DIII-D is the largest magnetic-fusion facility in the US and is used by more than 700 researchers at 100 institutions worldwide. The DIII-D tokamak is a donut-shaped vacuum chamber that is surrounded by electromagnets that confine a plasma at a temperatures exceeding 10 times that of the Sun, enough to fuse hydrogen to produce energy.

Since July 2023, engineers and technicians have installed new systems to better control the fusion plasma. This includes a range of new diagnostic instruments as well as enhancements to the way that the plasma is heated.

Another change is to the tokamak's divertor system, which removes exhaust heat and impurities from the tokamak. Engineers have installed a new configuration called a "shape and volume rise" divertor, which consists of a series of modular divertor configurations that the DIII-D will now test when experiments start up later this month.

The new divertor will allow plasma shapes to be studied that are expected to produce high fusion power performance but were not possible with DIII-D's previous divertor geometry.

Work on the upgraded facility is also expected to support experiments that will be performed at the ITER experimental fusion reactor, which is currently being built in Cadarache, France.

"The upgrades provide us with exciting new capabilities and key enhancements," notes DIII-D director Richard Buttery. "Our scientists will be able to use our upgraded systems and diagnostics to answer key questions on commercial industry-relevant technology, materials, and operations".