What's Up UA? - Laser 'Lightning Rods' Channel Electricity Through Thin Air - Tucson Local Media: University Of Arizona

What's Up UA? - Laser 'Lightning Rods' Channel Electricity Through Thin Air

Font Size:
Default font size
Larger font size

Posted: Monday, August 25, 2014 9:13 am

By zapping the air with a pair of powerful laser bursts, researchers at the University of Arizona have created highly focused pathways that can channel electricity through the atmosphere.

The new technique can potentially direct an electrical discharge up to 10 meters (33 feet) away or more, shattering previous distance records for transmitting electricity through air. It also raises the intriguing possibility of one day channeling lightning with laser power.

Described in a paper published in The Optical Society’s new open-access journal Optica, the current system may have near-term, lifesaving applications in areas such as the remote detonation of land mines, the researchers speculate. The laser system could easily pinpoint an active land mine and then carry an electric pulse strong enough to safely discharge harmful explosives from afar.

The team used a femtosecond laser to create a thin column of plasma – a special charged state of matter – in the air between two electrodes. A femtosecond is one millionth of a billionth of a second. Femtosecond lasers emit pulses that last only a few tens of femtoseconds.

Before this narrow plasma channel has a chance to dissipate, an almost simultaneous burst from a nanosecond laser – lasting a million times longer than a femtosecond pulse – retraces the same path, giving it an extra jolt of heat and the staying power necessary to transmit electricity.

The team was led by Pavel Polynkin, associate research professor of optical sciences at the University of Arizona College of Optical Sciences.

"By creating a combined one-two punch of laser light, we could first open a doorway through the air and then wedge it open just long enough to control and direct electricity through the atmosphere," said Polynkin, the paper's corresponding author. "This incredibly rapid double burst of energy is what was needed to overcome some otherwise daunting challenges."

Using Lasers to Channel Lightning

The idea of using lasers to channel electricity through the air, which is not normally conductive, was first proposed in the 1970s and further explored through the 1990s. The research was based on the idea that by superheating a very narrow column of air, it would be possible to create a straight path along which an electric charge could flow.

These early attempts used nanosecond lasers, which were the most practical lasers at the time due to their intense power and very short duration. The highly focused laser beams superheated a narrow line of air molecules, stripping off their outer electrons and producing a filament of charged plasma. The higher-than-normal concentration of free electrons in the plasma overcame the atmosphere’s natural insulator properties, making it much more conductive. Under laboratory conditions, researchers were, at the time, able to produce a filament of approximately 1 meter in length.

With the advent of more advanced femtosecond lasers, however, Polynkin and his team felt they could utilize the advantages brought about by both femtosecond and nanosecond lasers and achieve much better results through combining the two types of lasers in a single powerful beam.

Earlier this year, a joint team from the UA and the University of Central Florida, which included the authors of the new Optica paper, presented a new approach involving a high-intensity laser beam inside a "dress beam" refueling the primary beam and sustaining it over much greater distances than were previously possible. 

"In both experiments, we used two synchronized laser pulses to produce plasma in air," Polynkin said. "But the nature of the second pulse is different in the two cases. Instead of the dress beam, which only lasted femtoseconds, we now use a much more energetic pulse of longer duration – several nanoseconds – that we call heater pulse."

Extending the Reach and Duration With More Lasers

The current breakthrough was achieved by sending a femtosecond laser light pulse as the "igniter" and a nanosecond pulse as a "heater" along the same path, and by understanding how the atmosphere behaves when it was subjected to these extremely energetic light pulses. The researchers recognized that it wasn't the actual plasma created by the lasers that made the atmosphere more conductive; it was the subsequent superheating that lowered the density of the filament of air. Without some additional input of energy, however, this zone of lower density quickly collapsed. To improve both distance and duration, a second energy source was needed to rapidly reheat the air, stabilizing the filament just long enough to carry an electrical current.

"Since the first femtosecond laser already blazed the trail, we were able to harness a second nanosecond laser, following the same path, to rapidly pump more heat into the system," said Polynkin. "This channel lasted considerably longer, so we had the potential to extend the previous distance record by more than tenfold."

The filaments the researchers created significantly lowered what is known as the electrical breakdown point, the voltage that is needed to overcome the insulating effect of the atmosphere. Lightning, because of its incredibly high voltage, routinely overcomes the air's natural resistance, although in highly random and unpredictable ways.

Based on their initial results, the researchers believe that other forms of heater beams, such as microwaves or long-wavelength lasers, could further increase the distances they were able to achieve, though other issues would need to be addressed before applications like channeling lightning could be achieved.

As a next step, the researchers are planning on using a microwave beam in place of the nanosecond laser to more efficiently heat the channel and perhaps achieve better results.

© 2017 Tucson Local Media. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

More about

Welcome to the discussion.

