Neutron yield enhancement and suppression by magnetization in laser-driven cylindrical implosions

Abstract

In inertial confinement fusion, an externally applied magnetic field can reduce heat losses in the compressing fuel thereby increasing neutron-averaged ion temperatures and neutron yields. However, magnetization is only beneficial if the magnetic pressure remains negligible compared to the fuel pressure. Experiments and three-dimensional magneto-hydrodynamic simulations of cylindrical implosions on the OMEGA laser show ion temperature and neutron yield enhancements of up to 44% and 67%, respectively. As the applied axial magnetic field is increased to nearly 30 T, both experiments and simulations show yield degradation. For magnetized, cylindrical implosions, there exists an optimal magnetic field that maximizes the increase in yield. Limiting the fuel convergence ratio by preheating the fuel can further increase the benefit of magnetization. The results demonstrate that it is possible to create a plasma with a density of order 1 g/cm3 and an ion temperature greater than 1 keV with a magnetic pressure comparable to the thermal pressure, a new regime for laser-produced plasmas on OMEGA.