Posted on 04/08/2003 8:52:09 AM PDT by woofie
Scientists at Sandia National Laboratories have re-created a star's fire.
In a series of experiments using the lab's Z machine over the past nine months, they demonstrated the ability to generate tiny bursts of nuclear fusion, the same energy that fuels H-bombs and stars, the researchers said at a meeting of the American Physical Society in Philadelphia. "We're trying to create a star in the laboratory," said Jeff Quintenz, head of Sandia's fusion research program.
The research is driven by a need to duplicate the conditions on a nuclear battlefield. But it also means Z's unique technological approach has demonstrated that it can compete with more established nuclear fusion technologies, which backers hope will some day generate plentiful and clean energy supplies.
"It's a big deal," Quintenz said.
Sandia scientist Ray Leeper presented the results to physicists at the Philadelphia meeting.
In the long run, Sandia's achievement provides another possible technological path toward the elusive but so far impractical goal of producing power with nuclear fusion.
In the short run, it means Sandia's Z technology is now one of three techniques capable of producing fusion in the lab, Quintenz said in an interview.
The "lab," in this case, is a massive machine filling a building the size of a basketball gymnasium.
The Z machine is shaped like a giant bicycle wheel, with large electrical storage devices around the outer edges. On a precise cue, all the electricity is discharged in an instant down the wheel's spokes at a small target in a steel chamber at the hub of the wheel.
The tiny target being blasted experiences, for an instant, radiation and temperature similar to those found in stars or nuclear weapons.
For the fusion experiments, the Sandia scientists used that blast to crush targets the size of a BB packed with hydrogen.
In the instant of the blast, the experiment concentrated enough heat and pressure for hydrogen atoms to fuse together, creating helium and throwing off high-energy neutrons in the process.
The temperature at the heart of the reaction reached 10 million degrees Celsius, Quintenz said.
For those who see fusion as a future energy source, the Sandia experiment suffers from the same problem as other laboratory fusion efforts. The amount of energy required to ignite the reaction is far greater than the amount produced by the resulting fusion.
But for Sandia's primary purpose, nuclear weapons research, Z's fusion is invaluable, Quintenz said.
One of Sandia's jobs is to certify that U.S. nuclear weapons can survive a nuclear battlefield. Duplicating nuclear fusion in the lab allows them to simulate that "hostile environment" under controlled conditions, Quintenz said.
The experiments provide data Sandia can use in its computer simulations of how U.S. nuclear weapon components would fare when blasted with radiation during a nuclear attack.
The scientists first achieved fusion nine months ago, doing some 30 experiments to verify the result. "We want to be real cautious," Quintenz said. "We don't want to get it wrong."
The proof of fusion is in the burst of neutrons thrown out by the reaction. Fusion happens when two atoms — in this case deuterium, a kind of hydrogen — are squeezed together so tightly they fuse into a single atom.
For the Z reaction, pairs of deuterium atoms were fused to make helium, throwing off a fast-moving subatomic particle called a neutron in the process.
"The name of the game in fusion is the production of neutrons," Quintenz said.
The scientists had to precisely measure the speed and direction of those neutrons to demonstrate they were produced by nuclear fusion and not something else.
My wife makes her chili in a pot that may hold it.
A magnetic "bottle".
Same logic they use with SDI: prove to me that "works" before I approve funding... More foot-dragging.
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