Thursday, January 24, 2013

Directed energy weapons are in the spotlight again

We've spoken often of the impending advent of battlefield directed energy weapons in these pages.  It's getting closer and closer.  Today Ares reported:

DARPA plans to buy a second Hellads high-energy laser system from General Atomics Aeronautical Systems (GA-ASI), to provide to the Office of Naval Research (ONR) for the demonstration of a laser weapon system against targets relevant to surface ships.

Hellads is a liquid-cooled, solid-state laser that has been under development for DARPA for several years. GA-ASI is building a 150kW Hellads laser to be integrated with an existing US Air Force beam control system for a ground demonstration in 2014.

DARPA's notice of intent to award a sole-source contract to GA-ASI says that, because the existing Hellads laser is committed to the Air Force demo and cannot be made available to the Navy, it wants to acquire a second, identical system for the ONR demo, also planned for 2014.

After focusing its directed-energy research for years on the free electron laser, ONR has launched a program to mature available solid-state electric laser technology with a goal of getting laser weapons on ships more quickly.

There's more at the link.

This is a very important development.  Modern anti-ship missiles are too fast to be reliably engaged by counter-missile or cannon defense systems.  Some (e.g. the Chinese DF-21) are ballistic missiles, reaching up beyond the stratosphere and then descending at hypersonic velocities under satellite guidance to hit their targets.  Others (e.g. the Russo-Indian BrahMos) are supersonic, coming in at Mach 2-3 compared to the subsonic speeds of earlier-generation anti-ship missiles such as the US Harpoon, the French Exocet or the Israeli Gabriel.  All modern anti-ship missiles are capable of being fired en masse, to swamp the target's defenses by arriving in a swarm, some of which are bound to get through.  Even a single hit from a modern weapon is potentially capable of inflicting a 'mission kill', if not of sinking its target;  and if enough get through, they might sink even the largest carriers.

The only counter that appears possible to such 'swarm attacks' is the high-energy laser.  It's a light-speed weapon, which means there's no discernible delay between pressing the firing button and the laser arriving at its target.  No allowance need be made for the target's course and speed, the direction and strength of the wind, or any other factors.  If it can be seen, it can be hit.  Also, no ammunition resupply is needed - only enough electrical power to power the laser, and keep coming long enough for sufficient repeat shots to be fired to take out a swarm of incoming weapons.

I find it significant that in an era of budgetary restraint, when even basic ship maintenance is suffering, DARPA and ONR are willing to spend money on this weapon.  That, more than anything else, shows the immense importance that planners are placing on getting directed-energy weapons into service.  Without them, our current fleet is increasingly vulnerable, and may actually become irrelevant.



Rev. Paul said...

I remember seeing an article in the Navy Times (c. 1976?) about a ship-based laser system the Navy's Arctic Research Lab was working on. It required a generator so large that it would only fit on a carrier, IF they could make it work.

Things have progressed a bit since then.

Scott said...

From back in the SDI days, there was an unclassified test of a 5megawatt mid-infrared laser (MIRACL). That laser took about 5 seconds to destroy any missile it was pointed at, whether a Titan ICBM or a TOW antitank missile.

I've used that 25megajoule energy level for combat-effective lasers ever since. Unfortunately, that means that a serious defense laser would have to be 100megawatts or so. Quarter-second laser pulses, plus the time to align to the next target equals roughly 3 kills per second. A free-electron laser is the most efficient in terms of converting electrical energy into coherent light, but it's still only about 65% efficient.

That 100MW (output) laser would need 165MW input. That's about the same as the entire powerplant of a Los Angeles-class sub.