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Dropout
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You got temperature and/or pressure, and one simple atom to play with. What's the big deal?
As MaWM indicated it's many ionized atoms (free nuclei and electrons) magnetically confined in a plasma. The plasma is loosing energy very rapidly due to phenomena like brehmsstrahlung and cyclotron radiation, while nuclei scatter more often than they fuse.Dropout said:You got temperature and/or pressure, and one simple atom to play with. What's the big deal?
Dropout,Dropout said:You got temperature and/or pressure, and one simple atom to play with. What's the big deal?
Dropout said:You got temperature and/or pressure, and one simple atom to play with. What's the big deal?
Confinement time ala Larsen would apply to confinement approaches, inertial or magnetic. Confinement time does not seem to apply to any of the several beam - beam approaches (e.g. IEC). That is, there's no intention to do ignition; they are purely 'driven' schemes. - Not that IEC has shown any possibility of power productionMorbius said:"..., AND for a long enough time.
mheslep,mheslep said:Confinement time does not seem to apply to any of the several beam - beam approaches (e.g. IEC). That is, there's no intention to do ignition; they are purely 'driven' schemes.
Morbius said:mheslep,
The designs for the NIF - the National Ignition Facility are intended to "do ignition".
Morbius said:The designs for the NIF - the National Ignition Facility are intended to "do ignition"
Jeff,JeffKoch said:Yes, but it's hard to imagine making a practical fusion reactor with ICF, in large part because of the required repetition rate.
Maybe these problems will eventually be solved, but probably not in our lifetimes.
Jeff,JeffKoch said:Yes, I know people are thinking about reactors - there are some interesting concepts, They have to be fired somehow into the reactor at 10 Hz, aimed with micron precision over meter distances, in a manner that doesn't ruin the ice.
And at this point we don't really even understand the requirements on an ignitable target, all we have are simulation predictions that (based on long history) will almost certainly turn out to be wrong in significant ways.
Morbius said:ALL of your concerns HAVE been addressed.
Morbius said:You are wrong again here. We DO understand - not just in simulations - but from experiment what the requirements of an ignitable target are.
Jeff,JeffKoch said:You sound like a designer.This is very naive, because Halite/Centurion experiments used a multi-terrajoule driver (a bomb), not a megajoule laser - you can afford to be sloppy when you have so much energy available.
From the referenced Jason's report:Morbius said:If you are citing the Federation of American Scientists website - then you are NOT on the
"cutting edge" of the technology like those of us who are actually developing the software
and designs. [ Besides that JASON report is nearly 3 years out of date. ]
Care to comment? Did NIF implement any of the Jason report's recommendations?...5. What is the prospect for achieving ignition in 2010?
First attempts to achieve ignition on NIF are likely to take place in 2010 — this is an
important and valuable goal that has strongly focused the efforts of the NIF Program. The
scientific and technical challenges in such a complex activity suggest that success in the
early attempts at ignition in 2010, while possible, is unlikely. ...
Morbius said:For Heaven's sake - use your BRAIN!
mheslep said:Did NIF implement any of the Jason report's recommendations?
Morbius said:If you are citing the Federation of American Scientists website - then you are NOT on the "cutting edge" of the technology like those of us who are actually developing the software and designs.
Thanks, Coin, that's a good article. Nice little summary of power input into ITER.Coin said:http://www.theoildrum.com/node/2164 It is kind of long but it is worth the effort. Basically there are several very serious engineering hurdles to making a fusion reactor that can be used to actually produce power. Even once you can sustain a plasma, some of the parts involved in actually getting energy out of that plasma present multi-decade engineering challenges all by themselves! There is also the problem that operating a fusion reactor consumes some unusual substances like tritium, so you have to engineer your reactor to for example create more tritium as it goes... there's a timetable they expect to resolve all these issues on, but it is not trivial. Worth a look...
