When Shocking Things Happen To Otherwise Normal Materials

Gupta is a shock physicist. That means he and his colleagues study what happens to things when they are subjected to very high pressures very quickly. One of their principal tools is a 40-foot-long gas-fired gun deep in the basement of the Physical Sciences building at Washington State University. They use it to fire large flat projectiles at objects of interest, which they then examine for physical and chemical changes.

Gupta's is actually not as odd an occupation as one first suspects. Though Gupta is most interested in the pure science of it all, there are practical things to be done with shock waves. Industrial diamonds are made with shock waves. The newest method of choice for treating kidney stones is with very small shock waves.

The prevailing theory of dinosaur extinction pictures a giant meteor crashing into the earth, creating enormous shock waves. And the conditions that shock dynamacists examine mirror those in the unimaginably hot heavy interiors of the earth and the other planets.

Gupta and his colleagues are currently writing up the results of experiments over the past year using shock waves to examine soil contaminated with several organics.

Another phenomenon relevant to shock dynamics is a nuclear explosion.

When President George Bush established a moratorium on nuclear testing in 1992, he left the U.S. nuclear stockpile in a curious limbo. Although the missiles are still armed, without setting one off once in a while, no one can say with absolute certainty how well they'll work if needed.

But now, following a somewhat uncertain post-Cold War period, the national weapons labs, Sandia, Los Alamos, and Lawrence Livermore, have a new lease on life. Under the umbrella of the Department of Energy funded "Science-Based Stockpile Stewardship" program, it is now their job to demonstrate, without actual testing, the safety and reliability of those aging bombs.

Sandia has a brand new computer that can do a trillion calculations a second. Not only does it hold a speed record, it is part of the effort to simulate atomic blasts. Livermore and Los Alamos are also acquiring comparable machines. Officials at Livermore are cleared to build a $1.8 billion laser assemblage, the National Ignition Facility, that will be used to generate miniature explosions for studying the reliability of the aging hydrogen bombs. And Los Alamos is home to the new Dual-Axis Radiographic Hydrotest Project, whose X-ray machines will examine how warhead parts perform during tests with conventional explosives.

But esoteric as all this sounds, it is actually very applied stuff. The scientists at the national labs need some very basic information to support and feed their models and simulations. Such as how certain materials behave under certain conditions--such as very high pressure within a very short time frame.

Which of course is where WSU and other academic institutions come in.

As was announced by the Department of Energy on June 23, Gupta is the director of the newly formed Institute for Shock Physics. Gupta sees this institute filling three roles in relation to the SBSS: doing fundamental research, training scientists, and working in partnership with the national labs.

In light of this relationship, what universities are particularly good at, says Gupta, is taking on hard, long-term, fundamental problems. Universities provide young, bright minds who bring new ideas to difficult questions. Universities are also, relatively speaking, cost effective for fundamental research.

All of this is important, says Gupta, because the SBSS represents a major shift in perspective (or "paradigm," if you will), from the "make it work" mentality of the Cold War and early nuclear era to developing a predictive capability. The SBSS must answer questions such as what happens to the materials within the bombs over time and will they work if called upon?

As such, the institute will study such things as equations of state of materials under appropriate conditions of interest, material yielding and failure, chemical decomposition of condensed explosives, interface response, and material response at high energy densities. The institute's role will also be, as Gupta puts it, "to help uncover surprises." One example is the role of aging on the shock response of materials.

But the overarching goal that Gupta holds out for the next several years is what he calls "atoms-to-continuum" understanding and modeling of the phenomena involved. All this means is striving to achieve a detailed understanding of a given shock phenomenon from the atomic level all the way through to the macroscopic effect. The boom, in other words, at both ends of its short-lived reality.

Gupta emphasizes that they will be studying only non-nuclear materials and only be looking at basic phenomena.

Shock experiments are tricky things. As Gupta understates it, "They are very fast." And that's it. If you didn't catch the effects very quickly, as in a few billionths of a second, you're out of luck. And these aren't the kind of experiments you do on a whim.

Also, the ideal scientific experiment allows one to isolate conditions to test variables. That can be hard to do with an experiment that's over in a few billionths of a second. And how do you measure the effects of a million atmospheres?

That's the job of this new institute. And it has the pedigree. Washington State University has a lengthy tradition of shock research, reaching back to the late 1950s. WSU physicist George Duvall, under whom Gupta trained, is a pioneer of the field. Over the years, approximately 65 graduate students and post docs have trained here.

Gupta is very proud of the role the new institute will play in national security. But what really drives him is the freedom given the several faculty members who will be associated with the institute to explore new ground. A recurring theme with him is how unwilling contemporary science has become to take risks.

"I believe every professor must tackle hard problems," he says. "I can do research that will let me publish routinely. So what? Big deal.

"I want to tackle problems that may not be do-able."

Do-able or not, the journey should be interesting.

(Funding for the WSU Institute for Shock Physics was announced on June 23 by Dr. Victor Reis, Assistant Secretary for Defense Programs, Department of Energy, during a televised news conference that linked Washington, D.C., and the university campus in Pullman. The Department of Energy will provide $10 million over the next five years to WSU researchers as a part of its strategic investment in selected scientific disciplines important to the Science Based Stockpile Stewardship program. Reis said the SBSS program is the result of a directive by President Clinton to the DOE laboratories to maintain scientific capabilities to sustain a safe and reliable nuclear stockpile without conducting nuclear tests.)

ts111