Philip B. Snyder is a 🏷️#physicist and Vice President of Plasma Physics at 📝Commonwealth Fusion Systems, and the originator of EPED, the model the field uses to predict how high a tokamak's 📝pedestal will stand. Before joining CFS he directed fusion energy research at 📝Oak Ridge National Laboratory and was Director of Theory and Computational Science at 📝General Atomics. He holds a BS in computational physics from Yale and a PhD in plasma physics from Princeton, and is a Fellow of the American Physical Society.

His 2002 model established what limits the edge. The steep pressure gradient in the edge 📝transport barrier drives a large 📝bootstrap current, which stabilises high-mode-number ballooning while simultaneously feeding low-mode-number peeling; the coupled peeling–📝ballooning mode at intermediate mode number is what constrains the pedestal and triggers an 📝edge localized mode. EPED closes that stability calculation against a second constraint, kinetic ballooning mode onset, fixing pedestal height and width with no parameters fitted to observation. Measured pedestals agree with it to within 20–25 % on 📝DIII-D, 📝JET, 📝Alcator C-Mod, JT-60U, 📝ASDEX Upgrade and COMPASS. EPED also predicted a second, much higher pedestal branch — Super 📝H-mode — before anyone observed it; C-Mod experiments subsequently reached roughly 80 kilopascals, the highest pedestal pressure measured on a tokamak. 📝Jerry Hughes, a co-author on the 2011 EPED paper, carried the same framework into 📝SPARC's pedestal projection. For 📝ARC, a neural-network surrogate trained on about 14,000 EPED runs sets the core boundary condition at a pedestal top near 360 kilopascals, on the peeling branch some 10 % below the peeling–ballooning transition. That figure is a projection, not a measurement, and the ARC physics basis names SPARC as where the model gets validated at reactor field.