Lasers as lightning rods just became a reality thanks to a new study
According to a report published in Nature Photonics, an intense laser pointed at the sky can act as a virtual lightning rod and alter the route of lightning strikes.
The research could improve lightning protection strategies for vital infrastructure like power plants, airports, and launch pads.
A "Franklin rod," an electrically conducting metal mast that intercepts lightning discharges and directs them safely to the ground, is now the most popular lightning protection device.
These rods, also known as "rod and reel" lightning rods, work by attracting and conducting electrical charges from a thunderstorm to the ground. They consist of a pointed metal rod placed on top of a building or other structure and a wire that runs from the rod down to a grounding system.
When a thunderstorm approaches, the electrical charges in the storm clouds are attracted to the pointed rod, which acts as a conductor. The charges are then safely conducted down the wire to the ground, reducing the risk of damage from a lightning strike.
Interestingly, if the research is anything to go by, an alternative might be a laser beam pointed at the sky. Such a virtual rod would also be highly mobile.
Using lasers as lightning rods is nothing new
The use of lasers as lightning rods is a theoretical concept that is still being researched. The idea is that a high-powered laser beam could be directed into the atmosphere in order to ionize a path for lightning to follow, in effect "guiding" the lightning strike to a specific location where it can be safely grounded.
This concept is based on the principles of laser-induced breakdown, where a high-intensity laser beam creates a plasma channel in a gas, which can then conduct electricity. That is, until now.
Intense laser pulses have been used to guide lightning strikes in laboratory settings before; however, there has never been a field finding that experimentally shows lightning guidance by lasers.
On the Säntis Mountain in northeastern Switzerland, Aurélien Houard and associates conducted experiments in the summer of 2021 to determine whether a laser might direct a lightning strike. A massive car-sized laser that can fire up to 1,000 pulses per second was placed next to a communications tower that experiences lightning strikes about 100 times yearly.
The scientists noted that during more than 6 hours of operation during thunderstorm activity, the laser changed the path of 4 upward lightning discharges. High-frequency electromagnetic waves produced by lightning strikes were used to pinpoint the strikes to confirm their observations.
Greater X-ray burst detection during the time of the impacts also confirmed successful lightning directing. High-speed cameras directly captured one of the strikes, which was later proved to have followed the laser path for more than 164 feet (50 meters).
According to the scientists, the findings contribute to our present understanding of laser physics in the atmosphere and could be used to create fresh approaches to lightning protection.
You can read the study for yourself in the journal Nature Photonics.
"Lightning discharges between charged clouds and the Earth's surface are responsible for considerable damages and casualties. It is, therefore important to develop better protection methods in addition to the traditional Franklin rod. Here we present the first demonstration that laser-induced filaments—formed in the sky by short and intense laser pulses—can guide lightning discharges over considerable distances.
We believe that this experimental breakthrough will lead to progress in lightning protection and lightning physics. An experimental campaign was conducted on the Säntis mountain in northeastern Switzerland during the summer of 2021 with a high-repetition-rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by very high-frequency interferometric measurements, and the number of X-ray bursts detected during guided lightning events greatly increased.
Although this research field has been very active for more than 20 years, this is the first field result that experimentally demonstrates lightning guided by lasers. This work paves the way for new atmospheric applications of ultrashort lasers and represents an important step forward in the development of a laser-based lightning protection for airports, launchpads, or large infrastructures."
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