San Diego. The DIII-D National Fusion Program has completed a series of important enhancements to its fusion facility, providing researchers with several first-of-a-kind tools for controlling and understanding the function of fusion plasmas. These upgrades will further strength DIII-D’s standing as one of the most flexible and capable magnetic fusion research facilities in the world.
The new technologies installed during the 11-month upgrade will play a key role in developing the scientific basis for fusion as a reliable and nearly limitless energy source. When experiments restart in early June, researchers will converge on San Diego to use these tools to optimize the performance of fusion plasmas and help bring practical fusion energy closer to realization.
According to DIII-D Director David Hill, the new systems will enable unprecedented flexibility in developing solutions for future fusion reactors.
“These upgrades will provide researchers with several new capabilities, enabling them to explore physics phenomena that are important to making fusion viable,” Hill said. “Furthermore, the knowledge gained with these upgrades will inform experimental plans for the ITER project currently under construction in France, as well as the next steps for the U.S. fusion program.”
Operated by General Atomics (GA) in San Diego, DIII-D is a U.S. Department of Energy Office of Science user facility and a world-class fusion laboratory where 650 researchers from the U.S. and across the globe explore a wide range of topics from fundamental plasma science to fusion power plant operations.
At the heart of the facility is the DIII-D tokamak, a toroidal (doughnut-shaped) chamber surrounded by powerful electromagnets that confine plasmas – a state of matter with large quantities of ionized particles – at temperatures exceeding 10 times those of the Sun.
At these high temperatures, hydrogen isotopes fuse together and release energy.
The facility has been offline since May 2018 as a team of more than 100 engineers and technicians from GA and collaborating institutions worked to install new capabilities for driving current in the tokamak. Controlling how this current is distributed is a key tool for optimizing performance in fusion plasmas.
The largest upgrade project was the installation of a new steerable neutral beam system. Weighing more than 50 tons, it will allow researchers to vary the angle at which high-energy atoms are injected into the plasma for heating and control, enabling researchers to produce, study and exploit advanced physics important in making fusion reactors economical in the future.
The team also installed an innovative system that researchers expect will significantly reduce the amount of power required to drive electrical current in the plasma. This system is predicted to double the current-drive efficiency by injecting microwaves from the top of the tokamak, rather than from the side. Significant progress was also made toward installing a new, advanced antenna to launch ultra-high frequency “helicon” radio waves, which are more efficient and work over a wider range of plasma densities than earlier radio wave systems. Final installation of the helicon antenna is planned during the next opening of the tokamak this fall.
In other work, the team used a new 3-D laser scanning system to precisely align the upper divertor, which allows heat to dissipate prior to contacting the internal surfaces of the tokamak. This upgrade, in combination with newly installed measurement systems, will allow researchers to assess how the immense heat generated during plasma operation is best vented out of the tokamak.
The DIII-D Program has been the recipient of numerous scientific awards for pioneering research. For the upcoming experimental campaign, the program received over 500 proposals for experimental time, with many researchers planning to exploit the recently-installed upgrades.
“The new upgrades continue DIII-D’s rich history of providing innovative solutions to key issues in fusion development,” said Mickey Wade, deputy director for Magnetic Fusion Energy at GA. “It is my expectation that these upgrades will place DIII-D experimental time in high demand in the coming years, as researchers seek to capitalize on these new capabilities.”
