Collisionless coupling between super Alfvénic ions and an ambient plasma parallel to a background magnetic field is mediated by a set of electromagnetic ion/ion-beam instabilities including the resonant right hand instability (RHI). To study this coupling and its role in parallel shock formation, a new experimental configuration at the University of California, Los Angeles utilizes high-energy and high-repetition-rate lasers to create a super-Alfvénic field-aligned debris plasma within an ambient plasma in the Large Plasma Device (LAPD). We used a time-resolved fluorescence monochromator and an array of Langmuir probes to characterize the laser plasma velocity distribution and density. The debris ions were observed to be sufficiently super-Alfvénic and dense to excite the RHI. Measurements with magnetic flux probes exhibited a right-hand circularly polarized frequency chirp consistent with the excitation of the RHI near the laser target. We compared measurements to 2D hybrid simulations of the experiment.

We present a new experimental platform for studying laboratory astrophysics that combines a high-intensity, high-repetition-rate laser with the Large Plasma Device at the University of California, Los Angeles. To demonstrate the utility of this platform, we show the first results of volumetric, highly repeatable magnetic field and electrostatic potential measurements, along with derived quantities of electric field, charge density and current density, of the interaction between a super-Alfvénic laser-produced plasma and an ambient, magnetized plasma.

The right-hand resonant instability (RHI) is one of several electromagnetic ion/ion beam instabilities responsible for the formation of parallel magnetized collisionless shocks and the generation of ultra-low frequency (ULF) waves in their foreshocks. This instability has been observed for the first time under foreshock-relevant conditions in the laboratory through the repeatable interaction of a pre-formed magnetized background plasma and a super-Alfvénic laser-produced plasma. This platform has enabled unprecedented volumetric measurements of waves generated by the RHI, revealing filamentary current structures in the transverse plane. These measurements are made in the plasma rest frame with both high spatial and temporal resolution, providing a perspective that is complementary to spacecraft observations. Direct comparison of data from both the experiment and the Wind spacecraft to 2D hybrid simulations demonstrates that the waves produced are analogous to the ULF waves observed upstream of the terrestrial bow shock.

The collisionless interaction between a laser-produced carbon plasma (LPP) and an ambient hydrogen plasma in a background magnetic field was studied in a high shot rate experiment which allowed large planar data sets to be collected. Plasma fluorescence was imaged with a fast-gated camera with and without carbon line filters. The resulting images were compared to high-resolution two dimensional (2D) data planes of measured magnetic field and electric potential. Several features in the fluorescence images coincide with features in the field data. Relative intensity was used to determine the initial angular velocity distribution of the LPP and the growth rate of instabilities. These observations may be applied to understand fluorescence images from similar experiments where 2D planes of field data are not available.Published by Elsevier B.V.

We present optical Thomson scattering measurements of electron density and temperature in a large-scale (∼2 cm) exploding laser plasma produced by irradiating a solid target with a high-energy (5–10 J) laser pulse at a high repetition rate (1 Hz). The Thomson scattering diagnostic matches this high repetition rate. Unlike previous work performed in single shots at much higher energies, the instrument allows for point measurements anywhere inside the plasma by automatically translating the scattering volume using motorized stages as the experiment is repeated at 1 Hz. Measured densities around 4 × 1016 cm−3 and temperatures around 7 eV result in a scattering parameter near unity, depending on the distance from the target. The measured spectra show the transition from collective scattering close to the target to non-collective scattering at larger distances. Densities obtained by fitting the weakly collective spectra agree to within 10% with an irradiance calibration performed via Raman scattering in nitrogen.