Christopher J. Stolz, Lawrence Livermore National Laboratory, Livermore, CA
On December 5, 2022, Ignition (gain >1) was demonstrated at the National Ignition Facility (NIF) and repeated on July 30, 2023. On the NIF there are 832 high fluence 1ω transport mirrors of which ~36 are exchanged annually due to laser damage initiated typically from debris within the beam tubes or 3ω backscatter from the target. Multiple technologies are currently used to mitigate these laser damage sources including spectral filtering, gas knives, and spot blockers. One of the contributing factors for achieving Ignition was an increase from 1.9 to 2.05 MJ of 3ω laser energy on target. New technologies are being developed to safely ramp up NIF in energy with minimal laser damage, to achieve a goal of even higher gain. For the transport mirrors, these new technologies include non-stick monolayers that would be deposited over the e-beam deposited multilayer mirrors to improve the efficiency of the gas knives at removing debris, femtosecond laser machining to arrest laser damage growth thus enabling increasing the range of laser conditioning before installation, and the substitution of alumina for hafnia as the high index material for improved 3ω laser damage resistance of the mirrors closest to the target chamber.