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Skunk Works Reveals Compact Fusion Reactor Details

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Compact Fusion Reactor Diagram_0

Neutrons released from plasma (colored purple) will transfer heat through reactor walls to power turbines. Credit: Lockheed Martin

Hidden away in the secret depths of the Skunk Works, a Lockheed Martin research team has been working quietly on a nuclear energy concept they believe has the potential to meet, if not eventually decrease, the world’s insatiable demand for power… Read more at http://aviationweek.com/technology/skunk-works-reveals-compact-fusion-reactor-details

Written by physicsgg

October 16, 2014 at 11:46 am

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Z machine makes progress toward nuclear fusion

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The UW’s current fusion experiment, HIT-SI3. It is about one-tenth the size of the power-producing dynomak concept.U of Washington

The UW’s current fusion experiment, HIT-SI3. It is about one-tenth the size of the power-producing dynomak concept.U of Washington

Fusion energy almost sounds too good to be true – zero greenhouse gas emissions, no long-lived radioactive waste, a nearly unlimited fuel supply.

Perhaps the biggest roadblock to adopting fusion energy is that the economics haven’t penciled out. Fusion power designs aren’t cheap enough to outperform systems that use fossil fuels such as coal and natural gas. Read the rest of this entry »

Written by physicsgg

October 13, 2014 at 5:05 pm

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Nuclear fusion milestone passed at US lab

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The achievement is the first of its kind anywhere in the world

The achievement is the first of its kind anywhere in the world

Researchers at a US lab have passed a crucial milestone on the way to their ultimate goal of achieving self-sustaining nuclear fusion.

Harnessing fusion – the process that powers the Sun – could provide an unlimited and cheap source of energy.

But to be viable, fusion power plants would have to produce more energy than they consume, which has proven elusive.

Now, a breakthrough by scientists at the National Ignition Facility (NIF) could boost hopes of scaling up fusion.

NIF, based at Livermore in California, uses 192 beams from the world’s most powerful laser to heat and compress a small pellet of hydrogen fuel to the point where nuclear fusion reactions take place.

The BBC understands that during an experiment in late September, the amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel – the first time this had been achieved at any fusion facility in the world.

This is a step short of the lab’s stated goal of “ignition”, where nuclear fusion generates as much energy as the lasers supply. This is because known “inefficiencies” in different parts of the system mean not all the energy supplied through the laser is delivered to the fuel…..
Read more at http://www.bbc.co.uk/news/science-environment-24429621

Written by physicsgg

October 8, 2013 at 7:23 am

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Scientists propose a solution to a critical barrier to producing fusion

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From left: physicists Luis Delgado-Aparicio and David Gates.
(Photo credit: Elle Starkman, PPPL Office of Communications)

By John Greenwald
Physicists have discovered a possible solution to a mystery that has long baffled researchers working to harness fusion. If confirmed by experiment, the finding could help scientists eliminate a major impediment to the development of fusion as a clean and abundant source of energy for producing electric power.

An in-depth analysis by scientists from the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) zeroed in on tiny, bubble-like islands that appear in the hot, charged gases—or plasmas—during experiments. These minute islands collect impurities that cool the plasma. And it is these islands, the scientists report in the April 20 issue of Physical Review Letters, that are at the root of a long-standing problem known as the “density limit” that can prevent fusion reactors from operating at maximum efficiency.

Fusion occurs when plasmas become hot and dense enough for the atomic nuclei contained within the hot gas to combine and release energy. But when the plasmas in experimental reactors called tokamaks reach the mysterious density limit, they can spiral apart into a flash of light. “The big mystery is why adding more heating power to the plasma doesn’t get you to higher density,” said David A. Gates, a principal research physicist at PPPL and co-author of the proposed solution with Luis Delgado-Aparicio, a post-doctoral fellow at PPPL and a visiting scientist at MIT’s Plasma Science Fusion Center. “This is critical because density is the key parameter in reaching fusion and people have been puzzling about this for 30 or 40 years.”

