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Wendelstein 7-X Fusion Reactor Produces Its First Flash of Hydrogen Plasma (gizmag.com)
Zothecula writes: Experimentation with Germany's newest fusion reactor is beginning to heat up, to temperatures of around 80 million degrees Celsius, to be precise. Having fired up the Wendelstein 7-X to produce helium plasma late last year, researchers have built on their early success to generate its first hydrogen plasma, an event they say begins the true scientific operation of the world's largest fusion stellarator.
And I wish them godspeed. Energy and information are the fundamental limits of the human condition. Fundamental leaps in either arena will be transformative.
So I've read the Wikipedia articles on the 7-X and on stellarators in general, but I'm not a physicist.
Can someone knowledgeable tell me how to feel about this? Does this represent meaningful progress toward fusion power? If so, how meaningful? Is fusion still 50 years away, or are we down to 49 now?
Sorry, what definition of precise are we using here?
I'll be glad when we get through this shakedown period of falling editorial quality by ... well, by timothy, actually.
Lost at C:>. Found at C.
You should feel whatever you feel, unless you're a robot, in which case: /apply feeling hopeful.
Part of the fusion problem is keeping the hydrogen confined in the plasma. A stellator does this by shaping the magnetic field in such a way that the plasma twists and constricts itself. So instead of constraining a moving plasma, the moving plasma constrains itself.
This requires a precise shaping of the magnetic field via superconducting magnets, and the design of these has only recently become possible with advanced calculations on supercomputers.
So this is a test run of a new kind of fusion reactor. If it works, it will change the world. And so far so good, but we won't know until it works until all following tests succeed.
I'm not particularly knowledgable, just an armchair physicist. I can only dream of a different path taken where I would have done this research. And keep in mind that fuel costs are a tiny drop in the bucket for a modern fission reactor. They could increase 100-fold without significantly altering the end-user cost of power. Fusion is still going to require big, expensive plants (they will just have lower fuel and waste handling costs). With that being said, there are a few BIG problems to overcome (but no one climbed a mountain with a single step).
Materials - Tritium / Deuterium fusion is NASTY, but it's what we're going to be able to get to at first. As in, higher neutron-flux than a commercial fission reactor nasty. Neutron damage causes lots of weird effects including metal embrittlement and radioactivation. Getting confinement good enough for net power generation is a big problem, but so is keeping the machine pieces operable for an economically feasible length of time.
Energy harvesting - T + D fusion is again unpleasant for this. Because a large portion of the energy released from this fusion is in the neutron it throws, most of the schemes for turning fusion into electrical power involve using the neutron to heat stuff up (like a liquid lithium blanket) and then go through a standard heat-to-steam turbine cycle. Less than ideal.
Confinement - We're going to start with T + D fusion. Which has already been super hard to get a magnetic field the right shape and strength to support. But where we want to end up is simple Hydrogen (a proton) + Boron. There are several challenges (power balance, temperature/pressure/density) here but they can be summarized as being 500 times greater than simple T + D fusion. This kind of fusion won't produce nearly as many neutrons, which means most of the energy will be in the form of charged particles that can be directly harvested for energy. Which is great, but it's 500 times as hard as the thing we haven't achieved yet.
As a former program officer for the Office of Fusion Energy, US Department of Energy I can assure you even if the Stellarator "works", it will not be a practical source of power. The complex engineering and cost make harvesting energy from fusion impractical.
I could fill a page on enumerating them. For one -- fast neutrons can destroy any material known. No one has come up with a design for the the first wall that captures the neutrons and energy.
The old quip is "Fusion has been 25 years in the future for the last 50 years.
The "50 years away" stuff is a really unfair criticism. The amount of progress that's occurred in the past several decades is many orders of magnitude - JT-60 has even gotten to Q=1.25, which means they were getting 25% more power out than they were putting in to maintain the reactor in steady-state operation.
Part of the reason that this concept got started was because of a big mistake early on with the ZETA program. Unbeknownst to them, A) heavy electron bombardment of their detectors was leading to false spectral shift readings, making them think that the temperature was much hotter than it was, and B) there was a possible method to create neutrons that they were unaware could be significant - heavy localized acceleration of ions causing spallation impacts. The unfortunate part was, by coincidence, (B) happened to produce roughly the amount of neutrons that would be expected by (A). So they thought that they were just a short step away from a viable fusion reactor, when in reality they weren't even close. Due to the more primitive technology at the time, not only did they not have detailed computer models that could have warned them to expect the neutrons, but they also didn't have a convenient way to measure neutron energies (it was this that later proved their early conclusions wrong). Their lack of computer models also meant that they were unaware of how much of a problem drift would be.
