China's Fusion Reactor Reaches 100 Million Degrees Celsius (abc.net.au)

hackingbear shares a report from the Australian Broadcasting Corporation: The team of scientists from China's Institute of Plasma Physics announced this week that plasma in their Experimental Advanced Superconducting Tokamak (EAST) -- dubbed the 'artificial sun' -- reached a whopping 100 million degrees Celsius which is six times hotter than the core of the Sun. This temperature is the minimum required to maintain a fusion reaction that produces more power than it takes to run. The Chinese research team said they were able to achieve the record temperature through the use of various new techniques in heating and controlling the plasma, but could only maintain the state for around 10 seconds. The latest breakthrough provided experimental evidence that reaching the 100 million degrees Celsius mark is possible, according to China's Institute of Plasma Physics. "While the U.S. is putting new restrictions on nuclear technology exports to China, inventions and findings of EAST will be important contributions to the development of the International Thermonuclear Experimental Reactor (ITER)," writes Slashdot reader hackingbear. The reactor is currently being built in southern France with collaboration from 35 nations. According to the Australian Broadcasting Corporation, it is expected to be "the first device to consistently produce net energy, producing 500 megawatts of clean and sustainable power."

Comments

Re:Sun's core too cold for fusion, sort of

[timeOday]

Oh, that reminds me when I asked my chemistry teacher why water would evaporate even below the boiling point. He said something similar, the temperature is the average but on occasion a molecule gets enough energy to exceed the threshold (thus cooling the others when it leaves with its heat). Similar? Or not?

But how much is that in electron volts?

[Ungrounded Lightning]

China's Fusion Reactor Reaches 100 Million Degrees Celsius

Plasma energy sounds really large when you express it in temperature. But a more convenient gauge may be the voltage needed to accelerate the particles to velocity magnitudes correspondng to that sort of energy. This is also directly applicable to fusion systems, such as the Farnsworth-Hirsch or Bussard's Polywell, which use electric fields to accelerate the particles into the reaction volume.

Both electrons and hydrogen nuclei have a charge magnitude of 1, so dropping them across a potential difference of N volts adds N electron volts of energy to each particle. Then, if you let the plasma thermalize to a Maxwellâ"Boltzmann distribution, the electron temperature will be (by definition) the temperature of the distribution is about 2/3 that corresponding to the average electron energy.

So to go from degrees Celsius degrees (of a thermalized plasma) to electron volts:
  - Subtract 273.15 - a .003% drop in the bucket. (Kelvin step sizes are the same but Celsius starts at 273.15 Kelvin.)
  - Divide by 11,605 to get electron volts.
  - Multiply by 2/3 to get the average energy of the electrons and ions.

That's an acceleration voltage of 6,025 volts (or 9,037 if you're going to react them before they thermalize). That's right in the ballpark for high-end vacuum tube technology - like the second anode on a CRT. (Those ran about 3000 to 6000 V in the 1940s, and about 25,000 V when modern color tubes were being replaced by flat panels.)

You can see why we all had high hopes for things like Polywell, where (if it worked as expected) a "gassy vacuum tube" that would fit in a strip-mall store's back room, with all supporting equipment (mostly mid-20th-century style electronics), and provide 100 MW of DC at cross-country power line voltages.

Of course many of the other methods for directly heating plasma heat the electrons much more than the ions. So the average energy of the plasma may be substantially lower.

Re:Sun's core too cold for fusion, sort of

[Anonymous Coward]

Similar in that statistically unlikely things happen quite often with enough time or space.
The mean free path of a neutrino is calculated to be several light years through solid lead before hitting a particle.
However neutrinos are emitted by the sun so frequently and neutrino detectors are so large that we can detect them reasonably frequently.

ITER wont produce power

[angel'o'sphere]

It will run at 400 - 600 seconds and will produce more energy than it consumes, that is all. There is no power plant attached nor will there ever be: https://www.iter.org/sci/Goals

And the power production is not clean as long as we use deuterium + tritium, the reactor vessel will have to be replaced around every 10 years and discarded as highly radioactive waste.

Regarding sustainability: ITER will attempt to breed tritium ... lets see how good that works. Otherwise we had to farm tritium from the sea, which is energy intensive and causes another spot in the chain to work with an radioactive element.

Re:Gravitational plasma confinement/optical densit

[dryeo]

My understanding is that the energy output, per cubic meter, is about the same as the human body, 50-100 watts or whatever. Just that there are a lot of cubic meters in the core of the Sun, so it adds up. As the AC says, proton-proton fusion is slow, even at the pressures and temperatures at the core.

Re: could only maintain the state for 10 seconds

[jd]

Not really. The only direct products you make will be Helium-4 (stable), Helium-5 and Helium-6. You could smash up or change isotope a carbon, nitrogen or oxygen atom, I suppose. But you're talking very short half-lives.

The concrete is a problem. Fortunately, the Iranians have a recipe that is less likely to powder or fail. So, with trade restored under the joint agreement, we're ok.

Oh.

Re:Apparently not

[mikael]

They keep running into problems. I've read a few papers, and they would hit problems such as the metals used weren't strong enough to withstand the magnetic fields they were generating. That was fixed. Then the plasma rings would start to twist, buckle, warp and pinch into singularities. Stellerators fixed that problem by putting some torsion into the plasma rings. Tokamaks fixed that problem by adding extra magnetic field randomness or something to break up the standing waves. That fixed that problem. Then the neutron bombardment started poking holes in the metal structure, which weakens it over time. Maybe that has been fixed, but it keeps going round and round.