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  • #733
    BreakableBreakable
    Keymaster

    http://www.popsci.com/technology/article/2010-01/nif-moves-59-million-degrees-closer-fusion-power

    The scientists measured the record-breaking temperature by looking at the X-ray radiation emitted by the imploding gold capsule. The data shows that the lasers are hot enough, and targeted correctly enough, to proceed to the next step: actual fusion.
    Currently, there’s no date for when the lab will attempt to implode actual fusion fuel, but it will probably take at least a couple of months. In the meanwhile, to get an idea of the kinds of temperatures and energies the NIF scientists are dealing with, just take a look at that giant yellow thing in the sky

    #5799
    BreakableBreakable
    Keymaster

    I changed the title after some thinking. I thought it was about q>1, but it was about ignition temperature.

    #5800
    AvatarDr_Barnowl
    Member

    BBC report on NIF

    Look at the photo of the chamber near the bottom – all 130 metric tonnes of it. And it doesn’t even include all the ancillary equipment like the lasers.

    I hadn’t realized how much the alignment of the holhraum mattered either ; I just thought they blasted the outside of it, but another picture indicates the beams have to thread through the holes in either end.

    So if you want to use this for serious energy generation, not only do you have to have an ammunition factory churning out at least 10 fuel pellets a second, you have to have a gun that can shoot them 10 times a second… with extreme precision. The pellets are of course the most expensive bullets on the planet, made of a gold-uranium alloy with a beryllium core, all of which is a cheap coating for the tritium in the fuel mix.

    Plus all the engineering challenges of getting a huge bank of lasers to fire 10 times a second, and extracting useful working heat from a reaction chamber the size of someones apartment – so somehow you have to get all those heat exchangers in without disrupting any laser paths.

    Ok… so they’re dropping an order of magnitude more energy in their pellet (669 kJ vs 10s of kJ as per “paper 1”), after a quick search we find the holhraum is made of a gold-plated uranium-gold alloy (funny how they never mention the “uranium” part in the press releases ..), and that they are using around a milligram of fuel, which is enormous compared to a DPF plasmoid.

    Do any of the people who are actual physicists here take it seriously? Does it have civilian value or is it just a testbed for nuclear weapons without the weapons?

    #5802
    AvatarAeronaut
    Member

    Do any of the people who are actual physicists here take it seriously? Does it have civilian value or is it just a testbed for nuclear weapons without the weapons?

    Big science= big budgets= secure careers for government physicists, staffs, and vendors. It may well turn out to be the Cold War without the obvious weapons focus. I’m not a physicist, or even an engineer. At least not today, and not that I can show the sheepskins to prove. I see NIF, ITER, et al as being potentially useful… in the (unspecified future) as basic materials science research.

    The gotcha is the phrase ‘in the unspecified future’, which also serves a second purpose of supporting the status quo by conditioning the general population to consider fusion as something that even the gov a mint, wit all the time and money and talent they’ve been throwing at the problem, can’t do it, it can’t be done.

    Only a tiny percentage of the public reads beyond the top 3 results of a search, let alone past the first page or two. And SEO is designed to favor dot gov and dot edu domains, especially when they have thousands of pages about fusion research and related keywords. [end rant]

    #5803
    Avatartcg
    Member

    Perhaps the most important thing to remember about NIF and ITER is that they are primarily for research. The cheap generation of electricity is a peripheral objective, or smokescreen, if you prefer. These projects are designed to sop up as much government research money for as long as possible. In my line of work this is known as “milking the cow”.

    Few people have noticed that DPF devices have already achieved nuclear fusion, in one case nine years ago. The primary goal of the Lawrenceville project is the construction of a machine which will generate abundant cheap electricity, and although many obstacles remain to be overcome, progress has been steady.

    ITER and NIF will generate a lot of static, but whoever shows up first with results will get the prize.

    #5805
    AvatarKeithPickering
    Participant

    A few key points:
    1. The NIF breakthrough here is being able to use the plasma itself to focus the laser energy. The announcement today was basically that they’ve figured out how to do that. Which leads them to be confident that they will be able to achieve theoretical net gain by (I’ve read) sometime this summer.
    2. There is no way to turn this device into a practical electrical generator, as the posts above make clear.
    3. The real problem is one of headline-stealing and meme creation. I’m reminded of Langley vs. the Wright brothers in 1902/03. Langley had Smithsonian big bucks behind him, he built the big expensive, heavy machine, and it failed. The Wrights had nothing but ingenuity and the right approach. The Wrights did succeed, but nobody knew and nobody took the story seriously. If Langley failed, it must be impossible, right?

    #5807
    AvatarAeronaut
    Member

    The airplane is an excellent analogy, Keith. The Wright brothers got their glider technology proven before tacking a drive train onto it. They solved their challenges in the right order. Their big mistake was their paranoid secrecy once they’d done it a few times.

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