Climate and energy representatives from national laboratories, universities, government and industry joined a 2022 White House summit devoted to garnering support for fusion energy. The event, “Developing a Bold Decadal Vision for Commercial Fusion Energy,” marked the first step in a Biden-Harris initiative to accelerate commercial fusion, a clean energy technology that uses the same fusion reactions that powers the sun and stars.

The DOE used the gathering to emphasize its support for the development of fusion energy. U.S. Secretary of Energy Jennifer Granholm announced a plan to provide up to $50 million to support U.S. scientists conducting experimental research in fusion energy science.

“To get to commercial fusion, we have a lot to do, but we have the tools to do it,” said  Steve Cowley, director of PPPL. “We understand how to make a plasma at 100 million degrees and how to hold it, and that is an intellectual triumph that will drive us through to commercial fusion,” he said.

“What a thrill to be here when the U.S. is launching a push to make the first fusion electricity,” Cowley said after the summit. “That’s what we came to this field for, and that’s what we‘re going to deliver.”

Private industry panelists were optimistic about the government’s expression of support for fusion energy. “The government investment and the government publicity will act as a magnetic force throughout the world,” said Andrew Holland, chief executive officer of the Fusion Industry Association. 

In closing remarks, Geraldine Richmond, DOE undersecretary for science and innovation, said the fusion energy effort in the DOE will be agency wide. Strong backers will include the Office of Science, the Advanced Research Projects Agency-Energy, the National Nuclear Security Administration, and the Office of Nuclear Energy. “We will continue to rely on the top minds at the DOE laboratories for ideas,” she said. “DOE will help clear the path toward commercialization whatever way we can.”

The U.S. fusion community has recently urged an immediate effort to design and construct a cost-effective pilot plant to generate electricity in the 2040s. Unique capabilities of the PPPL tokamak, the National Spherical Torus Experiment-Upgrade (NSTX-U) that is currently under repair, have made its design a candidate for that role. “It’s all about trying to project whether this route is favorable for a cost-effective pilot plant and beyond,” said principal physicist Walter Guttenfelder, lead author of a paper in the journal Nuclear Fusion that details the latest findings.

Fusion produces vast energy by combining light elements such as hydrogen in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei, or ions. Plasma composes 99% of the visible universe and fuels fusion reactions that produce heat and light that create and sustain life on Earth.

The spherically shaped NSTX-U produces high-pressure plasmas required for fusion reactions in a relatively compact and cost-effective configuration. Operating capabilities of the facility are greatly enhanced over its pre-upgraded predecessor. “The primary motivation for NSTX-U is to push up to even higher powers, higher magnetic fields supporting high-temperature plasmas to see if previously observed favorable trends continue,” Guttenfelder said.

Considerable progress has been made in understanding and projecting how NSTX-U can advance the development of fusion energy, according to the Nuclear Fusion paper. “The next step,” said Guttenfelder, “is to see if new experiments validate what we’re predicting, and to refine the predictions if not. These steps together will enable more confident projections for future devices.”

Mention fusion energy and people will think of the breakthroughs happening at PPPL in fusing or combining the nuclei of hydrogen isotopes. But there are other kinds of fusion power, including one long shot that just got a big boost from the Department of Energy’s Advanced Research Projects Agency-Energy.

This audacious project is investigating the “holy grail” of clean fusion energy, said Nat Fisch , a professor of astrophysical sciences at Princeton University and the principal investigator of the new project. Unlike the deuterium-tritium (DT) fusion pursued for decades, he and his team want to exploit the fusion reaction of a proton with a boron-11 ion (pB11).

“Of course, the easiest fusion reaction by far is DT,” said Fisch, who is also the director of the Program in Plasma Physics at the University and the associate director for academic affairs at PPPL. “It is difficult enough, but still the most sensible approach to pursue, and I was taught in graduate school that the pB11 reaction cannot be practical. Yet, pB11 is the holy grail of really clean, really abundant fusion energy.”

The Princeton project, “Economical Proton-Boron11 Fusion,” is not just a variant on DT fusion, but employs an entirely different fusion reaction. Both types of reactions release enormous energy, but the pB11 reaction requires a far higher temperature than the DT reaction. “Hence, the pB11 reaction has been discounted as a real possibility for economical fusion power,” Fisch said.

However, the pB11 reaction is tantalizing, he said. Reasons include the fact that both protons and boron-11 are readily available, naturally and cheaply. Both are non-radioactive, whereas the tritium in DT fuel is and must be carefully contained. Also, the pB11 reaction produces no radioactivity-producing neutrons, which the DT fuel does.

