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Much of Livermore's Experimental Test Site, known as Site 300, supports the DOE's science-based Stockpile Stewardship Program. Explosions, called shots, result from destructive tests of high explosives and other nonnuclear weapon components-100 to 200 of them a year for the last 10 years. Powerful x-ray machines, interferometers, high-speed cameras, and other diagnostic equipment record shot information in the first nanoseconds after detonation. The tests are important for improving understanding how aging affects chemical high explosives in stockpiled weapon systems and of compatibility of explosives with other materials.
Nondestructive tests at Site 300 include subjecting prototype explosives to vibration and extreme heat, possible conditions encountered during transport. Other work includes fabricating, machining, and assembling test devices prior to testing.
The article also describes the process of a test at Site 300 and the measures taken to protect the environment in the course of testing and experiments at the site.
A thorough understanding of hydrogen, the most common and most abundant element in the universe, is an important part of understanding basic matter. Until recently, there was no way to subject hydrogen to extremely high pressure-such as that found on giant, hydrogen-bearing planets.
In conjunction with the new techniques, diagnostics, and instrumentation developed at Livermore, laser scientists ran experiments to shock hydrogen at extreme pressures using the Nova laser, causing hydrogen to metallize. The phenomenon was accurately recorded by the suite of experimental instrumentation and then plotted and analyzed.
The surprising experimental data showed hydrogen to compress more than expected and metallize at lower pressures and at a more gradual rate than previously theorized. There is good confidence in the results: the data points at lower shock pressures overlap those of an earlier Livermore hydrogen shock experiment performed with a light-gas gun and agree with a hydrogen model posited by another Livermore scientist. Hydrogen theorists now are working to revise models to fit the data and use them to better define high-density hydrogen equations of state, long considered uncertain.
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