Gyrotrons are microwave oscillators generating a temperature of up to 150 million degrees Celsius in the reactor, similar to a very big microwave. This high temperature makes the tritium fuel reach the plasma state required for fusion. To guide microwave radiation from the gyrotrons into the plasma and in order to maintain a vacuum and keep the radioactive tritium inside the reactor, a team around Dr. Dirk Strauss and Professor Theo Scherer of KIT’s Institute for Applied Materials (IAM) designs appropriate window units.
The Diamond disks guide radiation of more than one megawatt power into the ITER research reactor, numerous diamond windows have been designed by IAM and produced in cooperation with industry partners. Meanwhile, scientists are also working on window units for ITER’s successor called DEMO, in which power will be produced from 2050 onwards. As a consequence of planned multi-frequency operation of the microwave heating system in DEMO, however, new types of gyrotrons will be required.
The disks are made of synthetic diamond by chemical vapor deposition (CVD), a special coating technique. The CVD diamonds grow on a silicon surface in a small vacuum reactor filled with a gas mixture. By means of microwave irradiation, this mixture is turned into a plasma, similar to what happens in a fusion reactor, but with much smaller energy consumption. The plasma consists of atomic hydrogen that prevents undesired graphite formation and a small amount of methane that supplies carbon for the diamond. Diamond only grows at few micrometers per hour so it takes weeks to reach the 2-millimeter thickness that is needed. The diamond disks will cost millions of dollars for the DEMO reactor.
Currently diamond disks have a polycrystalline structure but future disks could use monocrystalline diamond.
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I wonder if production could be scaled up ? Also could diamond be grown on a curved surface ?
The article says “The CVD diamonds grow on a silicon surface”.
What do you actually disagree with from the article?
substrate of silicon in this case. silicon carbide also usable. cvd often uses beryl for diamond growth at moderate temps.
Especially if they get a reasonable level of funding… frankly I can only dream about what would happen if they got a Manhattan Project level of funding.
Quote – “power will be produced from 2050 onwards”
Cvd deposition on what type of material? you need a matrix to do Cvd or Pvd depositions. Report need to study Physics or consult a coating technologist.” Diamond like” coatings have been around for ages. A rumor that GM tested coating on Car windows back in the late 80 early 90’s. Cost and dis-torsion major negatives.
“Fusion power is just 20-30 years off” – Researchers since the 1950’s
The email links aren’t working.
My feelings exactly. At this rate, the fusion start-ups will demonstrate break-even before ITER is even finished being built.
That’s way cool! It’s probably a waste of money since it’s part of ITER but that’s still so cool!