Friday, November 13, 2009

Energy Beam and Hypersonic Weapons No Longer "Sci-Fi"

Advanced research at the Naval Postgraduate School (NPS) is perfecting directed energy and hypersonic weapons that may soon join the handful of inventions that have transformed the military's ability to deliver energy fast, accurately and at a safe distance.

When the musket was added to the infantryman's standard issue, common sense dictates the impact it had on the sword; and when cruise missiles were introduced to naval fleets, strategies and concepts of operations on how ships can support battle changed completely.

Now, directed energy and hypersonic weapons could well herald the next era in naval armaments. In 2008, the Electromagnetic Rail Gun (EMG) was officially named an Innovative Naval Prototype (INP) by the Office of Naval Research, and by 2010 the Free Electron Laser (FEL) is also to be designated an INP – testaments to the priority the Navy places on these new weapons systems.

Two Naval Postgraduate School faculty members from the Department of Physics, Pprofessor Bill Colson and Senior Lecturer Bill Maier, are bringing these cutting edge directed energy weapons to fruition. With the help of several students and researchers, they are researching and developing advanced high-energy technologies that could revolutionize maritime warfare over the next few decades.

"These are futuristic weapons," Colson said. "But if they work as we think they will, they are going to revolutionize the way ships defend themselves -- as revolutionary as guns were to swords." Colson was referring to a concept he has been working on for several years -- utilizing a high-energy, free electron laser for shipboard defense.

"The FEL is a speed-of-light weapon," Colson explained. "We can now 'see' threats at the speed of light, thanks to advanced radar systems. Directed energy will enable us to deliver lethal power to destroy those threats also at the speed of light…There will be no effective evasive maneuvers."

In addition to the system's speed, it's accuracy is impressive.

"The FEL is a 'surgical' weapon," Colson noted. "We don't just track and hit an incoming missile in flight; we hit a specific part of that missile that most readily leads to its destruction."

Free Electron Laser research has also just entered a new era at the Naval Postgraduate School. Colson, who has been researching the weapon system for more than 20 years, recently led the school's acquisition of Stanford University's FEL. With a FEL now on campus, he and his students and other researchers can now test their concepts on the actual cutting-edge technology, in addition to leading collaborations with other laboratories and industry.

Earlier this year, NPS FEL researchers successfully demonstrated the first test firing of the injector cathode of the newly acquired FEL, which Colson called "the first beam from the new Stanford FEL system achieved at NPS." Naval Postgraduate School President Daniel Oliver fired the first official test shot with Provost Leonard Ferrari and the dean of the Graduate School of Engineering and Applied Sciences also in attendance.

Equally advanced, and equally revolutionary, is Maier's research on the Electromagnetic Rail Gun. With an EMG, projectiles sliding along a pair of fixed rails are accelerated by passing a high current down one rail, through the projectile, and back down the other rail.

Navy rail gun systems in development nominally use currents as high as six million amperes to produce 35,000 Gs of acceleration over 10 meters. In Maier's lab on the NPS campus, a current of only about 300,000 amperes produces projectile acceleration of about 500,000 Gs over a distance of less than one foot, to velocities of several times the speed of sound.

Unlike the FEL, which is primarily a defensive weapon, this futuristic, hypersonic weapon holds the potential of replacing medium-range offensive cruise missiles for some DoD applications.

"The rail gun is designed for targets within a range of approximately 200 to 300 nautical miles," Maier explained. "It might take 15 to 20 minutes for a cruise missile to reach its target at this distance, whereas a rail gun projectile might take only six minutes or so to reach the target. And, as opposed to just one cruise missile, you could launch maybe 10 rail gun projectiles in a very short time."

Rail gun projectiles also don't require any explosives -- the energy from the projectile's impact at hypersonic speeds is enough to cause sufficient damage to the target. Its projectiles will, however, require some kind of incorporated self-guidance system, given the long distances they will need to travel.

Although rail gun research is conducted at several laboratories and universities, Maier and his students are conducting what he calls "innovative research" on concepts and designs for the futuristic weapon. This summer, he and his team tested a round barrel design, which would be much cheaper to both build and maintain.

Another major benefit of both the FEL and EMG is that neither requires chemical propellants of any kind. Instead, as Maier noted, the ship's existing fuel powers their generators, making it safer for onboard Sailors who are at much greater risk if a ship carrying a high volume of explosives is hit by an incoming.

The potential cost savings for these new breakthrough weapons is also extraordinary. A medium range cruise missile can cost anywhere from $500,000 to $1 million, while a rail gun projectile would cost on the order of $10,000. Given their smaller size, ships can easily store and manage a large quantity of rail gun ammunition.

The cost savings with the Free Electron Laser are even greater. As Colson notes, since the ship's existing fuel source powers the FEL's generators, the cost of firing the laser equates to "maybe a couple of gallons of the ship's fuel."

In support of directed energy research, the Naval Postgraduate School will soon open a new laboratory dedicated to supporting the FEL program, later this year. Currently, more than a dozen students are conducting their master's thesis work on the FEL and rail gun.

Colson and Maier, who teach one of the only courses dedicated to FEL and Rail Gun technology anywhere, hope to see the fruits of their research ready for shipboard testing by 2020.

Kellie Arakawa (NNS)
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