The hunt for fusion energy is one that has been plagued by false starts and overly-optimistic announcements. This week, however, researchers at the National Ignition Facility in California announced a major new step: firing all of its 192 lasers together for the first time, and channeling the beam into an area no bigger than a pencil eraser.
That tiny target is called the hohlraum. It’s a gold-plated cylinder intended to contain the hydrogen isotopes deuterium and tritium, which would fuse together during a potential fusion reaction. In this test, documented in the journal Science this week, the 192 lasers heated up the hohlraum to “only” about 6 million degrees Fahrenheit. But, team member Jeffrey Atherton says, the NIF is working its way up to the really powerful reactions. “The point is that we were doing it at a scale that’s about 20 times larger than has been done, with a laser power that accordingly is about 20 times higher than has been done, with a precision and efficiency that hasn’t been done before,” he said [MSNBC].
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Last week’s official dedication of the National Ignition Facility, the massive experiment in nuclear fusion, has set some physicists to plotting ways in which nuclear fusion could be put to work in a new generation of nuclear power plants. Although doubters say that NIF may not even be able to produce a controlled fusion reaction, the same reaction that occurs in the heart of the sun and in thermonuclear weapons, boosters such as U.S. Energy Secretary Steven Chu are already discussing how fusion energy could best be harnessed.
Chu notes that the Obama administration’s decision to halt construction of the Yucca Mountain repository for nuclear waste has renewed interest in reactors that could actually reduce the nuclear waste produced by traditional nuclear power plants. There are “a resurgence of hybrid solutions of fusion fission where the fusion would impart not only energy, but again creates high-energy neutrons that can burn down the long-lived actinides” [Technology Review], says Chu. Actinides are a group of radioactive chemical elements, including plutonium and uranium, which compose some of the radioactive waste from traditional fission reactors.
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Luminaries gathered today at a lab in Livermore, California to toast the opening of the National Ignition Facility, a massive physics experiment aiming to recreate the reaction that takes place in the hearts of stars: nuclear fusion. “Bringing Star Power to Earth” reads a giant banner that was recently unfurled across a building the size of a football stadium [The New York Times]. Scientists are now ready to begin firing the world’s most powerful laser, comprised of 192 separate beams, at a target the size of a match head. Yet for all the celebration and hoopla, doubters note that there’s no guarantee that the fusion researchers will achieve their goal.
The project’s director, Ed Moses, said that getting to the cusp of ignition (defined as the successful achievement of fusion) had taken some 7,000 workers and 3,000 contractors a dozen years, their labors creating a precision colossus of millions of parts and 60,000 points of control, 30 times as many as on the space shuttle. “It’s the cathedral story,” Dr. Moses said…. “We put together the best physicists, the best engineers, the best of industry and academia” [The New York Times]. The project has also cost at least $3.5 billion. NIF’s researchers will spend the next year gradually increasing the energy of the laser beams, and say serious ignition experiments will begin next year.
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Researchers in California are preparing to fire 192 lasers at a minuscule pellet of fuel to create their first nuclear fusion reaction, the same reaction that takes place in the center of the sun. Within two to three years, the researchers at the National Ignition Facility (NIF) expect to be creating fusion reactions that release more energy than it takes to produce them. If they’re successful, it will be the first time this has been done in a controlled way–in a lab rather than a nuclear bomb, that is–and could eventually lead to fusion power plants [Technology Review].
Earlier this month, technicians test fired all 192 lasers at once, concentrating their beams on a single focal point in the middle of the chamber. For the test, the chamber was empty. But when real experiments begin within the next few months, the target will be a tiny gold capsule the size of an extra-strength Advil. The goal is to mash the contents of the capsule, a BB-size pellet of hydrogen frozen to nearly absolute zero, until the hydrogen atoms fuse into helium and release a gush of energy [Forbes Magazine].
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Cold fusion is the dream that won’t die for some nuclear physicists. If they could replicate the nuclear reaction that powers our sun under room temperature conditions, the thinking goes, humanity would gain a clean source of nearly limitless energy. Work on cold fusion has been relegated to the margins of science since a much-hyped experiment 20 years ago was discredited, but now a new team of researchers says they’ve conducted experiments that should reinstate the field. “We have compelling evidence that fusion reactions are occurring” at room temperature [EE Times], said lead researcher Pamela Mosier-Boss, of the Space and Naval Warfare Systems Center in San Diego.
On March 23, 1989, physicists Stanley Pons and Martin Fleischmann claimed to have created fusion reactions in a tabletop experiment, at room temperature. [Watch a video of the annoucement here.] Their claims of producing small amounts of excess heat — energy — in their experiments were at first met with excitement, then skepticism and finally derision as other scientists were unable to reproduce the results [Houston Chronicle]. Most physicists eventually concluded that the extra energy was either a fluke or the product of an experimental error.
Mosier-Boss announced her team’s new findings at a meeting of the American Chemical Society yesterday, twenty years to the day since the earlier declaration. She has also published the work in the journal Naturwissenschaft.
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The long-cherished dream of creating nearly limitless clean energy from nuclear fusion–the same process that powers our sun–is looking slightly more possible thanks to a new series of experiments. Researchers working with a reactor at MIT’s Plasma Science and Fusion Center have managed to control the motion of million-degree plasma using high-power radio waves. “Ours is the first definitive result showing that high-power radio waves can significantly affect the flow of the plasma,” said physicist Earl Marmar [EE Times]. The radio waves successfully propelled the plasma inside the dount-shaped chamber without hitting the cooler vessel walls, which would halt the fusion reaction, and also prevented the plasma from causing turbulence, which can interfere with reactions.
Fusion is thought to have enormous potential for future power generation, because fusion plant operation would produce no emissions, fuel sources are potentially abundant, and it produces relatively little (and short-lived) radioactive waste. That’s unlike nuclear fission (the splitting apart of a heavy atom to release energy), the process that powers all existing nuclear plants [LiveScience]. However, researchers stress that commercial fusion power plants are still a long way off. Physicists still don’t know how to make a reactor that generates more power than it consumes, a rather large problem for a potential energy source.
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A researcher who stirred up controversy when he claimed to have carried out nuclear fusion in a table-top experiment has been found guilty of scientific misconduct by a panel at Purdue University. Many scientists have been eager to develop nuclear fusion — the process that powers the sun — as an unlimited source of clean energy and an alternative to fossil fuels. But scientists have struggled to unlock the secrets of fusion energy [Reuters].
In 2002, the researcher, Rusi P. Taleyarkhan, announced that he had carried out fusion at room temperature and using relatively cheap materials, and his results were trumpeted on the cover of the prestigious journal Science. The article was published over the vehement objections of several reviewers and was heavily criticized by other physicists [Los Angeles Times]. Now, the Purdue panel’s findings of scientific misconduct cast further doubts on the validity of Taleyarkhan’s experiments.
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