France tops China’s tokamak record with 22-minute plasma containment run

Nice number, but also not much more than a nice advance

France’s Commissariat à L'énergie Atomique et aux Energies Alternatives on Tuesday claimed it’s topped China’s recently-established for record maintaining fusion plasma in a tokamak, and therefore taken another step towards building a fusion reactor capable of producing cheap energy.

The Commissariat (French Alternative Energies and Atomic Energy Commission, or CEA) announced that its CEA WEST Tokamak maintained plasma for more than 22 minutes last week.

China’s Experimental Advanced Superconducting Tokamak maintained a steady-state high-confinement plasma operation for almost 18 minutes in January.

It’s not easy to create plasma, never mind maintain it, because doing so first requires heating gases under enormous pressure to the point at which some electrons are freed from atomic nuclei. The test at the CEA WEST Tokamak saw temperatures reach 50 million degrees.

The prospect of anything at that temperature getting out of hand is deeply unpleasant, so tokamaks use giant magnets and shielded walls (often built with Tungsten) to contain the plasma. The machines also need plenty of cooling.

The astounding temperatures involved mean it’s possible the shields can pollute plasma, an unwelcome prospect if it prevents production of the even hotter plasmas needed to power a fusion reactor.

CEA West isn’t powerful enough to produce the fusion plasma needed expected to produce electricity in a reactor. That job goes to the planned International Thermonuclear Experimental Reactor which is hoped to create plasma and contain it for the many minutes required to sustain a fusion reaction and use the resulting heat to produce steam and spin turbines to make electricity.

This test at CEA WEST was nonetheless rated as a welcome advance.

“This leap forward demonstrates how our knowledge of plasmas and technological control of them over longer periods is becoming more mature, and offers hope that fusion plasmas can be stabilised for greater amounts of time in machines such as ITER,” CEA wrote.

The CEA WEST team will now “double down on its efforts to achieve very long plasma durations – up to several hours combined – but also to heat the plasma to even higher temperatures with a view to approaching the conditions expected in fusion plasmas.”

The big unanswered question in all of this is whether a fusion reactor will reliably create more energy than is needed to produce plasma and operate a tokamak. At least one experiment has proved that’s possible. This effort at CA WEST saw “the injection of 2 MW of heating power.”

Future experiments will continue with increased power. ®