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07 Mar 2005
Are high-power chemical lasers ready for the battlefield? Northrop Grumman thinks so - its new business unit will tackle the transition from lab to deployment. Oliver Graydon reports.
At the beginning of last month, Northrop Grumman, the giant US defence contractor, announced that it was creating a new business unit, called Directed Energy Systems, to turn multikilowatt and megawatt lasers into a military reality. Art Stephenson, 62-year-old former director of NASA's Marshall Space Flight Center, has since been named as the unit's vice-president. Oliver Graydon spoke to Stephenson about the role of the business unit and the challenges in using lasers to defend the skies.
OG: Why set up the Directed Energy Systems unit, and why now? AS: We've had some significant events [occur] over the past 12 months that were the culmination of a lot of work over many years. These included "first light" on the airborne laser; the first power-up of a new phosphate laser called the strategic illuminator laser, and a new power level on the joint high-power solid-state laser [see box]. Coincidentally, all of these achievements happened on the same day, November 10, 2004.
Over the past year we had been thinking that it was time to focus our efforts and bring things together. We've been developing this high-power expertise for more than 30 years and have a lot of technology in the laboratory and test range, but nothing that has actually been used for real military purposes. We think that it is now time for that to happen with chemical lasers. Last year we demonstrated shooting down a salvo of three mortars. Prior to that, over the past four years, we have demonstrated the shooting down of various rockets and artillery.
There has recently been a heightened interest in directed-energy systems from the military and we just felt that now was the right time for these systems to start finding their way from the laboratory into the field.
What are likely to be the first applications of high-power lasers? We have been funded for years with the understanding that some day directed-energy weapons would find their way into defence applications. We've got very good data and test results that show that [these devices] are now ready. It's really up to the decision makers how this technology is used. We're interested in getting some high-power chemical lasers out there. We think that once they are used, people will discover that they are very effective. It remains to be seen what the first deployments will be.
Tell me about the structure of the new unit. The unit not only develops chemical lasers, there is also a large amount of effort concentrated on solid-state lasers. These solid-state devices are not yet ready to put in the field, but we think that its a question of when, not if. Two of Northrop's subsidiaries, Cutting Edge Optronics and Synoptics, are part of the new Directed Energy Systems unit.
Synoptics makes crystals and key materials for solid-state lasers, while Cutting Edge is developing high-power diode-array pumps. The plan is to bring the two firms closer together with our space technology division and other sectors that are developing lasers.
The number of people working in lasers across the entire corporation [Northrop Grumman] is around 1500. They are not all a part of the new unit, but about half of them are associated with the programmes and technology for which I am directly responsible.
Geographically, Directed Energy Systems is spread around quite a bit. We're located in Space Park at Redondo Beach, California, US, as well as at Edwards Air Force base, Whitesands testing ground and out at the two subsidiaries [Cutting Edge Optronics and Synoptics].
What about criticism that chemical lasers are not practical? The chemicals are not that hard to work with. We strongly object when people say that the chemicals are too dangerous or the logistics are too difficult. We regularly transport chemicals all over this country on the highways that we all drive on - it's no more dangerous than sending a gasoline tanker truck down the road. There are lots of myths out there about chemical lasers and they are just not true. People fear the possibility of a direct hit on a refueller, but the consequences would be no worse than a hit on a fully fuelled Humvee vehicle.
Why don't you forget about chemical lasers and go straight to solid-state lasers? Some people have advocated that approach, but we believe that even if you really accelerate the research, high-power solid-state lasers are still at least six years away. If you keep going at the current pace then they are nine years away. If you want to use a high-power [hundreds of kilowatts] laser in the next few years then it's going to be a chemical one.
We can also use the deployment of chemical lasers to learn a lot about beam tracking and targeting systems. That knowledge will be useful and can be directly transferred to solid-state lasers later on.
Are there technical barriers that need to be overcome before chemical lasers can be deployed?
We don't see any remaining technology barriers that will prevent a system being used in a combat situation. It's a matter of packaging the technology that we have in a way that's transportable. We're ready to build a system and we think that we can have something that is appropriately packaged in 13-18 months.
What's the current status of high-power solid-state laser development? We are working on the joint high-power solid-state laser programme and there the initial goal is to achieve [an output power of] 25 kW. After that it's a question of scaling up the power. Ultimately, we believe that solid-state lasers can be packaged smaller and can weigh less than their chemical counterparts.
There's also the obvious advantage of solid-state lasers being electrically powered rather than needing a gas supply. We think that we are about six to nine years away from having a solid-state 100 kW laser that can do the things that chemical lasers can do today.
Why do you think that it will be so long before high-power solid-state lasers are ready? We've been through it with chemical lasers. Taking them from the laboratory to a practical system is a big job that involves many prototypes and lots of testing. Chemical lasers demonstrated the power levels of our current solid-state lasers about 20 years ago. We are working with other sectors [of the business] to build laser systems for ships and airplanes and ground vehicles to see how you can package a laser to suit those various platforms.
Aside from military uses, do high-power chemical lasers have any potential commercial applications? I see them as a purely defence tool. We haven't found any commercial applications that require the kind of power that chemical lasers deliver. As we come up in power with solid-state lasers there might be some spin-off applications.
Cutting Edge delivered more than 1000 pump modules last year, but for large high-power lasers we are not expecting a large production run. We are hoping that we can get a chemical laser out there and then see how useful it is in the field and then attract more interest.
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