Figure from the DOE Report October, 2018

October 2018 DOE Report

Laser–Plasma Interaction Experiments on OMEGA EP

The LPIonEP-19A shot day on OMEGA EP (18 October 2018) explored the effect of density scale length and electron temperature on laser–plasma interaction (LPI) mechanisms. These experiments used planar thick CH slabs, irradiated by between one and four OMEGA EP beams in either 4-ns linear ramp or 2-ns square laser pulses, with different size phase plates (400 or 750 µm) used on the single-beam shots. The purpose of changing the phase plate was to alter the density scale length at the quarter-critical region, with the expectation based on OMEGA and the National Ignition Facility results that longer scale lengths will favor stimulated Raman scattering (SRS), while shorter scale lengths favor two-plasmon decay (TPD). The objective of this campaign is to probe the boundary between SRS- and TPD-dominated regimes. Previous OMEGA EP planar experiments, which used a large phase plate, showed predominantly SRS.

Shown here, (a) experimental setup and (b) time-resolved optical spectra from OMEGA EP shot 29234.

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