Megagauss-level premagnetization field production in helically-wound auto-magnetizing liners for Magnetized Liner Inertial Fusion (MagLIF)*

Pulsed-power driven auto-magnetizing (AutoMag) liners [1] are cylindrical tubes composed of discrete helical conduction paths separated by electrically insulating material.  AutoMag liners generate B_z > 100 T axial premagnetization field (pre-implosion) for the MagLIF magneto-inertial fusion concept. Initially, helical current in the AutoMag liner produces B_z in the cold fuel within the liner during a 200 ns, 1-2 MA current prepulse. After the fuel is magnetized, a rapidly rising main current pulse induces an electric field in the liner that is sufficient to force dielectric breakdown of the insulating material between helices. Liner current then reorients from helical to predominantly axial (ceasing B_z production) and the z-pinch liner implodes as the current rises to 20 MA in 100 ns. Proof-of-concept experiments on the 600 kA, 100 ns risetime Mykonos accelerator demonstrated the efficacy of the AutoMag field generation mechanism [2]. Recent AutoMag experiments on the Z Facility confirmed production of B_z > 100 T during a 2 MA prepulse and furthermore used radiography to determine the liner’s implosion integrity. Despite initially having a 3D density and conductivity topology, radiography data shows that AutoMag liners on Z implode with a high level of cylindrical symmetry.

[1] Slutz et al., Phys. Plasmas 24, 012704 (2017).

[2] Shipley et al., Phys. Plasmas 25, 052703 (2018).