Fusion, the process that powers the Sun, involves fusing two lighter atomic nuclei to form a single heavier one, releasing huge amounts of energy in the process. It is seen as a potentially limitless source of cheap, carbon-free energy, since its main fuel is a heavy isotope of hydrogen called deuterium, contained in sea water.
However, despite decades of experiments around the world, no organisation has yet been able to produce a self-sustaining fusion reaction capable of generating more energy than it consumes.
Now Oxford-based First Light Fusion, which is investigating energy generation from a process known as inertial confinement fusion, is investing £3.6m in a machine designed to trigger a reaction at a much lower cost than existing technology.
Their approach is inspired by the pistol shrimp, which clicks its claw to produce a shockwave that stuns its prey – the only known example of inertial confinement found on Earth.
The device, known as Machine 3, is a pulsed power machine, designed to discharge the energy needed to fire a high velocity projectile at a target, generating a process known as shock-driven cavity collapse.
As the projectile hits the target, it generates very high pressure, creating a shock wave that is transmitted through the target, according to Dr Nicholas Hawker, founder and chief executive officer of First Light Fusion.
“The shock wave hits a cavity, a circular void within the target filled with fusion fuel, and causes it to collapse extremely quickly,” said Hawker.
Their approach is inspired by the pistol shrimp, which clicks its claw to produce a shockwave that stuns its prey
This should create the intense temperatures and densities needed for a fusion reaction.
Machine 3, which is already under construction and is due to be completed by the end of the year, will be capable of discharging up to 200,000 volts and in excess of 14 million ampere – the equivalent of nearly 500 simultaneous lightning strikes – within two microseconds.
The high voltage machine consists of a bank of capacitors, all of which are charged to 100kV and discharged in parallel. Like all pulsed power machines, it is capable of storing energy over a long period of time and then discharging it very quickly.
If successful, the process should be far cheaper than laser-driven inertial fusion, the approach being pursued at the National Ignition Facility (NIF) in California.
“The cost per joule of energy is one of the most critical elements for fusion, and using Machine 3 to launch the projectile is 1000 times cheaper, per joule of energy, than using a laser,” said Hawker.
That is because the laser used for inertial confinement fusion requires extremely expensive optics and other components. The process is also very inefficient, he said.
Unlike more expensive pulsed power machines, Machine 3 will also be insulated in air, rather than by immersing the equipment in oil, to further keep costs down.
First Light Fusion, a spin-out from Oxford University, plans to begin experimenting with the machine in January 2019, and hopes to demonstrate fusion within the year. The next step in the technology’s development will be to achieve ‘gain’, whereby the amount of energy created by fusion outstrips that used to spark the reaction.
The company was founded by Hawker and Prof Yiannis Ventikos, head of the mechanical engineering department at University College London. Its advisory board includes Nobel Prize-winning scientist Prof Steven Chu and Prof Arun Majumdar, who both served in the US Department of Energy under President Barack Obama.