NASA researchers have detected nuclear fusion in metal loaded with deuterium. A metal such as erbium is loaded with deuterium atoms (aka deuterons) packing the fuel a billion times denser than in magnetic confinement (tokamak) fusion reactors. In the new method, a neutron source accelerates (heats) deuterons until they start colliding with a neighboring deuteron. This causes D-D fusion reactions. The neutrons were created through photodissociation of deuterons via exposure to 2.9+MeV gamma (energetic X-ray) beam. Upon irradiation, some of the fuel deuterons dissociate resulting in both the needed energetic neutrons and protons. They measured nuclear fusion reactions and they saw the production of even more energetic neutrons which is evidence of boosted fusion reactions or screened Oppenheimer-Phillips (O-P) nuclear stripping reactions with the metal lattice atoms.
Either reaction could be scalable to useful levels of power. The goal will be to create power systems for long-duration space exploration missions or in-space propulsion. It could be developed into electrical power or creating medical isotopes for nuclear medicine.
The metal lattice, loaded with deuterium fuel, is at room temperature overall but the new method creates an energetic environment inside the lattice where individual atoms reach equivalent fusion-level kinetic energies.
Vladimir Pines, Marianna Pines, Arnon Chait, Bruce M. Steinetz, Lawrence P. Forsley, Robert C. Hendricks, Gustave C. Fralick, Theresa L. Benyo, Bayarbadrakh Baramsai, Philip B. Ugorowski, Michael D. Becks, Richard E. Martin, Nicholas Penney, and Carl E. Sandifer, II
Phys. Rev. C 101, 044609 – Published 20 April 2020
Nuclear fusion reactions of D-D are examined in an environment comprised of high density cold fuel embedded in metal lattices in which a small fuel portion is activated by hot neutrons. Such an environment provides for enhanced screening of the Coulomb barrier due to conduction and shell electrons of the metal lattice, or by plasma induced by ionizing radiation (γ quanta). We show that neutrons are far more efficient than energetic charged particles, such as light particles or heavy particles in transferring kinetic energy to fuel nuclei (D) to initiate fusion processes. It is well known that screening increases the probability of tunneling through the Coulomb barrier. Electron screening also significantly increases the probability of large vs small angle Coulomb scattering of the reacting nuclei to enable subsequent nuclear reactions via tunneling.
Aspects of screening effects to enable calculation of nuclear reaction rates are also evaluated, including Coulomb scattering and localized heating of the cold fuel, primary D-D reactions, and subsequent reactions with both the fuel and the lattice nuclei. The effect of screening for enhancement of the total nuclear reaction rate is a function of multiple parameters including fuel temperature and the relative scattering probability between the fuel and lattice metal nuclei. Screening also significantly increases the probability of interaction between hot fuel and lattice nuclei increasing the likelihood of Oppenheimer-Phillips processes opening a potential route to reaction multiplication. We demonstrate that the screened Coulomb potential of the target ion is determined by the nonlinear Vlasov potential and not by the Debye potential. In general, the effect of screening becomes important at low kinetic energy of the projectile.
d-D nuclear fusion events were observed in an electron-screened, deuterated metal lattice by reacting cold deuterons with hot deuterons produced by elastically scattered neutrons originating from bremsstrahlung photodissociation. Exposure of deuterated materials (Er D3 ad Ti D2) to photon energies in the range of 2.5–2.9 MeV resulted in photodissociation neutrons that were below 400 keV and also the 2.45-MeV neutrons consistent with 2H(d,n) 3 He fusion.
Additionally, neutron energies of approximately 4 and 5 MeV for TiD2 and ErD3 were measured, consistent with either boosted neutrons from kinetically heated deuterons or Oppenheimer-Phillips stripping reactions in the highly screened environment. Neutron spectroscopy was conducted using calibrated lead-shielded liquid (EJ-309) and plastic (stilbene) scintillator detectors. The data support the theoretical analysis in a companion paper, predicting fusion reactions and subsequent reactions in the highly screened environment.
SOURCES- NASA, Physical Review C
Written By Brian Wang, Nextbigfuture.com