After a shutdown of nearly six months for upgrades, a powerful magnetic chamber on the campus of San Diego's General Atomics that is instrumental in the search to someday make nuclear fusion a practical source of energy is poised to restart operations.
The DIII-D National Fusion Facility at General Atomics fuses hydrogen atoms at extraordinarily high temperatures to recreate the power of the sun.
It's done in a magnetic chamber called a tokamak, a doughnut-shaped metal vacuum chamber surrounded by incredibly powerful magnets. Fuel consisting of hydrogen isotopes can be converted into plasma by heating the fuel to more than 180 million degrees Fahrenheit.
DIII-D, pronounced "dee-three-dee," is the largest tokamak in the United States.
"The sun is a hot ball of plasma," said Richard Buttery, director of DIII-D. "The sun holds itself together with gravity because it's got a lot of mass. We replace the mass with magnetic fields and we energize our coils, ramp it all up and we can contain the plasma."
Supported by the U.S. Department of Energy, DIII-D periodically undergoes a "vent" period for maintenance and upgrades. Work was paused in July 2021 but operations are scheduled to restart on Friday with two notable improvements.
One is the installation of a Toroidal Field Reversing Switch, which allows the redirection of 120,000 amps of current that power the primary magnetic field. The upgrade will allow researchers to switch directions of the magnetic fields within minutes instead of hours. No other tokamak has the capability to switch the direction of the magnetic field so quickly, General Atomics researchers say.
Another upgrade is a traveling-wave antenna that allows physicists to inject high-powered "helicon" radio waves into DIII-D plasmas so fusion reactions occur much more powerfully and efficiently.
"We've got new tools for flexibility and new tools to help us figure out how to make that fusion plasma just keep going," Buttery said. "We have all these eager scientists that are waiting to see how they can use all these upgrades and learn more about how to make fusion work."
Finding a way to harness fusion's vast potential has been a journey that has spanned decades.
Its promoters say the technological breakthrough needed to construct commercial fusion reactors would transform the energy sector by offering an almost infinite supply of power that emits no greenhouse gases.
Nuclear fusion is not to be confused with nuclear fission, the process used to generate electricity in nuclear power plants such as the now-shuttered San Onofre Nuclear Generating Station. Unlike fission reactors, fusion leaves behind no long-lived or highly dangerous radioactive waste.
But a long-running joke in the industry says commercial fusion is always 30 years away. Fusion technology developed the hydrogen bomb in the 1950s but as an energy source, fusion power has been generated only for short periods in the laboratory and no commercial reactors exist.
But with scientists and policymakers keen on finding carbon-free sources of power, fusion has garnered more attention.
The DIII-D facility has been instrumental in the design of ITER, a gigantic multinational fusion project under construction in France. ITER, pronounced "eater," will not produce a working power plant but the experiment is designed to show whether fusion technology can be commercially viable.
General Atomics is in the process of fabricating and shipping six modules that will be inserted into the heart of the ITER facility. Two of the modules that will make up what's called ITER's Central Solenoid — the world's most powerful magnet — have already been delivered to the project's site in southern France. A seventh module will also be shipped, acting as a spare.
"We're very confident (the ITER project is) going to work because it's a scaled up version of what we're doing here at DIII-D," Buttery said. "So we think its very much a doable reality."
Others have been much more skeptical.
ITER has been hampered by cost overruns and delays. The project's director-general, Bernard Bigot, said last fall the target for "first plasma" will not occur in 2025 as previously expected because of global disruptions due to the pandemic. Bigot expressed confidence the project's target to attain full fusion power project by 2035 can be met.
The latest price tag for ITER is $22 billion.
Some have complained that the money going to ITER will siphon funding for other clean energy projects, with a Green Party member of the European Parliament calling the project a "financial chasm" and a "scientific chimera." Others doubt whether the amount of power ITER expects to produce will be offset by the amount the project consumes.
Nonetheless, a number of private fusion companies are attracting big money from investors.
Commonwealth Fusion Systems, a spinoff of research done at MIT, has raised $4 billion since its founding in 2018. Last month it announced raising $1.8 billion, the largest funding round ever for a nuclear fusion company. Investors include Bill Gates and George Soros.
One month earlier, a fusion company near Seattle called Helion announced a funding round of $500 million.
In Foothill Ranch near Irvine, TAE Technologies is the world's largest private fusion energy company and last year the company touted producing stable plasma at more than 90 million degrees Fahrenheit in a compact reactor design.
This story originally appeared in San Diego Union-Tribune.
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