Fusion Power a Step Closer After Giant Laser Blast
By Ker Than for National Geographic News
Published January 28, 2010
Using the most powerful laser system ever built, scientists have brought us one step closer to nuclear fusion power, a new study says.
The same process that powers our sun and other stars, nuclear fusion has the potential to be an efficient, carbon-free energy source—with none of the radioactive waste associated with the nuclear fission method used in current nuclear plants.
Thanks to the new achievement, a prototype nuclear fusion power plant could be operating within a decade, speculated study leader Siegfried Glenzer, a physicist at Lawrence Livermore National Laboratory in California.
Glenzer and colleagues used the world's largest laser array—the Livermore lab's National Ignition Facility--to heat a BB-size fuel pellet to millions of degrees Fahrenheit.
"These lasers are pulsed, and for a very short amount of time"—one ten-billionth of a second—"the power they produce is more than all the power generated by the entire electrical grid of the United States" at any given moment, Glenzer said.
The test confirmed that a technique called inertial fusion ignition could be used to trigger nuclear fusion—the merging of the nuclei of two atoms of, say, hydrogen—which can result in a tremendous amount of excess energy. Nuclear fission, by contrast, involves the splitting of atoms.
The laser demonstration means scientists are now much closer to triggering nuclear fusion in a controlled setting—something that's never been done before and which is necessary if fusion is to be harnessed for energy.
Nuclear's Nice Side?
Performing nuclear fusion in the lab requires enormous amounts of laser power, but if perfected, controlled fusion should generate ten to a hundred times more electrical energy than is used to spark the nuclear reactions. Nuclear fusion, after all, is what allows stars to burn for billions of years.
And fusion could be not only powerful but clean and green as well.
Not only does nuclear fusion not produce long-lasting nuclear waste, but fusion could potentially be used to chemically neutralize radioactive pollutants and has been "proposed as a cure to our nuclear waste problem," Glenzer said. Simply put, neutrons released by fusion could rearrange radioactive atoms so they aren't radioactive anymore.
Nuclear fusion energy is also potentially carbon free, meaning it could be used to generate power without creating any more carbon dioxide gas, which contributes to global warming.
And while fossil fuels, such as oil and coal, and nuclear fission fuels, such as uranium, are limited resources, there's enough nuclear fusion fuel on, in, and around our planet "to power the Earth longer than the lifetime of the sun," Glenzer said.
Gold Fusion
During the laser experiment, the fuel pellet was placed inside a solid-gold cylinder about the size of a pencil eraser, which was hit by multiple laser beams.
The gold cylinder absorbed the laser energy and converted it into thermal x-ray energy.
The x-rays then ricocheted inside the cylinder and struck the fuel pellet from all sides. As the pellet absorbed the x-rays, it heated up—eventually reaching about 60 million degrees Fahrenheit (33 million degrees Celsius)—then collapsed in on itself.
The experiment was designed only to test the lasers' ability to heat the cylinder efficiently. Made largely of plastics and helium, the fuel pellet was not filled with enough actual fuel—chemical variants of hydrogen called deuterium and tritium—to actually trigger nuclear fusion.
Actual fusion, Glenzer said, will occur sometime this year.
With a fully loaded fuel pellet, "the implosion will be like squeezing a soccer ball to the size of a pinhead," he added. "The center of that spherical ball will get so hot that nuclear fusion starts."
Nuclear Fusion Plant by 2020?
If successful, the upcoming nuclear fusion experiment will create two classes of energetic particles: alpha particles and neutrons.
"The neutrons escape and can be used to do things like heat up water"—which could potentially be used to produce steam to drive turbines in an electrical plant, Glenzer said.
"The alpha particles remain trapped [in the burning sphere] and continue to heat the fuel and make it burn," as happens in a star.
Scientists estimate that if they can get to the point where they can burn about five fuel pellets a second, a power plant could continuously generate up to a gigawatt of energy—about what the city of San Francisco is consuming at any given moment.
A working prototype of a such a plant could be built in a decade, Glenzer said.
Cheaper to Burn Cash?
Nuclear fusion researcher Michael Mauel is "very excited" about the recent experiment and said it shows the ignition method works as expected.
But "whether or not we'll have lasers imploding pellets to make fusion energy—it's way too early to tell," said Mauel, who was not involved in the study, which will be published in the journal Science tomorrow.
In addition to the considerable engineering challenges involved in ramping up the laser systems for wide-scale use, the cost of the fuel pellets will also have to come down, said Mauel, a Columbia University physicist.
"Each one of these costs between ten [thousand] and a hundred thousand dollars," Mauel said. To use the pellet method to generate nuclear fusion power, "they'll have to cost less than ten cents a piece."
