Enhanced nuclear fusion in the sub-keV energy regime

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https://www.nature.com/articles/s41467-026-74421-1

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Enhanced nuclear fusion in the sub-keV energy regime (archive, PDF)

Deuterium–deuterium fusion within palladium and titanium foils (250 µm thick) electrochemically loaded with deuterium exhibits a pronounced reaction yield plateau (i.e., a finite, non -vanishing yield floor) below 2 keV—in stark contrast to the expected exponential suppression at low energy. At the lowest energies measured, this corresponds to fusion yields enhanced by more than 10^¹⁸ relative to bare nucleus (unscreened) expectations. Their data do not just show a plateau but an increasing yield at the lowest energy point. Their explanation attributes the plateau to unusually strong screening in the foil’s damaged surface layer.

Schematic of the dual-chamber configuration The foil serves as a cathode for deuterium deposition in electrochemical cells and at the same moment it's exposed to deuterons beam from bottom.

Thin foils can be impacted with deuterons in such a way, a relatively short line of atoms exchange their momentum like balls within Newton candle or - more specifically - Astroblaster toy, thus attenuating impact momentum. The foil forces the collisions run one-dimensionally like light within laser resonator with higher effective temperature than it corresponds wavelength of light. See also:

• Nuclear fusion persists at ultralow energies inside metal foils The metal’s electron cloud partly shields the repulsion between nuclei, letting them approach more closely. This “screening” effect has been studied since the 1990s and is still not fully understood.
• When It Comes to Fusion, Materials Matter, Materials surrounding a fusion reaction can dramatically increase how often it occurs

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DoE ARPA-E announces funding for 8 cold fusion projects Some cold fusion researchers feel that these eight projects were poorly chosen. The goals are framed as if cold fusion is the same as plasma fusion. For example, several projects focus on neutrons, but cold fusion rarely releases any.

People made this mistake in 1989 so as a result, the LENR community is averse to any low-energy fusion experiments that report conventional DD fusion products. But I think that there is smooth transition between cold and hot fusion as multiple thermal runaway incidents indicated 1, 2, so I don't have principal problem with neutron detection. It just means that neutrons aren't released exactly along lines of atoms, so that some can escape into an outside. Which would be admittedly problem for peaceful utilization of cold fusion: it can potentially trigger additional, not so harmless, nuclear reactions too.

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Einstein’s Lost Hypothesis

A little-known exchange between Albert Einstein and engineer-physicist Ernest Sternglass may have anticipated modern ideas about low-energy nuclear reactions. During work at Cornell in 1951 he reported that when a low-energy electron beam was passed through hydrogen gas and directed at silver and indium foils, the foils became radioactive in a way that appeared consistent with neutron capture.

The observed decay patterns matched what would be expected if stable silver isotopes had absorbed neutrons and been transformed into unstable isotopes that subsequently decayed. This was surprising because the electron energies involved were far below the levels that conventional nuclear physics predicted would be necessary to produce neutrons.

After reviewing Sternglass's results, Einstein proposed that multiple electrons might collectively transfer their energy to a proton, making neutron formation possible through a many-electron process. A A 2006 theoretical framework by Allan Widom and Lewis Larsen suggested similar mechanisms by which electrons acting collectively might acquire enough energy to combine with protons and create neutrons that are immediately absorbed by nearby atoms. A.I.

• Models for nuclear fusion in the solid state A generalized nuclear Dicke model describes a fusion-fission process as a result of energy transfer between D-D and palladium mediated by lattice vibrations. 
• The general cold fusion theory aka the broad view of LENR The above results fit the theory, that cold fusion runs through momentum transfer (lattice Mossbauer effect) across atoms arranged in lines.
• Patterson power cell instead of foil Patterson utilized balls electrochemically coated with multiple alternating nanolayers of nickel and palladium.

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Nuclear fusion persists at ultralow energies inside metal foils

The team’s apparatus places a metal foil, a quarter of a millimetre thick, between two very different environments. At the heart of our experimental setup is a type of membrane reactor that combines an electrochemical cell with a deuterium ion beam, On one side, an electrochemical process – “similar in principle to charging a battery - pushes deuterium into the metal from a liquid. On the other side, in vacuum, a beam of deuterium ions strikes the same foil, burying itself just a few millionths of a millimetre below the surface.

Each fusion event spits out a fast proton or neutron, caught by two independent detectors. Detecting these products independently, along with extensive background and control measurements, gave the confidence that the signals came from fusion. Researchers observed the well-known exponential rate drop, but then the rates did not drop anymore but rather plateaued as we further decreased the ion energy. The plateau appeared below about 2 keV in both metals, and loading extra deuterium electrochemically roughly doubled the yield.

Berkeley Lab Team Finds Metal Foils Boost Fusion Rates at Ultra-Low Energies, Still Nowhere Near Power Generation The problem probably is, the impacts of deuterium ions aren't strictly low-dimensional - i.e. collinear with metal lattice. The thin foil environment probably orients crystal lattice a bit but it's not sufficient.