Expected MHD Stability and Error Field Penetration in LM26 Magnetized Target Fusion Experiment at General Fusion

LM26 is a proof-of-concept magnetized target fusion (MTF) experiment. It will generate a toroidal plasma using coaxial helicity injection and confine it inside a solid lithium liner, which will act as a flux conserver and be inductively compressed in less than 3 ms. The plasma must remain MHD stable throughout the whole compression to maintain an energy confinement time longer than the compression time, so the plasma will heat to fusion conditions. We have previously calculated MHD stable trajectories in a simplified compression geometry [D Brennan et al. 2020 Nucl. Fusion 60, 046027; D Brennan et al. 2021 Nucl. Fusion 61, 046047].

Here we model the realistic LM26 compression geometry with COMSOL and OpenFOAM using a simplified plasma. The compressing plasma is reproduced with CORSICA and its ideal and resistive MHD stability is analyzed using RDCON [A Glasser et al. 2016 Phys. Plasmas 23 112506 ]. Geometric perturbations in the liner surface will grow during compression and be experienced by the plasma as increasing error fields. We model the error field penetration both analytically [A Cole, R Fitzpatrick 2006 Phys. Plasmas 13 032503 ] and nonlinearly with NIMROD. Our results allow us to identify viable trajectories through full compression.