Published January 28, 2010
Using the most powerful laser system ever built, scientists have brought us one step closer to nuclear fusion power, a new study says.
The same process that powers our sun and other stars, nuclear fusion has the potential to be an efficient, carbon-free energy source—with none of the radioactive waste associated with the nuclear fission method used in current nuclear plants.
Thanks to the new achievement, a prototype nuclear fusion power plant could be operating within a decade, speculated study leader Siegfried Glenzer, a physicist at Lawrence Livermore National Laboratory in California.
Glenzer and colleagues used the world's largest laser array—the Livermore lab's National Ignition Facility--to heat a BB-size fuel pellet to millions of degrees Fahrenheit.
"These lasers are pulsed, and for a very short amount of time"—one ten-billionth of a second—"the power they produce is more than all the power generated by the entire electrical grid of the United States" at any given moment, Glenzer said.
The test confirmed that a technique called inertial fusion ignition could be used to trigger nuclear fusion—the merging of the nuclei of two atoms of, say, hydrogen—which can result in a tremendous amount of excess energy. Nuclear fission, by contrast, involves the splitting of atoms.
The laser demonstration means scientists are now much closer to triggering nuclear fusion in a controlled setting—something that's never been done before and which is necessary if fusion is to be harnessed for energy.
Nuclear's Nice Side?
Performing nuclear fusion in the lab requires enormous amounts of laser power, but if perfected, controlled fusion should generate ten to a hundred times more electrical energy than is used to spark the nuclear reactions. Nuclear fusion, after all, is what allows stars to burn for billions of years.
And fusion could be not only powerful but clean and green as well.
Not only does nuclear fusion not produce long-lasting nuclear waste, but fusion could potentially be used to chemically neutralize radioactive pollutants and has been "proposed as a cure to our nuclear waste problem," Glenzer said. Simply put, neutrons released by fusion could rearrange radioactive atoms so they aren't radioactive anymore.
Nuclear fusion energy is also potentially carbon free, meaning it could be used to generate power without creating any more carbon dioxide gas, which contributes to global warming.
And while fossil fuels, such as oil and coal, and nuclear fission fuels, such as uranium, are limited resources, there's enough nuclear fusion fuel on, in, and around our planet "to power the Earth longer than the lifetime of the sun," Glenzer said.
Gold Fusion
During the laser experiment, the fuel pellet was placed inside a solid-gold cylinder about the size of a pencil eraser, which was hit by multiple laser beams.
The gold cylinder absorbed the laser energy and converted it into thermal x-ray energy.
The x-rays then ricocheted inside the cylinder and struck the fuel pellet from all sides. As the pellet absorbed the x-rays, it heated up—eventually reaching about 60 million degrees Fahrenheit (33 million degrees Celsius)—then collapsed in on itself.
The experiment was designed only to test the lasers' ability to heat the cylinder efficiently. Made largely of plastics and helium, the fuel pellet was not filled with enough actual fuel—chemical variants of hydrogen called deuterium and tritium—to actually trigger nuclear fusion.
Actual fusion, Glenzer said, will occur sometime this year.
With a fully loaded fuel pellet, "the implosion will be like squeezing a soccer ball to the size of a pinhead," he added. "The center of that spherical ball will get so hot that nuclear fusion starts."
Nuclear Fusion Plant by 2020?
If successful, the upcoming nuclear fusion experiment will create two classes of energetic particles: alpha particles and neutrons.
"The neutrons escape and can be used to do things like heat up water"—which could potentially be used to produce steam to drive turbines in an electrical plant, Glenzer said.
"The alpha particles remain trapped [in the burning sphere] and continue to heat the fuel and make it burn," as happens in a star.
Scientists estimate that if they can get to the point where they can burn about five fuel pellets a second, a power plant could continuously generate up to a gigawatt of energy—about what the city of San Francisco is consuming at any given moment.
A working prototype of a such a plant could be built in a decade, Glenzer said.
Cheaper to Burn Cash?
Nuclear fusion researcher Michael Mauel is "very excited" about the recent experiment and said it shows the ignition method works as expected.
But "whether or not we'll have lasers imploding pellets to make fusion energy—it's way too early to tell," said Mauel, who was not involved in the study, which will be published in the journal Science tomorrow.
In addition to the considerable engineering challenges involved in ramping up the laser systems for wide-scale use, the cost of the fuel pellets will also have to come down, said Mauel, a Columbia University physicist.
"Each one of these costs between ten [thousand] and a hundred thousand dollars," Mauel said. To use the pellet method to generate nuclear fusion power, "they'll have to cost less than ten cents a piece."
