by Mish Shedlock, Mish Talk:
Scientists have done some amazing things but not all of them have practical application, at least yet. Fusion is a great example.
Live Science reports the World’s Largest Nuclear Fusion Reactor is Finally Completed.
The International Fusion Energy Project (ITER) fusion reactor, consisting of 19 massive coils looped into multiple toroidal magnets, was originally slated to begin its first full test in 2020. Now scientists say it will fire in 2039 at the earliest.
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ITER contains the world’s most powerful magnet, making it capable of producing a magnetic field 280,000 times as strong as the one shielding Earth.
The reactor’s impressive design comes with an equally hefty price-tag. Originally slated to cost around $5 billion and fire up in 2020, it has now suffered multiple delays and its budget swelled beyond $22 billion, with an additional $5 billion proposed to cover additional costs. These unforeseen expenses and delays are behind the most recent, 15-year delay.
Scientists have been trying to harness the power of nuclear fusion — the process by which stars burn — for more than 70 years. By fusing hydrogen atoms to make helium under extremely high pressures and temperatures, main-sequence stars convert matter into light and heat, generating enormous amounts of energy without producing greenhouse gases or long-lasting radioactive waste.
But replicating the conditions found inside the hearts of stars is no simple task. The most common design for fusion reactors, the tokamak, works by superheating plasma (one of the four states of matter, consisting of positive ions and negatively charged free electrons) before trapping it inside a donut-shaped reactor chamber with powerful magnetic fields.
Impressive But …
Assuming the reactor originally scheduled for 2020 is finally operable by 2039, I will be impressed.
Heck, I am impressed at what we have already scientifically achieved. But I wonder what is the practical application of this.
Keeping the turbulent and superheated coils of plasma in place long enough for nuclear fusion to happen, however, has been challenging. Soviet scientist Natan Yavlinsky designed the first tokamak in 1958, but no one has since managed to create a reactor that is able to put out more energy than it takes in.
One of the main stumbling blocks is handling a plasma that’s hot enough to fuse. Fusion reactors require very high temperatures (many times hotter than the sun) because they have to operate at much lower pressures than is found inside the cores of stars.
The core of the actual sun, for example, reaches temperatures of around 27 million Fahrenheit (15 million Celsius) but has pressures roughly equal to 340 billion times the air pressure at sea level on Earth.
Cooking plasma to these temperatures is the relatively easy part, but finding a way to corral it so that it doesn’t burn through the reactor or derail the fusion reaction is technically tricky. This is usually done either with lasers or magnetic fields.
Question and Answer on Temperatures
How a reactor could produce temperatures of 27 million degrees without the operation melting is likely a puzzle to anyone who has been thinking clearly.
The article provides an answer. But what is the cost and how long can the reaction be sustained without a meltdown? Are there any other issues?
For those questions, let’s turn to a 2022 article. also from Live Science.
A Step Closer to a New Source of Power
Please consider A Step Closer to a New Source of Power
In the new experiments, the Joint European Torus (JET) in Culham near Oxford, England, produced blazingly hot plasmas that released a record-setting 59 megajoules of energy — about the same amount of energy unleashed by the explosion of 31 pounds (14 kilograms) of TNT.
Nuclear fusion — the same reaction that occurs in the heart of stars — merges atomic nuclei to form heavier nuclei. Nuclear physicists have long sought to produce nuclear fusion in reactors on Earth because it generates far more energy than burning fossil fuels does. For example, a pineapple-size amount of hydrogen atoms offers as much energy as 10,000 tons (9,000 metric tons) of coal, according to a statement from the International Thermonuclear Experimental Reactor (ITER) project.
“It took us years to prepare these experiments. And in the end we have managed to confirm our predictions and models,” Athina Kappatou, a physicist at the Max Planck Institute of Plasma Physics in Garching near Munich, Germany, told Live Science. “That’s good news on the way to ITER.”
JET, which began operating in 1983, now uses the hydrogen isotopes deuterium and tritium as fuel. Whereas a normal hydrogen atom has no neutrons in its core, a deuterium atom has one neutron and a tritium atom has two. Currently, it is the only power plant in the world capable of operating with deuterium-tritium fuel — although ITER will also use it when it comes online.
However, deuterium-tritium fusion poses a number of challenges. For example, deuterium-tritium fusion can generate dangerous amounts of high-energy neutrons, each moving at about 116 million mph (187 million km/h), or 17.3% the speed of light — so fast they could reach the moon in under 8 seconds. As such, special shielding is needed in these experiments.
For the new experiments, the previous carbon lining in the JET reactor was replaced between 2009 and 2011 with a mixture of beryllium and tungsten, which will also be installed in ITER. This new metallic wall is more resistant to the stresses of nuclear fusion than carbon, and also clings onto less hydrogen than carbon does, explained Kappatou, who prepared, coordinated and led key parts of the recent experiments at JET.
Another challenge with deuterium-tritium fusion experiments is the fact that tritium is radioactive, and so it requires special handling. However, JET was capable of handling tritium back in 1997, Kappatou noted.
Also, whereas deuterium is abundantly available in seawater, tritium is extremely rare. For now, tritium is produced in nuclear fission reactors, although future fusion power plants will be able to emit neutrons to generate their own tritium fuel.
In January, scientists at the National Ignition Facility in California revealed that their laser-powered nuclear fusion experiment generated 1.3 megajoules of energy for 100 trillionths of a second — a sign the fusion reaction generated more energy from nuclear activity than went into it from the outside.
The copper electromagnets that JET used could only operate for about 5 seconds due to the heat from the experiments. “JET simply wasn’t designed to deliver more,” Kappatou said. In contrast, ITER will use cryogenically cooled superconducting magnets that are designed to operate indefinitely, the researchers noted.
Questions Beget Questions
These are amazing achievements. But we must do much better than sustain a reaction for a world-breaking 100 trillionths of a second.
Something in this story is missing, like why does it take at least 15 years to do a test of something that is already built?
Also, the proposed process seems so much like a perpetual motion machine.
