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

U.S. Department of War · 2010-03-31 · 31 pages · text from the file's own layer

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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Typically in a chemical laser, 10 to 20 percent of the energy released in the chemical
reaction will result in lasing while the other 80 to 90 percent becomes heat.
Fortunately in a flowing gas laser, the heat can be easily removed from the resonator
region of the gain generator by the exhaust gas. It is this efficient heat removal
mechanism which has allowed chemical lasers to be scaled to such high average
powers. If a MW-class laser were required today or in the next few years, chemical
lasers provide the only available options. Because they use large quantities of
hazardous chemicals and need refueling, this type of laser is not a preferred choice by
the military.
The physics and scaling of chemical lasers such as OF, HF, and COIL are well
understood and, in principal, they could be scaled to power levels significantly beyond
the MW level. However, due to the maturity of these technologies, only marginal
further efficiency improvements are likely. As a result, the quantity of chemicals which
must be stored and consumed for a laser beyond ~ 10 MW would make the concept
highly impractical for space-based applications and extremely cumbersome for ground
based lasers. Additionally, the atmospheric degradation of a laser beam propagating
from ground to space makes these wavelengths impractical at power levels beyond 10
MW.
SOLID-STATE LASERS
The earliest and perhaps the most diverse laser category is the solid-state laser which
uses specific atoms or molecules as a lasing gain medium (called the dopant) uniformly
suspended in transparent crystalline or ceramic glass (called the host). For example,
the familiar Nd:YAG laser uses a few percent of neodymium (Nd) atoms as the dopant
suspended in a crystalline mix of yttrium, aluminum, and garnet (YAG). Figure 5 shows
some of the many combinations of solid-state laser dopants and hosts in use or being
developed today.
Wavelength (microns)
0.4 0. 5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
I : isibl e I
I a ·~ 0
Ruby
Rhodamine
I ~ear lnfra~d I I !11I I
·~ !,Sapphire
• ~~
I
Nd: YAG
Yb:YAG
Alex and rite Er: YAG
Er:Yb :YAG
Hosts can include:
Ruby~ Al20 3::Cr
-Sapphire - Al20 3
I
,J
Ho:
Nd:YAG X2 YAG"' Yittrium , Aluminum , Gamate"' Y3Al50 12
LuAG"' Lutetium , Aluminum, Gamate"' Lu3Al50 12
Yittira"' Y2 0 3
Figure 5. Common Solid-State Lasers and Their Wavelengths
A major advantage of solid-state lasers for mobile or portable applications is that they
only require electricity to power them although cooling is also needed. For example, a
5 second run of a 15 percent efficient 100 kW laser would require less than one
kilogram of gasoline or diesel fuel. No hazardous chemicals are needed and an
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 31 pages are in the text index: search them above, or from the library's search.