Scientists at Imperial College London have created an extremely rapid heating (laser-like) mechanism which they believe could heat certain material to ten million degrees (hotter than the core of the Sun) in much less than a million of a second.
As researchers put it in the journal published in Nature Communications, the new heating technique is about 100 times faster than rates currently seen in fusion experiments using the world’s most energetic laser system at the Lawrence Livermore National Laboratory in California. For years, high-power lasers have been extensively used to heat material as part of the effort to create fusion energy. When materials are heated, the energy from the laser first heats up the electrons in the target which in turn, then heat up the ion, making the process much slower.
However, the new method is a completely different approach and it could have one of the fastest heating rates. As the team came upon, when a high-intensity laser is fired at a certain type of material, it creates an electrostatic shockwave that directly goes straight into the ions, which in turn heats up the material much faster.
“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,” said Dr Arthur Turrell, the lead author of the study.
The researchers also used sophisticated computer modelling so that the ions does not accelerate away from the shockwave. Laser-induced electrostatic shockwaves normally push ions ahead of them, and this refuses ions being heated upon. So if a material contains a special combination of ions, they will be accelerated at different speeds, thereby making the friction induced due to acceleration to rapidly heat up the ions. The team also found that the effect would be strongest in solids with two ion types, such as plastics.
“The two types of ions act like matches and a box; you need both,” explained study co-author Dr Mark Sherlock from the Department of Physics at Imperial. “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,” added study co-author Professor Steven Rose. “In materials with only one ion type, the effect completely disappears.”
The ions are squeezed together to almost ten times the usual density of a solid material. The interaction between the electric field of shock, increase of density and collisions between difference species of ions, cause the material to heat up rapidly. Researchers believe this to be the fastest heating mechanisms discovered if demonstrated in the laboratory.
“Faster temperature changes happen when atoms smash together in accelerators like the Large Hadron Collider, but these collisions are between single pairs of particles,” said Dr Turrell. “In contrast the proposed technique could be explored at many laser facilities around the world, and would heat material at solid density.”
Researchers hope that this new method proposed here for the first time, could be relevant to new avenues of research in thermonuclear fusion energy. And in the future, they may be eventually able to replicate the Sun’s ability to produce clean energy.
[Hat Tip: Imperial College London, Nature Communications – Ultrafast Collisional Ion Heating By Electrostatic Shocks, Image via Shutterstock]