The scientists hit upon their theory in what Gates called “a 10-minute ‘Aha!’ moment.” Working out equations on a whiteboard in Gates’ office, the physicists focused on the islands and the impurities that drive away energy. The impurities stem from particles that the plasma kicks up from the tokamak wall. “When you hit this magical density limit, the islands grow and coalesce and the plasma ends up in a disruption,” says Delgado-Aparacio.

These islands actually inflict double damage, the scientists said. Besides cooling the plasma, the islands act as shields that block out added power. The balance tips when more power escapes from the islands than researchers can pump into the plasma through a process called ohmic heating—the same process that heats a toaster when electricity passes through it. When the islands grow large enough, the electric current that helps to heat and confine the plasma collapses, allowing the plasma to fly apart.

Gates and Delgado-Aparicio now hope to test their theory with experiments on a tokamak called Alcator C-Mod at MIT, and on the DIII-D tokamak at General Atomics in San Diego. Among other things, they intend to see if injecting power directly into the islands will lead to higher density. If so, that could help future tokamaks reach the extreme density and 100-million-degree temperatures that fusion requires.

The scientists’ theory represents a fresh approach to the density limit, which also is known as the “Greenwald limit” after MIT physicist Martin Greenwald, who has derived an equation that describes it. Greenwald has another potential explanation of the source of the limit. He thinks it may occur when turbulence creates fluctuations that cool the edge of the plasma and squeeze too much current into too little space in the core of the plasma, causing the current to become unstable and crash. “There is a fair amount of evidence for this,” he said. However, he added, “We don’t have a nice story with a beginning and end and we should always be open to new ideas.”

Gates and Delgado-Aparicio pieced together their model from a variety of clues that have developed in recent decades. Gates first heard of the density limit while working as a post-doctoral fellow at the Culham Centre for Fusion Energy in Abingdon, England, in 1993. The limit had previously been named for Culham scientist Jan Hugill, who described it to Gates in detail.

Separately, papers on plasma islands were beginning to surface in scientific circles. French physicist Paul-Henri Rebut described radiation-driven islands in a mid-1980s conference paper, but not in a periodical. German physicist Wolfgang Suttrop speculated a decade later that the islands were associated with the density limit. “The paper he wrote was actually the trigger for our idea, but he didn’t relate the islands directly to the Greenwald limit,” said Gates, who had worked with Suttrop on a tokamak experiment at the Max Planck Institute for Plasma Physics in Garching, Germany, in 1996 before joining PPPL the following year.
n early 2011, the topic of plasma islands had mostly receded from Gates’ mind. But a talk by Delgado-Aparicio about the possibility of such islands erupting in the plasmas contained within the Alcator C-Mod tokamak reignited his interest. Delgado-Aparicio spoke of corkscrew-shaped phenomena called snakes that had first been been observed by PPPL scientists in the 1980s and initially reported by German physicist Arthur Weller.

Intrigued by the talk, Gates urged Delgado-Aparicio to read the papers on islands by Rebut and Suttrop. An email from Delgado-Aparicio landed in Gates’ in-box some eight months later. In it was a paper that described the behavior of snakes in a way that fit nicely with the C-Mod data. “I said, ‘Wow! He’s made a lot of progress,’” Gates remembers. “I said, ‘You should come down and talk about this.’”

What most excited Gates was an equation for the growth of islands that hinted at the density limit by modifying a formula that British physicist Paul Harding Rutherford had derived back in the 1980s. “I thought, ‘If Wolfgang (Suttrop) was right about the islands, this equation should be telling us the Greenwald limit,” Gates said. “So when Luis arrived I pulled him into my office.”

Then a curious thing happened. “It turns out that we didn’t even need the entire equation,” Gates said. “It was much simpler than that.” By focusing solely on the density of the electrons in a plasma and the heat radiating from the islands, the researchers devised a formula for when the heat loss would surpass the electron density. That in turn pinpointed a possible mechanism behind the Greenwald limit.

Delgado-Aparicio became so absorbed in the scientists’ new ideas that he missed several turnoffs while driving back to Cambridge that night. “It’s intriguing to try to explain Mother Nature,” he said. “When you understand a theory you can try to find a way to beat it. By that I mean find a way to work at densities higher than the limit.”

