PIC Simulation of RF Electrode Implementation for Ponderomotive Plugging in the Novatron Mirror Configuration

The Novatron concept uses an axisymmetric double-cusp magnetic field configuration to achieve MHD interchange stability in an open field-line device [1]. Theoretical investigations have shown potential for reaching Q > 30 using axial plugging with ambipolar potentials and ponderomotive forces [2]. The focus of this work is the investigation of the ponderomotive force as a component in that plugging using particle-in-cell simulations.

Building on the implementations in [1], we have implemented RF electrodes in the particle-in-cell code WarpX and present validation results, including wave coupling, penetration depths, and power absorption profiles for different RF frequencies and field configurations.

The simulation tools we are developing provide the foundation for future ponderomotive plugging studies in full Novatron tandem mirror configurations. This will be used for improving the design of the upcoming Novatron 2 device.

References:

[1] Lindvall, K., et al. “Novatron: Equilibrium and Stability”. Physics of Plasmas (accepted, 2025).

[2] Scheffel, J., et al. “Axial Confinement in the Novatron Mirror Machine.” Nuclear Fusion 65, no. 6 (2025): 066011.