The Mirror Fusion Test Facility

A decade-long effort to build a machine to unlock the promise of nuclear fusion fell victim to budget constraints and competing science, and was shut down the day it was dedicated. It was never turned on.

Photos: Lawrence Livermore National Laboratory.

On Friday, February 21, 1986 a group of 300 scientists, engineers, contractors and government officials gathered for a dedication ceremony at Lawrence Livermore National Laboratory. After final diagnostic tests, the "Mirror Fusion Test Facility-B" (MFTF-B) completion was celebrated, and a letter from John Herrington, Ronald Regan's Secretary of Energy was presented to program director T. Kenneth Fowler extending his congratulations on a job well done.

On the very same day after nearly a decade of development and nearly a billion dollars* of funding, the project was shut down, the massive machine having never been turned on.

"I want all of you to know how much I regret the fact that, just as you complete this remarkable new facility, the budget pressures dictate that we must put it into standby and not operate it as you might have hoped. This is frustrating, and perhaps not the best use of our national talent and resources, but we must bring the deficit under control," wrote Herrington in the letter to Fowler.

Photos of the 400-ton "yin-yang" magnet mirrors used in the MFTF-B. Source: Lawrence Livermore National Laboratory. Photo 1, Photo 2. 

I came across photos from the construction of the components of the MFTF-B on Lawrence Livermore National Laboratory’s website and was captivated by a photo from 1980 showing a strange twisting mass of metal that at the time was the largest superconducting magnet in the world.

This 350 ton magnet was encased in stainless steel built in a distinct “yin-yang” shape, and its interior was cooled to temperatures of 425º F below zero, by pumping liquid helium through the vessel. Thirty miles of copper and niobium-titanium wire were wound over the course of a year to make the magnet’s conductor. The magnet was capable of generating magnetic fields 150,000 times that of Earth’s that could contain the 500-million Kelvin degree plasma generated by the fusion device.

A photo of the MFTF-B under construction in 1978. Source: LLNL

The Race for Fusion

“According to Greek mythology, fusion energy, the fire of the Sun is a gift hard won”, goes the first line of the T. Kenneth Fowler’s 1997 book, “The Fusion Quest”. Fowler continued, “Today, irresistibly drawn to the challenge of bringing fusion energy down to Earth from the stars, scientists tempt Zeus still.” The promise of mastering this elemental force is a clean, safe and near limitless energy source, which could literally save the planet.

While the more widely known process of nuclear fission has been producing energy at commercial scale in power plants since the 1950’s, harnessing nuclear fusion – which Fowler’s poetic description accurately captures as the same reaction taking place in the heart of the Sun – has been the subject of an international race for decades.

Only in December of 2022 did scientists at the National Ignition Facility at the Lawrence Livermore National Laboratory announce that they had achieved the first recorded fusion reaction with a net energy gain – meaning that it released more energy than was put in, which was a crucial milestone for the whole field, though it could be decades before this is put into practical use.

The energy crisis of the 1970s motivated the U.S. government to throw lots of money at alternative energy sources, and fusion was one of the big areas of interest.

According to the Department of Energy, the basic principle of nuclear fusion is the fusion of two lighter nuclei (such as the commonly used combo of deuterium and tritium) to form a heavier one (helium) which releases energy (and subatomic particles, such as neutrons). To do this, super-hot plasma is created in a vacuum to create the fusion reaction, and either lasers or powerful magnets are used to control and contain the plasma.

During this period of frenzied investment in the 70’s, two major directions for fusion research emerged: the torus or donut shaped “Tokamak” design utilized by Princeton Plasma Physics Laboratory, and MFTF-B's “magnetic mirror” based approach, with a linear vessel housing the superheated plasma bouncing the plasma off two opposing magnetic “mirrors” at either end of the chamber.

