Historical research guide · 0015 · 2022
Electron Screened and Enhanced Nuclear Reactions
Lawrence P. Forsley · Louis F. DeChiaro
In one minute
Lawrence Forsley, deputy principal investigator of NASA's Lattice Confinement Fusion project, and Louis DeChiaro, a senior physicist at the Navy's Indian Head warfare centre, gave this talk at the ICCF-24 solid state energy summit in July 2022. Their subject is electron screening. Two nuclei normally repel each other electrically — the Coulomb barrier — but pack enough electrons around them and that repulsion is partly cancelled, so the nuclei fuse at far lower energies. Edwin Salpeter calculated the effect for stars in 1954; astrophysics and accelerator experiments have since confirmed it. Forsley and DeChiaro show the same physics is available on a bench, inside the conduction band of a metal, where the electron density passes 10²³ per cubic centimetre. NASA calculations put the gain in reaction rate at up to twenty orders of magnitude below 10 keV. They then model it from first principles with density functional theory, matching a measured 0.8 per cent shift in beryllium-7's half-life when the atom is caged inside a buckyball.
Connection
Chapter 12 rests on one idea — that a lattice can lower the effective Coulomb barrier so fusion no longer needs a star's pressure or a tokamak's temperature — and this talk is the mechanism behind it, presented by the NASA and Navy team building the hardware. It is also the bench-scale form of the thesis's central move in chapters 3 and 13: change the field around a nucleus and you change the forces it feels.
From the source
Electron screening reduces the Coulomb barrier between charged particles. Salpeter calculated the effect in 1954, and astrophysical observations and laboratory astrophysics experiments have confirmed it.Abstract; slide 3, Electron Screening
Fermi degenerate strong screening occurs where the electron density exceeds 10²³ electrons per cubic centimetre — the cores of gas giant planets, white dwarf stars, the conduction bands of metals, deuterated LENR materials, and inertial confinement fusion targets at maximum compression.Abstract; Conclusion
In a palladium lattice a screening potential of 310 to 1900 eV raises the deuterium-deuterium fusion cross-section by potentially twenty orders of magnitude, and the effect works below 10 keV of kinetic energy — it grows as the energy falls.Slide 4, Pd Lattice Screening Potential Calculation
A 0.8 per cent change in the half-life of beryllium-7 has been observed when the atom is placed inside a fullerene cage, interstitial palladium or a diamond anvil, and density functional theory reproduces it: a 0.1 per cent compression of the electron cloud gives more than ten times the electron density at the nucleus.Slides 8 and 13, ⁷Be model system and electron density within a Bohr radius
Density functional theory can model these effects well enough to design the lattice in advance — band structure, local electron density, inhomogeneous interfaces, external electromagnetic fields, alternative elements, alloys and superlattices.Slide 9, Ab-initio computational lattice design
Specific thermal power from primary deuterium-deuterium reactions alone is calculated at 0.2 watts per cubic centimetre, with subsequent cascading reactions expected to give a four- to fivefold increase — about 1000 thermal watts from 1000 cubic centimetres of material.Slide 6, Gain: enhanced cross-section vs thermal power
The way in
https://ntrs.nasa.gov/citations/20220010783How to cite it
Lawrence P. Forsley, Louis F. DeChiaro (2022) Electron Screened and Enhanced Nuclear Reactions https://ntrs.nasa.gov/citations/20220010783