue Apr 26, 2016 12:52 am

This is something I have been interested in modeling for quite some time. Solving Poisson's equations to calculating realistic solutions for potential over space given chamber geometry is simple enough, but the true challenge will lie in simulating the dynamical conditions in the reactor with some degree of accuracy for the number of particles involved. I suspect some clever use of smoothed-particle hydrodynamics would be able to handle the majority of the non-fusing dynamics of the problem in some feasible computing timescale, but the two main problems with this would be that it is completely inapplicable at calculating high-energy individual particle interactions, such as scattering and actually fusing. Making a hybrid algorithm that can identify when high-energy reactions are likely to take place and simulate them separately but also handle the bulk of the dynamics seems pretty infeasible for a small group, as it would be so widely applicable that someone probably would have developed some solutions to this.

Unfortunately, there hasn't really been enough rigorous research on some of the dynamics of how fusors actually work for me to be convinced that this simulation is feasible. For example, the "fusion happens in free space" vs "fusion happens in the top layers of the permeable material in the accelerator grid" debate (I think this is your question #8), which has very little supporting evidence from either side as of the last time I checked. (I have been discussing an experimental design with Scott Moroch that might give solid evidence in favor of one side or the other, but this is just a concept at the moment and since my fusor is no longer in working order will likely need to be executed by him.) If it turns out that the latter is the answer to that debate, the problem likely gets even harder. Even if we could identify when high energy interactions were likely to take place, simulating the actual interactions between the particles and the grid that are necessary to even give a semi-accurate approximation is also likely to be pretty infeasible without liberal use of generalizing statistics. From my own experience, it takes several minutes running on CERN's lxplus clusters to simulate a single very simple Higgs-diphoton interaction in GEANT4 - obtaining enough accurate reaction simulations to be able to generalize without resorting to small-number statistics would take a very long time and would need to be iterated over many different conditions. All of this is ignoring the complete infeasibility of programming something like this in a small group.

That said, I still think there could be a lot of work that could feasibly be done in this area, though much of the simulation will need to be generalized and some aspects of it, particularly calculations involving fusion rates when the mechanism for fusion in fusors is largely unknown, should not be taken too seriously. Perhaps if I manage to stumble across another giant roadblock (read: horribly broken clustering algorithm used in the CMS) to my current research I'll have some time to devote to this.

Finally, here are some thoughts on your questions. Consider them not as answers but simply as educated guesses made after only a few minutes of thought:
1. This depends on the mechanism for fusion. I have no answer if fusion significantly involves material-deuteron interactions, but if it happens in free space, I suspect a needle-like design would be the best design (i.e. ratio is zero).
3. Probably due to scattering effects. If you collide a group of ions from equidistant starting locations, then ignoring energy lost to Bremsstrahlung/other forms of light emission, we'd expect about half of the particles to end up with a higher final energy after the first round of collisions.
4. Because the charge of the deuterons is not relative...? I'm not sure I understand this question.
5. Likely due to increased RMS distance allowing for more energetic collisions, so scattering effects are more noticeable, though this is a very naiive guess and the dynamics of this are likely much more complex.
6. I don't understand this question.
7. Similar to my answer to #1, particularly if the majority of fusion happens in free space (which I suspect it does but have little evidence to support). Needle-like electrodes will cause much much greater accelerations over a equally shortened distance; this would probably eliminate much of the energy loss from low-energy interactions and confine the particles to a steeper/narrower potential well. See the attached (very simplistic 2D) demonstration of this using some simplified geometry and potentials from my reactor.
8. I think this is the key question to give more insight into the previous questions.

~Ben
Attachments
sim.png
Simple potential models

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Re: Fusor Computer Modeling - Call for Contributions

Post by Richard Hull » Tue Apr 26, 2016 4:24 am

I have written to this point related to what is the main source of fusion in a fusor many times in past postings. There are many possibilities and I feel ALL the possibilites do, indeed, produce fusion. Which is the main one? Ha! Is the main one polluted and un-enhancable by all the other interactions, both good and bad, in the mix? A good mind will have to admit to both Deuterium-target fusion and fusion in velocity space and some limited IEC fusion as originally so niavely envisioned.

It is probably an equally niave effort to think an amateur fusor, as presented here, can be definitively modeled. Likewise, definitive, rock solid, empirical measurements to determine details related to the commanding processes in the fusion numbers is most likely beyond the casual or even a committed amateur.

I would imagine there are as many as 5 or 6 processes doing fusion in the fusor. What percentage of each are in play would, indeed, be nice to know. As this device is simple by its very design, there is undoubtedly a chaotic malestrom of interactions within the device....The good the bad and the ugly.

Still, the discussion within this particular thread is needed. Modeling of the simple fusor is a lofty and idealized goal.

The big boys have modeled their designs to death for years and years and at long last have a good handle on how not to do fusion to advantage.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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