“Our ideas on this are a real long shot,” Fisch said. “But I figure we have an obligation to fully explore the upside potential of pB11 fusion. Our proposal is purely theoretical, so it does not require the large resources associated with experiments. However, should our ideas work out, perhaps unlikely but fantastic if they do, we will need partners to help us navigate the key uncertainties experimentally.”

The DOE awarded PPPL more than $12 million to conduct experimental research into fusion energy science. This funding will help accelerate development of a pilot plant powered by the carbon-free fusion energy that drives the sun and stars and can counter climate change.

The three-year PPPL awards — with several more pending — cover research to speed the development of both doughnut-shaped tokamak fusion facilities and compact spherical tokamaks akin to the flagship National Spherical Tokamak Experiment-Upgrade (NSTX-U) at PPPL.

Fusion combines light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei, or ions, that makes up 99% of the visible universe — to release vast amounts of energy. PPPL and scientists around the world are seeking to reproduce and control fusion on Earth for a virtually inexhaustible supply of safe and clean power to generate electricity.

The PPPL awards are part of the $47 million of DOE funding to speed closing the remaining science and technology gaps prior to the construction of a power plant to produce net electricity from fusion at low capital cost. The largest share of the PPPL awards will fund exploring spherical tokamak physics on the SMART Facility under construction in Spain.

This award totals $5.1 million for work led by physicist Mario Podestà to explore the dependence of good plasma confinement on innovative plasma shapes in SMART. Researchers will compare their results to the confinement-dependence on larger tokamaks.

This collaboration is particularly timely given the growing number of public and private fusion programs focusing on the spherical configuration and is part of a broader set of collaborations between PPPL and other spherical tokamaks.

“This work should increase the flexibility of spherical tokamak operations,” Podestà said. “It will broaden the range of options for long-term use as a pilot plant.”

The U.S. fusion community has actively called for an immediate design effort for a cost-effective pilot plant to generate electricity in the 2040s. This effort and related community recommendations are documented in the 2020 report “Powering the Future: Fusion & Plasmas" of the Fusion Energy Sciences Advisory Committee.

Jon Menard, deputy director for research at PPPL, has led a study of the scientific and engineering challenges that a pilot plant will face. The study also defines performance requirements for a complementary facility the community is proposing to close key gaps to a pilot plant.

This facility, to be called the “EXhaust and Confinement Integration Tokamak Experiment (EXCITE),” would address challenges of integrating the pilot plant core and the edge exhaust region — a major issue. The proposed pilot plant must deliver heat from the high-density plasma core to the exhaust region at the tokamak’s edge.

“In a high-power compact pilot plant, this heat would be significant, and we want to make sure we understand how to handle it properly,” Menard said.

Also to be developed in the compact pilot plant is integrating a largely self-driven plasma current with a high-density plasma core. Today’s tokamaks use a central magnet called a “solenoid” to produce the current, which creates a magnetic field to bottle up the plasma so that fusion reactions can take place. However, there would be less room for a solenoid in the compact pilot plant the community envisions, producing the need for an internally generated plasma current.

The design and construction of the EXCITE facility would not necessarily delay the arrival of the pilot plant so long as both facilities are sufficiently flexible. “These facilities should not be completely serial but should be overlapping and their roles should be well-defined,” Menard said. “The smaller tokamak could be used to test ideas faster and more cheaply without dealing with the nuclear environment that the pilot plant would focus on.”

Meanwhile, the U.S. fusion community seeks to pursue innovative ways to refine the design and key features of the proposed pilot plant that would generate low capital-cost electricity in the 2040s — a demanding task that calls for resolving major gaps in the projected fusion facility. “The next step is to confront all the challenges that the pilot plant will face,” Menard said.

Essential new details about devices that use lasers to produce fusion energy have been uncovered by researchers at PPPL. The new data could lead to better designs of future laser facilities.

Major experimental facilities include tokamaks, the magnetic fusion devices that PPPL studies; stellarators, the magnetic fusion machines that PPPL also studies and have recently become more widespread; and laser devices in what are called inertial confinement experiments that these findings could improve.

The researchers explored the impact of adding tungsten metal, which is used to make cutting tools and lamp filaments, to the outer layer of plasma fuel pellets in inertial confinement research. They found that tungsten helps block heat that would prematurely raise the temperature at the center of the pellet and confirmed the results with measurements.

Researchers at PPPL have found a way to build strong, powerful magnets that aid the design and construction of fusion facilities. The magnets could help the world harness fusion to generate electricity without producing greenhouse gases that contribute to climate change.

The scientists found a way to build high-temperature superconducting magnets from material that conducts electricity with little or no resistance at higher temperatures than previous magnets Such magnets would comfortably fit within the tight space inside spherical tokamaks, which are shaped more like a cored apple than the doughnut-like shape of conventional tokamaks.

