China’s Experimental Advanced Superconducting Tokamak (EAST), an artificial sun, achieved a plasma temperature of 70 million degrees Celsius for 1,056 seconds (17.6 minutes) during its latest experiment in January 2022 which is the longest time of operation of its kind in the world. It has set a new world record after superheating a loop of plasma to temperatures five times hotter than the sun for more than 17 minutes. Earlier in May 2021, it had run at 120 million degrees Celsius for 101 seconds, and at 160 million degrees Celsius for another 20 seconds, which is over 10 times hotter than the sun. The EAST is one of the three major domestic tokamaks that are being operated in China—the other two being the HL-2A reactor and J-TEXT. The EAST is located at the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP) in Hefei, China.
No doubt, the breakthrough is a significant progress, but there is still a long way for China’s experimental sun to keep the temperature stable for a long time.
The experimental sun replicates the process of nuclear fusion that powers the sun. China seeks to unlock clean and limitless energy with minimal waste products and the experiment is expected to produce enormous amount of clean energy to power its cities. It is estimated to cost more than US$ 1 trillion by June 2022, when it would end the experiment.
About the Artificial Sun
EAST is an advanced nuclear fusion experimental research device. It is a doughnut-shaped reactor chamber where heated-up plasma has been trapped with a powerful magnetic field. It uses the same nuclear fusion process for energy-generation as is used by the sun. It also uses the process of atomic nuclei to generate large amount of energy into electricity by merging hydrogen atoms to create helium.
EAST followed China’s first superconducting tokamak device, dubbed HT-7, built by the Institute of Plasma Physics, in partnership with Russia in the early 1990s. In the beginning of its testing in the first phase, HT-7 had generated an electric current of 200 kiloamperes in three seconds. In May 2011, it became the first tokamak to successfully sustain H-Mode plasma for over 30 seconds at ~50 million Kelvin.
It had previously set another record in May 2021, by running for 101 seconds at an unprecedented 216 million degrees Fahrenheit (120 million degrees Celsius). The core of the actual sun, by contrast, reaches temperatures of around 27 million degrees Fahrenheit (15 million degrees Celsius). This time, it broke South Korea’s Korea Superconducting Tokamak Advanced Research (KSTAR) reactor’s record which had maintained 50 million degrees Celsius (90 million degrees Fahrenheit) for 70 seconds in 2016. China is also planning to complete a new tokamak fusion device by the early 2030s.
While this is a significant development, it may take China three decades before being able to see a fully functioning artificial sun. Once mastered, nuclear fusion could potentially provide unlimited clean energy at very low costs. Therefore, fusion energy is considered the ideal ‘ultimate energy’ for the future of humanity.
The process involved to create the artificial sun
In stars such as the Sun, hydrogen atoms combine to produce helium in the thermonuclear fusion. This thermonuclear fusion leads to release immense energy in the form of light and radiation. Usually, the atoms cannot fuse because the similar charges of the electron clouds, surrounding the atoms, repulse and keep them at bay from coming too close. The temperature in the core of the stars is about 15 million Kelvin which rips away all the electrons and plasma is formed. Further, due to gravity, the pressure builds up to 200 billion times greater than Earth’s atmospheric pressure and the density becomes 150 times more than that of water. In this blazing heat, the intense pressure, and dense core, the plasma of hydrogen fuses with each other to form helium and leads to the emission of enormous energy in the form of light and heat.
Imitating this process of the natural sun, fusion is ignited artificially in fusion reactors, called tokamaks. The EAST Tokamak device replicates the nuclear fusion and produces high levels of energy without generating large quantities of waste. For this purpose, fuel is heated to temperatures upto 150 million degrees to form a hot plasma ‘soup’ of subatomic particles. The plasma is kept away from the walls of the reactor with the help of strong magnetic field so that the plasma does not cool down and lose its potential to generate huge amount of energy.
The thermonuclear fusion reaction uses the isotopes of hydrogen, namely, deuterium and tritium. (Deuterium has a neutron and a proton in its nucleus. In contrast, ordinary hydrogen has only one proton. Tritium has two neutrons and one proton.) To create plasma for fusion, the mixture of deuterium and tritium has to be heated to temperatures 10 times hotter than the Sun’s centre. Using strong magnets, the weltering plasma is held in place made to swill around, beams collide, fuse, and release tremendous energy as heat. This heat is then removed from the reaction to boil water, produce steam, and turn a turbine to generate electricity.
For the first time, the Joint European Torus (JET) had experimented using the tritium fuel mix. They could harvest one-third of the input energy as an output, which was a significant step from earlier results. The experimental results from this JET indicated that the models used to design the international thermonuclear experimental reactor (ITER) are robust. These experiments would help validate ITER’s designs.
Challenges
One of the significant challenges in this experiment is the sudden appearance of plasma instabilities. If commercial energy has to be obtained, the plasma needs to be sustained at high temperatures for a long time. Therefore, the Chinese accomplishment of maintaining 2.8 times the sun’s temperature for 17 minutes is a milestone.
The Tokamak Nuclear Reactor
Tokamak is an acronym for tongue-twisting Russian terms ‘toroïdalnaïa kameras magnitnymi katushkami‘, which means ‘toroidal chamber with magnetic coils’. The Soviet scientist, Natan Yavlinsky, had designed the first tokamak in 1958. It works by superheating the plasma before trapping it inside a doughnut-shaped reactor chamber with powerful magnetic fields. However, no one has ever managed to create an experimental reactor that is able to put out more energy than it takes in.
Thirty-five countries, including India, Russia, Japan, South Korea, the United States, the United Kingdom, China, and European Union, are collaborating to build the largest tokamak as part of the ITER. China’s EAST is a part of the ITER.
The idea of developing a tokamak started in the year 1985. In March 2020, the machine assembly had started at Saint Paul-lez-Durance, Southern France. With the installation of the Cryostat, a device to cool the reactor covering the assembly is slated to be completed by the year 2025. The first plasma from this plant is expected to be produced by the end of 2025 or early 2026. After testing and troubleshooting, energy production is expected to commence by 2035.
The reactor is expected to generate 500 MW power and consume 50 MW for its operation, resulting in a net 450 MW power generation. Scientists, engineers, and technicians, from all the 35 participating countries, are experimenting with the hope of laying the foundation for their own national fusion energy programmes.
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