Fusor Master's Thesis

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Joe Gayo
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Fusor Master's Thesis

Post by Joe Gayo » Thu Jan 31, 2019 5:34 am


Joe Gayo
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Re: Fusor Master's Thesis

Post by Joe Gayo » Thu Jan 31, 2019 5:43 am

Charge exchange cross section data:

Charge Exchange Mean Free Path of Deuterium Ion and Background \ Hydrogen Gas, Data from Nuclear Fusion 10 (1970) p147

I extracted the points from the above article and used Mathematica for a non-linear curve fit -

Code: Select all

modelsol[x_] := Exp[-35.26659743591572/x^0.12476964001522374]/x^3.645879839797641;
x is ion energy in KeV and modelsol is cross section cm^2/N

Rex Allers
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Re: Fusor Master's Thesis

Post by Rex Allers » Thu Jan 31, 2019 8:38 am

Slight warning for those downloading the pure.tue.nl pdf, it's 38MB in size.

Joe, great to meet you this evening. Hope you continue to stimulate us with well thought out concepts and testing.

Per my mention of difficulties finding stuff with search engines these days,
I looked for "Charge Exchange Mean Free Path..." that was your data source and found nothing matching from any way I searched on a few engines. Wondering where you got access to it?

On your curve fit equation, do you think we can trust the accuracy with only 16 decimal digits in the coefficients? :-)
Rex Allers

Joe Gayo
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Re: Fusor Master's Thesis

Post by Joe Gayo » Thu Jan 31, 2019 3:20 pm

I really enjoyed our conversation as well.

Here is the link to the second paper:

https://escholarship.org/uc/item/6gr94826

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Rich Feldman
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Re: Fusor Master's Thesis

Post by Rich Feldman » Thu Jan 31, 2019 5:41 pm

For those not downloading the paper, Joe explained charge exchange over the table last night. If I got this straight:

Consider an accelerated deuterium ion traveling in rarefied mostly-neutral gas.
Joe's reading points to surprisingly large cross section at, say, 5 keV for a charge exchange (electron shell reaction) that neutralizes the original moving particle and ionizes the original stationary particle. I don't know if this is for atoms or molecular D2, before or after. :-)
He concluded that the Mean Free Path for that is pretty small for fusor dimensions and conditions.

Is that sort of right, Joe?

p.s. Doesn't "charge exchange collision" also sort of apply to the multiplication in a GM tube or proportional counter, unlike in a PMT ?
Mike echo oscar whisky! I repeat! Mike echo oscar whisky, how do you copy? Over.

Joe Gayo
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Re: Fusor Master's Thesis

Post by Joe Gayo » Thu Jan 31, 2019 6:12 pm

Correct. The average ion energy is greatly reduced by charge exchange (CX) and it’s correlated by the forums wall loading observations. The glow discharge fusor is dominated by fast neutral fusion and the charge exchange mean free path basically eliminates ion recirculation.

Lower pressure limits density in glow discharge approaches which is why ion guns are superior. However I’m pursuing another approach... size. Building a device that is smaller than the CX MFP at glow pressures. Point of clarification: I use standard KF40 flange interfaces in my device but the chamber is machined from a block of aluminum. The internal volume is smaller than CF2.75 or KF40.

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Richard Hull
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Re: Fusor Master's Thesis

Post by Richard Hull » Thu Jan 31, 2019 6:51 pm

I believe in past posts over the many years, re-circulation was found not to supply any significant fusion possibilities. An ancient paper from U of W did an experiment that proved the bulk of fusion is done by fast neutrals. (2000 time frame).

The wall deuterium lattice storage over time seen for the past 7 or 8 years is also a factor in maxing out fusion in any size fusor in daialy operation.

Finally, over the past 3 or 4 years we have seen tremendous gains in fusor devices of rather incredibly small size. This was not by design or any theoretical considerations, but due to sheer poverty of some would be fusioneers who could not afford bigger and more fancy chambers! These small 2.75 crosses and tees have allowed for lowered MFP, higher pressure deuterium operation and a far more efficient chamber wall storage result.

All of the above has been done by actual experiment.

Joe has voiced all of this nicely and attempting to give the past results a sound footing in theory.

I liken all of this discovery to the "lucky donkey effect" that I have spoken off so often in these forums..... Becquerel and Roentgen were lucky donkeys by the sheer "doing" and following a totally different path to work towards a completely different goal. They stumbled over science that would require years of careful theorizing to explain in a cohesive manner.

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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