The new Pegasus III fusion platform at the University of Wisconsin-Madison is now operational after years of work with tens of thousands of components.
Researchers at the University of Wisconsin-Madison have begun experiments that will advance the field of fusion energy.
A platform dedicated to the study of innovative techniques
The new Pegasus III facility is supported by the U.S. Department of Energy’s Office of Fusion Energy Science and provides a national platform to research innovative techniques for starting a plasma, the ultra-hot ionized gas that releases energy into a fusion reactor.
The ultimate goal of this research is to advance plasma science and understanding of fusion energy to help reduce the cost and complexity of future fusion energy systems, which could potentially provide an abundant source of energy. Clean energy by harnessing the process that powers our sun.
“Essentially, we are working on developing an innovative spark plug to ignite the fusion fire in future fusion energy systems,” explains Stephanie Diem, assistant professor in the Department of Nuclear Engineering and Engineering Physics, who leads Pegasus-III.
Three startup methods are considered
The Pegasus III platform consists of a compact donut-shaped magnetic bottle, called spherical tokamak, to contain plasmas at very high temperatures. Almost all tokamaks in the world rely on the magnetic induction of a central magnet, called a solenoid, to drive the current that creates and heats a plasma.
However, eliminating the need for a central magnet in a tokamak would greatly simplify the design and reduce the cost of these devices, thereby increasing their suitability for commercial power generation. That’s why UW-Madison researchers are using Pegasus-III to study several solenoid-less launch techniques, including local helicity injection, coaxial helicity injection and radio frequency waves.
“We are in a unique environment at UW-Madison where we can study all three of these methods in one device,” says Stephanie Diem. “We can not only test each technique individually, but also examine whether one technique can improve another. Additionally, we can manipulate the machine to design arbitrary experiments to test different theories, and this also provides a great hands-on learning opportunity for our students.”
Photo caption: Assistant Professor Stephanie Diem (left) discusses Pegasus III fusion research with graduate students Louise Ferris, Carolyn Schaefer and Tim Tierney. Photo credit: Joel Hallberg.
Towards models for larger devices
As they learn more about the fundamental plasma physics of these launch techniques, researchers will develop models for scaling to larger fusion devices.
Professor Diem says building Pegasus-III was a massive undertaking and a true team effort. “All that remains from the previous phase of the installation is the container and some solenoids,” she says. “We built completely new power supplies and a new, stronger toroidal magnetic field to confine the plasma, so it is a completely new facility.”
A challenge that was overcome despite the pandemic
The construction project began in 2020 with the onset of the COVID-19 pandemic, which brought additional challenges. Stephanie Diem attributes the project’s success to the flexibility, hard work and commitment of the research team.
“We have a great, very supportive research team and everyone has done an incredible job with the work they have put in,” says the researcher. “It wasn’t easy building a new facility and dealing with supply chain issues during a pandemic. That’s why I’m really proud of the entire team and very excited about working on Pegasus-III.”
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The new Pegasus III fusion platform at the University of Wisconsin-Madison marks a significant advance in fusion energy research. Built over several years, this unique facility will allow the study of innovative techniques for starting and heating plasma, with the aim of making future fusion reactors simpler and cheaper.
In particular, the researchers can test three promising starting methods without a central magnet. Their insights into the fundamental physics of plasmas are used to develop models for larger devices.
For better understanding
What is the goal of Pegasus-III?
The aim is to investigate innovative techniques for starting and heating plasma in fusion reactors in order to reduce the complexity and cost of future fusion energy systems.
Why is this experience unique?
Pegasus-III is the only facility in the world to test three promising plasma starting methods without a central solenoid valve on the same device.
Findings in plasma physics are used to develop models for designing larger and more efficient fusion reactors.
What challenges did the team overcome?
The construction work took place during the Covid-19 pandemic and required adjustments. The team demonstrated flexibility and perseverance.
Photo Caption: UW-Madison researchers are using the new Pegasus III platform to study innovative plasma launch techniques. Photo credit: Joel Hallberg.
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