Fusion Research Ignites Innovation

Photo courtesy of Princeton Plasma Physics Laboratory

Princeton Plasma Physics Laboratory used the technology they developed to decommission the Tokamak Fusion Test Reactor to develop the Miniature Integrated Nuclear Detection System. The Tokamak Fusion Test Reactor, a former Office of Science user facility, ran for more than a decade before the lab decommissioned it in 1999.

If you're heating something to 100 million degrees — three times hotter than the core of the sun — oven mitts and aprons aren't going to cut it. But researchers investigating how to produce fusion energy tackle this challenge every day. Fusion involves combining nuclei from two atoms into one, resulting in a small amount of mass transforming into a staggering amount of energy. Getting that reaction started and containing it requires some of the most high-tech equipment in science.

While sustained fusion power is still years away, several technologies that scientists have developed to research it have already moved beyond the lab. From enabling smartphones to scanning for radioactive materials, technologies originally produced for fusion research supported by the Department of Energy's (DOE) Office of Science are keeping us safe, secure, and connected.

Enabling Improvements in Semiconductors

When manufacturers needed to make electronics increasingly smaller in the 1990s, turning to fusion researchers may not have been the first thing on their minds. To make electronics smaller, faster, and more powerful, they needed to make semiconductors much smaller as well. The grooves and lines in semiconductors and other components needed to be at the atomic level, more than 100 times smaller than a human hair.

But fusion researchers at DOE's Oak Ridge National Laboratory (ORNL) knew something industry didn't — how to control plasma. A separate state of matter from solids, liquids, or gases, plasma is a collection of particles with positive and negative electric charges. It occurs when high amounts of power run through a gas. As it's chemically very reactive, it interacts readily with almost anything you put it in contact with.

The semiconductor industry wanted to put materials into chambers filled with plasma and use the resulting chemical reactions to strip off or add atoms. In theory, this process would give them the level of control they needed to make miniscule grooves and lines.

Unfortunately, the companies had unpredictable results when they used radio frequency (RF) waves to create the plasma.

"Mother Nature was not kind. It turns out that there are very complex connections between different frequencies of voltages," said Mark Kushner, a University of Michigan professor and director of the DOE Plasma Science Center there.

Because testing the RF power levels by hand was too complex and time-consuming, they sought outside expertise.

Fortunately, ORNL scientists had been using RF waves to heat up fuel for fusion for more than a decade.

"The government's here to help you; they can actually help you!" laughed ORNL's Gary Bell, recalling how manufacturers felt. "We got a big kick out of that."

Partnering with a consortium of semiconductor manufacturers and suppliers, ORNL researchers evaluated a number of RF power delivery systems and controls. Using knowledge and tools from fusion research, ORNL scientists helped companies reposition components and reprogram controls. They also helped build testing equipment and developed technician training.

"A lot of expertise that came in was developed through magnetic fusion energy research, through the people and understanding of plasma science," said Amy Wendt, a professor at the University of Wisconsin-Madison and a member of DOE's Fusion Energy Sciences Advisory Committee.

Modifying how they produced semiconductors allowed manufacturers to fit more components onto computer chips than ever before. Those improvements and others using plasma made it possible for companies to build smaller, lighter, more efficient cell phones, tablets, and computers.

Launching Jets From Aircraft Carriers

While smartphone components are some of our smallest technologies, fusion research has also set the stage for improving some of the world's biggest ones: aircraft carriers.

In the 1990s, the Department of Defense (DOD) realized that they could do better than the steam and hydraulic-powered catapults on aircraft carriers in use at the time. So they released a request for proposals for a technology that could store a huge amount of energy and release it almost instantaneously — over and over again.

Researchers at the DIII-D National Fusion Facility, an Office of Science user facility run by General Atomics (GA), were familiar with those challenges. In fact, they had to solve a similar problem back in 1978 before they could get a new iteration of their reactor up and running.

"GA is in a unique position to drive technology innovations, given its long history of using scientific research results to develop cross-cutting practical applications," said John Rawls, chief scientist at GA.

To control the 100-million-degree plasma inside of it, the DIII-D reactor produces huge magnetic fields. The machine creates and maintains these fields by running tremendous amounts of energy through giant magnets. When GA scientists designed the machine with funding from the Office of Science's predecessor in the 1970s, they developed the controls and inverters to release and control those bursts of energy.

Based on that expertise and existing technology, DOD chose GA to develop the Electromagnetic Aircraft Launch System (EMALS). This system speeds an aircraft down the deck of a carrier using a linear induction motor coupled to the same type of inverters that provided such precise electrical and magnetic control at DIII-D. The performance of the induction motor can be finely controlled to deliver the precise amount of acceleration and velocity necessary to launch an aircraft of a specific size and weight. Because it's much more precise than previous systems, EMALS minimizes the physical stress put on the aircraft, increasing their lifespans, and reducing costs.

