A broadband proton backlighting platform to probe shock propagation in low-density systems

Abstract

A proton backlighting platform has been developed for the study of strong shock propagation in low-density systems in planar geometry. Electric fields at the converging shock front in inertial confinement fusion implosions have been previously observed, demonstrating the presence of-and the need to understand-strong electric fields not modeled in standard radiation-hydrodynamic simulations. In this planar configuration, long-pulse ultraviolet lasers are used to drive a strong shock into a gas-cell target, while a short-pulse proton backlighter side-on radiographs the shock propagation. The capabilities of the platform are presented here. Future experiments will vary shock strength and gas fill, to probe shock conditions at different Z and T.

Kinetic physics in ICF: present understanding and future directions

“…Strong, persistent electric fields have been observed at spherically converging shock fronts [79]. Experiments have successfully imaged the electric field structure at shock fronts produced on the OMEGA-EP laser using proton radiography [22,23]. The low DT-vapor density (0.3 mg/cc) in the core of an ICF implosion is strongly shocked prior to the deceleration phase, producing plasma with Knudsen number in the range 0.2-0.8 where kinetic physics is likely to dominate.…”

Study of self-generated fields in strongly-shocked, low-density systems using broadband proton radiography

“…In this letter, we present results from a recently developed platform [16] using planar geometry and broadband proton radiography to investigate the shock front on the OMEGA-EP laser [17,18] Data from multiple proton energies are collected for each shot, which enabled discrimination of the ablator and shock front as well as quantitative constraining of the field strength. An electric field on the order of a few microns wide and 300 Volts potential at the front of a 0.5 Mbar, Mach 10 shock is reported.…”