Tuesday, October 19, 2021

Cold fusion

I remember reading a fax of a fax of Steven Jones' paper looking for excess neutron flux. It looked reasonable--when dissolved in palladium the effective density of deuterium is high enough (albeit still miniscule) that the nuclear wavefunctions can overlap to a degree that allows muons from cosmic rays to catalyze fusion. He found neutrons from that. The poor guy went kind of nuts as a 911-truther later. The Pons and Fleichmann razzle-dazzle overshadowed and unfairly tainted his work.

Can one do something similar deep inside the earth? Fukuhara et al say yes, one could fuse heavier nuclei than deuterium.

According to google the density near the core is only about 10g/cm^3, which is a bit over 3x the usual density for calcium carbonate. Why do I mention calcium carbonate?

This hypothesis suggests that heavier elements result from an endothermic nuclear transformation of carbon and oxygen nuclei confined in the aragonite CaCO3 lattice of the Earth’s mantle or crust, which is enhanced by the attraction caused by high temperatures ≥2510 K and pressures ≥58 GPa in the Earth’s interior

... 2(C) + 2 (O) + 4e∗ + 4𝑣̄𝑒 → 2(N2)↑ + (O2)↑+(H2O)↑ + 2n − 10.58MeV ...

The above-described reaction is favored by the physical catalysis exerted by excited electrons (e*) that were generated through stick-sliding during the evolution of supercontinents and mantle conversion triggered by collisions of major asteroid, and anti-electron neutrinos (𝑣̄𝑒) coming from the universe, epecially from the young sun, or by the radioactive decay of elements such as U and Th and nuclear fusion in the Earth's core that is described later.

(I adjusted their formula: Assume the standard O-16, C-12, and N-14.) Where do I start?

I suppose one starts by following their references in the hope that something might turn up. (What are "excited electrons?")

In it appears that he is talking about "electron capture." Amusingly enough, that's generally capture of inner orbital electrons, not the more likely to be excited outer ones. It also claims that the C-O bond distance in the lower mantle (0.085nm) would be about 35% smaller than at normal pressures, which makes sense, and is getting near what Jones got. But their density is a bit higher than I saw elsewhere.

There are, of course, almost no muons at that depth and what there are are highly interactive on their own account. So what does Fukuhara propose for the catalyst? Neutral pions, which result from photon interactions, and then interact with the electrons about to be captured. He says they observed fusion reactions in a liquid lithium cavitation experiment, but the abstract for that doesn't seem quite as compelling. Bombarding cavitating liquid lithium with deuterons is an interesting approach. But I don't see where they are supposed to get a significant density of deuterium inside the target for the d-d reactions. Hydrogen solubility is less than 2%, though maybe you'd get bubbles of D2 close to the beam spot if the beam is intense enough.

Anyway, back to the main subject. The rate seems mighty small. C + O + 2(e*) + 2(nu_e) → N + O + H + n - 5.29MeV(if I can dispose of the irrelevant chemical bits) still demands 2 neutrinos handy at the same time. They show up about 110/cm^3, so in a region .17nm on a side the rate for 1 at at time is quite low: 1.5E-21. Square that for 2 at a time. My atomic physics and nuclear physics are both a bit rusty, and I'm not sure I could come up with a good rate for electron capture in these circumstance.

The Earth is pretty big and has been around a while; even so I'm not sure the rate works for a significant amount of nuclear synthesis. And 5 MeV is a lot of energy to have around loose in chemical interactions, even at high pressures.

The first paper goes on to try to show that the internuclear distances are also small for Al, Si, etc in common rocks, but it also declines to estimate production rates.

My impression, based on the use of chemical equation balancing (bolded equation above) instead of the nuclear one (italics), and the use of the phrase "excited electrons", and the absence of overall rate estimates, is that the authors are somewhat outside their expertise, and maybe should have called in some help.


Deevs said...

My last comment got obliterated for some reason, so let's try again.

I took a class from Steve Jones about a year before he became persona non grata due to his 9/11 truther opinions. I remember he mentioned something about it once in class, but the significance didn't become apparent until the next year.

He was a great teacher, though, and I really enjoyed his class. Nice guy. I didn't learn he was also involved with the cold fusion brouhaha until years later.

james said...

Glad you had good experience with him. His cold fusion work looked perfectly reasonable. P&F's--not so much.