The world's fastest water heater uses X-ray lasers to heat water to about 100,000 degrees Celsius in about 75 femtoseconds – one-millionth of a millionth of a millionth of a second. It goes beyond boiling water, transforming it into plasma. But, the technology isn't for making tea.
The experimental setup was put together by a team of researchers in Sweden at the Center for Free-Electron Laser Science (CFEL) of DESY and Uppsala University, reports R&D Mag. This heater was built as a way for scientists to learn more about different states and peculiar characteristics of water. Going forward, the results could have practical uses for a better insight into biological samples.
"It is not the usual way to boil your water," said Carl Caleman who led the experiment where researchers made use of the X-ray free-electron laser Linac Coherent Light Source LCLS at the SLAC National Accelerator Laboratory in the US. They fired extremely powerful, ultra-short flashes of light through water.
"Normally, when you heat water, the molecules will just be shaken stronger and stronger," he explained. At that level, heating is nothing more than the violent movement of molecules. This can be achieved by heat transfer from a stove or an immersion rod seen in a kettle. For a more direct approach to heating, a microwave can make water swing back and forth faster and in tune with its own electromagnetic field.
The X-ray laser experiment takes it up a notch, explains Caleman. "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." Heating like this happens fast, really fast.
Scientists recorded phase transformation of water from liquid to plasma (a state of matter where electrons have been pulled out from atoms, what is left is an electrically charged substance and it is extremely hot) in less than 75 femtoseconds, or 75 millionths of a billionth of a second. In numbers, that is 0.000 000 000 000 075 seconds.
However, the plasma, "still remains at the density of liquid water, as the atoms didn't have time to move significantly yet," said co-author Olof Jönsson. On Earth, this state of matter is not found naturally. "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," he explained.
Water in its plasma state is not something that is found on Earth or even something that can be recreated easily. However, it is possible and an almost everyday occurrence in many people's homes to make use of superheated water.
Superheated water is liquid water that is well over the boiling point, but has not yet turned into steam. It might be possible to reach temperatures of up to 374 degrees Celsius. It is possible to reach such temperatures and keep water in its liquid form under high pressure like in pressure cookers and in cases where a container or bowl is too smooth and there are not enough nucleation sites for water to start boiling in microwave ovens.
The study was first published in the journal Proceedings of the National Academy of Sciences (PNAS).