Laser fusion test results raise energy hopes (UPDATE)
By Jason Palmer
Science and technology reporter, BBC News
A major hurdle to producing fusion energy using lasers has been swept aside, results in a new report show.
The controlled fusion of atoms - creating conditions like those in our Sun - has long been touted as a possible revolutionary energy source.
However, there have been doubts about the use of powerful lasers for fusion energy because the "plasma" they create could interrupt the fusion.
An article in Science showed the plasma is far less of a problem than expected.
The report is based on the first experiments from the National Ignition Facility (Nif) in the US that used all 192 of its laser beams.
Along the way, the experiments smashed the record for the highest energy from a laser - by a factor of 20.
Star power
Construction of the National Ignition Facility began at Lawrence Livermore National Laboratory in 1997, and was formally completed in May 2009.
The goal, as its name implies, is to harness the power of the largest laser ever built to start "ignition" - effectively a carefully controlled thermonuclear explosion.
INERTIAL CONFINEMENT FUSION 192 laser beams are focused through holes in a target container called a hohlraum Inside the hohlraum is a tiny pellet containing an extremely cold, solid mixture of hydrogen isotopes Lasers strike the hohlraum's walls, which in turn radiate X-rays X-rays strip material from the outer shell of the fuel pellet, heating it up to millions of degrees If the compression of the fuel is high enough and uniform enough, nuclear fusion can result Giant laser experiment powers up It is markedly different from current nuclear power, which operates through splitting atoms - fission - rather than squashing them together in fusion.
Proving that such a lab-based fusion reaction can release more energy than is required to start it - rising above the so-called breakeven point - could herald a new era in large-scale energy production.
In the approach Nif takes, called inertial confinement fusion, the target is a centimetre-scale cylinder of gold called a hohlraum.
It contains a tiny pellet of fuel made from an isotope of hydrogen called deuterium.
During 30 years of the laser fusion debate, one significant potential hurdle to the process has been the "plasma" that the lasers will create in the hohlraum.
The fear has been that the plasma, a roiling soup of charged particles, would interrupt the target's ability to absorb the lasers' energy and funnel it uniformly into the fuel, compressing it and causing ignition.
Siegfried Glenzer, the Nif plasma scientist, led a team to test that theory, smashing records along the way.
"We hit it with 669 kilojoules - 20 times more than any previous laser facility," Nif's Siegfried Glenzer told BBC News.
That isn't that much total energy; it's about enough to boil a one-litre kettle twice over.
However, the beams delivered their energy in pulses lasting a little more than 10 billionths of a second.
By way of comparison, if that power could be maintained, it would boil the contents of more than 50 Olympic-sized swimming pools in a second.
'Dramatic step'
Crucially, the recent experiments provided proof that the plasma did not reduce the hohlraum's ability to absorb the incident laser light; it absorbed about 95%.
But more than that, Dr Glenzer's team discovered that the plasma can actually be carefully manipulated to increase the uniformity of the compression.
The 130-tonne target chamber is kept under vacuum for the experiments "For the first time ever in the 50-year journey of laser fusion, these laser-plasma interactions have been shown to be less of a problem than predicted, not more," said Mike Dunne, director of the UK's Central Laser Facility and leader of the European laser fusion effort known as HiPER.
"I can't overstate how dramatic a step that is," he told BBC News. "Many people a year ago were saying the project would be dead by now."
Adding momentum to the ignition quest, Lawrence Livermore National Laboratory announced on Wednesday that, since the Science results were first obtained, the pulse energy record had been smashed again.
They now report an energy of one megajoule on target - 50% higher than the amount reported in Science.
The current calculations show that about 1.2 megajoules of energy will be enough for ignition, and currently Nif can run as high as 1.8 megajoules.
Dr Glenzer said that experiments using slightly larger hohlraums with fusion-ready fuel pellets - including a mix of the hydrogen isotopes deuterium as well as tritium - should begin before May, slowly ramping up to the 1.2 megajoule mark.
"The bottom line is that we can extrapolate those data to the experiments we are planning this year and the results show that we will be able to drive the capsule towards ignition," said Dr Glenzer.
Before those experiments can even begin, however, the target chamber must be prepared with shields that can block the copious neutrons that a fusion reaction would produce.
But Dr Glenzer is confident that with everything in place, ignition is on the horizon.
He added, quite simply, "It's going to happen this year."
"Fusion Power a Step Closer After Giant Laser Blast" published from http://news.nationalgeographic.com/news/2010/01/100128-nuclear-fusion-power-lasers-science/
"Laser fusion test results raise energy hopes" published from http://news.bbc.co.uk/2/hi/science/nature/8485669.stm
Science and technology reporter, BBC News
A major hurdle to producing fusion energy using lasers has been swept aside, results in a new report show.
