Tractor Laser Beam

An international team of researchers has proposed and demonstrated an efficient approach for triggering, trapping and guiding electrical discharges in air. Their technology is based on the use of a low-power laser beam that traps and transports light-absorbing particles in mid-air.

Experimental configuration and principles of optical vortex beam for discharge control and guidance: at first, microparticles are prepared and placed in an enclosed container with vertically aligned electrodes (left); an applied electric field through the container lifts the particles by electrostatic forces; some of the lifted particles cross the hollow core doughnut-shaped CW laser beam and get trapped in it; the vortex laser beam is guides particles in the mid-air: particles from a container are transported into a parallel plate chamber through a hole in one of the electrodes; in addition, particles are heated by the same laser beam thus creating a thermal channel between the electrodes that results in a subthreshold electrical breakdown; the inset shows a photograph of the experimental setup with particles trapped in the beam. Image credit: Shvedov et al., doi: 10.1038/s41467-020-19183-0.

“We used a laser beam that mirrors the same process as lightning and creates a path that directs electrical discharges to specific targets,” said first author Dr. Vladlen Shvedov, a researcher in the Laser Physics Centre at Australian National University and Texas AM University at Qatar.

“The experiment simulated similar atmospheric conditions to those found in real lightning.”

“We can imagine a future where this technology may induce electrical discharge from passing lightning, helping to guide it to safe targets and reduce the risk of catastrophic fires.”

The team’s tractor beam works by trapping and heating graphene microparticles in the ambient air.

By heating the graphene microparticles trapped in the beam, the researchers were able to create the necessary conditions for electric breakdown and transmission along the laser’s path using only an ordinary laser.

They used a laser intensity a thousand times less than that in any previous attempts, meaning any potential technology to control lightning could be much cheaper, safer and more precise.

“The discovery has important applications for reducing bushfire risk as the tractor beam can be guided over long distances and allows for precision control of the lightning’s discharge,” said co-lead author Professor Andrey Miroshnichenko, a researcher in the School of Engineering and Information Technology at the University of New South Wales.

“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.”

The discovery also has potential for the micro-scale control of electrical discharge in medicine and manufacturing applications.

“The medical applications include optical scalpels for the removal of hard cancerous tissue to non-invasive surgery techniques,” Professor Miroshnichenko said.

“We are really at the start of learning what this completely new technology might mean.”

The team’s work was published in the journal Nature Communications.

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V. Shvedov et al. 2020. Optical beaming of electrical discharges. Nat Commun 11, 5306; doi: 10.1038/s41467-020-19183-0