Debris mitigation in pinhole-apertured point-projection backlit imaging

Abstract

This is a preprint of a paper intended for publication in a journaI or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.

Modeling NIF experimental designs with adaptive mesh refinement and Lagrangian hydrodynamics

“…Simulations were done to test this hypothesis and then it was also confirmed with experiments on Omega [5]. Figure 5 shows a time progression of the simulation of the tilted pinhole array.…”

“…For instance, the "hot holraum" experiments of Schneider et al [4], posed a potential risk to the optics systems in the case that a jet of hot material might shoot out of the hohlraum's laser entrance hole (LEH) back at the optics. For the hydrodynamic campaign of Robey, et al [5], the major concern was not damage to the optics, but instead it was important to understand the debris pattern of a pinhole array that was hit by x rays from the primary target.…”

Optimization of experimental designs by incorporating NIF facility impacts

“…To confirm this predication, we conducted a set of experiments on the Omega laser [4]. We summarize the results here.…”

Long duration backlighter experiments at Omega

“…Previous experiments used a vacuum gap between the emitter and pinhole [9]. In that setup, the laser-driven emitter was launched like a flyer plate at the pinhole substrate, colliding with it and generating large pieces of solid spall, which were launched directly at the detector.…”

“…Lasers hitting the surface of the backlighter will cause a shock wave to propagate towards the high-z substrate, which can also cause hydrodynamic motion of the substrate and pinhole closure. This backlighter has a history of debris issues, and so a mitigation scheme must be in place to avoid damaging a detector on-axis with the tantalum surface normal direction [9].…”