The largest nuclear fusion experiment in the world, the Joint European Torus (JET), has begun a new wave of testing this month.
In a statement from the UK Atomic Energy Authority, it was announced that EUROfusion researchers at JET, which is located in Oxford, England, have begun testing nuclear fusion using helium and hydrogen, and then deuterium and tritium fuels.
Nuclear fusion is the process that powers the Sun: hydrogen atoms collide, fusing together to form a helium atom, releasing enormous amounts of energy as they do. The reaction requires a large amount of energy to get started, however, as the hydrogen atoms need to collide at very high speeds in order to fuse.
“We take light hydrogen atoms, we fuse them together, that produces an atom of something else,” JET Senior Manager Fernanda Rimini told Newsweek. “And this something else has a little bit less mass than the two original ones. So, because of Einstein’s equation, E = MC2, that mass is transformed into energy. That’s how fusion produces energy. There are lots of reactions that you can use: the one that we use has two isotopes of hydrogen that are called deuterium and tritium.”
Deuterium and tritium are hydrogen atoms with one and two neutrons in their nucleus along with their single proton, respectively. This fuel is heated and compressed in order to create a super hot, super pressurized hydrogen plasma, which is required for fusion. This plasma is then contained using magnets.
“[JET] is an experimental reactor, but it was never designed to actually produce electricity or produce energy in excess of what we put in,” Rimini said. ” This is what is called magnetic confinement fusion. [JET], I think, is the biggest of these experiments that are operational in the world at the moment.”
JET broke the world record for sustained fusion energy last year with 59 megajoules of sustained fusion energy being produced over five seconds.
“The record is that not only we have produced fusion, measurable fusion, and we have produced about twice as much as we did in 1997,” Rimini said. “But we produced it over five seconds, so it’s quite steady, it’s quite long, it’s as long as we can because the experiment really is not designed to last for much longer.”
If we harnessed nuclear fusion fully, we could generate electricity using only hydrogen as fuel, and producing only helium as a by-product, without any greenhouse gases or toxic radioactive leftovers.
Several roadblocks lie in our way to reaching this point, however. We only just managed to achieve ignition at a research lab at NIF, which essentially means that the reaction itself produced enough energy to be self-sustaining. Secondly, there are various issues involved with holding the intense temperatures of the plasma inside the tokamak nuclear fusion reactor.
“An essential element of the ITER Research Plan is to explore control of the plasma interaction with the wall at high fusion temperatures,” ITER’s Head of Science and Operation, Dr. Tim Luce said in the statement.
“It’s a problem because the plasma is very, very hot, and all the energy that you put in, to heat this plasma to the 150 million degrees has to come out either as radiation or as the energy conduction, basically,” Rimini said. “The walls of the machine in the experiment, in our case, are made of metal, and this metal comes in and kind of pollutes our plasma.”
According to the press release, in the next 16 weeks of experiments at JET, EUROfusion researchers will study the behavior of the plasma as well as test the impact of helium on JET’s tungsten and beryllium wall. These small-scale tests at JET will help to enable ITER in France to hit the ground running once construction is complete.