Wednesday, September 2, 2009

Toward a Better Understanding of Nuclear Ignition

As the nation’s nuclear weapons age, the U.S. government is turning to researchers and scientists at universities such as UC San Diego to figure out safe and reliable ways to estimate their longevity and to understand the physics of thermonuclear reactions in the absence of underground testing currently prohibited under law. (Read the full story by Andrea Siedsma here.)

Hoanh Vu--a research scientist in the Electrical and Computer Engineering Department at the UCSD Jacobs School of Engineering--and colleagues won a three-year, $510,000 grant from the National Nuclear Security Administration (NNSA)to use computer simulation tools to figure out how to successfully achieve controlled, miniaturized nuclear ignition of spherical fuel pellets in laboratory environments using lasers as energy drivers.

The Jacobs School researchers are collaborating with Los Alamos National Laboratory (NM), Lodestar Research Corporation and the Laboratory for Laser Energetics at the University of Rochester in New York.

“The way nuclear weapons work is that there is a spherical core of deuterium-tritium that is driven by a radiation source to nuclear ignition; we know that these bombs work because they have worked underground,” Vu said. “But the nuclear materials inside these fuel cores, primarily deuterium-tritium, and the radiation sources that drive these cores to nuclear ignition, have a relatively short shelf life. We don’t know with any certainty if these weapons still work. Since we can’t test them on a full scale, what do we do? We actually look at the physics and scale down the problem so we can test the viability of these weapons in a safer and more controlled environment.

“These weapons are massive so we try to scale it down to pellets that are millimeter-size,” Vu continued. “The method of choice for compressing these fuel pellets is using a laser, which provides a radiation source.”