Today, the U.S. Navy is using EMALS on the USS Gerald R. Ford (CVN 78). It is also installing EMALS on all future Ford-class aircraft carriers.

"We were able to advance numerous first-of-kind technologies, including the creation of the world's most powerful linear motor and new inverter drives, to produce an integrated EMALS system that has a smaller footprint, greater efficiency, and requires less manning and maintenance to help save costs and improve reliability," said Scott Forney, president of General Atomics Electromagnetic Systems. "To top it off, we offer a flexible design that has the potential for installation on other platforms requiring different catapult configurations and aircraft support."

Developing New Materials for Extreme Conditions

Fusion reactions create some of the most high-stress environments in the universe. The materials used in reactors must withstand staggeringly high pressures, temperatures, and radiation.

"We're taking materials outside their usual comfort zone," said Steven Zinkle, a University of Tennessee professor with a joint appointment at ORNL.

The plasma bombarding a fusion reactor's walls can remove and re-deposit a single atom a billion times a year. Through it all, the walls need to stay tough, maintain stability, and absorb as little radiation as possible in a very stressful environment for building materials.

"If you're going to make a fusion reactor work, it's all about the materials," said Bell.

To build a better reactor, ORNL researchers helped develop a new type of stainless steel that could resist temperatures up to 1560 degrees F.

It turns out that fusion researchers weren't the only ones who needed steel that could withstand extremely high temperatures. Because advanced diesel engines run hotter than conventional ones, they needed advanced materials to match. ORNL's materials group realized that this new steel could meet that challenge. After the Office of Science's fusion group completed the basic research, DOE's Vehicle Technologies Office took it over, supporting an agreement between ORNL and equipment manufacturer Caterpillar to adapt the material for vehicles. In 2007, Caterpillar started using it in all of their heavy-duty highway truck engines. Since then, the material has generated millions of dollars of revenue.

Even the best steel isn't tough enough for fusion reactors' inner walls. To provide further protection, ORNL developed radiation-tolerant silicon carbide ceramic composites. These composites can survive temperatures of up to 2700 degrees F.

Recognizing the potential of this material, NASA and other agencies supported further design and processing research on these composites. In rocket nozzles, thrusters, gas turbines, and even conventional nuclear reactors, this material can now simplify components and increase efficiency.

While laboratories often develop these innovative materials, they also provide equipment and expertise that enable private companies to do so as well. Using tools developed for fusion research at DOE's Princeton Plasma Physics Laboratory (PPPL), Lenore Rasmussen found a way to use plasma to improve the attachment of her Synthetic Muscle™ technology to metal electrodes. She also used the laboratory's resources to test the material's resistance to extreme temperatures and radiation. Since then, NASA has tested how well the material resists radiation on the International Space Station. Rasmussen is now working to commercialize the technology. In the future, companies may use it in prosthetic limbs and robotics.

Detecting Radioactive Materials for Security

Building a fusion reactor is hard enough. Retiring it can be even tougher. Charles Gentile and his colleagues at PPPL faced this dilemma in 1999. They needed to decommission the lab's Tokamak Fusion Test Reactor that had been running for more than a decade.

Staff first needed to identify radioactive elements in the vacuum vessel, the container that housed the fusion reactions. So they created a portable detection unit to collect data, as well as software to process that data. After they finished disassembling the reactor, the technology sat on the shelf.

But in 2001, they saw the opportunity for their invention to have a second life. The federal government had put out a call for technologies that could have applications in homeland security. The team determined that their device had the potential to accurately identify in real time radionuclides that might be used in "dirty" bombs. With a $400,000 grant from the U.S. Army, PPPL staff adapted their technology. They revised it so it could run in any weather, be used by non-nuclear scientists, and detect a wider array of radioactive substances.

Now, the Miniature Integrated Nuclear Detection System is a combination hardware and software system that's the size of a thermos. In one second, it can sense one-billionth of the material needed to build a credible dirty bomb. It can scan moving vehicles, luggage, packages, and cargo for more than 20 different types of radioactive substances. So far, security firms have used it at a major bus and commuter rail center as well as major U.S. ports.

As fusion technology advances, the work that goes into it will continue to yield unexpected benefits.

As Gentile said, "It's nice that we do have these technologies that come out of the laboratory that can help people in other areas."

The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information please visit https://science.energy.gov.

Shannon Brescher Shea is a senior writer/editor in the Office of Science, [email protected].