Commonwealth Fusion Systems Outlines SPARC Plans to Achieve Net Fusion Gain in 2027

Commonwealth Fusion Systems (CFS) has outlined new operating strategies for its SPARC fusion reactor, identifying multiple approaches to achieving net fusion energy gain (Q>1). Announced on 2 November 2026, the plans will be presented at the American Physical Society's Division of Plasma Physics conference, where CFS researchers will discuss how different magnetic field strengths, plasma configurations and predictive models could help the company reach its first major fusion performance milestone.

CFS is currently assembling SPARC at its headquarters in Devens, Massachusetts, with supporting systems undergoing commissioning. The company expects to begin operating the machine in 2027. Its initial objective is to demonstrate Q>1, meaning that the fusion reaction produces more power than the external heating power supplied to sustain the plasma. This milestone would not mean that SPARC generates net electricity for the grid, but would establish an important foundation for commercial fusion development.

 

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SPARC Designed to Achieve Q>1 Through Two Operating Modes

 

SPARC is a tokamak that uses high-temperature superconducting magnets to confine plasma at temperatures approaching 100 million degrees Celsius. Its magnets are designed to generate fields of up to 12.2 tesla, approximately 400,000 times stronger than Earth's magnetic field at the equator. CFS plans to pursue Q>1 through a lower-confinement plasma configuration, known as L-mode, operating at the machine's maximum magnetic field.

An alternative approach involves high-confinement mode, or H-mode, which can sustain higher plasma pressure and temperature with improved confinement. According to CFS, this configuration could achieve Q>1 using a lower magnetic field of approximately 8 to 9 tesla, although it requires more sophisticated plasma control. Clayton Myers, who leads CFS's plasma diagnostics team, said, "Part of the reason we’re confident SPARC will meet this early performance goal is because we have different paths to success."

 

Advanced Modelling to Guide Fusion Performance

 

CFS researchers are combining computational models to predict how different operating conditions will affect SPARC's performance. The work includes evaluating magnetic configurations, plasma behaviour, electrical current ramp-up and fuel management to identify suitable operating scenarios before experiments begin. These models will inform decisions during the machine's initial operating campaign.

The company is also working with universities and research laboratories to develop and validate the physics tools used to predict fusion performance. Phil Snyder, Vice President of Plasma Physics at CFS, said, "We work with a great team of collaborators to develop and test world-class physics tools for predicting and optimizing SPARC performance, for the Q>1 mission and beyond." The results will undergo further scientific review as CFS shares its research with the wider plasma physics community.

 

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SPARC Testing to Support Commercial ARC Fusion Plant

 

Once SPARC achieves its initial Q>1 objective, CFS plans to explore higher fusion gain using stronger magnetic fields and improved plasma confinement. These experiments will help researchers study burning plasma physics, including how energy generated by fusion reactions affects the behaviour and stability of the plasma itself.

The findings are intended to inform CFS's ARC power plant, which is being designed to convert fusion energy into electricity for commercial use. The company is also presenting aspects of ARC's preconceptual design and associated research at the conference. Snyder said, "We’re in the home stretch now. We’re assembling SPARC, and we expect to turn it on next year." Achieving Q>1 would represent an important technical milestone, although sustained operation, electricity generation and commercial deployment will require further development.

 

Source: Commonwealth Fusion Systems