Commonwealth Fusion runs SPARC's cryogenic system at 8 kelvin

Commonwealth Fusion Systems said on September 16 that SPARC's full cryogenic system has run at its 8 kelvin operating temperature, the point at which the tokamak's high-temperature superconducting toroidal field magnets are cold enough to hold a plasma without quenching. The plant feeds three supercritical helium loops at 8, 15 and 80 kelvin and is essentially the same hardware CFS plans to use at its 400 MW ARC plant in Chesterfield County, Virginia. The company framed the result as part of commissioning ahead of the dry dress rehearsal, an integrated test that runs every SPARC support system as if a fusion pulse were happening without the tokamak itself.