It's a very different situation today. There's really no question that we can viably produce fusion power today. The real question hanging over our heads is, what is it going to cost? How can we engineer a system to produce power affordably? And that's the real question that's going to take a lot of work to figure out. One thing is for sure, though: the higher the magnetic fields you can get for a given cost, the vastly easier it becomes. And these new high temperature superconductor tapes could push us leaps and bounds even beyond ITER, whether you go with a stellerator, a more traditional tokamak, or really anything else that employs magnetic fields. It's very encouraging for the field to see a route that already looked to be on a positive path get such a "bonus".
It's times like this I wish I had a friend named 'The Professor'.
Germany's newest fusion reactor is beginning to heat up, to temperatures of around 80 million degrees Celsius
80 million Celsius? That's on par with a Hot Pocket that's been microwaved too long. I wonder if they are using Hot Pocket technology. ;)
Anons need not reply. Questions end with a question mark.
There is also the element of funding for R&D. In the late 70's the DoE produced a fusion roadmap based on different funding levels. There was a crash program forcast which would have led to commercial fusion in 10-15 years, a robust development program that would led to fusion in 15-20 years, and a point where if funding remained below a certain level, would never lead to commercial fusion. Guess what funding level was chosen (well below the "fusion never" level). So the joke of "fusion is the technology of the future and always will be", is a result of no real investment being made. Sure ITER may be a $15billion project, but its also a 50 year long project. First announced in 1985, first plasma wont occur till 2025, that's 40 fricken years later, not exactly demonstrative of an intensive focus on developing fusion energy. Compared to what we invest in developing other sources of energy, its chump change
As an engineer working in the fusion field, I would not agree it's quite so rosy a picture. *Lots* of issues need to be solved technologically, although I agree with you the physics side of Tokamaks is relatively understood. I.e. it would be a huge shocker if ITER didn't produce the power expected. Tokamaks are however very unreliable with stability, and whether or not these can be controlled and mitigated enough for reliable power production remains to be seen. Further, going from ITER to DEMO is like launching a rocket to space vs. going to the moon; the high energy neutron flux from a fusion reactor will centimeters of the first wall to powder. Getting enough lithium around the wall for tritium breeding and heat removal for a steam cycle is very difficult.
In the end, it's all economics as you say. I can't imagine with the present state of technology a viable commercial fusion reactor online until past 2100. ITER will be ~2030, DEMO ~2070 if ITER cost/is any clue. Say you're making a decision for a company - would you rather spend $20 billion dollars on a very finicky tokamak fusion reactor with tremendous maintenance costs (tritium recycling, lithium management, disruption and instability mitigation systems, etc.), or a gen III or IV nuclear reactor - perhaps a thorium molten salt reactor - that produces the same power reliably for a small fraction of the cost?
Commercial fusion will happen eventually, but in my opinion not without tremendous advances in materials science and superconducting magnets. One can imagine with clever first wall materials and >20 T fields using advanced BSCCO superconducting materials (or other) a reactor might become as affordable as a fission reactor of the same power output. Contrary to what fusion researchers will have you believe, fusion will always be in economic competition with fission.
This PDF sums it up pretty nicely: http://www.askmar.com/Robert%20Bussard/The%20Trouble%20With%20Fusion.pdf
WTF is this? A knowledgeable reply containing a citation to a scholarly article?
Has Slashdot come to THIS?
I'm taking my sockpuppet and going home.
Germany migrates away from nuclear fission power, yes. But Germany is still funding science, and that not only if there is "return on investment" to be expected before the next elections.
Might be that fusion power won't be required right when it becomes feasible. But humankind might be happy to have it at hand during the next ice age.
The plasma facing material faces a flux of 1 neutron per 17,6Mev. By contrast, nuclear fuel cladding faces a flux of ~2,5 neutrons per 202,5 Mev, or 1 per 81 MeV. It's certainly higher, but it's not a whole different ballpark. And yes, you're dealing with higher energy neutrons but in a way that can help you - you've often got lower cross sections (for example), and in most cases you want the first wall to just let neutrons past.
There's a number of materials with acceptable properties. Graphite is fine (no wigner energy problems at those temperatures). Beryllium is great, and you need it anyway. In areas where the blanket isn't, boron carbide is great. Etc. These materials aren't perfect, but they're not things that get rapidly "converted into dust" by neutrons. Really, it's not the first wall in general anyway that I'd have concerns about, it's the divertor. The issue isn't so much that it takes a high neutron and alpha flux and "erodes" fast - that doesn't change the reactor's overall neutrons per unit power output ratio, and if you have a singular component that needs regular replacement, said replacement can be optimized. The issue is that you have to bear such an incredible thermal flux on one component. Generally you want to spread out thermal loads, it makes things a lot easier.
It's times like this I wish I had a friend named 'The Professor'.