LPI Experiments with Long Scale-length Plasmas at the Nike Laser*

Experiments at the Nike laser are exploring low density (5-25 mg/cm³) CH foam targets for studies of laser plasma instabilities (LPI). This ongoing effort has produced larger volume plasmas with estimated 5-10x longer density and velocity scale-lengths versus solid targets. The platform is being used to examine the effects of wavelength shifting and bandwidth changes on cross beam energy transport (CBET). A first round of experiments has utilized a backlighter beam as a low intensity probe interacting with the tightly focused main beams that create a high intensity pump (~1-2x10¹⁵ W/cm²). Nike’s focal zooming of the main beams was exploited to heat a large target volume (~1 mm) at lower intensity (10¹²-10¹³ W/cm²) prior to the pump-probe interactions. The new configuration of target diagnostics is presented with example data from the current shot campaign. This poster also discusses LPSE simulations performed for the CBET studies and plans for SRS and TPD studies in these foam targets with the associated laser configurations.