Increasing Angular Momentum in Pulsed-Power Driven quasi-Keplerian Rotating Plasma Experiments

We present new results from the Rotating Plasma Experiment (RPX) platform developed on the MAGPIE pulsed-power generator (1.4 MA, 500 ns drive time). RPX was designed to simulate aspects of astrophysical accretion disks in the laboratory by driving quasi-Keplerian, differentially rotating plasmas by an off-radial inward-convergence of 8 magnetized ablation flows generated by a wire array Z pinch [1,2].

Using a simplified model and scaling laws, we show that the initial angular momentum can be greatly increased by selecting the appropriate wire array radius. Consequently, these experiments drive higher rotation velocities, resulting in a detailed characterization of the angular frequency and specific angular momentum stratifications.

The data shows that rotating plasmas are 4 mm diameter and have a hollow density structure. In addition, a hollow-density, rotating axial jet is launched from the experiment. The 3 velocity components of this jet (radial, azimuthal and axial) are measured simultaneously using a Thomson Scattering system with three independent directions of observation. The axial jet rotates at a maximum velocity of ∼40 km/s and has an axial velocity of ∼100 km/s. In the low-density core T_i = T_e ∼ 40 eV, whereas on the edges there is an ion temperature increase up to T_i ∼ 100 eV. Finally, we show the plasma flows in this configuration are quasi-Keplerian, demonstrating that RPX is a robust platform to drive astrophysically relevant rotating plasmas.

[1] M. Bocchi, et al., ApJ 767, 84 (2013)

[2] V. Valenzuela-Villaseca, et al., arXiv:2201.10339 (2022)