Lattice confinement fusion (LCF) is a type of nuclear fusion in which deuteron-saturated metals are exposed to gamma radiation or ion beams, such as in an IEC fusor, avoiding the confined high-temperature plasmas used in other methods of fusion.[1][2]
History
editIn 2020, a team of NASA researchers seeking a new energy source for deep-space exploration missions published the first paper describing a method for triggering nuclear fusion in the space between the atoms of a metal solid, an example of screened fusion.[3] The experiments did not produce self-sustaining reactions, and the electron source itself was energetically expensive.[1]
Technique
editThe reaction is fueled with deuterium, a widely available non-radioactive hydrogen isotope composed of one proton, one neutron, and one electron. The deuterium is confined in the space between the atoms of a metal solid such as erbium or titanium. Erbium can indefinitely maintain 1023 cm−3 deuterium atoms (deuterons) at room temperature. The deuteron-saturated metal forms an overall neutral plasma. [dubious – discuss] The electron density of the metal reduces the likelihood that two deuterium nuclei will repel each other as they get closer together.[1]
A dynamitron electron-beam accelerator generates an electron beam that hits a tantalum target and produces gamma rays, irradiating titanium deuteride or erbium deuteride. A gamma ray of about 2.2 megaelectron volts (MeV) strikes a deuteron and splits it into proton and neutron. The neutron collides with another deuteron. This second, energetic deuteron can experience screened fusion or a stripping reaction.[1]
Although the lattice is notionally at room temperature, LCF creates an energetic environment inside the lattice where individual atoms achieve fusion-level energies.[3] Heated regions are created at the micrometer scale.
Screened fusion
editThe energetic deuteron fuses with another deuteron, yielding either a 3helium nucleus and a neutron or a 3hydrogen nucleus and a proton. These fusion products may fuse with other deuterons, creating an alpha particle, or with another 3helium or 3hydrogen nucleus. Each releases energy, continuing the process.[1]
Stripping reaction
editIn a stripping reaction, the metal strips a neutron from accelerated deuteron and fuses it with the metal, yielding a different isotope of the metal.[1] If the produced metal isotope is radioactive, it may decay into another element, releasing energy in the form of ionizing radiation in the process.
Palladium-silver
editA related technique pumps deuterium gas through the wall of a palladium-silver alloy tubing. The palladium is electrolytically loaded with deuterium. In some experiments this produces fast neutrons that trigger further reactions.[1] Other experimenters (Fralick et al.) also made claims of anomalous heat produced by this system.
Comparison to other fusion techniques
editPyroelectric fusion has previously been observed in erbium hydrides. A high-energy beam of deuterium ions generated by pyroelectric crystals was directed at a stationary, room-temperature ErD2 or ErT2 target, and fusion was observed.[2]
In previous fusion research, such as inertial confinement fusion (ICF), fuel such as the rarer tritium is subjected to high pressure for a nano-second interval, triggering fusion. In magnetic confinement fusion (MCF), the fuel is heated in a plasma to temperatures much higher than those at the center of the Sun. In LCF, conditions sufficient for fusion are created in a metal lattice that is held at ambient temperature during exposure to high-energy photons.[3] ICF devices momentarily reach densities of 1026 cc−1, while MCF devices momentarily achieve 1014.
Lattice confinement fusion requires energetic deuterons and is therefore not cold fusion.[1]
See also
editReferences
edit- ^ a b c d e f g h Baramsai, Bayardadrakh; Benyo, Theresa; Forsley, Lawrence; Steinetz, Bruce (February 27, 2022). "NASA's New Shortcut to Fusion Power". IEEE Spectrum.
- ^ a b Steinetz, Bruce M.; Benyo, Theresa L.; Chait, Arnon; Hendricks, Robert C.; Forsley, Lawrence P.; Baramsai, Bayarbadrakh; Ugorowski, Philip B.; Becks, Michael D.; Pines, Vladimir; Pines, Marianna; Martin, Richard E.; Penney, Nicholas; Fralick, Gustave C.; Sandifer, Carl E. (April 20, 2020). "Novel nuclear reactions observed in bremsstrahlung-irradiated deuterated metals". Physical Review C. 101 (4): 044610. Bibcode:2020PhRvC.101d4610S. doi:10.1103/physrevc.101.044610. S2CID 219083603 – via APS.
- ^ a b c "Lattice Confinement Fusion". NASA Glenn Research Center. Retrieved March 1, 2022.
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