It would be desirable to have a continually operating plant. The power generation cycle is critical for a viable system, at least in todays environment.Power will be feed into the ITER plasma in three main ways: by transformer action causing up to 15 million amps to flow in the plasma; by neutral high energy beams of deuterium and tritium fired into the plasma; and by radio frequency energy fed in from antenna patches in the walls to excite resonances in the plasma, Transformer action is very efficient but necessarily pulsed. The other two forms of heating are less efficient but can be continuous. ITER is expected to generate 500MW of fusion energy output, with less than a tenth of that input power (Q>10) and hold that power for 400 seconds. Also it should generate 500MW output for an hour at an input of one fifth the input energy (Q>5). Although it is not stated as an aim, there is the hope that it might achieve what is called ignition where enough of the fusion energy remains in the plasma to keep the reaction going without the need of external input energy (Q = infinity). This will require higher plasma densities than needed with external energy input.
mheslep said:Confinement time ala Larsen would apply to confinement approaches, inertial or magnetic. Confinement time does not seem to apply to any of the several beam - beam approaches (e.g. http://en.wikipedia.org/wiki/Inertial_electrostatic_confinement" ). That is, there's no intention to do ignition; they are purely 'driven' schemes. - Not that IEC has shown any possibility of power production
The US has been against the French option because of France's opposition to the US-led invasion of Iraq.
Count Iblis said:http://news.bbc.co.uk/2/hi/science/nature/3336701.stm"
ITER was delayed because the participants couldn't agree on where to build it. When most were in favor of building it in France, the Iraq war started and the US didn't like that idea anymore:
What a way to make decisions on science and technology
Come up with 10 billion euros, and one can put a fusion reactor anywhere one likes.Count Iblis said:http://news.bbc.co.uk/2/hi/science/nature/3336701.stm"
ITER was delayed because the participants couldn't agree on where to build it. When most were in favor of building it in France, the Iraq war started and the US didn't like that idea anymore:
What a way to make decisions on science and technology
http://europa.eu/rapid/pressReleasesAction.do?reference=MEMO/05/226ITER construction costs are estimated at 4.57B€ (at 2000 prices), to be spread over about ten years. Estimated total operating costs over the expected operational lifetime of about twenty years are of a similar order.
This month, funders of the €10 billion ITER fusion project, which seeks to demonstrate that a burning plasma can be controlled to produce useful energy, face the daunting task of keeping the project's budget under control, as scientists present a wish list of design changes.
http://en.wikipedia.org/wiki/Superconducting_Super_Collider#CancellationDuring the design and the first construction stage, a heated debate ensued about the high cost of the project. In 1987, Congress was told the project could be completed for $4.4 billion, but by 1993 the cost projection exceeded $12 billion.
http://www.hep.net/ssc/new/history/appendixa.htmlDetailed design and early construction work was proceeding on all major machine components. "The conventional construction for the first stage of the injection complex, consisting of the ion source and a linear accelerator stationed in a 250-meter tunnel, was complete." The first circular accelerator in the chain, the Low Energy Booster (LEB), consisting of a 600-meter circumference ring filled with resistive magnets, was designed and 90% of the tunnel complete. The next element in the sequence, the Medium Energy Booster (MEB), consisting of a ring of 4.0 kilometers in circumference, again using resistive magnet technology, was designed and excavation of the tunnel had started. The third and final accelerator before entering the large collider rings, the High Energy Booster (HEB), consisting of 10.8 kilometer circumference tunnel filled with superconducting magnets, was under design. Finally, for the 87.1 kilometer circumference collider ring, the excavation of seventeen shafts was complete, and the tunnel boring, begun in January 1993, had proceeded rapidly, with 77,065 feet (roughly 23 kilometers) completed by fall 1993.
I find Rider helpful. He shows why some of the IEC and other ideas, as envisioned at the time must fail, and, like any good work, shows you where not to waste your time and the obstacles that must be overcome. He does not shut the door on everything fusion; towards the back of that thesis there are some work-around suggestions and a good quote from Mark Twain about the perils of 'knowing absolutely' that a problem can never be solved.gdp said:Todd H. Rider investigated such systems from a very generic (e.g., Kinetic Theory and 2nd Law) viewpoint in his Ph. D. Thesis in Nuclear Engineering, http://dspace.mit.edu/handle/1721.1/11412"
His basic (and quite depressing) conclusions are as follows:
...
mheslep said:I find Rider helpful. He shows why some of the IEC and other ideas, as envisioned at the time must fail,...