A few months back, we talked about the 200-trillion-watt Trident Laser that is capable of producing plasmas several times hotter than the sun’s core. This time around, a group of scientists has devised an entirely new technique that could enable lasers to heat certain types of materials to temperatures higher than the sun’s center, in less than 20 quadrillionths of a second. Recently published in the Nature Communications journal, the research was conducted by theoretical physicists at the Imperial College London, and could pave the way for new methods of power generation through thermonuclear fusion.
According to the researchers, the newly-developed heating technique would likely be 100 times faster than the world’s most powerful and energetic laser system, known as the National Ignition Facility, currently housed at California-based Lawrence Livermore National Laboratory. The new mechanism, the scientists believe, could heat certain materials to over 11.6 million degrees Celsius (approx. 20.8 million° F), in a matter of a million millionth of one second.
In a world where fossil fuels are fast nearing complete exhaustion, fusion offers a valuable solution for the ongoing global energy crisis. Basically a process that powers the sun as well as the stars, fusion generates energy when two light atomic nuclei come together and fuse to form a heavier nucleus. The process usually takes place under incredibly high pressures and temperatures, similar in degree to the kind found at the center of the sun. To recreate these extreme conditions inside a fusion reactor, scientists have long relied on high-energy lasers that, more often than not, entail longer heating periods. This is because such lasers first heat the electrons present in the target, which in turn heat the ions, thus making the process relatively slow.
In the new research, the scientists have discovered an innovative technique, by which the heating time can be significantly reduced. According to them, when a high-power laser is shot at a particular type of material, it generates powerful electrostatic shock waves that are capable of directly heating the ions. Speaking about the breakthrough, Dr. Arthur Turrel, the study’s lead author, said:
It’s a completely unexpected result. One of the problems with fusion research has been getting the energy from the laser in the right place at the right time. This method puts energy straight into the ions.
Generally, these laser-created electrostatic shock waves push the ions further in front, without heating them. Equipped with advanced supercomputer modelling, however, the team was able to find certain exceptions to this scenario. For instance, when the laser is shot at materials containing specific combinations of ions, the resultant shock waves cause the ions to accelerate at different speeds. This in turn generates friction between the ions, thus heating them up quite rapidly. This effect, according to the researchers, was found to be strongest in case of solids composed of two types of ions, like plastics. The team explained:
The two types of ions act like matches and a box; you need both. A bunch of matches will never light on their own – you need the friction caused by striking them against the box… That the actual material used as a target mattered so much was a surprise in itself. In materials with only one ion type, the effect completely disappears.
One of the main reasons behind such a swift heating process is the material’s high density. As the electrostatic shock waves pass through a dense substance, the constituent ions, which are already squeezed together to nearly ten times their normal density, undergo incredibly strong friction and are therefore, heated up within tens of femtoseconds. Speaking about the technology, which currently exists only theoretically, Turrell added:
Faster temperature changes happen when atoms smash together in accelerators like the Large Hadron Collider, but these collisions are between single pairs of particles. In contrast the proposed technique could be explored at many laser facilities around the world, and would heat material at solid density.
Image Credits: Space