Many countries are experimenting with future fusion reactors, which promise clean and unlimited energy from the stars. One of the nations that is making a greater effort in recent years is China. If just six months ago it announced that its experimental advanced superconducting tokamak reactor ( EAST ) had been able to maintain a plasma temperature of 120 million degrees Celsius for 101 seconds, now the same team has achieved another feat: holding the plasma for 1,056 seconds (17 minutes). Of course, at a lower temperature: 70 million degrees Celsius.
The previous record set by EAST set was in May by running for 101 seconds at a higher temperature of 20 million°C.
'We achieved a plasma temperature of 120 million degrees Celsius for 101 seconds in an experiment in the first half of 2021. This time, the steady-state plasma operation was maintained for 1,056 seconds at a temperature close to 70 million degrees Celsius, which has left a solid scientific and experimental basis for a better understanding of the operation of fusion reactors," he said in a statement Gong Xianzu, a researcher at the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP), who is in charge of the experiment carried out in Hefei, capital of the province of Anhui, in eastern China.
The goal is to emulate the power of the stars and create huge amounts of energy by injecting a small amount of deuterium gas and tritium (hydrogen), which is heated to high temperatures and becomes an ionized plasma . However, for a chain fusion reaction to occur , this plasma has to be heated up to 150 million degrees Celsius , more than twice the amount reached by the Chinese reactor, which has also carried out the experiments only with deuterium, without get to introduce tritium.
A success, but not a milestone
Because the reactors will be functional when they manage to keep the plasma at those temperatures for a long time. 'This is a serious experiment, the biggest Chinese machine. But it is not, in the world environment, the one that achieves the best parameters in terms of merger profit; that is to say, in energy obtained compared to that used in the reaction ", explains to ABC Joaquín Sánchez, director of the National Fusion Laboratory, dependent on Ciemat. "They have specialized in long pulses, which is technologically interesting, but to a lesser degree from a physics point of view."
In fact, there are no scientific publications yet (not even in prepress format) explaining the specific experiment, so there are some gaps in how this success has been achieved. «With the existing public information it is not known if the temperature of the electrons has been increased, which is the most probable; or that of ions, which is more difficult to rise when long pulses fed by radio frequency are made ”, indicates Sánchez. " There has been progress in stretching the pulse, but it is not a 'historic' breakthrough ."
Differences with the ITER project
The Chinese prototype is the first tokamak model with a non-circular cross section, although the Asian giant has other similar experiments, such as the HL2M and the HL2A , whose difference is that they are not superconducting and are smaller. The EAST would be the most similar machine to the ITER project, (International Thermonuclear Experimental Reactor), a large-scale scientific experiment aimed at proving that fusion reactors are viable. This prototype, created by an alliance between the European Union, Japan, the United States, South Korea, India, Russia and China itself, aims to generate a plasma in which ten times more energy is produced through fusion than is it is inserted to keep it warm.
In a commercial reactor, the high-energy neutrons produced by the fusion are collected in the lithium envelope which, apart from regenerating the tritium to maintain the reaction, heats the coolant and generates steam. This steam will drive turbines to produce electricity.
It is expected that the first test start on the premises of Cadarache (France) from 2026 , although the infrastructure is still under construction. However, when the experiments begin, they will be much more ambitious than those in China alone: in the first tests the aim is to reach 500 seconds of work at high power (slightly more than 8 minutes) and 1,500 at medium power (25 minutes). ), in both cases with temperatures above 100 million degrees and with energy gain. "If we compare it with EAST, it is another dimension," says Sánchez.
Reference: Chinadaily