The controlled fusion of atoms - creating conditions like those in our Sun - has long been touted as a possible revolutionary energy source.
However, there have been doubts about the use of powerful lasers for fusion energy because the "plasma" they create could interrupt the fusion.
An article in Science showed the plasma is far less of a problem than expected.
The report is based on the first experiments from the National Ignition Facility (Nif) in the US that used all 192 of its laser beams.
Along the way, the experiments smashed the record for the highest energy from a laser - by a factor of 20.
Star power
Construction of the National Ignition Facility began at Lawrence Livermore National Laboratory in 1997, and was formally completed in May 2009.
The goal, as its name implies, is to harness the power of the largest laser ever built to start "ignition" - effectively a carefully controlled thermonuclear explosion.
INERTIAL CONFINEMENT FUSION 192 laser beams are focused through holes in a target container called a hohlraum Inside the hohlraum is a tiny pellet containing an extremely cold, solid mixture of hydrogen isotopes Lasers strike the hohlraum's walls, which in turn radiate X-rays X-rays strip material from the outer shell of the fuel pellet, heating it up to millions of degrees If the compression of the fuel is high enough and uniform enough, nuclear fusion can result Giant laser experiment powers up It is markedly different from current nuclear power, which operates through splitting atoms - fission - rather than squashing them together in fusion.
Proving that such a lab-based fusion reaction can release more energy than is required to start it - rising above the so-called breakeven point - could herald a new era in large-scale energy production.
In the approach Nif takes, called inertial confinement fusion, the target is a centimetre-scale cylinder of gold called a hohlraum.
It contains a tiny pellet of fuel made from an isotope of hydrogen called deuterium.
During 30 years of the laser fusion debate, one significant potential hurdle to the process has been the "plasma" that the lasers will create in the hohlraum.
The fear has been that the plasma, a roiling soup of charged particles, would interrupt the target's ability to absorb the lasers' energy and funnel it uniformly into the fuel, compressing it and causing ignition.
Siegfried Glenzer, the Nif plasma scientist, led a team to test that theory, smashing records along the way.
"We hit it with 669 kilojoules - 20 times more than any previous laser facility," Nif's Siegfried Glenzer told BBC News.
That isn't that much total energy; it's about enough to boil a one-litre kettle twice over.
However, the beams delivered their energy in pulses lasting a little more than 10 billionths of a second.
By way of comparison, if that power could be maintained, it would boil the contents of more than 50 Olympic-sized swimming pools in a second.
'Dramatic step'
Crucially, the recent experiments provided proof that the plasma did not reduce the hohlraum's ability to absorb the incident laser light; it absorbed about 95%.
But more than that, Dr Glenzer's team discovered that the plasma can actually be carefully manipulated to increase the uniformity of the compression.
The 130-tonne target chamber is kept under vacuum for the experiments "For the first time ever in the 50-year journey of laser fusion, these laser-plasma interactions have been shown to be less of a problem than predicted, not more," said Mike Dunne, director of the UK's Central Laser Facility and leader of the European laser fusion effort known as HiPER.
"I can't overstate how dramatic a step that is," he told BBC News. "Many people a year ago were saying the project would be dead by now."
Adding momentum to the ignition quest, Lawrence Livermore National Laboratory announced on Wednesday that, since the Science results were first obtained, the pulse energy record had been smashed again.
They now report an energy of one megajoule on target - 50% higher than the amount reported in Science.
The current calculations show that about 1.2 megajoules of energy will be enough for ignition, and currently Nif can run as high as 1.8 megajoules.
Dr Glenzer said that experiments using slightly larger hohlraums with fusion-ready fuel pellets - including a mix of the hydrogen isotopes deuterium as well as tritium - should begin before May, slowly ramping up to the 1.2 megajoule mark.
"The bottom line is that we can extrapolate those data to the experiments we are planning this year and the results show that we will be able to drive the capsule towards ignition," said Dr Glenzer.
Before those experiments can even begin, however, the target chamber must be prepared with shields that can block the copious neutrons that a fusion reaction would produce.
But Dr Glenzer is confident that with everything in place, ignition is on the horizon.
He added, quite simply, "It's going to happen this year."
"Fusion Power a Step Closer After Giant Laser Blast" published from http://news.nationalgeographic.com/news/2010/01/100128-nuclear-fusion-power-lasers-science/
"Laser fusion test results raise energy hopes" published from http://news.bbc.co.uk/2/hi/science/nature/8485669.stm
