Laser Beams That Control Electrical Discharges Could Potentially Redirect Lightning

Laser tractor beams can control the direction of sparks in the laboratory, and the makers think their work can be scaled up to redirect lightning to stop forest fires. John D Sirlin/Shutterstock.com 

Physicists have used laser tractor beams to alter the path of electrical discharges in the laboratory. They believe their work could be scaled up to stop lightning igniting fires, instead redirecting it to safety, as well as having medical applications.

Tractor beams aren't just a science fiction plot device evil forces use to capture the plucky heroes' spaceships, prior to their last-minute escape. Dr Vladlen Shvedov of the Australian National University has previously made hollow laser beams, putting a spot at the beam's center so everything behind it is dark. Particles trapped in such beams can be controlled, including dragging items towards the beam's source. In doing so Shevdov's technique allowed tractor beams to work over distances 100 times as long as previous efforts.

Now Shvedov and Professor Andrey Mirochnichenko of the University of New South Wales have reported in Nature Communications these beams can be used to guide the path of electrical discharges.

The secret is to trap particles in the dark heart of the tractor beam, Mirochnichenko told IFLScience, and then use the laser to heat them up. Electrical discharges then follow the “thermal channel” this creates.

For all the hype about arson during Australia's immense 2019-2020 bushfires, most were started by lightning. The same is true for wildfires elsewhere, gender reveal parties and deliberate deforestation aside. The paper's authors hope one day their technique could be used to direct the thunderbolts of the gods to where it can do no harm.

Preventing fires over areas the size of a nation is a big step from the laboratory, but Mirochnichenko pointed out to IFLScience lasers can travel as far as you like in a straight line. He imagines drones flown beneath storm clouds shooting out tractor beams to keep large areas of forest free from lightning strikes, at least when following rains are not anticipated to put the fires out.

Laser guidance of sparks has been achieved before, but only by ionizing the atmosphere to create a charge path along which electricity propagates. That requires impractically powerful lasers for anything over a tiny scale.

Shvedov and Mirochnichenko on the other hand, need just one-thousandth as much energy to hold and heat their particles. In some cases dust already in the atmosphere could do the job, Mirochnichenko told IFLScience, but the experiments instead emitted graphene particles to fill the same role. Lasers running on just a few hundred milliwatts proved suitable for lab conditions.

“We have an invisible thread, a pen with which we can write light and control the electrical discharge to within about one-tenth the width of a human hair,” Miroshnichenko said in a statement.

Before the idea is scaled up for fire control the authors think there will be other uses, including medical applications, such as less invasive methods of removing cancerous tissue.

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