WHAM breaks magnetic field record in breakthrough nuclear fusion experiment

Researchers involved in the Wisconsin HTS Asymmetric Mirror (WHAM) experiment have taken a significant step towards making clean, carbon-free fusion power a reality.

The WHAM team, led by University of Wisconsin-Madison physics professor Cary Forest, generated plasma using the strongest steady magnetic field ever applied in such a device.

On July 15, 2024, the team formed and held a plasma with a magnetic field strength of 17 Tesla using high-temperature superconductor (HTS) magnets. This magnetic field strength is more than twice as powerful as those used in high-resolution MRI scanners, setting a new world record for magnetically confined plasmas.

“First plasma is a crucial first step for us in that direction,” Forest explained, emphasizing the significance of the development toward achieving viable fusion energy.

The team’s achievement is the result of a four-year collaboration involving Realta Fusion, a UW-Madison spinoff, MIT, and Commonwealth Fusion Systems (CFS), with support from the US Department of Energy.

Revitalizing the magnetic mirror

The magnetic mirror concept, a method to confine charged particles, was a leading fusion energy approach in the US until the 1980s, when limitations in existing technology hindered the ability to control magnetically confined plasma.

Magnetic mirrors create a “magnetic bottle” to trap energetic plasma. The WHAM experiment revitalized this concept thanks to advances in superconductor technology, especially the development of HTS magnets.

The WHAM device employs two powerful magnets at either end of a cylindrical chamber. These magnets compress the plasma and cause hydrogen ions to bounce back and forth, increasing the likelihood of fusion reactions occurring as the ions collide.

“It’s setting a world record in magnetic field strength for magnetically confined plasmas and is equipped with intense heating systems while still being a hands-on experiment for both graduate and undergraduate students,” said Realta Fusion’s co-founder and UW-Madison scientist Dr. Jay Anderson.

Driving innovation

The success of WHAM could pave the way for more compact and potentially lower-cost fusion systems. The experiment now operates as a public-private partnership between UW-Madison and Realta Fusion, the company founded to commercialize mirror fusion.

“Today’s demonstration puts the compact magnetic mirror firmly back in the race towards commercial fusion energy,” noted Kieran Furlong, CEO of Realta Fusion, in a statement . “It’s a giant leap forward for a concept that promises economically viable, zero-carbon heat and electricity.”

Realta Fusion is one of eight companies selected for the Department of Energy’s milestone funding program which aims to accelerate the development of commercial fusion energy, similar to NASA’s approach to fostering private space exploration.

The company has ambitious plans for the future, including developing two demonstration reactors. The first, called Anvil, will build upon WHAM’s design to provide further data and material testing capabilities. The second, named Hammer, will feature an evolved design with multiple magnets, potentially enabling longer reactors with increased power output.

The WHAM team will now focus on addressing key challenges in plasma stability, confinement, and overall efficiency. Their findings will be crucial in determining the viability of magnetic mirror fusion as a practical energy source.