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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 1 November 2010, was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It describes nanosatellite technologies and proposes launching nanosats into orbit with laser Lightcraft propulsion. It also covers a weapon mission selection study and multi-megawatt laser options. The author recommends that the Department of Defense and NASA bring Lightcraft R&D back to the United States and restart the X-50LR flight demonstration program.
“beam of light”10 pages
UNCLASSIFIED/ /F8~ 8FFl&I.«1k WliEii a,.klf electron beam ( \ I,:--- ■■>ti■-- undulator ) resonator mirror 0 z I. 0 0 z electron beam phase-space evolution Figure 30. Free-Electron Laser Electron Beam Phase-Space Evolution (courtesy of the Naval Post-Graduate School FEL Lab). In the quantum picture of how FELs operate, the "wiggling" electrons radiate light and that light then gets stored between the resonator mirrors. And additional light radiation (that enters the resonator) in the presence of "stored light" results in stimulated emission, which is the lasing process. The classical interpretation of this process is that the electrons travel with the light radiation and exchange energy with it. Some electrons gain energy while some lose energy to the light radiation. The electrons in the beam will "bunch" within each optical wavelength, thus these bunched electrons will radiate coherently to produce laser light. This mechanism is represented graphically in Figure 29 and Figure 30. The main appeal of free-electron lasers (FELs) is that they can be built for emission frequencies ranging from the terahertz region, through the infrared and visible spectrum, up to X-rays. Also, a single device often allows wavelength tuning over a large range and the output power can be scaled up very high. As in many spectral regions, it is not easy to make resonator mirrors; many FELs work without such mirrors and rely on amplified spontaneous emission. This can still be relatively efficient if the gain is high enough. One then actually has a superluminescent source. The big disadvantage of FELs is their very large and expensive setup; they can only be used at large facilities. The benefits of FELs are: • Continuously wavelength tunable, i.e., they can produce different wavelengths during operation. • Designable to produce a range of wavelengths, from microwaves to X-rays. • Scalable to very high beam power because they use a vacuum for their gain medium - laser medium cannot be damaged. • Not affected by heat problems that are common in other laser technologies. 59 UNCLASSIFIED/ ,'P8R:: 8PPI@Itllt 1!!191!! 8HLY
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 77 pages are in the text index: search them above, or from the library's search.