What is a nuclear fusion and have scientists found a breakthrough?
NUCLEAR fusion has baffled scientists for almost a century.
But after a US laboratory announced it is on the cusp of a breakthrough in research, we take a look at the phenomenon.
What is a nuclear fusion?
Nuclear fusion occurs when two small, light nuclei join together to make one heavy nucleus.
The reaction occurs in the sun and other stars when two hydrogen-nuclei fuse together under high temperatures and pressure to form a nucleus of a helium isotope.
Energy is released during the process as the total mass of the resulting single nucleus is actually less than the mass of the two original nuclei - and this leftover mass becomes energy.
It is a little complicated, but Albert Einstein's equation - E=mc2 - explains it.
It means "energy equals mass times the speed of light squared - and in short, it says that energy and mass are interchangeable and can be converted into each other.
Fusion reactions take place in a state of matter called plasma — a hot, charged gas made of positive ions and free-moving electrons that has unique properties distinct from solids, liquids and gases.
It was first discovered in the 1930s by a man named Hans Bethe.
Initially research into fusion in the UK, US and USSR was kept a secret while experts decided in there were military applications, such as thermonuclear weapons, but by the mid-1950s studies were taking place around the world.
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Why is it so difficult to achieve a nuclear fusion?
A major issue with fusion is that it requires the fusing of positive nuclei, which repel each other as they have the same charge.
The fusion of two nuclei needs to happen so quickly that the repulsion of the charge does not have time to stop it from happening.
Fusion on the sun takes place at very high temperatures - exceeding 10 million degrees Celsius - and must happen in a confined space or surrounded by extreme pressure.
This makes it incredibly difficult to produce, therefore stumping scientists for years.
But experts are desperate to replicate fusion on earth as it could provide virtually limitless green energy.
Have scientists found a breakthrough?
In short, yes. Scientists have spent the best part of a decade attempting to reach "ignition point" where a full fusion reaction is possible.
Now, for the first time ever, they have achieved the goal.
The US National Ignition Facility (NIF) confirmed that a successful experiment on August 8 "made a significant step" forwards.
And the breakthrough is being described as the most significant in 50 years.
Nuclear scientists using lasers the size of three football fields said on August 17 they had generated a huge amount of energy from fusion, possibly offering hope for the development of a new clean energy source.
Experts focused their giant array of almost 200 laser beams onto a tiny spot to create a mega blast of energy - eight times more than they had ever done in the past.
Although the energy only lasted for a very short time - just 100 trillionths of a second - it took scientists closer to the holy grail of fusion ignition, the moment when they are creating more energy than they are using.
Kim Budil, the director of Lawrence Livermore National Laboratory, which operates the National Ignition Facility in California where the experiment took place this month, said: "This result is a historic advance for inertial confinement fusion research."
Nuclear fusion is considered by some scientists to be a potential energy of the future, particularly because it produces little waste and no greenhouse gases.
Professor Steven Rose, co-director of the center for research in this field at Imperial College London, said: "The NIF teams have done an extraordinary job.
"This is the most significant advance in inertial fusion since its beginning in 1972."
But co-director Jeremy Chittenden warned making this a useable source of energy will be a "long process" involving "overcoming significant technical challenges".
What's the difference between fission and fusion?
Fusion and fission are both types of energy-releasing reactions.
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The major difference is that fusion sees the fusion of two or more smaller nuclei into one larger one, while fission is the splitting of atoms into two or smaller ones.
Fission is currently used in nuclear power plants where the bonds of heavy atomic nuclei are broken to release energy.
