Fuel Gains Achieved for Nuclear Fusion
Many recognize nuclear fusion as the ultimate power source, as it could one day deliver prodigious amounts of power from relatively cheap hydrogen isotopes. While many facilities around the world have been working on a variety of fusion projects, none have yet achieved ignition, which is when more energy is released than was used to confine the fuel. Researchers at Lawrence Livermore National Laboratory using the National Ignition Facility (NIF) however have achieved 'fuel gains' for the first time, which is when more energy is released than was put into the fuel.
Instrumental in achieving this was triggering a bootstrapping with alpha particles. Alpha particles consist of two protons and two neutrons (a helium nucleus), and are released as a result of the fusion process. The bootstrapping process is when those particles deposit their energy back into the deuterium-tritium fuel, heating it further and increasing the rate of fusion, which then releases more alpha particles. The researchers also modified the laser pulse that compresses the fuel to prevent the breakup of the polymer shell around it, and help the bootstrapping occur. This led to more than an order of magnitude increase in performance.
Along with achieving fuel gains, the researchers also found that their results matched computer simulations better than ever before, which is very important for NIF. The primary purpose of NIF is to provide experimental insight for the Stockpile Stewardship Program, which works to keep the nation's nuclear weapon stockpile safe, secure, and reliable without directly testing them.