The new Chinese research tokamak fusion reactor in Heifi produced a plasma towards the end of September. They didn’t elaborate much beyond that so I don’t know how meaningful this is. A neon sign also produces plasma.
I had heard earlier that a test of the superconductive magnets was also a success. In my view that is actually a more substantial development because previous research reactors have used copper wire electromagnets and because of their resistance they rapidly heat up limiting operation to about a minute before they overheat.
A minutes operation doesn’t allow testing critical devices like the diverter which removes helium “ash” from the plasma. Because helium is heavier, it tends to move towards the outside of the plasma where it can be skimmed off by a diverter. The diverter is critical to the long term operation of the reactor, how it will respond to the constant bombardment of very energetic ions needs to be evaluated. That requires operation for longer periods of time. That’s what superconductive magnets can provide. Because they have no electrical resistance, they do not heat up.
There were non-trivial obstacles to overcome. Superconductors, at least high temperature superconductors that can be economically cooled, tend to be made from brittle ceramics not easily formed into wire which can be wound into coils. Superconductors lose their superconductivity when they are subject to a magnetic field exceeding some critical value. The value of magnetic fields required to contain a plasma at the temperatures required for fusion to occur can be in the order of eight to fifteen Teslas, until recently these fields were not achievable with superconductors.
Given the obstacles, I view the successful operation of the superconductive magnets as actually much more significant than the generation of a plasma. However, it is good to know that progress is continuing. Here are a link to the only article I can find (Associated Press article):