PICATINNY ARSENAL, N.J. (June 21, 2012) -- Scientists and engineers at Picatinny Arsenal 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 warfighters and can picture the LIPC system saving U.S. lives," Fischer said.

http://www.army.mil/article/82262/

More Good News About The 'Scientific Accident That May Change The World'

by Chris Clarke
on February 21, 2013 2:51 PM

Graphene supercapacitors | Photo: UCLA
That battery life video that had gone viral due to a recent post on UpWorthy (and which we told you about Tuesday) now has an update. We told you that researchers at Ric Kamen's lab at UCLA had found a way to make a non-toxic, highly efficient energy storage medium out of pure carbon using absurdly simple technology. Today, we can report that the same team may well have found a way to make that process scale up to mass-production levels.

Explained: Understanding Distributed Generation
The recap: Graphene, a very simple carbon polymer, can be used as the basic component of a "supercapacitor" -- an electrical power storage device that charges far more rapidly than chemical batteries. Unlike other supercapacitors, though, graphene's structure also offers a high "energy density," -- it can hold a lot of electrons, meaning that it could conceivably rival or outperform batteries in the amount of charge it can hold. Kaner Lab researcher Maher El-Kady found a way to create sheets of graphene a single carbon atom thick by covering a plastic surface with graphite oxide solution and bombarding it with precisely controlled laser light.

English translation: He painted a DVD with a liquid carbon solution and stuck it into a standard-issue DVD burner.

The result: Absurdly cheap graphene sheets one atom thick, which held a surprising amount of charge without further modification.

That work was reported a year ago; we mentioned it due to the video virally making the rounds this week. Late Tuesday, UCLA announced that El-Kady and Kaner have a new article in press, in the upcoming issue of Nature Communications, describing a method by which El-Kady's earlier, slightly homebrewed fabricating process shown in the video can be made more efficient, raising the possibility of mass production. As the authors say in their article abstract,

More than 100 micro-supercapacitors can be produced on a single disc in 30 min or less.
El-Kady and Kaner found a way to embed small electrodes within each graphene unit, and place the whole thing on a flexible substrate that allows the supercapacitor to be bent. The team is already claiming energy density comparable to existing thin-film lithium ion batteries.

In the video we shared Tuesday, Kaner says that this technology, if it pans out, offers possibilities like a smart phone getting a full day's charge in a second or two, or an electric car reaching "full" in a minute. This week's press release from UCLA offers other intriguing possibilities:

The new micro-supercapacitors are also highly bendable and twistable, making them potentially useful as energy-storage devices in flexible electronics like roll-up displays and TVs, e-paper, and even wearable electronics. The researchers showed the utility of their new laser-scribed graphene micro-supercapacitor in an all-solid form, which would enable any new device incorporating them to be more easily shaped and flexible. The micro-supercapacitors can also be fabricated directly on a chip using the same technique, making them highly useful for integration into micro-electromechanical systems (MEMS) or complementary metal-oxide-semiconductors (CMOS). As they can be directly integrated on-chip, these micro-supercapacitors may help to better extract energy from solar, mechanical and thermal sources and thus make more efficient self-powered systems. They could also be fabricated on the backside of solar cells in both portable devices and rooftop installations to store power generated during the day for use after sundown, helping to provide electricity around the clock when connection to the grid is not possible.
Kaner says that his lab is now looking for partners in industry that can help make these graphene supercapacitors on an industrial scale.

It's tempting to be cynical about the possibility of a magic bullet energy storage solution; such a breakthrough could solve any number of problems from annoying dead smart phones to two-hour charge times for electric cars to an inefficient power distribution grid, and it's easy to really want this kind of thing to be true. Plenty of seemingly promising technical innovations in the last few years haven't lived up to their hopeful hype. There's always the chance that further study will reveal a fatal flaw in graphene supercapacitor technology. But for the time being, ReWire officially has its hopes up, at least a little.

http://www.kcet.org/news/rewire/science/more-good-news-on-those-carbon-supercapacitors.html