Detailed benchmarking of the Nernst effect in magnetized HED plasma*

The Nernst effect plays a key role in magnetic flux transport in magnetized high energy density (HED) plasmas with high β and large temperature gradients. It is present in inertial confinement fusion plasmas and during the preheat phase of magnetized liner inertial fusion. State-of-the-art extended magneto-hydrodynamic (MHD) and kinetic codes include the Nernst effect but differ in physics and implementation, resulting in many discrepancies. Detailed experimental benchmarking of these models is crucial for understanding and controlling magnetized plasma systems.

 

We report on a new experimental platform at the OMEGA laser facility to benchmark the Nernst effect in HED plasma by directly measuring Nernst velocity and plasma conditions. A laser beam heats an H₂ gas jet to generate a plasma plume, which propagates parallel to an external magnetic field. Proton radiography, using 15 MeV and 3 MeV monoenergetic protons from a D³He implosion, measures magnetic field cavitation and advection velocity. Plasma parameters (ne, Te) and radial bulk flow speed are measured by 2ω optical both space and time-resolved Thomson scattering. The experimental results are compared with 1D MHD GORGON simulations.