Commonwealth Fusion Systems Magnet Success Propels Fusion Energy Toward the Grid

DEVENS, Mass., November 18, 2024 — Commonwealth Fusion Systems (CFS) announced today it successfully built and tested a record-breaking electromagnet called the Central Solenoid Model Coil (CSMC), a major step on the company’s path to bring clean, abundant fusion power to the grid.

The CSMC success, paired with a similar achievement with the Toroidal Field Model Coil (TFMC) test in 2021, validates the two types of high-temperature superconducting (HTS) magnets that CFS needs for SPARC, a machine called a tokamak the company is building to demonstrate net fusion power. The TFMC proved out magnets that operate with steady electrical current, and the CSMC did the same for magnets with current pulses that ramp up and down.

“This is an important milestone on the road to commercialization,” said Brandon Sorbom, Co-Founder and Chief Science Officer. “When we hit the button and put current through the magnet, it performed like a champ and hit all its major test objectives. The fact that our team was able to develop this technology all the way from benchtop to a fully integrated, at-scale superconducting magnet in just a couple of years is huge.”

Over the last four years, CFS developed a HTS cable technology called PIT VIPER for tremendously powerful pulsed-power magnets like SPARC’s central solenoid (CS) and poloidal field (PF) magnets. PIT VIPER’s design includes a new design with internal electrical insulation to minimize heating when rapidly ramping current in an HTS magnet.

The CSMC cements CFS’ magnet leadership, showing the company’s ability to establish its HTS supply, manufacture PIT VIPER cables at scale, design and validate the CSMC systems over a 45-experiment campaign, and operate it under SPARC-like conditions. CFS can now confidently scale up CS and PF magnet manufacturing.

CSMC test results included:

• Ramping electrical current up to 50,000 amps, the maximum operational current planned in SPARC. That’s as much electricity as 250 modern American houses would consume if each were drawing maximum power.
• Using that current to create a 5.7 tesla magnetic field, about 100,000 times the strength of Earth’s magnetic field.
• Rapidly discharging the magnet at a rate of about 4 tesla per second to observe the cable’s response. The resulting data lets CFS validate computer models of SPARC magnet's behavior during fusion operations. 
• Reaching a record stored energy for pulsed magnets of 3.7 megajoules — about the total energy of 5 full-size pickup trucks driving at 60 mph. Such a high stored energy requires a magnet that’s both large and strong.
• Demonstrating the merits of CSMC’s novel fiber optic-based system to detect overheating events called quenches that can damage the magnet if not addressed.

Experts from CFS and the Massachusetts Institute of Technology (MIT) together tested both the TFMC and CSMC at MIT’s Plasma Science & Fusion Center (PSFC) in Cambridge, Massachusetts — the same lab where CFS co-founders got their start before spinning out CFS in 2018, and where CFS and MIT designed, built, and tested the SPARC TFMC between 2019 and 2021. The long-term collaboration helped develop CSMC’s superconducting cables and extended decades of work at the university on the high magnetic field approach underlying SPARC. The CSMC test took place from August to October using an updated version of the ultracold chamber called a cryostat that the TFMC test employed.

“Where the mission of the TFMC was to demonstrate a steady strength, the CSMC needed to demonstrate speed,” said Ted Golfinopoulos, one of the MIT Principal Investigators who led more than 30 PSFC scientists, engineers, and technicians who helped design, build, and test the CSMC. “Hundreds of hands have touched this coil, from its inception on the drafting board to its long and complicated test program. The ingenuity, perseverance, and heart shown by this close-knit team was as impressive as the coil that sprang from their labors.”

Fusion, the process that powers the sun, combines two lighter atoms into one heavier one, releasing tremendous amounts of energy in the process. It’s inherently safe, uses abundant fuel, and produces no high-level radioactive waste.

Awards from two US Department of Energy efforts, Advanced Research Projects Agency–Energy (ARPA–E) and Fusion Energy Sciences (FES), helped to fund the CSMC program.

CFS is building SPARC at its headquarters in Devens, Massachusetts. The company plans to produce its first plasma in 2026 and net fusion energy shortly after. SPARC paves the way for ARC, the company’s first power plant. CFS expects ARC to deliver power to the grid in the early 2030s.

About Commonwealth Fusion Systems

Commonwealth Fusion Systems is the world’s leading and largest private fusion company. The company’s marquee fusion project, SPARC, will generate net energy, paving the way for limitless carbon-free energy. The company has raised more than $2 billion in capital since it was founded in 2018.