The CEO and co-founder of Commonwealth Fusion Systems — the MIT spinout building SPARC and ARC using high-temperature superconducting magnets, now the world’s best-funded private fusion company.
ReviewedLast reviewed: 9 Aug 2026·Category: Scientists & Pioneers
Career
Robert D. Mumgaard earned his Ph.D. in plasma physics from MIT, working at the Plasma Science and Fusion Center (PSFC) on Alcator C-Mod. In 2018, he co-founded Commonwealth Fusion Systems (CFS) with Dennis Whyte and other MIT faculty and students, spinning out the high-field HTS magnet approach pioneered at MIT.[1]
Commonwealth Fusion Systems
CFS milestones: Under Mumgaard’s leadership, CFS raised over $2 billion in private investment, demonstrated a record-setting 20-tesla HTS magnet in September 2021, and broke ground on the SPARC tokamak facility in Devens, Massachusetts. SPARC aims to produce net energy from fusion (Q > 2) in the late 2020s.
Vision
Mumgaard has articulated a clear commercial path: SPARC proves the physics, ARC (the follow-on commercial plant) proves the economics. His strategy focuses on the high-field compact tokamak approach — using REBCO high-temperature superconducting magnets to achieve ITER-level performance in a device roughly 1/40th the volume.[2]
He has been a prominent advocate for the private fusion industry, testifying before the U.S. Senate and advocating for fusion regulatory frameworks.[3]
Sources
Creely, A.J. et al. "Overview of the SPARC tokamak." Journal of Plasma Physics, 86, 865860502, 2020.
Chandler, D.L. "MIT-designed project achieves major advance toward fusion energy." MIT News, September 2021.