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Germany Fires Up Bizarre New Fusion Reactor (sciencemag.org)
New submitter insitus writes: On 10 December, Germany's new Wendelstein 7-X stellarator was fired up for the first time, rounding off a construction effort that took nearly 2 decades and cost €1 billion. Initially and for the first couple of months, the reactor will be filled with helium—an unreactive gas—so that operators can make sure that they can control and heat the gas effectively. At the end of January, experiments will begin with hydrogen in an effort to show that fusing hydrogen isotopes can be a viable source of clean and virtually limitless energy.
You don't have to "draw off" energy - the plasma is more than happy to lose heat to its surroundings. The biggest challenge with fusion is to stop the plasma from giving up its energy too fast!
That said, for continuously operating toruses you do have to "draw off" the "ash" (helium) by means of an "exhaust" system that juts up into the outer reaches of the plasma stream (where the heavier helium concentrates), which is "a" challenge (the component is subject to a very hostile environment and faces huge thermal loads), but it's not a showstopper challenge by any means.
Nothing says 'welcome to the neighborhood' like a gunny sack full of dead squirrels.
I should have wikied before I posted:
https://en.wikipedia.org/wiki/...
Take a look at the specs in TFA. The magnets in this system are cooled with liquid helium to -270 deg C. The plasma sits inside the magnets. Thus any energy extracted from the plasma has to cross the boundary of the magnets, while at the same time not upsetting the magnets themselves.. What I want is an explanation of how this aspect is being considered. Once you have the energy out of the core you can pipe it into turbines to produce electricity. But that part is easily done.
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Hey, to be fair.... Their Zeppelins where the killer technology of the day and even though they sparked a bit less than a revolution in transportation technology they certainly where on the cutting edge. Had the Hindenburg not burned and crashed in Lakehurst JN, live on the radio, I dare say these things would have at least changed the investment mix in passenger aviation up until war broke out two years later...
What you really need to look out for is how useless various Germen inventions turn out to actually be to the Germans themselves. They have had horrible luck in their timing... The zeppelin rage which would have ended abruptly at the start of WW2, even without the burn and crash that ended it 2 years sooner. The development of modern rocketry, only to have it's effectiveness fail to alter the effort to prevail in war, the fielding of the ONLY jet fighter of WW2 which out classed and out ran ANYTHING flying only too late to make a difference. Their inventions of navigating aircraft to precise locations over long distances using this new radio technology and the invention of RADAR prior to WW2. No Germany has lots of luck inventing things, but horrible luck with the timing and application of them.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
For Tokamaks, the energy-generation method involves catching high-energy particles emitted from the fusion reaction using a system on the outer shell of the containment vessel. This implies that the shell will degrade over time and need replacement, and that the containment vessel must be transparent to those particles. I'm going to assume that for an actual power-generating Stellarator design, there'd be a similar set-up -- unless there's some method by which the oddly-shaped magnetic field causes controlled amounts of particles to escape at well-defined points.
You're quite right in asking how the energy comes out. This is indeed one of the major challenges of fusion energy.
Nothing says success like the juxtaposition of "Germany" and "technological innovation involving a hydrogen filled container".
Hydrogen didn't bring down Hindenburg. It was pilot error. Here is what most likely happened:
Hindenburg was 12 hours late and would be even more late due to a thunderstorm. To prevent being so late that they had to delay the return trip too, the captain decided to go closer to the thunderstorm than normally allowed. On arrival, he decided to land even though the winds exceeded the limits for allowing landing. So far everything has been facts. The next is speculation based on circumstantial evidence and later tests.
A gust of wind threw Hindenburg out of the landing approach and to counter that, full rudder was applied. This was not allowed during landing due to structural stress and a wire holding the shape of the "cigar" snapped and punctured a hydrogen container. The ship was statically charged from flying too close to the thunderstorm. As a guidewire touched the ground and the front of the ship at the same time, the front suddenly started burning, presumably started by a static discharge. Based on color descriptions of the fire, the fire started in the water protecting coat on the canvas. After that burned for a while, it reached the leaked hydrogen.
Here is the thing: if the ship used helium and not hydrogen, it would still have burned and crashed. It was doomed even before the hydrogen caught fire. Even prior to the accident, the coating was disputed due to safety concerns. It was really good at keeping the water out, but the fire hazard was ignored and some of the few knowing this objected in writing. This writing still exist. Also had the captain decided to delay further due to safety concerns, nothing bad would have happened to him and the accident would have been avoided. However his pride didn't allow that and on behalf of Germany he wanted to return to Europe in time for the passengers to make it to the Coronation of King George VI and Queen Elizabeth. Sure that was important, but important enough to crash?
This type of accident is not unique to Germany or the past. In 2001, American Airlines Flight 587 taking off from New York encountered wake turbulence from the plane ahead of it. The pilot used the rudder quite a lot to counter it, despite the fact that full rudder is banned at that altitude/speed due to structural concerns of the plane. Parts of the tail fell off, the plane went out of control and crashed into Queens. It turned out that the pilot did precisely what he was told to do during training and a faulty training program was the main cause of the accident. Needless to say wake turbulence countermeasure training changed overnight.