ITER construction site
A super-wide-angle view shows the fusion reactor under construction in France. (ITER Photo)

The world’s biggest and most expensive nuclear fusion research project, known as ITER, says it’s halfway done with the construction effort leading to the startup of its seven-story-high reactor in 2025.

ITER’s ambition to demonstrate a sustained fusion reaction that produces a net gain in energy is matched by the estimated cost, which exceeds $20 billion.

The 35-nation consortium began construction a decade ago, under an unusual arrangement that calls for the various countries to contribute components for the reactor taking shape at Cadarache in southern France. The United States is responsible for 9 percent of the total cost.

“ITER” originally stood for International Thermonuclear Experimental Reactor, but now project leaders prefer to characterize the name as a Latin word meaning “The Way” — that is, the way to the world’s energy future.

Today, ITER Director-General Bernard Bigot declared that the construction work has passed the halfway point on the timeline leading to “first plasma,” when deuterium and tritium are to be heated to high temperature in the reactor’s giant tokamak chamber.

During a visit to Washington, D.C., Bigot expressed concern that the United States was cutting back on its budgeted contributions to ITER. He noted that the amount went from a planned $105 million in 2017 to $50 million, and that the budget for 2018 anticipated a cut from $120 million to $63 million.

“If the U.S. does not provide the necessary funds in 2018, then there will be an impact on the entire project,” he told Reuters.

Bigot said the Trump administration was reconsidering the funding issue, with a decision coming as early as this week.

Fusion is the reaction that powers the sun, involving the combination of hydrogen nuclei under conditions of high pressure and high temperature. When the nuclei combine, that creates one helium nucleus and converts a smidgen of extra mass directly into energy.

ITER is pursuing a path to fusion power that’s relatively low-risk but high-cost, known as magnetic confinement fusion. Atoms of deuterium and tritium, two isotopes of hydrogen, will be heated into a plasma while being squeezed by super-strong magnetic fields in a doughnut-shaped chamber.

“First plasma” is scheduled for 2025, but ITER says it could take 10 more years to reach full-power operation. Even then, the reactor isn’t likely to produce power for commercial use. Instead, the insights gained during ITER’s experiments are expected to help engineers design and build commercially viable fusion power plants.

In parallel with ITER, several privately funded ventures are pursuing lower-cost, higher-risk avenues to controlled fusion, with a potentially quicker reward (or failure).

A Canadian company called General Fusion has won backing from Amazon billionaire Jeff Bezos. California-based TAE Technologies, meanwhile, counts Microsoft co-founder Paul Allen as an investor. Another fusion company, Helion Energy, is headquartered in Redmond, Wash., and has attracted funding from PayPal co-founder Peter Thiel.

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