Defense

June 25, 2012

Picatinny engineers set phasers to ‘fry’

by Jason Kaneshiro
Picatinny Arsenal, N.J.

A guided lightning bolt travels horizontally, then hits a car when it finds the lower resistance path to ground. The lightning is guided in a laser-induced plasma channel, then it deviates from the channel when it gets close to the target and has a lower-resistance path to ground. Though more work needs to be done, Picatinny Arsenal engineers believe the technology holds great promise.

Scientists and engineers at Picatinny Arsenal in New Jersey are busy developing a device that will shoot lightning bolts down laser beams to destroy its target. Soldiers and science fiction fans, you’re welcome.

“We never got tired of the lightning bolts zapping our simulated (targets),” said George Fischer, lead scientist on the project.

The Laser-Induced Plasma Channel, or LIPC, is designed to take out targets that conduct electricity better than the air or ground that surrounds them. How did the scientists harness the seemingly random path made by lightning bolts and how does a laser help? To understand how the technology, it helps to get a brief background on physics.

“Light travels more slowly in gases and solids than it does in a vacuum,” explained Fischer. “We typically think of the speed of light in each material as constant. There is, however, a very small additional intensity-dependent factor to its speed. In air, this factor is positive, so light slows down by a tiny fraction when the light is more intense.”

“If a laser puts out a pulse with modest energy, but the time is incredibly tiny, the power can be huge,” Fischer continued. “During the duration of the laser pulse, it can be putting out more power than a large city needs, but the pulse only lasts for two-trillionths of a second.”

Why is this important?

“For very powerful and high intensity laser pulses, the air can act like a lens, keeping the light in a small-diameter filament,” said Fischer. “We use an ultra-short-pulse laser of modest energy to make a laser beam so intense that it focuses on itself in air and stays focused in a filament.”

To put the energy output in perspective, a big filament light bulb uses 100 watts. The optical amplifier output is 50 billion watts of optical power, Fischer said.

“If a laser beam is intense enough, its electro-magnetic field is strong enough to rip electrons off of air molecules, creating plasma,” said Fischer. “This plasma is located along the path of the laser beam, so we can direct it wherever we want by moving a mirror.”

“Air is composed of neutral molecules and is an insulator,” Fischer said. When lightning from a thunderstorm leaps from cloud to ground, it behaves just as any other sources of electrical energy and follows the path of least resistance.

“The plasma channel conducts electricity way better than un-ionized air, so if we set up the laser so that the filament comes near a high voltage source, the electrical energy will travel down the filament,” Fischer elaborated.

A target, an enemy vehicle or even some types of unexploded ordnance, would be a better conductor than the ground it sits on. Since the voltage drop across the target would be the same as the voltage drop across the same distance of ground, current flows through the target. In the case of unexploded ordnance, it would detonate, explained Fischer.

Even though the physics behind the project is sound, the technical challenges were many, Fischer recalled.

“If the light focuses in air, there is certainly the danger that it will focus in a glass lens, or in other parts of the laser amplifier system, destroying it,” Fischer said. “We needed to lower the intensity in the optical amplifier and keep it low until we wanted the light to self-focus in air.

Other challenges included synchronizing the laser with the high voltage, ruggedizing the device to survive under the extreme environmental conditions of an operational environment, and powering the system for extended periods of time.

“There are a number of high-tech components that need to run continuously,” said Fischer.

But despite the challenges, the project has made notable progress in recent months.

“Definitely our last week of testing in January 2012 was a highlight,” said Tom Shadis, project officer on the program. “We had a well thought-out test plan and our ARDEC and contractor team worked together tirelessly and efficiently over long hours to work through the entire plan.

“The excellent results certainly added to the excitement and camaraderie,” added Fischer.

As development continues, Shadis said that those involved with the project never lose sight of the importance of their work.

“We were all proud to be serving our war fighters and can picture the LIPC system saving U.S. lives,” Fischer said.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines October 22, 2014

News: Northrop challenges 3DELRR contract award - Northrop Grumman has formally issued a protest against the US Air Force’s decision to award its next-generation ground based radar to competitor Raytheon.   Business: Defense firms prefer GOP, but spread campaign cash between political parties - For every campaign contribution from a major arms manufacturer to a Republican candidate...
 
 

News Briefs October 22, 2014

Military converges on scene of Kansas jet crash Military personnel are investigating at the site in southeast Kansas where an Oklahoma Air National Guard fighter jet crashed after a midair collision with another one during a training exercise. The F-16 crashed Oct. 20 in a pasture about three miles northeast of Moline, an Elk County...
 
 
Courtesy photograph

Upgrades ‘new normal’ for armor in uncertain budget environment

Courtesy photograph The current Paladin is severely under-powered and overweight so its speed of cross-country mobility is pretty restricted. The Paladin Integrated Management program is designed to address a number of these we...
 

 

ISR: A critical capability for 21st century warfare

The progressive adaptations and breakthroughs made in the intelligence, surveillance and reconnaissance arena have changed the way wars are fought, and the way commanders think about the battlespace. “Whether we have airmen exploiting full motion video data or serving downrange in the (Central Command) area of responsibility, these individuals make up an enterprise of 30,000...
 
 

Lockheed Martin teams with Roketsan of Turkey on new standoff missile for F-35

Roketsan and Lockheed Martin signed a teaming agreement Oct. 22 for collaboration on the SOM-J, a new generation air-to-surface Standoff Cruise Missile for the F-35 Lightning II. The SOM system is an autonomous, long-range, low-observable, all-weather, precision air-to-surface cruise missile. The SOM-J variant is tailored for internal carriage on the F-35 aircraft. The companies will...
 
 

Army Operating Concept expands definition of combined arms

The Army Operating Concept, published Oct. 7, expands the idea of joint combined-arms operations to include intergovernmental and special operations capabilities, said Gen. Herbert R. McMaster Jr. The new concept includes prevention and shaping operations at the strategic level across domains that include maritime, air, space and cyberspace, he said. It’s a “shift in emphasis,”...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>