Imagine walking through a field on a cloudless day when you suddenly hear the 130-decibel roar of a fighter jet. But you can’t spot the jet, or even tell which direction the sound is coming from. Rather, it seems to originate from the thin air in front of your face, like a shout from an angry, Old-Testament God. No, you aren’t hallucinating. And you aren’t Moses. You’re experiencing a new type of military weapon intended not to kill but to startle an enemy into retreat. It’s called the Laser-Induced Plasma Effect, or LIPE, a weapon that the U.S. military hopes to begin testing in coming months.
LIPE is the brainchild of the Joint Non-Lethal Weapons Program, a group tasked with inventing better options for crowd control and checkpoint security. The noise comes from a unique manipulation of matter and energy to produce loud sounds at specific target locations, sort of like an incredibly precise missile of noise. Here’s how it works:
Matter comes in four states: solid, liquid, gas, and what’s called plasma, the one least familiar to most people, though it’s actually the most common state of matter in the universe. You can think of it as gas plus. In the plasma state, high doses of energy have pulled electrons from their atomic nuclei, creating ions. A bunch of these hanging out is a state of matter that isn’t a liquid or solid and doesn’t behave exactly like a gas either, but rather has magnetic and electric properties and can take the form of light (think neon lights, or the Sun).
LIPE’s lasers fire extremely short bursts (around a nanosecond, or a billionth of a second) of directed high energy at a target. That target could be on a person, a windshield, or merely a single point in space. The energy, relatively harmless at the LIPE levels, separates electrons and nuclei at the target area to create a blue ball of plasma. Additional pulses of directed laser energy manipulate the ball to make a noise that seems to come from nowhere.
“We’ve demonstrated it in the lab at very short ranges. But we haven’t been able to demonstrate it at even 100 meters. That’s … the next step,” said David Law, the technology division chief at JNLWD.
The total cost will be about $3 million, paid out in two $1.5-million small-business-innovation-research contracts to Physical Optics Corp., which is working on the lighting effects, and a Tucson-based company called GEOST, which is working on the sound.
All of that may sound cutting-edge (in addition to loud), but LIPE is not the military’s first attempt to harness the unique properties of plasma matter to achieve strange effects. In 2002 ,a JNLWD program called the Pulsed Energy Projectile sought to create a sound effect that could “literally knock rioters off their feet” New Scientist reported a decade ago. It was supposed to be released in 2007;Instead, the project vanished. In 2004, the Navy tested plasma’s capabilities as a missile deflector in an initiative called Plasma Point Defense, another project with goals well beyond what the technology at the time could deliver.
Such early plasma weapons were heavy — many weighed more than 500 pounds — and required enormous power to deliver very limited effects.That slowly began to change.
In 2005, a company called Stellar Photonics was working on a precision sound weapon for JNLWD under a $2.7 million contract that was part of a program called Plasma Acoustic Sound System, or PASS. By 2009, JNWLD was testing it, with some success. A lot had changed. “What we do with these prototypes to date is power them off of just a regular car battery. They don’t take a lot of energy, but there is … very high peak power, which is what makes this thing work,” said Law.
The short-term goal for PASS was a loud sound effect at a range of 100 meters, very similar to LIPE. What LIPE promises is far more volume. “Current plasmas maybe achieve 90 to 100 dB … we are trying to get to be around 130 dB or a little more,” Law said. He likened the difference to a lawn mower versus a fighter jet. “Every dB is a factor of 10 times the loudness… We’ve been working this in bits and pieces since 2009, but it really has been just over the past couple years that the laser technology has matured enough to be able to potentially get this kind of sound out,” said Law.
Will it work out this time? The world will know soon enough. Law’s goal is to test at 100 meters in coming months and evaluate the program in its entirety by next May.