The high-foot implosion campaign on the National Ignition Facility
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
If you could identify only one key skill that a primary or secondary designer should possess, it would be the ability to design an implosion that works reliably and as advertised. Being able to harness an implosion is a key skill because of what an implosion does – an implosion is a “pressure amplifier” that takes absorbed energy and turns that energy, with significant energy loss, into pressure. The pressure generated in implosions is used to compress materials to high densities in the primary designers case, and high densities and temperatures in the secondary designers case. While primary designers and their simulation tools can be tested against experiments at scale fielded at high-explosive facilities around the NNSA complex, secondary designers are much more limited in the experimental facilities that can access relevant conditions (facilities such as Omega at the Laboratory for Laser Energetics, the Z-machine at Sandia National Lab in Albuquerque and the National Ignition Facility at Livermore are more-or-less it). Ignition conditions are the highest-pressure and therefore hardest conditions to access with facility levels of energy, but the struggle to obtain ignition has been an illuminating test of the stockpile stewardship model. If you thought the criteria for ignition is when the fusion energy output from an inertially confined fusion (ICF) implosion exceeds the energy delivered to the target, you’d be wrong. While the above definition is used for milestone tracking purposes, the actually definition of ignition that has been used in fusion research since 1957 is when the power produced by the fusing region exceeds the rate at which energy is lost from the fusing region due to x-ray radiation processes and heat conduction processes. This simple statement about fusion power and rates of energy loss lead to a quantitative criterion for ignition that is known as the “Lawson Criteria.”
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48; AC52-07NA27344
- OSTI ID:
- 1129989
- Report Number(s):
- LLNL--TR-653133
- Country of Publication:
- United States
- Language:
- English