Pulsed power driven preheat using a cryogenic Ice fiber for MagLiF experiments on Z

In the Magnetized Liner Inertial Fusion scheme (MagLIF), metal liners are rapidly imploded by a fast-rising current (~20MA in ~100ns) to compress a magnetized, preheated fuel and efficiently reach fusion conditions. Experiments on the Z facility use the Z-Beamlet laser to deposit up to ~2kJ of energy into the fuel prior to compression by the liner implosion. This preheat energy is limited by both the available laser energy, and backscatter risk for higher fuel densities. These experiments have achieved ion temperatures > 3keV and deuterium-deuterium fusion yields >1e13. However, the limited preheat energy results in high convergence implosions making the stagnation susceptible to implosion instabilities that can limit target performance. We present simulations of an alternate method of fuel preheat where the deuterium gas fill is replaced by a cryogenic deuterium ice fiber inside the MagLIF liner. Electrodes connecting to the target are then reconfigured to divert a fraction of the current (~4MA) to implode and heat the ice fiber prior to liner implosion. This preheat method can couple a higher energy to the fuel (>8kJ) that can then be systematically varied by adjusting the electrode configuration. We present simulation results exploring the design of MagLIF experiments to be tested on Z that use this preheat method to increase fuel preheat, reduce convergence and hence improve target performance while reducing susceptibility to implosion instabilities.