Plasma Shield: Missile Stopper?http://www.wired.com/dangerroom/2007/05/plasma_shield_m/
By David Hambling May 7, 2007 | 2:02 am
Real-life plasma shields to protect soldiers are only the beginning. The technology — which use a laser to create a curtain of miniature plasma explosions like firecrackers to turn away an enemy — could be adapted to turn it into a physical shield, capable of warding off projectiles.
Unlike existing defenses (like the much-hyped Trophy "force field") only hit incoming projectiles a few meters away. The Plasma Acoustic Shield System (PASS), on the other hand, has a range of a hundred meters – a huge advantage.
PASS can put a series of small plasma explosions in the path of an incoming rocket-propelled grenade (RPG), bullet or other projectile. These are only very small explosions, but since they can be precisely placed on the nose of the missile, this is not a problem. (Tracking a missile nose with a laser is exactly what laser infra-red countermeasures do at the moment.) We’re not trying to destroy the missile, or stop it, or even necessarily push it aside all that far: just make it tumble.
An RPG is a shaped-charge or HEAT warhead: basically a conical explosive charge lined with metal. When it detonates, the metal is blasted into a narrow, high-velocity, armor-piercing jet. If the round tumbles and is facing sideways or backward it will have little effect on any sort of armor. (It’s still bad news if you’re not armored though.)
A Plasma Shield producing a hundred detonations a second could put thirty of them in the path of an incoming RPG round if it’s going at 300 meter per second. That should be enough to cause fairly severe perturbation.
A similar rule applies to bullets: if it’s going sideways when it hits you, even a tungsten-cored round is not going to make it through a Kevlar. I’m not suggesting that PASS is the answer to everything – but if it’s being built anyway, then its defensive capabilities could explored.
(Of course you’ll need a compact, reliable device to spot and precisely track incoming rounds a hundred meters away…and here’s one I found earlier made by Nova Sensors.)
Plasma Shield might have an even better trick up its sleeve though, especially when larger versions are built. It relates to Russian work on plasma aerodynamics , the way that ionized gas influences the airflow around an object. (I’ve previously looked at some bizarre radioactive stealth technology from the 50’s related to this. ) Inject even a tiny amount of plasma into the airflow around a missile or aircraft, and the friction drops radically.
If only one side of the missile gets the plasma – well, it’ll be a bumpy ride.
In the 90’s the Russian physicist Rimily Avramenko proposed this method for taking out ballistic missiles:
Their action is based on focusing beams of electromagnetic energy produced by laser or microwave radiation into the upper layers of the atmosphere….A
cloud of highly ionized air arises at the focus of the laser or microwave rays, at an altitude of up to 50 kilometers. Upon entering it, any object–a missile, an airplane, is deflected from its trajectory and disintegrates in response to the fantastic overloads arising due to the abrupt pressure difference …What is fundamental in this case is that the energy aimed by the terrestrial components of the plasma weapon–lasers and antennas–is concentrated not at the target itself but a little ahead of it. Rather than "incinerating" the missile or airplane, it "bumps" it out of trajectory.
The Russians refer to such balls of plasma as plasmoids. Although there is some speculation that their high-power radar could produce plasmoids in the upper atmosphere for defensive use, this has not been proven. (Just, please, don’t mention HAARP.) But the laser system used in PASS has been proven.
Long, CEO of Stellar Photonics, which makes the PASS laser, tells me that future systems will have much greater range than the current laser. The focusing requirements are much simpler than for high-power energy weapons like the Airborne Laser (or ABL, a ray gun-equipped 747 jet), making longer ranges more feasible.
The technology which produces small plasma detonations in PASS could put larger plasmoids in the path of missiles and aircraft high in the atmosphere. Rather than using massive amounts of energy to burn through the missile’s casing, just a small amount of laser-created plasma could turn the missile’s own speed against it, tripping it up in a piece of cosmic judo. A small, low-energy pulse laser may turn out to be more effective for missile defense than the giant chemical laser in the $7.3 billion ABL.