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June 7, 1999
Yogi Gupta's Smashing Success
Arthur J Pais in Pullman
A hockey-puck-sized or smaller disc mounted on a projectile is fired at high speeds down a 40-foot-long steel barrel using compressed gas. Within several milliseconds, the projectile strikes a stationary target at the end of the barrel, smashing the sample into dust and rubble. Before the sample is destroyed, measurements are made in billionths of a second.
Yogendra Gupta and his team are not working on special effects for a new James Bond movie. Gupta, who lists James Bond and Pink Panther movies among his favorites, is an internationally recognized scientist and a professor of physics at Washington State University where he heads the Institute of Shock Physics established with a $ 10 million grant received from the US Department of Energy in 1997.
Each week, scientists in the Institute in Pullman City build various kind of targets (samples are typically crystals, metals, liquids) and then smash them in their laboratory - some of the smashing exercises lasting for much less than a second cost $ 1,000.
The experiments they conduct will determine what happens when objects collide at high speeds of up to 5,400 mph, producing high dynamic pressures lasting less than a millionth of a second.
The federal funding will support experimental and theoretical work of WSU faculty, students and research associates in a broad range of areas covering physics, chemistry, and materials science. Gupta stressed that an important component of this grant will be WSU's ability to attract the brightest graduate and undergraduate students to the program.
His fundamental research work has wide applications in the field of dynamic high pressure compression of materials which in turn is important to ensure that America's nuclear weapons stay in working order. He came to WSU in 1981 and expanded considerably the shock wave research effort pioneered by George Duvall and others in the 1960s. Besides defence-related research, a stronger and more diversified program in shock wave physics has the potential to address several other technical areas important to the state of Washington and the nation. These include aircraft safety, questions concerning explosion and impact, environmental issues related to soil remediation, and the synthesis and development of novel materials.
Gupta's laboratory is filled with sophisticated optical, X-ray and electronic equipment and computers. Its original "gun," built in 1968, fires four-inch diameter projectiles down a 40-foot long barrel at speeds in excess of 3,000 miles an hour. When it collides with the target, various sensors and recording equipment analyze the changes occurring at the molecular and atomic levels.
Two other "guns," one that can accelerate projectiles to speeds in excess of 5,000 miles an hour, are now part of the lab's impact facilities. Higher velocity impact facilities are planned for the future.
Shock wave research explores very rapid compression of materials that result in fast structural and chemical changes. Research in shock wave physics, nuclear physics and radiation physics furthers understanding of the ageing nuclear weapons.
In the past, US scientists could test nuclear weapons by detonating them underground. Without such tests, no one could say with certainty if the bombs would work as designed.
Since the United States initiated a self-imposed test moratorium in 1992, scientists have had to rely on high-speed computers to simulate nuclear blasts. Simulations require knowing how radioactive materials, which may decay over time, will behave when triggered to produce a nuclear blast.
"In the absence of testing, it is essential that innovative experiments, novel theoretical approaches, and computational advances be integrated to predict changes in ageing nuclear weapons," said Secretary of Energy Federico Peņa when the grant was awarded in 1997.
"Washington State University has been the home of some of the nation's leading shock physics research, and we look forward to the important contributions they will make, working with the department's laboratories for the nation's stockpile stewardship program."
"We are providing some of the scientific underpinnings in a field (shock physics) that is central to the nuclear stockpile," Gupta says.
The results of research by Gupta and his team are published in scientific journals and shared with the Department of Energy Laboratories -- Lawrence Livermore in California and Los Alamos and Sandia in New Mexico.
Shock waves produced by the impact cause physical and chemical changes in tiny industrial diamonds, rubies, sapphires or other materials placed in the target. To measure those changes, the scientists use optical equipment and lasers fired at the precise moment the target is struck.
Gupta, almost 50 years old, says he is at home in a world where pressures in the samples reach several million atmospheres (typical pressure in a car tire is two atmospheres), speeds reach thousands of miles per hour and time is measured in picoseconds, or trillionths of seconds.
''I enjoy my work," Gupta told a reporter recently. "The margin of error is very small, and I'm intrigued by that.
"I live in a world which involves very short times," says the scientist, called Yogi by his friends. "My wife thinks I have a very short attention span. Hopefully, she is talking about my research but I don't think so. It probably refers to the fact that I ask lots of questions and am always in a hurry." Gupta, an alumnus of the Birla Institute of Technology and Science in Pilani, has been in the United States since 1968.
When he talks about his research and experiments, he is very cautious. "There is too much of hype in the media about what scientists and medical researchers can accomplish," he says. "Some times the press plays up the merit of a research project, some times the scientists - in order to get more funds for their research - exaggerate the value of their findings.
"I have always believed that science is best done away from the public eye," he says. "Of course, a time comes when you have to reveal the potential usefulness of your research. But let us not promise too much." He understands why there is much hype in science as in Hollywood or the publishing business.
"Most research is funded with public funds," he says. "And there is always the question of accountability. Sometimes, scientists promise the most wonderful things. The attainment of limitless clean energy through fusion has turned out to be quite difficult."
However, he strongly believes that scientists must be optimistic and enthusiastic about their work and have to be intellectually curious. "Understanding some aspect of nature is the best reward a scientist can have."
"Fundamental science is about risk taking and having lots of failures," he says, adding that is why he believes that scientists should have a sense of humor and the ability to laugh at themselves when things wrong. Risk-taking is made easier if you do not take yourself very seriously."
"Given the nature of our work and the potential for high rate of failure, we should be laughing a lot," he says with a chuckle.
His experiments could be used commercially, he says, adding that in Japan attempts have been made to make new material using shock waves. "But who will come forth to fund the feasibility studies here," he says. "Most companies want to see returns quickly, like they see in the Internet or computer industry."
A patent is pending for a process to clean up contaminated soil by exposing it to shock waves. Pressure created by the shock waves can change the molecular structure of organic contaminants such as solvents to a benign form, Gupta said.
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