An integrated design study for the EXhaust and Confinement Integration Tokamak Experiment*

A high-level design study for a new experimental tokamak shows that advances in fusion science and engineering can be leveraged to close the remaining gaps between present devices and a future fusion pilot plant (FPP). This new US facility will access an operational space close to the projected FPP performance regime via a compact, high field, high power-density approach that utilizes advanced tokamak scenarios and high temperature superconductor magnets. Full-device optimization via system code calculations, physics-based core-edge modeling, plasma control simulations, and finite-element structural & thermal analysis has converged on a B_T=6T, I_P=5MA, R₀=1.5m, A=3 D-D tokamak with strong plasma shaping, long-legged divertors, and 50MW of auxiliary power. Such a device will match several absolute FPP parameters: pressure, exhaust heat flux, and bootstrap fraction. It will also narrow or close the gap in key dimensionless parameters: toroidal beta, normalized gyroradius, collisionality, and edge neutral opacity. Integrated neutron shielding preserves personnel access by limiting nuclear activation and maximizes experimental run time by reducing site radiation. In addition to design study results and optimization details, parameter sensitivities and uncertainties are also discussed.