Hot Electron and Shock Breakout Characterization in Shock Ignition Relevant Experiments*

Shock ignition is an alternative inertial confinement fusion scheme, which uses a strong convergent shock generated by a ∼10¹⁶ W/cm² spike laser pulse to ignite a pre-compressed fusion capsule. Understanding nonlinear laser-plasma instabilities and hot electron generation is critical for SI and has been studied extensively by the authors. We have recently conducted a series of experiments on the OMEGA EP and OMEGA-60 laser facilities exploring a variety of regimes relevant to shock ignition, with experimental parameters informed by radiation hydrodynamic simulations. To verify modeling of the plasma conditions with and without a high intensity UV beam interaction, the 4ω probe beam was utilized for Thomson scattering on OMEGA 60 at variable focal standoff from the initial target surface between 300 – 1100 μm, corresponding to plasma densities between n_crit to n_crit/10. Derived results will be presented and compared to expectations from FLASH simulations. In addition, simultaneously collected shock breakout measurements are presented using VISAR and SOP diagnostic techniques and are additionally compared to expectations. Such validations of simulation results will aid to inform future experiments conducted in this regime.