An article recently published on the IEEE Energywise blog heralds “Spacecraft of the Future,” which could be powered by lattice confinement fusion. While lattice confinement fusion is not a new concept and is definitely not ready for practical applications, it has been detected within metal samples by NASA researchers at the Glenn Research Center in Cleveland, Ohio, using an electron accelerator–driven experimental process.
Latticework: The “lattice” in lattice confinement fusion refers to the structure of the atoms in a solid metal sample. The NASA group used samples of erbium and titanium for their research, which was recently published in Physical Review C and described in a news brief. Under high pressure and ambient temperature, a sample is loaded with deuterium gas—an isotope of hydrogen with one proton and one neutron—at densities approaching 1023 ions/cm3. The positively charged deuterium nuclei, or deuterons, serve as a fuel and are held in place, surrounded by negatively charged electrons of the metallic lattice.
The process: According to NASA, once the samples have been prepared, an electron accelerator and nearby tungsten target generate a high-energy photon beam that is focused and directed into the deuteron-loaded sample. When a photon hits a deuteron within the metal, the deuteron splits into an energetic proton and neutron. That energetic neutron can then collide with another deuteron, accelerating it.
After multiple interactions, a deuteron can have enough energy to collide with a stationary deuteron, overcoming the electrostatic repulsion between the two positively charged deuterons and allowing them to fuse and release energy. Alternatively, a proton or neutron from an accelerated deuteron can be captured by an atom of the metal lattice, in what is known as an Oppenheimer-Phillips reaction, resulting in a different element or isotope. Both the fusion reactions and Oppenheimer-Phillips reactions can generate usable energy.
Potential applications: While emphasizing that current power levels cannot be used for practical applications, the researchers believe that, with more development, future applications could include power systems for long-duration space exploration missions or in-space propulsion, as well as terrestrial power generation or radioisotope production.
Want more? Visit the website of NASA’s Glenn Research Center for more about the recent research into lattice confinement fusion, including a short, informative video and full-text papers explaining the experiment (“Novel Nuclear Reactions Observed in Bremsstrahlung-Irradiated Deuterated Metals”) and the theory behind the experiment (“Nuclear Fusion Reactions in Deuterated Metals”).