Saturday 09/26/2015

Little goes right for the Wildcats

Saturday 09/19/2015

Records fall in lopsided win

Friday 09/04/2015

Arizona challenged by Roadrunners

Tuesday 08/18/2015

Arizona has few questions at QB

Thursday 08/06/2015

Cats open fall drills

Monday 03/09/2015

McConnell, Johnson finalists for awards Johnson Named FOY, Four Wildcats Honored by Pac-12

Monday 01/19/2015

Johnson named Player of the Week

Friday 01/16/2015

Wildcats down shorthanded Colorado

Monday 01/05/2015

Vote for Sean Miller & win $100,000 for the Tucson Ronald McDonald House

Monday 12/15/2014

Arts and Sciences Are Writing a New Love Story Together

Thursday 12/11/2014

More hardware for UA's Wright

Wednesday 12/10/2014

S.H.I.E.L.D half season finale delivers Cats get a glimpse of the future in blowout

Friday 11/14/2014

UA Eller College To Share Economic Outlook for 2015-2016

Wednesday 11/12/2014

UA Humanities Seminars

Tuesday 11/04/2014

What's Up UA? - Hiring Interns? Top 8 Tips for Companies

Wednesday 10/15/2014

What's Up UA? - Close Encounter 'One in a Million'

Monday 10/13/2014

What's Up UA? - Austin Hill: The Comeback Kid

Monday 10/06/2014

What's Up UA? - Health, Wellness Practices Highlighted by Chinese Culture Festival

Thursday 10/02/2014

What's Up UA? - Ready for a Super-Fast Internet? UA Scientists Are Fast at Work on It

Tuesday 09/30/2014

What's Up UA? - Using the Force: UA Police Officer Completes NASA Project

Monday 09/29/2014

What's Up UA? - How New Social Movements Take Root

Friday 09/26/2014

What's Up UA? - PBS 'NewsHour' to Feature Inspirational UA Student

Wednesday 09/24/2014

What's Up UA? - UA Paves Way to Redefine STEM Education

Monday 09/22/2014

What's Up UA? - Wildcats Rally, Hail Mary TD Defeats Cal, 49-45

Thursday 09/18/2014

What's Up UA? - When Job Loss Equals Weight Gain

Monday 09/15/2014

What's Up UA? - Don’t Underestimate Your Mind’s Eye

Thursday 09/11/2014

What's Up UA? - 'What I Wish I Had Known as a Freshman'

Tuesday 09/09/2014

What's Up UA? - UA Undergraduate Researchers Take to the Radio

Thursday 09/04/2014

What's Up UA? - Send Your Tweet – and Your Name – to an Asteroid

Tuesday 09/02/2014

What's Up UA? - Brown Foundations' $2.5 Million Kicks Off Catapult Corp

Thursday 08/28/2014

What's Up UA? - New Veterinary Degree Program Made Possible by $9M Gift is Critical for State

Monday 08/25/2014

What's Up UA? - Laser 'Lightning Rods' Channel Electricity Through Thin Air

Thursday 08/21/2014

What's Up UA? - UA Fall Enrollment Sets Record for Diversity, Number of Freshmen

Tuesday 08/19/2014

What's Up UA? - Remarkable Résumé: UA Student Journalist's Career Includes CNN, NYT Phoenix

Friday 08/15/2014

What's Up UA? - Through Innovative Partnership, 'Hot Shot' Team Tackles Yuma Produce Perils

Wednesday 08/13/2014

What's Up UA? - The UA Named a Top College by The Princeton Review

Monday 08/11/2014

What's Up UA? - UA Researchers Study Increasing Lifespan and Immune Function What's Up UA? - UA Undergrads Conducting Microgravity Research Aboard NASA's G-Force One

Monday 06/09/2014

What's up UA? - UA to Host U.S. and Mexico Officials Exploring Collaborations in Education, Innovation, Research

Thursday 06/05/2014

What's Up UA? - New Wilderness Medicine Class Hones Patient Care Skills in Rugged Conditions

Tuesday 06/03/2014

Track Cats Send Eight Athletes to TrackTown USA

Monday 06/02/2014

What's Up UA? - Bringing a Spacecraft Back From the Dead

Friday 05/30/2014

What's Up UA? - Heart Attack Patient Defies Odds with Tailored Surgical Treatment at UA Medical Center

Thursday 05/29/2014

What's Up UA? - UA Marketing Students Win National AT&T Competition

Tuesday 05/27/2014

What's Up UA? - Scientists Discover Genetic Basis of Pest Resistance to Biotech Cotton

Friday 05/23/2014

What's up UA? - Four UA Students Picked for Pat Tillman Foundation Scholarships

Wednesday 05/21/2014

What's Up UA? - Scientists Discover Genetic Basis of Pest Resistance to Biotech Cotton

Monday 05/19/2014

What's Up UA? - UA Tunnels Get Carbon Fiber Makeover


Follow us on Facebook

Online poll