Confinement properties of Infinity Two

We summarize confinement and performance projections for the optimized stellarator Infinity Two fusion pilot plant. Transport predictions are made using nonlinear electromagnetic gyrokinetic turbulence simulations along with drift kinetic neoclassical simulations [1]. A baseline operating point with deuterium–tritium fusion power P_fus,DT=800 MW at high fusion gain Q=40 is demonstrated. Higher power operating states, including ignition, are also predicted that remain below radiative (Sudo) density and MHD stability limits. Predicted energy confinement times are ~15% larger than ISS04 due to enhanced density gradients from pellet fueling and 3D shape optimization. Self-consistent predictions of density [2] using pellet fueling derived from neutral gas shielding equations [3] confirm the density profile shape and confinement enhancement. A strong outward convection of neon and tungsten is predicted in the outer half radius (due to trapped electron mode turbulence from strong density gradients), leading to flat or hollow profiles, respectively [4]. While weak peaking is predicted for helium ash, the core Z_eff is lower than originally assumed. Neoclassical transport remains negligibly small everywhere in the simulations confirming that turbulence dominates the solution of all transport channels. [1] W. Guttenfelder et al. Journal of Plasma Physics 91 (2025) E83. [2] N.R. Mandell et al., this conference. [3] E. Granstedt et al., this conference. [4] G. Le Bars et al., this conference