Nuclear fusion reactions in deuterated metals (theory)
Pines, Steinetz, Forsley et al.
Summary and citation · read the original at the source
In one page
This is the theory half of NASA Glenn's 2020 pair of fusion papers. Vladimir and Marianna Pines, with Arnon Chait, Bruce Steinetz, Lawrence Forsley and the Glenn team, ask what happens when deuterium fuel sits packed at high density inside a metal lattice and a small part of it is kicked into motion by fast neutrons. The lattice is not a passive container. Its conduction and shell electrons — plus the plasma a gamma beam stirs up — crowd in between two deuterium nuclei and screen their electric repulsion, so the Coulomb barrier the nuclei must tunnel through is lower than it is in free space. The paper works out how much lower, and shows that neutrons hand energy to deuterium nuclei far more efficiently than any charged particle can. Screening does something else as well: it makes hard, backward scattering more likely, which is the geometry tunnelling needs, and it opens a route to reactions with the lattice metal itself.
Why it matters hereChapter 12 rests on this paper. It is the mechanism that turns fusion from a confinement problem into a screening problem — the same move the thesis makes when it treats the Coulomb barrier as an adjustable quantity rather than a wall — and it is the theory NASA published alongside its own experimental detection of fusion inside a deuterated metal.
What it claims
01Deuterium fuel held at high density inside a metal lattice sits in an environment that screens the Coulomb barrier, because the lattice's conduction and shell electrons — or a plasma induced by gamma quanta — reduce the repulsion between reacting nuclei and so raise the probability of tunnelling.Abstract; Sections 3.1–3.4
Published and peer-reviewed02Neutrons are far more efficient than energetic charged particles — light particles such as electrons and positrons, or heavy ones such as protons, deuterons and alphas — at transferring kinetic energy to deuterium fuel nuclei to initiate fusion.Section 8, Summary of Results
Published and peer-reviewed03Electron screening significantly increases the probability of large-angle rather than small-angle Coulomb scattering between the reacting nuclei, which is an essential requirement for subsequent tunnelling and is carried into the astrophysical factor S(E).Sections 5.1–5.2; Section 8
Published and peer-reviewed04The screened Coulomb potential of the target ion is determined by the nonlinear Vlasov potential and not by the Debye potential, and the effect of screening becomes important at low projectile kinetic energy.Abstract; Section 3.2
Published and peer-reviewed05The familiar analytical and asymptotic expressions for the electron screening potential energy Ue hold only when the centre-of-mass energy is much larger than Ue; at or below Ue a direct calculation of the Gamow factor for the screened potential is required, or the enhancement factor comes out unreasonably high.Abstract; Section 3.1; Section 8
Published and peer-reviewed06Screening also raises the probability that hot fuel nuclei interact with the lattice metal nuclei, increasing the likelihood of Oppenheimer–Phillips processes and opening a potential route to reaction multiplication.Abstract; Section 4
What to watch
The way in
https://link.aps.org/doi/10.1103/PhysRevC.101.044609Published by the American Physical Society. NASA Glenn issued the same work as the public technical publication NASA/TP-20205001617, free to read at ntrs.nasa.gov.
How to cite it
Pines, Steinetz, Forsley et al. (2020) Nuclear fusion reactions in deuterated metals (theory). doi:10.1103/PhysRevC.101.044609
Where it sits in the curriculum