AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

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UNCLASSIFIED//rOR: orrlCIAL USE 014Lf
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Efficient, generally a FEL can transform 10% (> 60% for microwave tubes) of its
energy into laser radiation.
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Reliable, systems now run 24 hours per day for weeks.
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Can produce picosecond laser pulse widths.
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Systems are big (40 m x 60 m) and expensive ($1 Million to $100 Million).
The Naval Sea Systems Command's (NAVSEA) Directed Energy and Electric Weapon
Systems (DE&EWS) Program Office is supporting research, development and testing of
advanced high-energy/high-power FEL designs for the purpose of deploying them as
directed energy weapons onboard warships in the near future. The DE&EWS program is
emphasizing the development of disruptive innovations to reduce FEL system size,
weight, and operational (and lifetime) cost, as well as to increase overall system
operating efficiency. One design that has emerged to reach all of these goals is the
recirculating-beam FEL system (RBFEL), which uses a superconducting accelerator, RF
power liquid helium refrigerator, an electron beam injector, an electron beam dump,
and a modified laser resonator-undulator cavity that boosts the production of amplified,
coherent laser photons (see Figure 31). The superconducting accelerator gives good
efficiency and gradient while recirculation of the electron beam recovers beam energy
to increase efficiency and reduce the beam dump size.
Electron Accelerator
Beam
Dump
RF Power
Liquid Helium Refrigerator
Injector
IReflecting Minor
Undulator
Out-Coupling Minor
Figure 31. Recirculating-Beam FEL System {courtesy of the Naval Post-Graduate School ' FEL
Lab).
The key (typical) technical features of the Navy RBFEL are as follows :
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Total system volume: 16 m x 4 m x 4 m = 256 m3.
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Undulator/Wiggler
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Length: 46 cm to 60 cm.
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Period: 2.9 cm.
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Number of periods: 18.
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Magnetic field strength : 1 Tesla.
UNCLASSIFIED/fFOA QFFH31AL ~81!! 8HLY
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