Fusion energy: NIF experiments show initial gain in fusion fuel

Feb 12, 2014
Cryogenic target positioner with target. Credit: Dr. Eddie Dewald (LLNL and member of high-foot team)

Ignition – the process of releasing fusion energy equal to or greater than the amount of energy used to confine the fuel – has long been considered the "holy grail" of inertial confinement fusion science. A key step along the path to ignition is to have "fuel gains" greater than unity, where the energy generated through fusion reactions exceeds the amount of energy deposited into the fusion fuel.

Though ignition remains the ultimate goal, the milestone of achieving gains greater than 1 has been reached for the first time ever on any facility. In a paper published in the Feb. 12 online issue of the journal Nature, scientists at Lawrence Livermore National Laboratory (LLNL) detail a series of experiments on the National Ignition Facility (NIF), which show an order of magnitude improvement in yield performance over past experiments.

"What's really exciting is that we are seeing a steadily increasing contribution to the yield coming from the boot-strapping process we call alpha-particle self-heating as we push the implosion a little harder each time," said lead author Omar Hurricane.

Boot-strapping results when , helium nuclei produced in the DT process, deposit their energy in the deuterium-tritium (DT) fuel, rather than escaping. The alpha particles further heat the fuel, increasing the rate of fusion reactions, thus producing more alpha particles. This feedback process is the mechanism that leads to ignition. As reported in Nature, the boot-strapping process has been demonstrated in a series of experiments in which the fusion yield has been systematically increased by more than a factor of 10 over previous approaches.

Hohlraum geometry with a capsule inside through the cut-away of the hohlraum wall. Credit: Dr. Eddie Dewald (LLNL and member of high-foot team)

The experimental series was carefully designed to avoid breakup of the plastic shell that surrounds and confines the DT fuel as it is compressed. It was hypothesized that the breakup was the source of degraded fusion yields observed in previous experiments. By modifying the laser pulse used to compress the fuel, the instability that causes break-up was suppressed. The higher yields that were obtained affirmed the hypothesis, and demonstrated the onset of boot-strapping.

The experimental results have matched computer simulations much better than previous experiments, providing an important benchmark for the models used to predict the behavior of matter under conditions similar to those generated during a nuclear explosion, a primary goal for the NIF.

The chief mission of NIF is to provide experimental insight and data for the National Nuclear Security Administration's science-based Stockpile Stewardship Program. This experiment represents an important milestone in the continuing demonstration that the stockpile can be kept safe, secure and reliable without a return to nuclear testing. Ignition physics and performance also play a key role in fundamental science, and for potential energy applications.

"There is more work to do and physics problems that need to be addressed before we get to the end," said Hurricane, "but our team is working to address all the challenges, and that's what a scientific team thrives on."

Explore further: Omega Laser Facility completes record 25,000 experiments

More information: Paper: dx.doi.org/10.1038/nature13008

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User comments : 6

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vlaaing peerd
1 / 5 (1) Feb 13, 2014
and we score! earth fusion vs sun fusion 1 - 999999999999~
1 / 5 (1) Feb 13, 2014
while interesting I'm still not sure why D-T neutron generators could not be used as a heat and energy source.
Feb 13, 2014
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Feb 13, 2014
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2.3 / 5 (3) Feb 13, 2014
This seems to be the same claim that was circulating a few months back. The difference this time is that they have published their results, and not only made a press-release. The pulse shaping they seem to be describing in the article isn't a new technique on the whole, but the specifics of the pulse shaping employed here probably are. Pulse shaping in general has been part of laser fusion research since the 1960s. It involves varying the laser pulse so that the pellet compresses in very specific ways. Here is another article about these results from when they were first announced several months ago. I doubt that anyone in the scientific community actually thinks that fusion power plants will ever come from NIF-like configurations.
1.8 / 5 (5) Feb 14, 2014

"Ignition – the process of releasing fusion energy equal to or greater than the amount of energy used ...."

My comments: it is greater than the amount of energy [?] used to confine the fuel

"Boot-strapping results when alpha particles, ...., thus producing more alpha particles."

"The experimental series was carefully designed to avoid breakup of the plastic shell that surrounds and confines the DT fuel as it is compressed.....previous experiments."

My comment- proper shielding gives value of exact energy released, which is more than our imagination. This will also change the value of E=mc². The value of E is the energy which give us desired result but it does not means energy released is equal to E only.


I am continuously writing in my blog [http://swarajgrou...-in.html]
3.7 / 5 (3) Feb 14, 2014
What is far different now is that our computers have become enabling modeling technology such that our results are now closely aligned with the computer models. Our new models are showing how to succeed, step by step. We are now doing those steps, and making progress exponentially where before we groped in the dark. A prime example is 'focus fusion', a process being built in a small New Jersey lab. The success of this small project is the incremental following of successively more precise and accurate computer models. Such is possible because of those computers of today with far greater capabilities than our father's and mother's pooters.
1 / 5 (4) Feb 15, 2014
I have already hinted in my blog on 20th, June'2013, ABOUT 8 MONTHS AGO [http://swarajgrou...-in.html] that I can explain "Why the value of energy in E = mc² is more than the calculated value"