Scaling of magnetized inertial fusion with drive current rise-time

The Magnetized Liner Inertial Fusion (MagLIF) concept [Slutz et al. Phys. Plasmas 17, 056303 (2010); Gomez et al. Phys. Rev. Lett. 113, 155003 (2014)] is being studied on the Z facility at Sandia National Laboratories. MagLIF is a specific example of the more general Magnetized Inertial Fusion (MIF) approach to fusion. Numerical simulations indicate that yields approaching 100 kJ should be possible on the Z machine and much higher yields (10–1000 MJ) should be possible with pulsed power machines producing larger drive currents (45–60 MA) [Slutz et al. Phys. Plasmas 23, 022702 (2016)]. A significant advantage of MIF is that the implosions can be driven more slowly than conventional inertial fusion. In general, the efficiency of pulsed power machines increases with the current rise-time; however, we show by numerical simulation that the current and energy required to obtain a given fusion gain increase monotonically with the current rise-time over the range (10–500 ns). These results can be used to optimize the design of future accelerators to drive MIF concepts such as MagLIF. We also show that the required preheat energy increases strongly with current rise-time, which indicates that very long current rise-times are not desirable at least for MagLIF.