High repetition rate mapping of the interaction between a laser plasma and magnetized background plasma via laser induced fluorescence

The laminar coupling of energy between a laser-produced plasma and a background magnetized plasma was investigated via planar laser induced fluorescence diagnostic and magnetic flux probes. Experiments performed on the Large Plasma Device at the University of California, Los Angeles, mapped out the two-dimensional spatiotemporal evolution of the laser-plasma (debris) ion velocity distribution function (VDF) to assess debris-background coupling in a sub-Alfvenic regime. The acquisition of these data necessitates high repetition rate (1 Hz) as each dataset is the accumulation of thousands of laser shots, which would not be feasible in single-shot experiments. Fully kinetic, three-dimensional particle-in-cell simulations are compared to the measured VDFs to provide a framework in which we can understand the coupling of a sub-Alfvenic plasma flow through a preformed, magnetized plasma. The simulations display the same departure from the expected gyromotion of the debris plasma as observed in the experimental data, and in conjunction with the measured magnetic field traces, have led to the direct observation of the collisionless coupling via laminar fields. Published under an exclusive license by AIP Publishing.

Automated summary

The laminar coupling between a laser-produced plasma and a background magnetized plasma was investigated through experiments and simulations. The experiments utilized planar laser induced fluorescence diagnostic and magnetic flux probes to study the two-dimensional spatiotemporal evolution of the ion velocity distribution function. The simulations confirmed the observed coupling and the collisionless nature of the process.