Characterization of Quasi-Keplerian, Differentially Rotating, Free-Boundary Laboratory Plasmas

Area of Science:

• Plasma physics
• Astrophysical fluid dynamics
• High-energy density physics

Background:

• Astrophysical disks and jets are crucial phenomena in the universe.
• Understanding their formation and dynamics requires advanced simulation techniques.
• Previous experiments often relied on boundary forces to induce rotation.

Purpose of the Study:

• To simulate the physics of astrophysical disks and jets using pulsed-power driven plasma.
• To investigate rotation mechanisms not reliant on boundary forces.
• To characterize the properties of the generated rotating plasma jet.

Main Methods:

• Utilized pulsed-power driven differentially rotating plasma experiments.
• Employed wire array Z pinches to inject angular momentum via ablation flow ram pressure.
• Analyzed plasma jet confinement by combined ram, thermal, and magnetic pressures.

Main Results:

• Generated a rotating plasma jet with subsonic rotation (max velocity 23±3 km/s).
• Observed a quasi-Keplerian rotational velocity profile.
• Measured a positive Rayleigh discriminant (κ²∝r⁻².⁸±⁰.⁸ rad²/s²).
• The plasma completed 0.5-2 rotations within ~150 ns.

Conclusions:

• Demonstrated a novel method for simulating astrophysical disk and jet physics.
• Confirmed that rotation can be driven by internal pressure gradients, not just boundary forces.
• The observed quasi-Keplerian profile and stability characteristics provide valuable data for astrophysical models.