NIF INVITED: The Road to Ignition: An Historical Overview*

This talk reviews the many twists and turns in the long journey that culminated in ignition in late 2022 using the laser heated indirect-drive approach to imploding DT filled targets at the National Ignition Facility (NIF), located at the Lawrence Livermore National Laboratory (LLNL). 

We describe early origins of the Laser Program at LLNL, and key developments such as the paradigm shifting birth of High Energy Density (HED) studies with lasers, changes in choice of laser wavelength, and the development of key diagnostics and computer codes. Fulfilling the requirements of the multi-faceted Nova Technical Contract was a necessary condition for the approval of the NIF, but more importantly, the end of the Cold War and the cessation of Nuclear Testing, were key catalysts in that approval, along with the ready-and-waiting field of HED. 

The inherent flexibility of the field of laser driven ICF played a huge role in achieving success at the NIF. We describe how the original "point design" target evolved, through the lessons of experiment, in every single way: The capsule's materials and size were changed; The hohlraum's materials, size, laser entrance holes, and gas fills were also all changed, as were the laser pulse shapes that go along with all those changes. The philosophy to globally optimize performance for stability (by lowering the implosion convergence) was also key, as was progress in target fabrication, and in increasing NIF's energy output. The persistence of the research staff, and the steadfast backing of our supporters were also necessary elements in this success. 

 We gratefully acknowledge 7 decades of researchers' endeavors, and 4 decades of the dedicated efforts of many hundreds of personnel across the globe who have participated in NIF construction, operation, target fabrication, diagnostic and theoretical advances, that have culminated in ignition.