1975 photo of the Princeton Large Torus at the Princeton Plasma Physics Laboratory, which is an example of a "tokamak" fusion reactor design. Source: Princeton Plasma Physics Laboratory, Public domain, via Wikimedia Commons

Research at Lawrence Livermore National Laboratory developing the mirror based approach showed promise in smaller scale tests, which led to the decision to go all in on a large scale device. The fact that other major labs were going all in on the tokamak approach, left an opening for hedging the big fusion bet on this potential alternate path. The question of whether there was enough sound evidence to ramp up to the scale of the MFTF-B was subject to debate at the time, and the final decision seemed to partly come down to ideology and gut instinct.

In a really thorough 1987 Science magazine story on the MFTF-B Edwin Kintner, who was the associate director of the Department of Energy’s Office of Energy Research at the time said as much. Looking back on the decision to go all in on the MFTF-B, Kintner is quoted as saying “Everybody was concentrating on tokamaks. I thought it was necessary for these tokamak guys to have to look over their shoulders.”

In the same article, MFTF-B program director Fowler is quoted as saying, “You could debate the decision, but it wasn’t illogical. Building big machines is a mixture of lead times, resources, prudence and gambling.”

Below: "Mirror Fusion Test Facility magnet system— Final design report. Sept. 3, 1980. Source: Lawrence Livermore National Laboratory."

"Just-completed and never-used"

The Reagan administration’s decision to mothball the machine came as a gut punch to the researchers. Lawmakers tried to fight for extra funds to throw a lifeline to the program or to salvage parts of the project to perform some science in a more limited scope. The money and time spent on the project was weighing heavy in the comments recorded in hearings held by the House Subcommittee on Energy Research and Production in February of 1986.  

Congressman Fortney ("Pete") Stark of California made a particularly impassioned plea to extend the life of the project. Citing the Reagan Administration's proposed budget, Stark wrote "This proposal would mothball the just-completed and never-used Mirror Fusion Test Facility-B (MFTF-B) at the Lawrence Livermore National Laboratory." Stark continued, "A lot of hard work and money has been invested in the world's largest superconducting, tandem mirror fusion experiment. For close to 8 years some of the finest scientists and engineers in America have dedicated their time and energy to the project. $350 million dollars have been invested in MFTF-B."

The MFTF-B under construction in 1983. Source: Lawrence Livermore National Laboratories.

Stark included some of the photos of the facility for the record, showing its impressive scale. "As you see the facility is truly an incredible accomplishment. Even to those who have not had years of scientific training, the enormous complexity of the project can be appreciated. Please let me repeat: 8 years of dedicated manpower and $350 million dollars have been pumped into the MFTF-B."

In the years following the shutdown of the program, parts of the machine were scavenged for other projects, and the rest was scrapped in 1998. Building 431 at Lawrence Livermore National Laboratory sat empty for a number years and was eventually demolished around 2005 after determining that the site did not meet the threshold of historical significance to be protected on the National Register of Historic Places.

The installation of a magnet into the MFTF-B in 1981. Source: LLNL

Recent breakthroughs reignite hopes for fusion

With the recent news of Lawrence Livermore National Laboratory's National Ignition Facility achieving the first net energy gain nuclear fusion reaction, the outlook for prioritizing fusion research looks bright.

Having achieved "ignition" for the first time on December 5, 2022 by creating a reaction where more energy is released than consumed, it turns out a third approach was the key to success: containing the plasma within high powered lasers. In fact, the successful ignition employed another huge, expensive machine – this one equipped with 192 massive lasers all focused on a tiny pellet, pounding it with 2 million joules of energy, creating a fusion reaction that only lasted for 100 trillionths of a second.

"Crossing this threshold is the vision that has driven 60 years of dedicated pursuit — a continual process of learning, building, expanding knowledge and capability, and then finding ways to overcome the new challenges that emerged. These are the problems that the U.S. national laboratories were created to solve.”

Another huge, expensive fusion machine. But this one worked. The target chamber of the National Ignition Facility at Lawrence Livermore National Labs (LLNL). Source: LLNL 

* In 1986, the total cost of the project was described in Congressional testimony as costing $350 million, which would equal $965.4 million according to the BLS.