divertor is the region at the edge of a magnetically confined plasma that exhausts heat and spent fuel particles — the highest heat-flux component in a 📝Tokamak.
The divertor is best understood against its predecessor, the 📝limiter, a material structure inserted directly into the plasma edge. A divertor removes that contact point from the confined plasma entirely: shaped magnetic fields peel the outermost layer of 📝plasma away from the core and steer it through an 📝X-point — where the last closed magnetic surface crosses itself — into a separate chamber, where the field lines end on armored target plates. Impurities knocked loose at the targets are born far from the core, so a diverted plasma stays cleaner, and the geometry is what made the high-confinement 📝H-mode regime accessible.
The price of that geometry is concentration: the exhaust arrives in a ribbon of plasma only centimeters wide, so divertor targets absorb some of the highest steady heat fluxes of any engineered surface. 📝ITER's 📝tungsten-armored divertor targets are designed to withstand 10 to 20 megawatts per square meter, and reactor-scale machines must spread or radiate away still more power — the motivation for operating regimes such as 📝divertor detachment. 📝Adam Kuang projected SPARC's unmitigated parallel heat flux above 10 gigawatts per square meter and answered it with a 📝strike-point sweep; 📝Thomas Eich answered the same problem for 📝ARC with argon-seeded detachment in tightly 📝baffled outer legs, in 📝The ARC Physics Basis (2026).