Commonwealth Fusion Systems is building SPARC — a compact, high-field tokamak using high-temperature superconducting (HTS) magnets — at its 47-acre campus in Devens, Massachusetts. SPARC is designed to be the world's first commercially relevant fusion energy machine to achieve net energy generation (more energy out than in). CFS raised $1.8 billion in Series B funding in November 2021 from investors including Temasek Holdings, Bill Gates, and Eni. Construction is nearing completion — CFS hosted public site tours in March 2026 at its Devens campus. The CFS website states first plasma is targeted for 2027. CFS also demonstrated a world-record 20 Tesla HTS magnet in September 2021. Google signed a 200 MW PPA with CFS for its ARC commercial fusion plant to follow SPARC. CFS's ARC power plant is planned for the early 2030s.