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 August 28, 2015

Business: Rafale, Mistral on agenda for Le Drian in Malaysia, India¬†– French Defense Minister Jean-Yves Le Drian is due to visit Malaysia Aug. 30, with talks expected to cover the Rafale fighter jet and Mistral helicopter carrier, website La Tribune reported. U.S. Army to choose new landing craft next year¬†– In line with the Pentagon’s...
 
 

News Briefs August 28, 2015

Boeing plans to lay off some Southern California workers Boeing has announced that it plans to lay off employees at its Southern California-based satellite division. The Los Angeles Times reports that the aerospace giant said Aug. 25 that it will lay off as many as several hundred employees at the El Segundo factory. Boeing says...
 
 

Special tactics Airmen killed in hostile incident

Two special tactics airmen, who were deployed in support of Operation Freedom’s Sentinel, were killed near Camp Antonik, Afghanistan, Aug. 26. Capt. Matthew D. Roland, 27, and SSgt. Forrest B. Sibley, 31, were at a vehicle checkpoint when two individuals wearing Afghan National Defense and Security Forces uniforms opened fire on them. NATO service members...
 

 

Hurricane Hunters to fly Tropical Storm Erika

The Air Force Reserve Hurricane Hunters are operating out of Homestead Air Reserve Base, Fla., flying their state-of-the-art WC-130J Super Hercules into Tropical Storm Erika in support of the National Hurricane Center in Miami. The 53rd Weather Reconnaissance Squadron flew four missions into the tropical storm from their deployed location at St. Croix in the...
 
 
LM-MUOS

U.S. Navy, Lockheed Martin ready to launch MUOS-4 Aug. 31

The U.S. Navy and Lockheed Martin are ready to launch the fourth Mobile User Objective System secure communications satellite, MUOS-4, from Cape Canaveral Air Force Station, Fla., Aug. 31 aboard a United Launch Alliance Atlas V...
 
 

Pentagon probing alleged distorting of war intelligence

The Pentagon’s inspector general is investigating an allegation that the military command overseeing the anti-Islamic State campaign distorted or altered intelligence assessments to exaggerate progress against the militant group, a defense official said Aug. 26. The official was not authorized to discuss the probe publicly and so spoke on condition of anonymity. The investigation was...
 




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=""> <s> <strike> <strong>