X-ray laser boils water into strange plasma state hotter than Earth's core
Waiting for water to boil is a minor inconvenience that we've all experienced, but maybe we're just using the wrong tools. Instead of a kettle, next time try the world's most powerful X-ray laser, which has now been used to boil water to 100,000° C (180,000° F) in 75 millionths of a billionth of a second – turning it into a new, plasma-like state of water in the process.
The device that can now also claim the title of world's fastest water heater is the Linac Coherent Light Source (LCLS), a laser that fires incredibly intense X-ray pulses with enough energy to cut through steel. In the past, the LCLS has been used to image viruses, create a "molecular black hole", make it rain diamonds and recreate the conditions at the center of a star.
This time, researchers from the German Electron Synchrotron ( DESY) and Uppsala University focused that intense energy onto one of the strangest substances in the universe – water. The team was aiming to learn more about this life-giving liquid, and the different phases it can exist in. Normally, heating water increases the motion of its molecules, but the LCLS took a more aggressive approach.
"Our heating is fundamentally different," says Carl Caleman, lead researcher on the study. "The energetic X-rays punch electrons out of the water molecules, thereby destroying the balance of electric charges. So, suddenly the atoms feel a strong repulsive force and start to move violently."
With the electrons kicked out, the water turns from a liquid into a plasma in under 75 femtoseconds. This is no ordinary plasma though.
"But while the water transforms from liquid to plasma, it still remains at the density of liquid water, as the atoms didn't have time to move significantly yet," says Olof Jönsson, co-author of the study. "It has similar characteristics as some plasmas in the Sun and the gas giant Jupiter, but has a lower density. Meanwhile, it is hotter than Earth's core."
The researchers are planning to use these measurements and simulations of the process to study this new, exotic state of water. The ultimate goal is to learn more about water in general, which is quite unique in terms of properties like density, heat capacity and thermal conductivity. The experiment also helps researchers understand how to use the LCLS and other X-ray lasers to image different types of molecules.
The research was published in the journal Proceedings of the National Academy of Sciences.