Historical research guide · 0011 · 2022
A New Way of Triggering Nuclear Fusion
T Benyo · L Forsley · B Steinetz · B Baramsai
In one minute
Four NASA Glenn researchers — Theresa Benyo, Lawrence Forsley, Bruce Steinetz and Bayarbadrakh Baramsai — wrote this report for IEEE Spectrum to explain a way of doing fusion that needs neither the giant magnets of a tokamak nor the laser array of an inertial-confinement shot. The trick is the metal itself. Certain metals soak up hydrogen isotopes and hold them at about 10²³ deuterons per cubic centimetre — nine orders of magnitude denser than a magnetically confined plasma — while the metal’s own electrons screen the deuterons’ positive charge, so the nuclei can approach and tunnel through the Coulomb barrier that normally keeps them apart. The team lit the fire with a gamma beam: thumb-sized vials of titanium deuteride and erbium deuteride were irradiated with photons up to 2.9 MeV, knocking neutrons loose that kicked deuterons hard enough to fuse. Neutron spectroscopy caught the 2.45 MeV fusion signature plus higher peaks near 4 and 5 MeV. The underlying measurements were published in Physical Review C in 2020.
Connection
This is the peer-reviewed NASA result that chapter 12 rests on: a lattice lowers the effective Coulomb barrier locally, which turns fusion from a confinement problem into a materials problem. It is the first door in the thesis’s chain — change the local conditions a nucleus sits in, and the barrier moves.
From the source
Some metals hold hydrogen isotopes at about 10²³ ions per cubic centimetre at room temperature, roughly a billion times the density of a magnetically confined plasma, so the metal atoms themselves confine the fuel.Lattice Confinement Fusion
The lattice atoms’ electrons screen the positive charge of the deuterons, letting them approach closely enough to tunnel the Coulomb barrier; screening has been measured to raise fusion rates as if the deuterons carried an extra kiloelectron volt or more — the equivalent of 11 million degrees — while the metal stays cool.NASA Demonstrates Lattice Confinement Fusion
Fusion was triggered in ambient-temperature titanium deuteride and erbium deuteride by a bremsstrahlung photon beam of up to 2.9 MeV from a Dynamitron electron accelerator; turning the accelerator off safely stops the reactions.A Match to Light the Fusion Fire
Neutron spectroscopy shows the 2.45 MeV deuterium–deuterium fusion peak together with higher-energy peaks near 4 and 5 MeV, which the team attributes to boosted fusion or to screened Oppenheimer–Phillips stripping reactions in the highly screened lattice.Figure 3, NASA Demonstrates Lattice Confinement Fusion
The demonstrated reaction is externally driven and sub-critical; the team proposes isotopic neutron sources such as AmBe or ²⁵²Cf to start it, neutron reflectors to make it self-sustaining, and pairing fusion neutrons with fission fuel.The Path Forward
NASA presents lattice confinement fusion as a repeatable method of inducing fusion without magnetic fields or lasers; whether the reaction rates can be scaled far enough for clean nuclear power is the question the work leaves open.Conclusion
The way in
https://ntrs.nasa.gov/citations/20210025501How to cite it
T Benyo, L Forsley, B Steinetz, B Baramsai (2022) A New Way of Triggering Nuclear Fusion https://ntrs.nasa.gov/citations/20210025501