Plasma Physics Seminar (Phys 769)

Dr. Sergei Nikitin, Naval Research Laboratory

Production of Cumulative Jets Generated by Laser-Driven Collapsing Hollow Cones

Cumulative plasma jet formation is observed during implosion of hollow cones at Mbar pressures generated by laser ablation of the cones outer surfaces. Cones of base diameter 500 žm and 90 - 130o apex angles fabricated from 4-10 mg/cm2 Ni or Al foils are irradiated at ~ 1013 W/cm2 intensities by laser pulses generated by Pharos laser at NRL (1.054-mm wavelength, ~4 ns FWHM, sub-ns front edge, flat top spatial profile). Formed jets are side-lit at 0-100 ns delays with ns pulses of 0.65 keV X-rays and monochromatically imaged with ~100 mm spatial resolution onto detector by a curved mica crystal. For some cone geometries, cumulative jets of ion densities ~1020 cm-3 propagate at velocities >10 km/sec. Similar results obtained by imploding wedges. Observed cumulative jets are transitional from the explosive-driven jets to astrophysical jets and can be used to simulate the interaction of astrophysical jets with ambient matter in the lab.

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