Enhanced performance in quasi-isodynamic max-$J$ stellarators with a turbulent particle pinch

Abstract

Recent stellarator reactor designs demonstrate mostly outward turbulent particle transport, which, without advanced fueling technology, inhibits the formation of density gradients needed for confinement. We introduce ``SQuID-$τ$'', a self-fueling quasi-isodynamic stellarator capable of sustaining density peaking through inward particle transport caused by turbulence. Temperature and density profile predictions based on high-fidelity gyrokinetic simulations demonstrate enhanced performance, significantly relaxing constraints on the size and magnetic field strength for reactor designs.

Figures (4)

• Figure 1: The self-fueling quasi-isodynamic stellarator design SQuID-$\tau$, shown with its filamentary coil set.
• Figure 2: Total heat fluxes from GX simulations for Stellaris (top; dashed) and SQuID-$\tau$ (bottom; dashed), compared with those of W7-X standard configuration (solid) for $\eta(\rho) = \eta_\mathrm{exp}$ and $\eta(\rho) = \eta_\mathrm{crit}$, respectively. Note that data appears in order of increasing $s = \sqrt{\psi/\psi_\mathrm{edge}}$, from left to right in the figures.
• Figure 3: Experimental profiles (fitted) of reference scenarios, compared against theoretical profiles, including (solid) and excluding (dashed) neoclassical contribution to heat flux. The edge/core boundary conditions for theoretical temperature profiles are set to the experimental values.
• Figure 4: Accessible design points for a stellarator reactor with fusion gain $Q = 1$.