Kinetic simulations of a deuterium-tritium z pinch with $>$10$^{16}$ neutron yield

Fully kinetic, collisional, and electromagnetic simulations of the time evolution of an imploding z-pinch plasma have been performed as first reported in D. R. Welch, \textit{et al.} [\textit{Phys. Rev. Lett}. \textbf{103}, 255002 (2009)]. Using the implicit particle-in-cell (PIC) code L\textsc{sp,} multi-dimensional (1-3D) simulations of deuterium and deuterium-tritium z-pinches provide insight into the mechanisms of neutron production. The PIC code allows non-Maxwellian particle distributions, simulates finite mean-free-path effects, performs self-consistent calculations of anomalous resistivity, and permits charge separation. At pinch current $I <$ 7 MA, neutron production is dominated by high energy ions driven by instabilities. The instabilities produce a power-law ion-energy distribution function in the distribution tail. At higher currents, roughly half of the neutrons are thermonuclear in origin and follow a $I ^{4}$ neutron yield scaling. High-current, multi-dimension simulations ($>$ 40 MA with $>$ 10$^{16}$ neutron yield) suggest that the fraction of thermonuclear neutrons is not sensitive to $I$, and the strong dependence of neutron yield on current will continue at still higher currents. Scenarios for fusion breakeven and possible ignition will be discussed.