Thomas H. Eich is a 🏷️#physicist and the Divertor and Boundary Operations Lead at 📝Commonwealth Fusion Systems, where his subject is how a fusion machine survives its own exhaust. He is lead author of "Power and particle exhaust for the ARC fusion power plant" (2026) and of the 2025 paper mapping the 📝separatrix operational space from ASDEX Upgrade measurements onto 📝SPARC scenarios.

Eich's field is the boundary: the few centimeters of 📝scrape-off layer separating a plasma core hotter than the sun's from 📝divertor tiles that must not melt. Before joining CFS he worked at the Max Planck Institute for Plasma Physics, where his 2013 Nuclear Fusion paper on the scaling of near-scrape-off-layer power width — drawn from ASDEX Upgrade and 📝JET data and written with implications for 📝ITER — became a standard reference for sizing the exhaust problem in next-step machines. Of 📝ARC he has said: "The real challenge for a next-generation machine like ARC is to manage both of these requirements, the hot core and the cool edge, at the same time." The exhaust solutions his 2026 paper sets out — 📝divertor detachment, 📝impurity seeding, divertor geometry — are modeled projections for a machine not yet built.