Scaling of the Sheared-flow-stabilized Z Pinch toward Reactor Conditions*

Zap Energy Inc. (ZEI) is scaling the sheared-flow-stabilized (SFS) Z pinch toward fusion reactor conditions. The UW and LLNL collaborated on the Fusion Z-Pinch Experiment (FuZE) at the UW. FuZE has demonstrated long-duration D-D fusion production periods of 5-10 microseconds [Zhang \textit{et al.}, PRL 2019], thousands of times longer than the 1 ns MHD m$=$0 (sausage) and m$=$1 (kink) instability growth times. FuZE has reached up to 400 kA pinch currents, 1-2 keV ion temperatures, 1-2x10$^{\mathrm{23}}$ m$^{\mathrm{-3}}$ densities, and neutron yields up to $Y_{n}$\textit{ \textasciitilde }10$^{\mathrm{7}}$ neutrons / pulse. An adiabatic model, 2-temperature MHD calculations, and experimental results all indicate a strong dependence of neutron yield with pinch current, $Y_{n}$\textit{ \textasciitilde I}$^{11}$. A new device, FuZE-Q, is being built at ZEI with the goal of reaching equivalent scientific breakeven (scaling D-D operating conditions to ``equivalent'' Q if it were operated instead with D-T) at approximately 600 kA pinch currents. Status, plans, and reactor embodiment designs will be presented.