Will China's artificial sun compel India to develop its own fusion reactor?

Currently, the hottest place in the world is 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' has been created by heating electrically charged gas, or plasma to 120 million degrees Celsius for 101 seconds and 160 million degrees Celsius for 20 seconds. This is ten times hotter than the 15 million degrees Celsius temperature at the Sun's core.

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 into plasma, they release energy that can be harnessed to generate electricity.

Double-edged sword

As with most technologies, nuclear fusion is a double-edged sword finding use in hydrogen bombs. But used benignly, it offers several advantages. Just half a kilogram of fusion fuel would produce the same amount of energy as four million kilogram of fossil fuels. Also, it does not leave behind any highly radioactive waste as churned out by conventional nuclear power stations and is thus considered to be the future of clean energy.

Another benefit is that fusion reactors run on something as cheap as deuterium, an isotope of hydrogen—a virtually endless fuel source that can be separated from seawater by electrolysis. Compare this with the complex and expensive methods required to extract uranium-235 from its sources for fission reactors, and it is easy to see why fusion energy is the holy grail of nuclear power research.

Tapping fusion power

But tapping fusion power is easier said than done. Initial hopes of researchers in the 1950s were dashed by the enormity of the technical problems involved—controlling the complex behaviour of plasma which contains the atomic nuclei to be fused and sustaining temperatures at over 100 million degrees Celsius.

Remember the diagrams of atomic nuclei from your high school physics books—how positively charged atomic nuclei repel each other? For pairs of nuclei to overcome the repelling force and merge, they have to be squeezed very closely 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 which produce light and heat over billions of years. On Earth, however, since we cannot generate such high pressures, the corresponding temperatures for nuclear fusion necessarily have to be well over 100 million degrees Celsius. No wonder even the most advanced fusion reactors consume more power than they give back, producing little more than the energy to light a tiny cycle lamp bulb.

So physicists believed the best way to harness star power would be to confine plasma in a magnetic field using huge fusion reactors where the atomic nuclei could fuse.

And that is only part of the problem. Once you create such immense temperatures, they have to be maintained for a long time before energy is generated.

For years, scientists have been working on achieving this with special reactors called tokamaks: doughnut-shaped chambers where giant magnetic rings corral the superhot plasma and spin the charged particles around so that they fuse at extremely high temperatures. The larger the tokamak, the better the insulation it provides for confining the fusion particles for longer periods, and more energy produced.

But even with the latest technology, it has not been possible to sustain these high temperatures long enough to trigger fusion reactions. And this makes China's EAST feat a breakthrough.

Largest fusion reactor

However, for realising the potential of fusion energy globally, a lot depends on the International Thermonuclear Experimental Reactor (ITER) being built in southern France—expected to be the world's largest fusion reactor when it becomes operational in 2035. Nevertheless, they are critics who argue that it is only a technology demonstrator and it won't be until the second half of this century that practical controlled fusion is achieved, if at all.

After the International Space Station, the ITER is the largest human endeavour with international collaboration and includes the US, Russia, South Korea, Japan, China, India and the European Union.

India could be a dark horse in this pursuit as it has a major role in the ITER. Scientists from the Institute of Plasma Research in Ahmedabad are guiding the industrial production of the ITER's critical components like the in-wall 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.

India's progress

Since building its first tokamak 'Aditya' in the 1980s, India has made remarkable progress in fusion research and operates an advanced Steady State Superconducting Tokamak (SST) which overcomes the ‘on-off’ nature of conventional tokamaks in heating plasma. Only a few countries have developed these next-generation SSTs.

The EAST, for instance, is a tokamak designed for steady-state operation and the Chinese engineers who built it were all nurtured by the ITER programme. India should perhaps take a leaf out of China's notebook and use its participation in the ITER to get a leg-up on building an indigenous fusion reactor on Indian soil in the next few decades.