New Code Slashes Design Time for Fusion’s Complex Magnetic Puzzles todayheadline

A new computer code developed by Princeton physicists could dramatically accelerate the path to practical fusion energy by solving one of the field’s most persistent challenges: balancing ideal physics with what engineers can actually build.

The code, named QUADCOIL, can evaluate complex magnet designs in just 10 seconds – a task that typically takes traditional programs between 20 minutes and several hours. This efficiency breakthrough could make stellarators – a promising but notoriously complex type of fusion device – significantly more affordable to construct.

“QUADCOIL predicts the complexity of the magnets quickly, helping you avoid the plasma shapes that are great physics-wise but not helpful for actually building a fusion facility,” said Frank Fu, a graduate student in the Princeton Program in Plasma Physics at the Princeton Plasma Physics Laboratory (PPPL) and lead author of the paper describing the code.

The development comes at a critical time for fusion research, as scientists worldwide race to develop practical fusion energy systems that could eventually provide abundant, clean power without the radioactive waste associated with conventional nuclear fission.

The Stellarator Challenge

Stellarators represent one of the most promising approaches to fusion energy, but their complex, twisted magnetic field designs have historically made them expensive and difficult to build compared to their more symmetrical cousins, tokamaks.

Unlike traditional design approaches that treat plasma physics and engineering requirements separately, QUADCOIL integrates basic engineering considerations from the beginning of the design process.

Fu explained the concept with an analogy: “Think of two teams building a car engine: one that designs the engine and another that builds it. QUADCOIL, in a sense, moves one person from the build team to the design team to keep an eye on how the design might affect the final product. The estimate will be rougher than what you would get if you actually built the car and added up the expenses, but the process is faster and leads to specifications that are sensible.”

This research pairs PPPL’s expertise in sophisticated plasma computer codes with its extensive history of developing stellarators – a concept that the Lab originated 70 years ago.

Three Key Innovations

According to the research team, QUADCOIL offers three distinct advantages over existing methods: speed, additional predictive capabilities, and flexibility.

The code not only calculates magnet configurations dramatically faster than previous methods but also generates data about properties that other codes cannot, including the magnets’ curvature and how much magnetic force they experience.

“In short, QUADCOIL has three innovations: it calculates more quickly, predicts more properties than other codes can and is flexible,” Fu said.

The flexibility extends to allowing scientists to input various engineering specifications, generating magnet shapes more relevant to their particular needs. These specifications can include information about magnet materials and shapes.

Making Fusion More Affordable

The cost implications could be significant. By rapidly filtering out designs that would require prohibitively complex magnets, researchers can focus their efforts on configurations that maintain good plasma performance while being feasible to build.

“One of the major challenges in designing stellarators is that the magnets can have complex shapes that are hard to build,” said Elizabeth Paul, an assistant professor of applied physics and applied mathematics at Columbia University and one of the paper’s co-authors. “This problem tells us that we need to be thinking about magnet complexity at the very beginning. If we can use computer codes to find plasma shapes that both have the physics properties we want and can be formed using magnets with simple shapes, we can make fusion energy more cheaply.”

For fusion energy to become commercially viable, reducing construction costs while maintaining performance is essential – exactly the balance QUADCOIL is designed to achieve.

Looking Forward

Fu and his collaborators are already working on an enhanced version of QUADCOIL that will go beyond simply evaluating designs to actively suggesting improvements to plasma shapes.

While the current prototype runs on a standard laptop computer, the team anticipates that future versions will require more powerful hardware with advanced graphical processing units. Fu also plans to integrate QUADCOIL into larger software suites for comprehensive stellarator design.

“Developing a stellarator requires a lot of computation,” Fu said. “I’m trying to make the design process as smooth as possible.”

The research involved collaborators from multiple institutions, including Alan Kaptanoglu at New York University’s Courant Institute of Mathematical Sciences and Amitava Bhattacharjee, the former head of theory at PPPL. Financial support came from the Department of Energy’s Scientific Discovery through Advanced Computing program and the Simons Foundation.

As the quest for practical fusion energy continues, computational tools like QUADCOIL represent critical stepping stones toward making what was once considered a distant dream increasingly attainable. By bridging the gap between theoretical physics and practical engineering constraints, such innovations could help accelerate fusion’s journey from laboratory curiosity to commercial power source.