AAWSAP DIRD, State of the Art and Evolution of High-Energy Lasers, March 2010

This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 31 March 2010. It was produced under the Advanced Aerospace Weapon System Applications Program. It reviews chemical, solid-state, fiber, ultra-short pulse and free-electron lasers, as well as beam control, atmospheric propagation, DoD laser history and how spacecraft could be damaged by lasers. It projects that electrically powered lasers could enable MW-class weapons and spacecraft laser weapons within 20 years. It ends with shielding recommendations for spacecraft.

From the source:Release of 2026-09-18 Incident: 3/31/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the development of high-energy laser weapons and notes that, although lasers had already become important military tools for ranging, guidance, and other lower-power uses, true weapon-class systems remained limited by power generation, beam control, atmospheric propagation, and logistics. The report reviews major laser types along with the optical, tracking, and thermal-management systems needed to make them militarily useful. It argues that high-energy lasers can offer important advantages over kinetic weapons in speed, precision, and low collateral damage, especially against softer or fast-moving targets, while also emphasizing that practical deployment has long been hindered by hazardous chemical fuels, thermal blooming in the atmosphere, power-supply constraints for mobile systems, and waste-heat removal.

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The reasons are t hat they avoid separate (and usually hazardous) fuels to carry/refuel
and allow propagation at wavelengths that are favorable for use from the earth or in
space. In addition to significant progress in compact, rugged, reliable and efficient
laser systems for spacecraft, major developments in energy generation and storage will
be needed. These lasers might be expected to have an overall "wall plug" efficiency of
25 percent, which requires at least four times the laser output power in prime power to
generate the laser beam. A MW solid -state laser wou ld require at least 4 MW of
electrical power while lasing. If a low duty-cycle were allowab le, much of the required
lasing energy could be accumu lated from a sma ller prime-power source and stored in
batteries, capacitors or flywheels . I n addition to the energy req uired to support lasing,
the residual energy (3 MW from a 25 percent efficient MW laser) in the form of heat
must be stored and then removed from the spacecraft.
Solid-state lasers will be the optimum candidate for power in the sub-MW to MW range
due to t heir ruggedness and relative simplicity. An FEL would be t he prime candidate
for power well above a MW. This type of laser lends itself better to heat removal from
the gain medium than a solid-state laser. This ability of an FEL to be scaled to higher
power comes with considerable additional complexity and a requirement for about a
MW of continuous power to maintain a large cryogenic refrigeration system wh ich cools
the niob ium accelerator cavity with liquid helium at 2K. The future development of
appropriate higher temperature superconducting materials may lessen this
requirement. The storage and removal of heat from any of these electrically powered
lasers may prove to be a more stressing task than generation of the required prime
power for lasing.
Table 1 provides an esti mate of the irradiance that various potential space-based laser
systems could provide. It assumes a wavelength of 1 μm, a transm itting telescope of 1
meter diameter and a system beam quality of about 1.5. I f t he transmitting telescope
were increased to 3 meter diameter, the same irradiance would be delivered at 3 times
the range.
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