Kinetic simulations of a deuterium-tritium Z pinch with >1016 neutron yield

Abstract

Fully kinetic, collisional, and electromagnetic simulations of the time evolution of an imploding and burning Z pinch plasma have been performed. Using the implicit particle-in-cell (PIC) code, multidimensional (1D and 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 low pinch current, 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 with deuterium-tritium fuel, the vast majority of the neutrons is thermonuclear in origin and neutron yield follows an I4 neutron yield scaling with current. High-current, multidimension simulations (up to 40 MA with > 1016 neutron yield) suggest that the fraction of thermonuclear neutrons increases with current and the strong dependence of neutron yield with current will continue at still higher currents. Scenarios for fusion breakeven and possible ignition in the 40–80 MA regime are discussed.