Ok, so this will be my last military technology themed post for a little while. So I posted Death on Sky and the Water about our new aircraft carrier, and Captain Kirk and the Zumwalt Destroyer about our new and technologically sophisticated destroyer class ship, which are both technology demonstrators and platforms for future deployments of currently experimental technologies. This post is about those future technologies. The biggest worry for the country and the military is ballistic missile defense. At the moment, our defenses are pretty questionable. Currently our anti-ballistic missile weapons are other missiles guided by high-energy, exceedingly sophisticated radars and guidance systems and we got a bunch of them. We’ve got the Ground Based MidCourse defense (US Missile Command), the THAAD (US ARMY) the Standard Missile 3 (US NAVY), and everyone’s favorite, the Patriot (US ARMY), and even the Arrow (a US/Israeli collaboration), but these projects, while promising, are extremely challenging from a technical standpoint, and it’s taken them a long time to get to any sort of reliable kill ratio. Thankfully they’re quickly (relatively) headed toward obsolescence by directed energy weapons. That’s right. Lasers. There’s a couple of different projects the military is working on and some have already been deployed.
Perhaps the technology with the most field testing would be the THEL or Tactical High Energy Laser. It was a chemical laser that was effective at shooting down rockets and artillery shells during the rockets and artillery shelling that Israel suffered in the early 2000s. The laser works by combining an isotope of hydrogen (deuterium) with a Fluorine gas. If this highly energetic reaction happens in a focusing chamber, they can shoot an electromagnetic wave through the chemical through the reaction which will create an exceedingly powerful laser. For the science nerds who were wondering they use deuterium instead of just regular hydrogen, it’s because the emission spectrum is far more conducive to working inside an atmosphere. It can last as long as you have chemical reactants but it’s high costs are somewhat prohibitive. Typically several thousand dollars a shot. The Israelis cancelled the project in 2005 because of it’s insanely high cost. Costs be damned though it was effective and there are calls for a replacement system called Skyguard. Skyguard is much more powerful and mobile, but the high costs remain so it’s future is uncertain. Needless to say the exceedingly hazardous and volatile chemicals made it unattractive to the US Navy which is the frontline against ballistic missile defense for the US.
The next weapon is the LaWS or Laser Weapons System (The navy really went out on a limb for that name). With a great deal of fanfare, the navy deployed this weapon on a ship headed to the Persian Gulf. If you want to google it, you can see tests of the weapon destroying drone aircraft. This laser is a solid state laser. It works similarly to the LED lights that are everywhere only at really high power, and at very specific frequencies. As electricity travels through the medium it excites electrons (In an LED laser light that you shine to freak out your cats the medium is a little semiconductor filament). That is to say the electrons in the medium rise to a higher energy level. When they come back down to a the normal unexcited state they emit a photon (A light particle). Add enough photons together you have laser powerful enough to cut through steel like butter. The military isn’t there yet, but it’s working on it. At the moment they’ve got it working a bit like a blow torch. There are a number of challenges for the LaWS. For one, it’s pretty sensitive to the weather. The air and water in the atmosphere absorb the energy giving a range limit. I would imagine the navy is excited about figuring out the operation and limits of the device and determining what it’s maintenance and upkeep will be.
After the LaWS is the HELLADS or the High Energy Liquid Laser Area Defense System. You might have guessed the biggest difference between a solid state laser and a liquid state one. The HELLADS uses dyes (typically large organic molecules) set inside a liquid solution as its lasing medium. The dyes work by having their electrons excited by a light source (another laser in this instance). The dyes fluorescence (electron absorbs the energy, gets excited, returns to the ground state and releases a photon) passes back through the dye via mirrors increasing its amplitude with every pass. This project is being carried out by DARPA for the Air Force. It’s goal is to get this thing small enough, and powerful enough to fit on a fighter jet which it seems is well on its way to doing. It’s currently at the White Sands Missile range now for phase 4 testing (testing against simulated tactical targets).
The next weapons system actively being researched is the FEL: Free Electron Laser. This is the exciting one. The LaWS that takes several seconds to burn down a drone is less than 100 Kilowatts (though I couldn’t find it’s exact output). The HELLADS is to have 150 Kilowatts. The FEL is supposed to have an energy output range in the megawatts (Kilowatts equals 1000 watts, a megawatt would be a million watts. Your light bulb used to be 60 watts but with all the LED stuff who knows what it is now. Probably only 10 or 20 but that’s neither here nor there). This is the laser that the Navy wants to put on it’s cruisers and carriers to burn down ballistic missiles. Needless to say these lasers are going to have been exceedingly powerful to destroy a missile traveling at several times the speed of sound a continent and a half away. Currently Navy research has successfully tested a 100 kilowatt prototype and is working on a full power prototype scheduled for completion in 2018. Deployment another ten or twenty years after that. Oddly enough, it’s one of those few military projects that, so far, has been ahead of schedule. The physics for the FEL are a little more complicated, but they allow for much greater power output. There is no lasing medium. Which is to say, there are no chemicals running around having their electrons excited in order to create photons or semiconductor chips. In this case electrons are accelerated to very near the speed of light with particle accelerator. As a result, you can get very high energies without extremely high heat build up that’s so problematic with other laser technologies. Once out of the accelerator, the beam of electrons then travels through, I kid you not, a “wiggler”. It’s a series of magnets that have their polls in opposite directions. This causes the electrons to release photons. For reasons that are weird, at really high energies the electrons start to bunch together and each bunch is separated from each other by a single wavelength. Once this happens and all the electrons are synced up, they start to emit energy that’s several orders of magnitude higher than the initial stream of electrons. We’re still 10-20 years from seeing FELs on the battlefield, but practical prototypes have already been demonstrated. Ballistic Missiles are on their last legs as a relevant technology.
30 years from now there will be fleets of anti-ballistic weapons on ships, and planes. The previous military doctrine was based on having a couple of missile interceptors for every incoming ballistic missile of which there were thousands and thousands, all of which would have to be independently tracked and targeted by a pretty wonky system by today’s standards. A Reagan-esque system was unworkable (one idea was to have a laser powered by a nuclear explosion. Results were inconclusive). But if you can knock down missiles instantly and reliably then our patterns of Cold War era thinking may finally change.