Analysis of Preheat Propagation in MagLIF-like Plasmas

The preheating and pre-magnetization of fusion fuel are key features in Magnetized Liner Inertial Fusion (MagLIF) configurations. Typically, the energy of the preheat laser is deposited in a central region of the fuel and propagates outward, generating magneto-hydrodynamic structures that impact the fuel mass distribution and magnetic flux compression during the subsequent implosion.

We present a theoretical analysis of preheat propagation in a magnetized plasma under conditions typical for MagLIF. In this regime, the preheat-driven expansion induces the stratification of the fuel and magnetic field, which accumulate in a dense outer shelf bounded by the leading shock. We show self-similar solutions of the model and support them with FLASH simulations. Our analysis indicates that, asymptotically in time, the regions where the magnetization of the fuel is significant tend to become localized at the interface separating the outer shelf from the inner hot core [1]. We assess the implications of this stratification on the magnetic flux conservation and performance of fully integrated MagLIF FLASH simulations. This analytic framework is beneficial for designing MagLIF targets, including for upcoming ignition-scale facilities such as Pacific Fusion’s 60-MA Demonstration System [2].

[1] F. Garcia-Rubio et al., Submitted to Special Issue on Pulsed Magnetic Fusion Energy to Phys. Plasmas (2025).

[2] A. Alexander et al., Accepted to Special Issue on Pulsed Magnetic Fusion Energy to Phys. Plasmas (2025).