AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

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storage device capable of cooling DEW systems. Their 3 MJ device is the first large­
scale module capable of storing heat at a high rate as required for DEW systems, and it
stores heat at an average rate of 230 kW. Heat is stored in a 35 kg module by melting
a wax-type phase change material (see Figure 21). These materials, by themselves,
cannot support the high heat transfer rate and must be combined with other materials
to enhance their thermal properties in order to make them work. Thermal
management is one of the many challenges of the high-power BSSSL devices used in
DEW systems, which produce tremendous amounts of waste heat. Rejecting heat from
these systems in real time is not practical, making thermal energy storage a necessity.
The cost of BSSSL systems and related infrastructure are becoming competitive with
that of the proposed 10 MW electron gun-driven CO2/gas mixture lasers. BSSSL costs
are continuously decreasing as their technology matures and as more systems become
widely available for testing and operational deployment. The HELLADS matched-index­
of-refraction liquid cooling technique and General Atomics' advanced thermal energy
storage device will also dramatically improve the cost competitiveness of BSSSL
systems compared to all chemical and gas dynamic laser systems by producing greater
efficiencies in solid-state lasing operation while at the same time increasing the average
beam power.
Figure 21. Phase Change Materials Allow Storage of Large Intermittent Heat Loads While
Slow Regeneration Removes Heat from Aircraft (courtesy of P. Saunders, AFRL/RDS,
Kirtland AFB, NM).
High Power Fiber Laser
From 2006 to 2009, a newly emergent class of solid-state lasers, called high -power
fiber lasers (HPFLs), has undergone transformational innovations resulting in a 10-fold
increase in near diffraction-limited beam output power of a single-fiber laser operating
with broadband output in the 1 µm wavelength region with 90% optical efficiency, >
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