LIQUID LASERS HEATING UP

It’s not easy build­ing a laser weapon. And the hard­est part might be keep­ing the ray gun cool.
Take the Airborne laser, for exam­ple. The blaster-​​carrying, mod­i­fied 747 sched­uled for test flights later this decade has a pow­er­ful chem­i­cal laser can­non that heats up to 540 degrees cel­sius when fired. Each few-​​second blast needs to be fol­lowed by min­utes of cool-​​down time. 8,000 gal­lons of hydro­gen per­ox­ide and other chem­i­cals has to be flushed out and chilled to pre­pare for the next blast.
Next-​​generation, solid state lasers aren’t much eas­ier to han­dle. True, there are no chem­i­cal vats. But the gases, liq­uids, and mists required to keep these ray guns cool are plenty bulky. And they, too, need to be swept out before the laser can fire again. It’s one of many rea­sons why lasers are being planned for big, clunky planes like the 747 and not for fighter jets.
For years, Darpa, the Pentagon’s way-​​out research arm, has been bankrolling a project to cool a high-​​energy laser with a liq­uid that has the same angle of refrac­tion as the mir­rors inside the blaster. That way, the ray gun can fire away, even while it’s being cooled. The weapon should take up a whole lot less room. And that could pave the way to putting a blaster “on a ground vehi­cle, a heli­copter, a jet,” accord­ing to Charles Manor, a spokesman for Lockheed Martin, which was recently named the weapon sys­tem inte­gra­tor for this High Energy Liquid Laser Area Defense System (HELLADS) project.
The San Francisco Chronicle notes that General Atomics maker of the Predator drone will build HELLADS’ laser, “while Lockheed will develop the system’s abil­ity to pin­point and track a tar­get.“
The goal is to have, by 2009, a pow­er­ful blaster that’s be “an order of mag­ni­tude” lighter than com­pa­ra­ble lasers five kilo­grams for every kilo­watt of energy pro­duced.
The HELLADS project is “cur­rently in the third of five phases,” General Atomics says.

The cur­rent phase con­sists of devel­op­ing the tech­nol­ogy nec­es­sary to demon­strate a sub­scale [15 kw] pro­to­type laser sys­tem in the lab­o­ra­tory. This sub­scale demon­stra­tor shall be con­structed in the same geom­e­try and oper­ate with a flu­ence com­pa­ra­ble to that of the final weapon sys­tem.
As cur­rently envi­sioned, the fourth phase shall con­sist of a ground-​​based laser weapon sys­tem demon­stra­tor with an approx­i­mate aver­age power of 150 kW. The laser weapon sys­tem demon­stra­tor con­structed in this phase shall employ a design and mate­ri­als which demon­strate the abil­ity of the final weapon to achieve low spe­cific weight (5 kg/​kW) and a com­pact geom­e­try suit­able for deploy­ment on tac­ti­cal sys­tems [like a Humvee or a fighter plane].
The final phase con­sists of the engi­neer­ing, fab­ri­ca­tion, inte­gra­tion and demon­stra­tion of a com­plete HELLADS weapon sys­tem on a tac­ti­cal platform.

That plat­form might even be robotic, Darpa chief Tony Tether told Congress back in 2003.
With HELLADS, the next-​​generation Predator B or the heavily-​​armed Unmanned Combat Aerial Vehicle “could pro­tect fixed instal­la­tions or pop­u­la­tion cen­ters from attack, patrol a bor­der, or patrol a demil­i­ta­rized zone with the capa­bil­ity to react to hos­tile actions and engage tac­ti­cal mis­siles, rock­ets, or artillery at the speed of light.” Darpa wants to spend $60 mil­lion over the next three years on the system.

May 17th, 2005 | Lasers and Ray Guns | Comments Off Both comments and pings are currently closed.