Conquering the limit could provide essential improvements for future tokamaks that will need to produce self-sustaining fusion reactions, or “burning plasmas,” to generate electric power. Such machines include proposed successors to ITER, a $20 billion experimental reactor that is being built in Cadarache, France, by the European Union, the United States and five other countries.

Why hadn’t researchers pieced together a similar theory of the density-limit puzzle before? The answer, says Gates, lies in how ideas percolate through the scientific community. “The radiation-driven islands idea never got a lot of press,” he says. “People thought of them as curiosities. The way we disseminate information is through publications, and this idea had a weak initial push.”

PPPL, in Plainsboro, N.J., is devoted both to creating new knowledge about the physics of plasmas – ultra-hot, charged gases – and to developing practical solutions for the creation of fusion energy. Through the process of fusion, which is constantly occurring in the sun and other stars, energy is created when the nuclei of two lightweight atoms, such as those of hydrogen, combine in plasma at very high temperatures. When this happens, a burst of energy is released, which can be used to generate electricity….

Read more: www.pppl.gov

Written by physicsgg

April 23, 2012 at 10:39 pm

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Inside the fusion furnace of California’s star chamber

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Tiny stars are being created by the world’s largest and most energetic lasers in the hope of tapping what could be a relatively clean energy source – nuclear fusion.

The National Ignition Facility at Lawrence Livermore National Laboratory in California is at the forefront of efforts to harness the power of fusion. It is also being used to understand how materials behave under extreme temperatures and pressures, similar to those found inside a detonating nuclear warhead.

Laser's-eye view of its target : A view of a cryogenically cooled hydrogen fuel target as seen by one of the facility's super-powered lasers. The target is cooled to below hydrogen's freezing point of -259 °C to make it denser. It must then be further compressed to 100 times the density of lead.

Pulses from 192 high-powered lasers converge inside the 10-metre-diameter target chamber (main photo and bottom left) to deposit up to 500 trillion watts of power for 20 nanoseconds. The target is a gold-plated cylinder the size of a pencil eraser (8.4 millimetres by 4.6 millimetres), called a hohlraum. Inside is a polished beryllium sphere measuring 2 millimetres across (bottom centre), which contains deuterium and tritium, isotopes of hydrogen.

The target chamber: Pulses from the NIF's lasers arrive at the centre of the chamber within a few trillionths of a second of each other, aligned to a tolerance within the diameter of a human hair.

The hohlraum is placed precisely in the centre of the chamber by a positioner (bottom right) before the lasers are switched on. When the lasers strike the hohlraum, their energy is converted to X-rays that burn away the beryllium, compressing the fusion fuel. Temperatures soar to 100 million °C and the isotopes fuse, creating conditions approaching those found only inside stars and thermonuclear weapons.

The bullseye: Before each experiment, a positioner precisely centres the target in the chamber and acts as a stand-in to align the laser beams.

The stellar splash of energy and radiation is studied through diagnostic ports in the target chamber. The chamber is 30 centimetres thick and made of metal covered by a layer of concrete laced with boron to absorb the neutrons.

Dropping in: A lift allows technicians to enter the target chamber for inspection and maintenance.

The facility set new records for neutron yield and laser energy last month. By the end of next year, Livermore hopes to reach “ignition” – the point when more energy is produced from fusion than is used to generate the laser pulse.

Outside the chamber: On 10 March 2009, a 192-beam laser shot delivered 1.1 million joules of ultraviolet light to the centre of the target chamber, breaking the megajoule barrier for the first time.

