Damage Sources for the NIF Grating Debris Shield (GDS) and Methods for Their Mitigation

The primary sources of damage on the National Ignition Facility (NIF) Grating Debris Shield (GDS) are attributed to two independent types of laser-induced particulates. The first comes from the eruptions of bulk damage in a disposable debris shield downstream of the GDS. The second particle source comes from stray light focusing on absorbing glass armor at higher than expected fluences. We show that the composition of the particles is secondary to the energetics of their delivery, such that particles from either source are essentially benign if they arrive at the GDS with low temperatures and velocities.