Fusion Energy Breakthrough

Subject :Science and technology

Recently, Scientists in the United States have achieved a net gain in energy for the first time from a nuclear fusion reaction which is considered as the most dependable source of energy in future.
The experiment was conducted at the Lawrence Livermore National Laboratory in California.

About the Experiment

The experiment forced a minuscule amount of hydrogen into a peppercorn-sized capsule, for which scientists used a powerful 192-beam laser that could generate 100 million degrees Celsius of heat.
It is also called ‘Inertial Fusion’.
At some other places, including the international collaborative project in southern France called ITER (International Thermonuclear Experimental Reactor) in which India is a partner; very strong magnetic fields are used for the same purpose.
The laser beam was hotter than the Sun’s centre and helped to compress the hydrogen fuel to more than 100 billion times that of Earth’s atmosphere.
Under the pressure of these forces, the capsule started imploding on itself and leading to the fusion of hydrogen atoms and the release of energy.

Difference between the US experiment and ITER experiment held in early 2022

In ITER (a multi-country effort in which India is involved), they held the plasma in the vessel by a method called ‘magnetic confinement’. Wherever the particles go, they encounter magnetic forces that push them right back inside.
In the US experiment, they used another method called ‘inertial confinement’. The laser beams, 192 of them, coming from all around the capsule, denied an escape route for the particles in the plasma to shoot out. In fact, the laser energy compresses the particles.
Most scientists say that magnetic confinement is a better way.
Another significant difference is that while ITER produced energy from fusion, there was no ‘net gain’. But in the case of the US experiment, an energy gain was reported.

Future Prospects of the achievement

Attempts to master the fusion process have been going on at least since the 1950s, but it is incredibly difficult and is still at an experimental stage.
The nuclear energy currently in use across the world comes from the fission process.
Besides greater energy yield, fusion is also a carbon-free source of energy, and has negligible radiation risks.
Though the achievement is significant, it does little to bring the goal of producing electricity from fusion reactions any closer to reality.
By all estimates, use of the fusion process for generating electricity at a commercial scale is still two to three decades away.
The technology used in the US experiment might take even longer to get deployed.

Fusion Process

Fusion is a different, but more powerful, way of harnessing the immense energy trapped in the nucleus of an atom.
In fusion, nuclei of two lighter elements are made to fuse together to form the nucleus of a heavier atom.
A large amount of energy is released in both fusion and fission processes, but substantially more in fusion than fission.
This is the process that makes the Sun and all other stars shine and radiate energy.

Complexity involved in the process

When two positively charged nuclei come close to each other, they repel, or move away from each other, because fundamentally, like charges (positive-positive or negative-negative) repel and unlike charges (positive-negative) attract.
So, to fuse two nuclei into one larger nucleus, you need to overcome the force of repulsion.
It is like bringing together the north poles or south poles of two magnets. The closer you bring the positively charged nuclei, the more energy you need to bring them further closer.
But at a particular point (called ‘Coloumb barrier’) the nuclei yield. If you bring them as close as a millionth of a billionth of a meter (or, one ‘femtometer’), the repulsive forces are overpowered by the attractive nuclear forces.
At this distance, the nuclei rush into each other’s arms and fuse into one.
The trick is to ride over the hump called the Coloumb barrier; the way to achieve this trick is to keep giving energy.

Why hrdrogen and its isotopes are used ?

Because the hydrogen atom has only one proton — therefore, the lowest positive charge.
The next element, helium, has two protons, the next, lithium, has three, and so on. It is easier to try to fuse two nuclei with the least charge.
They use isotopes of hydrogen, D and T, because these nuclei have one and two neutrons, respectively.
The presence of neutrons increases the nuclear forces of attraction, which come into play once the Coloumb barrier is crossed.

Difference between fusion and fission process :-

About ITER (International Thermonuclear Experimental Reactor)

It is an international nuclear fusion research and engineering megaproject aimed at creating energy by replicating on Earth the fusion processes of the Sun.
When operational it would become the biggest machine anywhere in the world which would be more complex than the Large Hadron Collider at CERN or the LIGO project to detect gravitational waves.
Currently, the ITER reactor is in the machine assembly phase.
India joined the ITER project in 2005.
The Institute for Plasma Research in Ahmedabad, a laboratory under the Department of Atomic Energy, is the lead institution from the Indian side participating in the project.