Tuesday, March 07, 2023

Cold fusion

Some years ago I read an overview of cold fusion research. It gave the history and the various experiments current and completed. Some were variations on the "try to dissolve deuterium in palladium", while others used different metals--in one case powdered nickel. That wanted high temperature, with a small amount of heat released--which would result in a quite inefficient heat engine. (The survey was pre-Rossi and his infamous E-CAT.)

I wanted to see what more recent work said, and began poking around. After a while I noticed that I'd have to write a brand new survey myself to cover the material, and I think I'll leave that to experienced nuclear physicists.

There's not a lot of evidence for the $d + d \rightarrow He^{*}$ reaction. The Navy funded $d + Li$ research, but I didn't find any results published. (Why $Li$? Because it was present as a hydride to introduce the $d$ in some of the experiments.)

Some fancy schemes have been invoked--to try to see if the effective electron mass could be increased so you could get something akin to muon-catalyzed fusion. Atomic physicists have looked at how much hydrogen actually dissolves deep into the metal and how much is superficial, and into ways of loading more hydrogen in, and so on. I wondered if $d + Pd^{n} \rightarrow p + Pd^{n+1}$ would work, but that would probably produce $\gamma$'s also (2?) from excited $Pd$--not detected, and anyhow the potential barrier is higher than for $d + d$.

Doing the experiments right is hard, and some give tantalizing results. Some see neutrons--at energies that don't make a lot of sense, except that: well, it turns out that when you dissolve hydrogen in palladium, certain preparations are susceptible to cracking. Cracking can produce microscopic local high voltages, and those can accelerate $d^{+}$ to high enough energies to dissociate the deuterium on collision and release neutrons. Not many, but detectable. Who'd have guessed? FWIW, one survey article (on the positive side) claimed that the non-cracking preparations of palladium were the ones that provided anomalous energy.

I don't believe in cornucopias, but you can get room temperature fusion with $\mu^{-}$ particles, and I won't swear there aren't other ways. I'm not convinced any of these other things are the hoped-for fusions, but there are certainly some odd things going on. And, I'm afraid, there's some carelessness, and dishonesty (Rossi).

UPDATE: Remember that lightning can produce antimatter.

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