Since the magnets could be positioned apart from other machinery in the spherical tokamak’s central cavity to confine the million-degree plasma that fuels fusion reactions, researchers could repair them without having to take anything else apart. “To do this, you need a magnet with a stronger magnetic field and a smaller size than current magnets,” said Yuhu Zhai, a principal engineer at PPPL and lead author of a paper reporting the results in IEEE Transactions on Applied Superconductivity. 

High-temperature superconducting magnets have several advantages. They can be turned on for longer periods than copper magnets since they don’t heat up as quickly. This will suit them better in future fusion plants that run for months at a time. And the wire in such magnets is able to transmit the same amount of electrical current while producing a stronger magnetic field than a copper wire many times wider.

The magnets could also help scientists continue to shrink the size of tokamaks, improving performance and reducing construction cost. “Tokamaks are sensitive to the conditions in their central regions, including the size of the central magnet, or solenoid, the shielding, and the vacuum vessel,” said Jon Menard, PPPL’s deputy director for research. “A lot depends on the center. So if you can shrink things in the middle, you can shrink the whole machine and reduce cost while, in theory, improving performance.”

PPPL and Laboratory Director Steve Cowley were featured on the July 23, 2022, “CBS Saturday Morning” show in a segment titled “Inside an Experimental Fusion Energy Laboratory.” The segment is available to view on the CBS News site.

In the segment, CBS News correspondent Jeff Glor takes a tour of PPPL and visits the National Spherical Torus Experiment-Upgrade (NSTX-U) control room and test cell. “Progress is being made,” Glor said at the start of the program. “To get a closer look, we traveled to Princeton, New Jersey, to see what life is like at 200 million degrees.”

“I was delighted to see PPPL highlighted in the CBS program and even happier that the program focused on the great potential of fusion energy as a game-changing source of electricity that does not produce carbon and will be clean, green and affordable,” Cowley said.

Fusion is the perfect energy source, Cowley told Glor, and noted that the National Academies of Science recently called for a move to fusion energy by 2035.

Fusion energy is the process that powers the sun, which is made of the plasma that fuels fusion reactions in laboratory experiments, Cowley said. “Hope is closer to reality when you take a look at a tokamak,” Glor said.

Glor and Cowley viewed a video of an NSTX-U plasma. “And the goal is to have that sustained for hours?” Glor asked. “Hours, days, months, years,” Cowley replied. Fusion energy would make steam that generates electricity for the national power grid, Glor explained.

Cowley pointed out that fusion energy is safe and there are no meltdowns or explosions if the process fails. Fusion energy can be used in combination with other renewable energy sources such as wind and solar, he said. “The obvious advantage of fusion is that you don’t need sun or wind to get the job done,” Glor responded.

“What we really need to do is drive the innovation — it’s ideas,” Cowley said. “Bright scientists coming into the field and solving the remaining problems. I think we can do fusion. Our big challenge at the moment is to do it at a cost that the consumer wants to pay for electricity.”

Research by PPPL scientists has played a supporting role in a major advance in the production of fusion power at the Joint European Torus (JET) in the U.K. In the new breakthrough by the EUROfusion consortium that contributes to JET, the largest and most powerful tokamak fusion facility in current use created its highest ever production of experimental fusion energy.

That energy totaled 59 megajoules for five seconds, a fusion power output that averaged 11.8 million watts. That output was more than two-and-a-half times the record JET achieved in 1997.

Studies conducted ahead of JET’s five-month experimental campaign last year with high-power deuterium-tritium (D-T) fuel included those delivered by PPPL. “We provided and operated a diagnostic to measure the loss of energetic ions,” said Mario Podestà, the PPPL physicist who led the work. “Such ions produce fusion reactions and provide heat to the plasma, and understanding why they are lost is the first step to improving their confinement.”

The results proved essential. “The collaboration between PPPL and JET has been very important in order to study and characterize fast ions losses before the campaign,” said Jeronimo Garcia, the JET Task Force leader responsible for the collaboration between JET and PPPL. “I am convinced that the diagnostic managed by PPPL will provide key physics about energetic particles in D-T.”

PPPL’s now-dismantled Tokamak Fusion Test Reactor (TFTR) became a pioneer user of D-T in 1991 and set a then-record for producing fusion power in 1992. JET also began its D-T use in 1991 and set the previous record in 1997.  

The British tokamak has long been a testbed for ITER, which applauded the new results. “A sustained pulse of deuterium-tritium fusion at this power level — nearly industrial scale — delivers a resounding confirmation to all of those involved in the global fusion quest,” said the late Bernard Bigot, who passed away last year as ITER Director-General.  “For the ITER project, the JET results are a strong confidence builder that we are on the right track as we move forward toward demonstrating full fusion power.”