A researcher at the
defensecompany
Boeing
has filed a patent for a sci-fi-esque cloaking device that would protect
soldiers from intense shock waves generated by explosions.
The
just-issued patent (No. 8,981,261) to Boeing envisions stopping shock waves
using a veil of heated, ionized air. Such a "shield" would damp the force of
explosions. It doesn't build an invisible wall of force, but rather
makes shock waves bend around objects, just as some high-tech materials bend
light and make things invisible.
Brian
J. Tillotson, a senior research fellow at Boeing, said the idea occurred to him
after noticing the kinds of injuries suffered by soldiers who served in Iraq
and Afghanistan. "We were doing a much better job of stopping
shrapnel," Tillotson told Live Science. "But they were coming home with
brain injuries."
Though
the armor plating on a military vehicle might stop the debris from a roadside
bomb from injuring a soldier, it can't shield against theshock waves generated
by such explosions. The blast wave goes right through a human body and
causes massive trauma. (This is why the action-movie scenes where the hero runs
ahead of an explosion and escapes harm are pure fiction.)
Tillotson's
invention is a device that would heat the air in front of the spot where the
bomb goes off. In one version, a detector "sees" an explosion before
the shock wave hits. The detector is connected to an arc generator, basically
two ends of a circuit connected to a large power source. When the system
generates enough current, an arc of electricity jumps between the two ends of
the circuit, like a bolt of lightning. [Science Fact or
Fiction? The Plausibility of 10 Sci-Fi Concepts]
That
arc heats and ionizes, or charges, particles of air. The heated air would work
as a shield by changing the speed at which shock waves travel, and therefore
bending them around a protected soldier, Tillotson said.
Sound waves (and
other wave types) propagate faster in hot air, Tillotson said. For that reason,
the shock wave would speed up when it hits the heated air around the electrical
discharge. As the shock wave speeds up, it would change direction slightly, or
refract, away from the person or object behind the arc. That bending occurs
because of the change in speed of the wave, and the shape of the area of hot
air the shock wave hits determines the exact direction.
The
process resembles the way lenses bend light, Tillotson said.
"With
a convex lens you focus the light," he said. "A concave lens spreads
it out." Light waves move slower in glass, so when light hits a glass
surface it bends. The lens must be concave to spread out that light.
Because shock waves move faster in hotter air, a spherical or cylindrical area
of hot air will cause the shock wave to bend, this time spreading out just like
the light through a concave lens, becoming weaker. In doing so that hot-air
shield could deflect shock waves.
Arc
generators aren't the only way to ionize air. Lasers would also work, Tillotson
said. A laser fired across the path of an explosion would ionize and heat the
air around the beam, creating the lensing effect.
In
another method, a strip of some metal could be placed on the side of a truck,
for example. "Put a couple of kilo-amps [thousands of amperes] through a
strip of metal, and it will vaporize," he said. The vaporized metal once
again heats the surrounding air.
One
issue for all of these methods of damping shock waves is the amount of power
required. But Tillotson noted a lot of research in this area shows promise in
decreasing that power suck. In addition, even a high-powered
laser doesn't have to be on for long, perhaps a fraction of a
second, to heat the air sufficiently. "It's basically a solved
problem," he said of the power supply.
This
isn't the only technology patent
for Tillotson; he has at least a half-dozen others in areas such as
aerodynamics and beamed power sources, and even other methods of damping shock
waves. Whether this particular technology becomes a reality will depend, as
many do, on future interest (and funding) from government and the private
sector.
Tillotson's
invention is a device that would heat the air in front of the spot where the
bomb goes off. In one version, a detector "sees" an explosion before
the shock wave hits. The detector is connected to an arc generator, basically
two ends of a circuit connected to a large power source. When the system
generates enough current, an arc of electricity jumps between the two ends of
the circuit, like a bolt of lightning. [Science Fact or
Fiction? The Plausibility of 10 Sci-Fi Concepts]
That
arc heats and ionizes, or charges, particles of air. The heated air would work
as a shield by changing the speed at which shock waves travel, and therefore
bending them around a protected soldier, Tillotson said.
Sound waves (and
other wave types) propagate faster in hot air, Tillotson said. For that reason,
the shock wave would speed up when it hits the heated air around the electrical
discharge. As the shock wave speeds up, it would change direction slightly, or
refract, away from the person or object behind the arc. That bending occurs
because of the change in speed of the wave, and the shape of the area of hot
air the shock wave hits determines the exact direction.
The
process resembles the way lenses bend light, Tillotson said.
"With
a convex lens you focus the light," he said. "A concave lens spreads
it out." Light waves move slower in glass, so when light hits a glass
surface it bends. The lens must be concave to spread out that light.
Because shock waves move faster in hotter air, a spherical or cylindrical area
of hot air will cause the shock wave to bend, this time spreading out just like
the light through a concave lens, becoming weaker. In doing so that hot-air
shield could deflect shock waves.
Arc
generators aren't the only way to ionize air. Lasers would also work, Tillotson
said. A laser fired across the path of an explosion would ionize and heat the
air around the beam, creating the lensing effect.
In
another method, a strip of some metal could be placed on the side of a truck,
for example. "Put a couple of kilo-amps [thousands of amperes] through a
strip of metal, and it will vaporize," he said. The vaporized metal once
again heats the surrounding air.
One
issue for all of these methods of damping shock waves is the amount of power
required. But Tillotson noted a lot of research in this area shows promise in
decreasing that power suck. In addition, even a high-powered
laser doesn't have to be on for long, perhaps a fraction of a
second, to heat the air sufficiently. "It's basically a solved
problem," he said of the power supply.
This
isn't the only technology patent
for Tillotson; he has at least a half-dozen others in areas such as
aerodynamics and beamed power sources, and even other methods of damping shock
waves. Whether this particular technology becomes a reality will depend, as
many do, on future interest (and funding) from government and the private
sector.
