Dwindling fossil fuel supplies and global warming have compelled scientists to explore alternative and clean energy sources. In such a scenario, the process of nuclear fusion seems to be the appropriate answer. Unlike nuclear fission reactions in which nuclei of heavy elements split apart to produce energy, in fusion process, the lighter nuclei such as hydrogen fuse toghther under tremendous pressure and temperature, releasing huge amount of energy.
Hydrogen, the ingradient for fusion reactions, is among the most abundant elements available in the universe. Since its existence, the earth has been receiving this power from the fusion reaction taking place at the heart of the sun.
Scientists all over the world have been trying hard to harness nuclear fusion in laboratory since 1905, the year Albert Einstein derived the famous mass-energy equivalence equation E= mc². It means that the mass can be converted into energy and vice-versa. According to the equation, the fusion or combination of tiny atoms together could release tremendous amounts of energy.
Under Einstein’s theory, the amount of energy released from one gram of matter is enough to power 28,500 bulbs each of 100-watt for a year. Until now, the fusion reaction has only been possible inside nuclear weapons for destruction and highly unstable plasmas created in incredibly strong magnetic fields.
The work at National Ignition Facility (NIF) in California would pave the way to use fusion energy not for destruction rather for constructive energy use. Scientists at NIF are attempting to create an artificial sun on earth. For the past 100 years, this goal seemed impossible, but with the astronomical strides in science and technology, scientists believe that they are at the edge of cracking one of the biggest problems in physics, i.e., harnessing the power of nuclear fusion in the laboratory.
The project work on the £1.2-billion nuclear fusion experiment is going to be completed very soon. The stage is set to ignite a tiny man-made star inside a laboratory and trigger a thermonuclear to generate a temperature greater than 100 million °C and a pressure billions times higher than those found on earth.
The amount of fuel used in the process would be little bigger than a pinhead. The success of the project would mark the first step towards building a practical nuclear fusion power station, which would be a source of safe, secure and carbon-free limitless energy.
Researchers at NIF will fire 192 separate laser beams capable of producing 500 trillion watts of power into a billionth of a second, which is 1,000 times the electric generating power of the US. The result would be an explosion in a 32ft wide reaction chamber producing at least 10 times the amount of energy used to create it. According to Ed Moses, director of the facility, it is like creating the conditions that exist inside the sun and tapping into the real solar energy as fusion is the source of all energy in the world.
The structure used in the experiment covers an area the size of three football pitches. A single infrared laser will be directed through almost a mile distance consisting of lenses, mirrors and amplifiers to create a beam more than 10 billion times more powerful than a household light bulb.
It is housed in a hanger-sized room, cleared of dust particles to prevent any impurity getting into the beam. Then the laser will be splitted into 192 separate beams and further converted into ultraviolet light. The ultraviolet light is focused onto a capsule at the centre of an aluminium and concrete-coated target chamber. The laser beams hitting the inside of the capsule should generate high-energy X-rays that, within a few billionths of a second, compress the fuel pellet inside until its outer shell blows off.
This explosion of the shell produces an equal and opposite reaction that compresses the fuel together until nuclear fusion reaction begins, thus, releasing a vast amount of energy.
It is not the only experiment conducted on nuclear fusion reaction. In France, work has already begun on building the International Thermonuclear Experimental Reactor (ITER) at a cost of £8 billion. The ITER would use magnetic fields to create the conditions for fusion. However, ITER’s first “burn” or reaction is not expected until 2022. In all the experiments attempted to create the conditions needed for nuclear fusion, lasers are seen as the most likely technique to be able to provide a viable electricity supply.
