Clean electrical power from a fusion reactor remains distant, but it's one step less so after a test where fusion energy output exceeded the energy pumped into a fuel pellet. February 13, 2014 7:39 AM PST This close-up photo shows the container, about the size of a pencil eraser, that contains a tiny pellet of deuterium-tritium fuel. Ultraviolet lasers pound it with enough energy to trigger fusion. (Credit: Lawrence Livermore National Laboratory) Scientists at Lawrence Livermore National Laboratory reported an important step on the way to fusion energy, a reaction in which fusing hydrogen gave off more energy than the lasers put in to initiate the reaction. Fusion, the reaction that powers the sun and the more powerful part of thermonuclear explosions, combines lightweight atoms like hydrogen and releases a lot of energy in the process. In contrast, with the fission reactions that powered the first atomic weapons and today's nuclear power reactors, heavy elements like uranium split to release energy. Scientists long have hoped to harness fusion's power to produce energy free from the the radioactive byproducts that are so troublesome with fission reactors. But controlled fusion has been extremely hard to create: it requires an extraordinarily high concentration of energy to get the reaction started and to produce enough extra energy to produce a self-sustaining reaction. Related stories Japan unveils $800 radiation-proof underwear Sweden faces its own shutdown: Cause? Jellyfish Yes, atomic bomb that fell in US almost went off, says document More bad news from Fukushima as reactor leaks continue An atomic anniversary for the Bikini Atoll (pictures) The researchers at LLNL's National Ignition Facility (NIF) achieved "fuel gains," meaning that they got more energy out of fusion from a tiny capsule about a millimeter across that contains deuterium and tritium, isotopes of hydrogen with one and two neutrons, respectively. It's machined with extremely high precision and mounted at the center of 192 ultraviolet lasers that pack a walloping 1.85 megajoules of energy. The results, published Wednesday in the journal Nature, yielded results ten times better than previous deuterium-tritium experiments, the researchers said. However, it was still well short of "ignition," in which the energy produced exceeds what the entire experiment used, not just the smaller amount that actually reached the fuel. Controlled fusion has proved a famously elusive idea, and NIF has worked for years to get this far. The researchers did see progress on another front called boot-strapping, a phenomenon that's part of achieving a self-sustaining fusion reaction. The boot-strapping process takes place when helium nucleii -- each one a pair of protons and a pair of neutrons produced by the fusion reaction -- imparts its energy to further fusion rather than escaping. "We also see...evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite," the researchers said. NIF's funding comes from the US government's Stockpile Stewardship program, designed to ensure nuclear weapons' reliability and storage safety even without underground nuclear tests. Improving the country's energy security, though, also is a goal.
Clean electrical power from a fusion reactor remains distant, but it's one step less so after a test where fusion energy output exceeded the energy pumped into a fuel pellet.
This close-up photo shows the container, about the size of a pencil eraser, that contains a tiny pellet of deuterium-tritium fuel. Ultraviolet lasers pound it with enough energy to trigger fusion.
(Credit: Lawrence Livermore National Laboratory)
Scientists at Lawrence Livermore National Laboratory reported an important step on the way to fusion energy, a reaction in which fusing hydrogen gave off more energy than the lasers put in to initiate the reaction.
Fusion, the reaction that powers the sun and the more powerful part of thermonuclear explosions, combines lightweight atoms like hydrogen and releases a lot of energy in the process. In contrast, with the fission reactions that powered the first atomic weapons and today's nuclear power reactors, heavy elements like uranium split to release energy.
Scientists long have hoped to harness fusion's power to produce energy free from the the radioactive byproducts that are so troublesome with fission reactors. But controlled fusion has been extremely hard to create: it requires an extraordinarily high concentration of energy to get the reaction started and to produce enough extra energy to produce a self-sustaining reaction.
Related stories
- Japan unveils $800 radiation-proof underwear
- Sweden faces its own shutdown: Cause? Jellyfish
- Yes, atomic bomb that fell in US almost went off, says document
- More bad news from Fukushima as reactor leaks continue
- An atomic anniversary for the Bikini Atoll (pictures)
The researchers at LLNL's National Ignition Facility (NIF) achieved "fuel gains," meaning that they got more energy out of fusion from a tiny capsule about a millimeter across that contains deuterium and tritium, isotopes of hydrogen with one and two neutrons, respectively. It's machined with extremely high precision and mounted at the center of 192 ultraviolet lasers that pack a walloping 1.85 megajoules of energy.
The results, published Wednesday in the journal Nature, yielded results ten times better than previous deuterium-tritium experiments, the researchers said.
However, it was still well short of "ignition," in which the energy produced exceeds what the entire experiment used, not just the smaller amount that actually reached the fuel. Controlled fusion has proved a famously elusive idea, and NIF has worked for years to get this far.
The researchers did see progress on another front called boot-strapping, a phenomenon that's part of achieving a self-sustaining fusion reaction. The boot-strapping process takes place when helium nucleii -- each one a pair of protons and a pair of neutrons produced by the fusion reaction -- imparts its energy to further fusion rather than escaping.
"We also see...evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite," the researchers said.
NIF's funding comes from the US government's Stockpile Stewardship program, designed to ensure nuclear weapons' reliability and storage safety even without underground nuclear tests. Improving the country's energy security, though, also is a goal.