The Lawrence Livermore National Laboratory recently announced that it is joining forces with British firm AWE, based in Aldermaston, and the Rutherford Appleton Laboratory in Harwell to develop laser fusion.
http://www.newscientist.com

Written by physicsgg

October 21, 2011 at 7:14 pm

UK joins laser nuclear fusion project

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By Jason Palmer

Hiper already has a vision for how fusion energy could be harnessed and distributed

The UK has formally joined forces with a US laser lab in a bid to develop clean energy from nuclear fusion.
Unlike fission plants, the process uses lasers to compress atomic nuclei until they join, releasing energy.
The National Ignition Facility (Nif) in the US is drawing closer to producing a surplus of energy from the idea.
The UK company AWE and the Rutherford Appleton Laboratory have now joined with Nif to help make laser fusion a viable commercial energy source.
At a meeting this week sponsored by the Institute of Physics and held at London’s Royal Society, a memorandum of understanding was announced between the three facilities.
The meeting attracted scientists and industry members in an effort to promote wider UK involvement with the technology that would be required to make laser fusion energy plants possible.
“This is an absolutely classic example of the connections between really high-grade theoretical scientific research, business and commercial opportunities, and of course a fundamental human need: tackling pressures that we’re all familiar with on our energy supply,” said David Willetts, the UK’s science minister.
The idea of harvesting energy from nuclear fusion is an old one.
The UK has a long heritage in a different approach to accomplishing the same goal, which uses magnetic fields; it is home to the Joint European Torus (Jet), the largest such magnetic facility in the world and a testing ground for Iter, the International Thermonuclear Experimental Reactor.
But magnetic fusion attempts have in recent years met more and more constricting budget concerns, just as Nif was nearing completion.
Part of the problem has been that the technical ability to reach “breakeven” – the point at which more energy is produced than is consumed – has always seemed distant. Detractors of the idea have asserted that “fusion energy is 50 years away, no matter what year you ask”…….
But Mr Willetts told the meeting that was changing. Read the rest of this entry »

Written by physicsgg

September 9, 2011 at 10:25 am

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Star power: Small fusion start-ups aim for break-even

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Nuclear fusion will cost a fortune – or will it? A new wave of upstart companies think they’ve found cheaper, quicker ways to build a second sun

Catching the sun

A VAST earth platform looms into view above the treetops of Cadarache in France’s sultry south-east. It measures 1 kilometre long by 400 metres wide, and excavators dotted around it are digging out pits to be filled with massive, earthquake-proof concrete foundations. These foundations need to be strong: 18 giant, supercooled superconducting magnets, each weighing 360 tonnes, will be part of a payload totalling 23,000 tonnes. This is the site of ITERMovie Camera, an international scientific collaboration with funding of €15 billion.

Meanwhile, in an undistinguished building 9000 kilometres away on an industrial park in Redmond, Washington state, a handful of researchers are gathered around a slender cylindrical apparatus about 16 metres long. There are no massive foundations and no expensive cryogenics. The object of the researchers’ interest is smaller than one of ITER’s magnets.

The disparity in scale is striking, especially when you consider both pieces of kit have the same goal: to harness the awe-inspiring power of nuclear fusion. Which project is more likely to realise fusion’s promise of clean, nigh-on inexhaustible energy? ITER certainly has the funding and the physics and engineering expertise. It would be most people’s bet. Yet some diminutive upstarts are now challenging that assumption.

What the newcomers lack in size, they make up in ingenuity and dynamism, their backers say. In Redmond and elsewhere, they have gathered some serious money behind their promise to produce the first commercial fusion reactors within years, not the decades ITER will require. Could an upset be on the cards?

There’s no secret to our interest in fusion: it is what powers the stars, including our sun. At the hundred-million-degree temperatures that exist in the sun’s core, the nuclei of light atoms fuse together to form heavier nuclei, liberating colossal amounts of energy – the energy that illuminates and warms our planet some 150 million kilometres distant. What we wouldn’t give to tame that power for ourselves.

It’s not that we haven’t mastered the basics. Humanity’s first successful experiment with fusion came on 1 November 1952, with the explosion of the first hydrogen bomb above the Pacific atoll of Enewetak in the Marshall Islands. That demonstrated two things. First, the energy needed to ignite a fusion reaction is huge: an H-bomb requires a Hiroshima-style atomic bomb to set it off. Second, once the reaction is under way, it is virtually uncontrollable…. Read the rest of this entry »

Written by physicsgg

August 16, 2011 at 7:59 am