Fusor without inner grid?

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Dennis P Brown
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Re: Fusor without inner grid?

Post by Dennis P Brown » Thu Dec 14, 2017 10:58 am

Well, trapping ions so that they do not lose energy is not unlike holding water in a ball of rubber bands - gonna leak badly. This ignores Bremsstrahlung loses, which for any significantly energetic electron is extremely severe and robs the plasma of energy no matter how perfect your magnetic/electro-static bottle because, you trapped them! The very goal you desire robs your plasma of energy.

OK, lets assume that your plasma 'leakage' is low (zero) and other loses are minimized (again, zero) so your containment energy cost is near zero and few ions lose energy by Bremsstrahlug (again, zero - all impossible but use this as the best case since it is); now, calculate how many ions achieve fusion via tunneling per sec in your 10 -100 micron gas; then calculate the energy so obtained from these fusion events (hint - many orders of magnitude lower than the 250 watts that a cubic meter of the Sun's ultra dense and super hot core releases every second) - in other words, if you were 100% perfect you're gonna get maybe 10^-3 watts per second for a cubic meter of plasma! Think this out - that assumes essentially zero losses and near 100% conversion of all possible tunneling captures per sec resulting in less energy production than a flashlight bulb yields in radiated energy/sec.

I could point out your claim that you get sufficiently low leakage out the ends that your net energy loss is less than fusion produces because you say so is not proof - as to why it will leak terribly and not trap your ions as you think can be shown by reading some of the vast scientific literature on mirror machines in fusion and their issues.

By the way, that is why tokamaks and stellarators were built - the ends are connected allowing the trapped ions to circulate as long as the plasma is stable (why that is not true for times past a few seconds isn't the point. Energy produced per sec tells us all we need to know.) In these devices, fusion via tunneling is essentially nil. So, why would yours produce more energy?

Dan Knapp
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Re: Fusor without inner grid?

Post by Dan Knapp » Thu Dec 14, 2017 12:48 pm

In the area of fusion, like many areas of science, there is not much really new under the sun. It is unfortunate that so many of the people with a “new” idea are unemcumbered by prior work. The “Fenley fusor” looks a lot like the “periodically oscillating plasma sphere (POPS)” that was studied extensively by the Los Alamos group twenty years ago. One can no longer claim lack of access to the scientific literature as an excuse. A little time googling can save one the embarrassment of reinventing the wheel.

John Fenley
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Re: Fusor without inner grid?

Post by John Fenley » Thu Dec 14, 2017 5:32 pm

I have looked at POPs, and I've also looked at "Beyond the Brillouin limit with the Penning Fusion Experiment" also by the same group.
Pops tried to oscillate a sphere, my device oscillates a cylinder. The cyclotron is a very well known, cylindrical, periodic system capable of reaching the desired energies. Each ion in my device follows a cyclotron trajectory but is excited by an ion beam, not Ds, forcing each trajectory to pass through the same point at the same time, rather than circle the same point at the same time.

Here is small excerpt from the PFX paper: "It was suggested recently that the local density might exceed n in a strongly nonequilibrium plasma. This local concentration may occur either in space or time."

So, it is like POPS, but the symmetry is different.

Honestly, I think it should behave a lot like beam on beam fusion with the big difference that non-fusion collisions, even at steep angles, keep ions on a desirable trajectory. It's something like the MIGMA but with a thermal distribution. Todd Rider(Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium) should have nothing to complain about.

Indeed my biggest worry is that, though it appears from my thought experiments and simulations that it MIGHT work, when I did the numerical calculations to determine energy output, I was sorely disappointed. My "giant" reactor in an MRI machine might put out 100 Watts of fusion power, though I did find that this number could be tweaked greatly by the precision of the timing of the ions entering the focus. Synchronization is easier when the device is smaller, so a smaller device might actually make more energy, and "there's plenty of room at the bottom".

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Richard Hull
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Re: Fusor without inner grid?

Post by Richard Hull » Thu Dec 14, 2017 8:42 pm

Once again, we await the spending and loss of treasure and hope that always accompanies "its gotta' work" ideas related to the fusion quest.

ITER is certainly the biggest throw away in fusion science yet funded. The Fenley idea is but a tiny expenditure. I say let that tiny amount of money flow provided, when it fails, the people living off the initial funding don't say, "if we just could have enough to make it 50 times larger, we know she would kick in and go like a bandit."

How big and costly does something have to be before we get that first kilowatt of usable electricity that is over unity?

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.

Patrick Lindecker
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Re: Fusor without inner grid?

