Currently, it is the hottest place in the world in China – the Institute of Plasma Physics, Chinese Academy of Sciences in Hefei, where scientists have come up with a nuclear reactor that replicates the nuclear fusion that takes place in the heart of the sun.
Called the experimental advanced superconducting Tokamak (EAST), this ‘artificial sun’ is created by heating electrically charged gas or plasma to 120 million degrees Celsius in 101 seconds and 160 million degrees Celsius in 20 seconds. This is ten times warmer than the temperature of 15 million degrees in the core of the sun.
Unlike fission reactors, where atoms are split to release energy, fusion reactors generate energy by fusing atoms together by colliding atoms at extremely high temperatures and pressures. When the atoms fuse together in plasma, they release energy that can be used to generate electricity.
As with most technologies, nuclear fusion is a double-edged sword that finds use in hydrogen bombs. But used benign gives it several benefits. Just half a kilo of fusion fuel would produce the same amount of energy as four million kilos of fossil fuels. Moreover, it leaves no strong radioactive waste that the conventional nuclear power plant equalizes, and is therefore considered to be the future of clean energy.
Another advantage is that fusion reactors run on something as cheap as deuterium, an isotope of hydrogen ̵
Interception of fusion power
But tapping fusion power is easier said than done. The scientists’ initial hopes in the 1950s were shattered by the enormous technical problems involved – controlling the complex behavior of plasma containing the atomic nuclei to be melted and maintaining temperatures above 100 million degrees Celsius.
Remember the diagrams of atomic nuclei from your physical books in high school – how positively charged atomic nuclei repel each other? In order for parks to overcome the repulsive force and merge, they must be pressed very close together.
In the sun – and in all stars – hydrogen atoms are pushed together at ultra-high pressures to produce temperatures touching 15 million degrees Celsius, producing light and heat over billions of years. But on Earth, since we can not generate such high pressures, the corresponding temperatures for nuclear fusion must necessarily be well above 100 million degrees Celsius. No wonder even the most advanced fusion reactors use more power than they give back, producing little more than the energy to ignite a small cycle bulb.
So physicists believed that the best way to harness stellar power would be to limit plasma in a magnetic field using huge fusion reactors where the atomic nuclei could melt.
And that’s just part of the problem. When you create such enormous temperatures, they must be maintained for a long time before energy is generated.
For years, scientists have been working to achieve this with special reactors called tokamaks: donut-shaped chambers, in which giant magnetic rings correlate the superhot plasma and rotate the charged particles so that they melt together at extremely high temperatures. The larger the tokamak, the better the insulation it provides to limit the fusion particles for longer periods and more energy produced.
But even with the latest technology, it has not been possible to maintain these high temperatures long enough to trigger fusion reactions. And this makes China’s EAST feat a breakthrough.
Largest fusion reactor
To realize the potential of fusion energy globally depends a lot on the construction of the International Thermonuclear Experimental Reactor (ITER) in the south of France – expected to be the world’s largest fusion reactor when it becomes operational in 2035. Nevertheless, critics say that it is only a technology demonstrator, and it will not be until the second half of this century that practically controlled fusion is achieved at all.
After the International Space Station, ITER is the largest human effort with international cooperation and includes the United States, Russia, South Korea, Japan, China, India and the European Union.
India may be a dark horse in this persecution as it has an important role in ITER. Researchers from the Institute of Plasma Research in Ahmedabad control the industrial production of ITER’s critical components such as screen shielding, cooling water system and cryogenics. In fact, the superstructure for the reactor’s main equipment, where a vacuum is maintained to help cool the plasma, is made by Larsen & Toubro.
Since the construction of its first tokamak ‘Aditya’ in the 1980s, India has made remarkable progress in fusion research and operates an advanced Steady State Superconducting Tokamak (SST) that overcomes the ‘on-off’ nature of conventional tokamaks in the heating of plasma. Only a few countries have developed these next-generation SSTs.
THE EAST, for example, is a tokamak designed for steady state operation, and the Chinese engineers who built it were all cared for by the ITER program. India should perhaps take a leaf out of China’s notebook and use its participation in ITER to get an idea of the construction of a native fusion reactor on Indian soil in the next few decades.