The DIII-D National Fusion Facility, operated by General Atomics for the U.S. Department of Energy, is a world-class laboratory that explores a wide range of topics from fundamental plasma science to how future fusion power plants will work. At the heart of the facility is the DIII-D tokamak, a toroidal (donut-shaped) chamber surrounded by powerful electromagnets that confine high-temperature plasmas. DIII-D is renowned for its operational flexibility, enabling cutting-edge research over a wide range of tokamak configurations. The DIII-D diagnostic set consists of more than 80 instruments capable of definitive measurements of parameters throughout the plasma.
DIII-D is the product of evolving fusion research at GA going back to the 1950s. Early tokamak designs, starting in the 1960s, were circular in cross-section, but GA scientists developed the “doublet,” a configuration with an elongated hourglass-shaped plasma cross-section. The Doublet I, II, and III tokamaks in the 1970s and 1980s showed that this approach allowed for a hotter and denser stable plasma. Further research led to a modification of Doublet III in the mid-1980s to DIII-D’s current D-shaped cross-section. Successes with this configuration inspired many other devices to adopt the D-shape, including JET (UK), TCV (Switzerland), ASDEX-U (Germany), JT-60U (Japan), KSTAR (Korea), and EAST (China).
With support from the DOE and substantial international collaboration, DIII-D has been conducting groundbreaking fusion research since the mid-1980s. DIII-D is a true user facility, with 106 participating institutions and a research team of more than 600 users. DIII-D’s success has had substantial influence on the design of ITER, an international project currently under construction in France with a goal of demonstrating high-power fusion operation, including key physics and operational issues. The DIII-D team maintains a comprehensive program of refurbishment, modernization, and system enhancements to keep its facility at the forefront of fusion science. This has made DIII-D one of the most productive tokamak facilities in the world.