ICF and SBSS. Current computer codes have limited capabilities to treat fully relativistic ionization and impact cross sections and reaction rates that are required to create reliable stand-alone simulation tools for design, analysis, and evaluation.

Much of the empiricism in weapons understanding and analysis is related to the fundamental issues of material mix and hydrodynamic instabilities. These issues can be addressed through experiments with the NEF, which would allow the detailed study of instabilities of many materials at densities and temperatures relevant to the stockpile. Experiments that simulate specific weapons-relevant geometries would be of particular interest.

Current and former members of the weapons community are debating the extent to which the data to be gained on facilities such as the NIF are applicable to the stockpile. As SBSS is a venture into uncharted technical and organizational territory, this issue can only be resolved by experience. Although many real engineering issues would not be tested directly on facilities such as the NIF, a skilled practitioner could use NIF experiments to develop an understanding of the relevant physics and apply the judgment he develops to analyze stockpile problems as they arise.

IGNITION

In terrestrial environments to date, significant thermonuclear burn in a dense plasma occurs only in weapons. Achieving ignition on the NIF would thus open a new realm of physical study relevant to weapons science, to basic research, and to energy production. Among the possibilities are the following:

  • The study of burn in the presence of mix. The physics of thermonuclear bum in the presence of mixed materials is central to nuclear weapons and to the consequences of defects and aging.

  • The diagnosis of ICF plasmas. Because of the sensitivity of burn to various plasma conditions (temperature, density, geometries, impurities, and others), the detection of burn products will be a novel diagnostic of ICF plasmas. For example, diagnosing highly compressed, somewhat asymmetric, and partly-mixed targets is very difficult. The copious fusion products, which can be used for imaging and spectral analyses, should provide the best diagnostic for implosion quality.

  • High-energy-density-phenomena. Ignition with the NIF would enable a closer approach to the energy densities of weapons (and some astrophysical situations) than that possible at any other laboratory facility; an x-ray spectrum desired for weapons effects studies would also be produced. In progressing from NOVA to the NIF to ignition with the NIF, each step represents approximately a one-order-of-magnitude increase in x-ray yield. Ignition on the NIF would create laboratory environments at multi-keV temperatures.

  • Proof-of-principle for inertial fusion energy (IFE). Much of the target physics for initial fusion energy (the use of ICF for commercial-scale power production) is driver independent. The NIF would enable study of the relative merits of direct and indirect drive, as well as a range of target designs. These studies will help to quantify the beam energy and beam quality requirements for ignition and for future reactor designs.



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