Eruption of Dynamic Jets from an Arched Magnetized Laboratory Plasma

Eruptive behavior of arched magnetized plasmas with dimensionless parameters relevant to the Sun's photosphere (β ≈10^-3, Lundquist number ≈ 10⁴, plasma radius/ion gyro-radius ≈ 20, ion-neutral collision frequency » ion cyclotron frequency) was explored in a laboratory plasma experiment. The arched plasma was kink- and torus-stable, therefore eruption leading to formation of a dynamic jet is not intuitive. Detailed measurements of plasma density, temperature, flow, and 3D magnetic field were performed. Development of a strong magnetic-shear in the arched plasma was identified to be the primary driver of the jet. Strong magnetic and thermal pressure gradients were observed near the birthplace of jets prior to its formation. The jet evolves impulsively with supersonic speeds (Mach 1.5) in the beginning. The plasma flow persists up to the resistive diffusion time in the arched plasma. Highly-twisted magnetic structure of the jet, as a consequence of diamagnetic-currents, was observed. Ion-neutral charge-exchange collisions were identified to be efficient in producing the cross-field current that plays an important role in controlling the dynamics of the jet.