Post by Patrick Lindecker » Mon Feb 25, 2019 3:55 pm

Hello John,

With some delay..., I read, with great interest, your patent. I noted that more or less the principle is the same as the SEM-fusor:
* radial electromagnetic confinement,
* axial electrostatic confinement.
However, the trick is, rather to inject ions (as with the SEM-fusor) to ionize molecules with an energetic beam, so that the created ions are going to rotate, all passing (theoritically) regularly at their birth point (so along the beam axis), the Larmor radius depending on the initial radial speed, this to increase the probability of collision (fusion or not). As this radial speed is, a priori, slow, this Larmor radius with be very short (let's say less than one cm).

However as it is aimed to electricity production, I have several questions, as I'm not sure to understand all.

To get fusion interaction, particles need kinetic energy (ideally 80 KeV for D-T fuel and more for others fuels). Is this one given by the two electrodes, supposed at a big positive voltage (not indicated on the patent), the axial periodic movement of the ions being the source of kinetic energy?

What about:
* the elastic collisions with neutrals, which are going to rapidly absorb the ions kinetic energy,
* the coulombian collisions which are going to thermalize the ions energy,
* the space charge which is going to spread radially the ions?
This because the very most probable are non-fusion collisions and also because the cyclotronic rotation period of the ions is going to rapidly change due to these interactions.

About the fusions production and yield, I have a doubt because the ions density will be weak and so will be the fusion production, this with a yield surely close to the standard (i.e about 1E-6 to 1E-9).
Note I suppose that you are not in the case of a full plasma (i.e no neutrals as on tokamaks), but with only a very small percentage of ions in the plasma.
Have you tested or simulated (with a particles simulation) your idea?

Regards
Patrick Lindecker

John Fenley
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Re: Fusor without inner grid?

Post by John Fenley » Fri May 31, 2019 9:41 pm

Thank you for taking a look at my device, you seem to understand the idea very well.

First, I'm only focusing on a prototype for now to prove the design. The MRI machine I intend to use has a field strength of .35T, and uses permanent magnets.

Though the initial energy of ionization will provide only a very small orbit, my hope is that repeated pulses will add energy to the ions. As the energy increases, over 15kev the radius will grow to around 10cm. 40cm(allowing a diameter on each side of the focus) is well within the uniform field volume of the MRI machine.

For now, the overall ion density will be very low, and appear more like beam on beam fusion during collisions.

The hope is to start with very low density and convert all neutrals into orbiting ions. Collisions will be most likely at the focus. The energy distribution will be thermal, and random in direction, but sychronised. With very low density, I will ignore the space charge for now, as well as any self generated magnetic fields as they should not be significant.

I have done a couple of simulations that show regular motion, and instability at high density, but I was limited by the capabilities of the software I used.

https://youtu.be/NnbfgTP7v5M

https://youtu.be/RT6nvmN7GB0

The hope is that the long total confinement times possible in a penning trap, can be combined with high energies required for fusion, while avoiding ion drift by localizing the collision volume to the diameter of the electron beam... a beam which can be made extremely narrow.

Patrick Lindecker
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Re: Fusor without inner grid?

Post by Patrick Lindecker » Sat Jun 01, 2019 9:33 pm

Hello John,

Thanks for the information.

I agree that the diamagnetic field can be neglected, but the space charge is fondamental if your plasma is not neutral and I think it's the goal here to dissociate D2 molecules in ions.

The space charge is an expanding pressure which is in equilibrium with the radial electrostatic and, mainly, the magnetic pressure (the electrostatic one being much weaker than the magnetic one).

If the density is very low (as in a Penning trap), the space charge and the fusion energy will be very low also, but the confinement will be very good. If the density is high, the space charge will be high also, coullombian collisions between ions will be numerous, the orbits will not be circular nor regular and you will lose ions. Moreover, the focus will be broad.

Note: in your diagram the solenoids must normally be at a distance L <= to the radius R to have a quasi-homogenous field. If L/R>1 (as displayed), you have a system of magnetic mirrors, with a radial magnetic field component and the axial B field not homogeneous at all.

I hope you will success.

Patrick Lindecker

John Fenley
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Re: Fusor without inner grid?

Post by John Fenley » Tue Jun 11, 2019 7:44 am

The rings in the patent diagram are the positive electrodes that provide end containment (probably about +60kv). The magnetic field is uniform, and externally generated by placing the chamber in an MRI machine. The field in an MRI machine is about as homogeneous a magnetic field as humans have ever made.

There is a worry that high space charges can disrupt the coordinated motion resulting in a loss of focus or timing. It is currently the biggest unknown with this design.

I have a couple of ideas, but until I can better simulate it, or build one, there is really no way to know if it will be a problem or not, and if so, at what ion densities.

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