A Thought Experiment on Ideal Conditions

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
S Silvawalker
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Re: A Thought Experiment on Ideal Conditions

Post by S Silvawalker » Mon Aug 03, 2020 3:27 pm


John Futter
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Re: A Thought Experiment on Ideal Conditions

Post by John Futter » Mon Aug 03, 2020 7:19 pm

Storm
I have taken time to look through your document
several things you need to improve on
1`./ vacuum your test rig has many leaks --this from the plasma pics you are at torr not millitorr. you need a good pirani gauge
2./ reusing electron optics means you have to use them at the design voltage and vacuum for crts around 2 x 10-8 torr and if a colour set of size 32" then about 36kV to run the optics
3./ I work in an ion beam lab and we go to a lot of trouble to remove electrons from our systems so that they do not neutralize any of our ions --we cannot steer or manipulate neutrals magnetically or electrostatically
4./ you need to get a copy of Simion to help with your design verification before you expend a great deal of time and money going down a dead end

S Silvawalker
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Re: A Thought Experiment on Ideal Conditions

Post by S Silvawalker » Mon Aug 03, 2020 7:32 pm

Screenshot_20200803-152227_Gallery.jpg
Screenshot_20200803-152227_Gallery.jpg (80.95 KiB) Viewed 468 times
I am using a very different setup to my one in 2018 and I now have a pressure in the 1 to 100 micron range. I modified the original circuitry of the sets to get the required voltages and filament currents. I have yet to run any simulations as I wanted to know I could fabricate my device before pushing the theory further since my university is unlikely to help and most of my work will be self funded.

Since I'm doing something I have found no evidence of anyone trying before even if i don't find what I'm looking for here this device will likely have more value as a pathfinder for my future builds.

S Silvawalker
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Re: A Thought Experiment on Ideal Conditions

Post by S Silvawalker » Mon Aug 03, 2020 7:40 pm

Re ionization seems to be caused by beam collisions in an EBIT so I wonder if that would solve the problem of neutral atom formation when combined with the accelerating potential? I will try to make simulations but that will be later on

Patrick Lindecker
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Re: A Thought Experiment on Ideal Conditions

Post by Patrick Lindecker » Mon Aug 03, 2020 8:36 pm

Hello,

Thanks for the interesting document. I looked at your main diagram and I hope that I undestood the principle.

It seems possible to create an electrons cloud in the A zone but at a price of an enormous electrons injection power.
Each electron is injected with a yield of 0.5 for a good ion gun (kinetic energy/electrical energy). The electron kinetic energy is completly lost by colliding the electrode 9 (kinetic energy -> mechanical and radiation energy). As you proposed a direct electrostatic conversion would be possible but it is complex and the yield (electrical energy/kinetic energy) is not equal to 1 (rather 0.6).

The confinement time of an electron in the cloud is extremely small, just the time to cross the A zone (several ns). The potential created in the A zone will be extremely low (mV or microV ?) except by using very powerful ion guns (but the final yield of this apparatus will be, at best, the same as the fusor one, about 1E-9). Note that the goal would be to have a potential of at least -35 kV.

In my opinion, the diagram misses only a way to confine electrons in the A zone during, let's say, 1 sec. In that case, the neutral pressure will have to be extremely low (<1 microPa) to avoid to lose electrons energy in collisions with neutrals.

Patrick Lindecker

S Silvawalker
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Re: A Thought Experiment on Ideal Conditions

Post by S Silvawalker » Mon Aug 03, 2020 9:12 pm

My idea is to not try and confine the electrons at all rather they never lose enough energy to recombine with the ions. Think of an electron beam ion trap but with 3 or 4 beams instead of 1. The key is that the electrons don't have to be lost and in a final system the losses can be minimized from the electron beams by slowing and recollecting the electrons after they pass the centre. It is based on the idea that in an idea world a particle accelerator with no collisions would only have to impart 1MeV to each ion to give the highest probability of fusion which could release more.

If any one point along the beam of electrons is treated as a point charge, equivalent to the number of electrons in that cross section of the beam, then the charges and masses of the infalling particles, assuming the electrons are fixed and solve for the required distance for the ions to gain 1 MeV. Assuming a beam current of 1 micro amp and only deuterons being accelerated the acceleration distAnce needed is 8 ish mm which fits my chamber. The remaining problem is finding a high enough accelerating voltage for the electrons such that they aren't scattered significantly by the infalling ions or other electron beams.

Patrick Lindecker
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Re: A Thought Experiment on Ideal Conditions

Post by Patrick Lindecker » Tue Aug 04, 2020 8:54 am

Thanks for the explanations.

>in a final system the losses can be minimized from the electron beams by slowing and recollecting the electrons after they pass the centre.
However, due to successive yields, you will recover perhaps 1/3 of the primary energy as a maximum. It seems difficult to do better.

OK to accelerate ions with electrons, via Coulomb collisions between ions and electrons. Of course, you know that energy transfer coefficient between a light particle (electron) and a heavy particle (D+) is low (a mean value of 2*me /mD+, so about 0.00054), with a big scattering angle for the electron an a very small one for the D+ ion.

However why not... Good testing.

Patrick Lindecker

John Futter
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Re: A Thought Experiment on Ideal Conditions

Post by John Futter » Tue Aug 04, 2020 9:55 am

Storm your new plasma pic still is about the 100's of microns
do not forget that mean free path at 1 micron is only 5cm and an electron hitting an air molecule is immediately going to disappear at some weird angle with out doing very much to the air molecule as pointed out by Patrick
As pointed out before Simion ( or Comsol multiphysics) does also allow electron trajectories and intereactions your University will /should have this program (ours do).

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Dennis P Brown
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Re: A Thought Experiment on Ideal Conditions

Post by Dennis P Brown » Tue Aug 04, 2020 10:45 am

Don't get discouraged - all new ideas run into problems and people here are trying to both help you understand issues with your ideas/approach and trying to help you correct possible short commings in your system. But new ideas that push at extremel parameters often require both good setups and more theoretical understanding.

To get realistic free paths for ions and electrons, both a very high quality vacuum system and a diffusion pumps w/cold trap or a turbo is absoultely required (generally, 10^-6 torr is a good bench mark.) There is no way around that issue. You simply can't accelerate electrons to high energy without a very good/high vacuum.

To accelerate electrons to 1 MeV requires that voltage! As pointed out, very little of that electron energy will be coupled to ions due to the mass difference and low propablity for a direct strike - you can't change physics. So to get a significant current at 1 MeV even for just the average fusor, would require a significant output of a power plant. That is an easy calculation and you really need to look at that - remember, current is everything when it comes to fusors and even then all you get is their trivial fusion rate.

S Silvawalker
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Re: A Thought Experiment on Ideal Conditions

Post by S Silvawalker » Tue Aug 04, 2020 7:30 pm

The necessary energy for the electrons in the beams and therefore the needed accelerating potential is still an unknown. The 1MeV stated was the approximate per ion energy to maximize their cross section for fusion in the case of deuterium and tritium and did not refer to the electrons. The image is from a run using some old oil I'm doing a series of oil changes and pump tests to get the pressure down. I will be back at my university after January so until then I only have so much time and space to work with and within so I am only going to be using a mechanical pump, which is rated to reach 0.75 microns although it is quite old. There won't be much scientific rigor to these tests but if I get any neutron detection then i will be confident it moving to the next build.

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