“BEAMS”49 pages
- p. 3 …Free-Electron Laser Electron Beam Phase-Space Evolution ....................... 59
Figure 31. Recirculating-Beam FEL System ........................................................... 60…
- p. 4 …HEL Beam Pointer/Tracker ................................................................... 65
Figure 35. Basic Shared Aperture Beam Control System ......................................... 66
Figure 36…
- p. 7 …This can only be achieved via laser propulsion in
which the laser beam energy that is…
- p. 15 …By launching
spacecraft on a beam of electromagnetic radiation, researchers will have developed the
first new…
- p. 16 …The laser beam's pulse
interacts with the mirror, spreading out and focusing into an annular…
- p. 17 …1) power supply; 2) high-power (megawatt-class)
laser beam generator/transmitter using novel beam optics…
- p. 20 …is to the right and the laser beam strikes the stretched-out parabolic
mirror/propulsion section…
- p. 21 …It
requires a beam power of 0.1 to 1 MW per kg of vehicle mass…
- p. 22 …The ground-based
megawatt-class laser beam generator is state-of-the-art technology. The cost…
- p. 25 …Figure 8 illustrates the adverse beam
propagation geometry associated with ETO laser propulsion by means of…
- p. 26 …Attenuation Effects on Captured Laser Beam Power 261.
0.4
0.J
0.2
0.1…
- p. 27 …Unfortunately the demonstrated laser beam power levels for the attractive 1.62 μm
wavelength, which suffered…
- p. 28 …Beam combining
of several 1 MW (or higher) FELs can achieve a total combined beam output…
- p. 31 …Appropriate rotation of a high-energy laser beam,
emanating from a ground/sea-based laser, guides…
- p. 32 …Appropriate rotation and translation of a high-energy laser
beam, emanating from a moving aircraft, guides…
- p. 33 …But
multiple target interception within allowable time is limited by relatively long beam-
riding time needed…
- p. 37 …In this case, it is envisioned that the high-
pulsed power within high-energy laser beams…
- p. 39 …In this case, airborne laser beams at 12 km altitude will not suffer the
significant propagation…
- p. 41 …sidelobes, creates multiple beams, and steers the ensemble of the
individual beams anywhere on Earth. The…
- p. 42 …Each picosat is gravity-
gradient stable, has a dipole array facing Earth, and a broader beam…
- p. 43 …Commands for beam sweep delays are superimposed on the time delays of each
nanosat. Each nanosat…
- p. 44 …piezoelectric membrane kept flat by an electron beam in response to an optical figure
sensor. MEMS…
- p. 46 …technical issues include large wavelength and
atmospheric absorption of the laser beam.
• Carbon Monoxide (CO) Laser…
- p. 47 …125 Hz@ 20μs.
• Laser power, P = 2.5 MW/beam x 4 beams = 10 MW.
• Laser…
- p. 50 …Each power oscillator optics module transmitting a 2.5 MW beam of
10.6 μm wavelength…
- p. 52 …Adding an eight amplifier chain that the system was designed for will
increase the beam power…
- p. 53 …However,
BSSSL beam power can be scaled up further by improving presently known gain media
and…
- p. 54 …scalable
to 1 MW beam power within 2 years.
Typical solid-state lasers have the following…
- p. 55 …A new technology that enables the scaling-up of BSSSL beam power is a recently
developed…
- p. 56 …at the same time increasing the average
beam power.
Figure 21. Phase Change Materials Allow Storage…
- p. 57 …This exponential growth in beam output power is the result of many factors,
including the parallel…
- p. 58 …Microlens -O _
,:1
Incoherent Beam Combining 'Ind1vidually Incoherent Gaussian Beams i=L
Controlled
/_/Steering • ... o~bined…
- p. 59 …Neodymium
Thulium (Tm 3+), Holmium
- Range of beam wavelengths(),) produced: 0.48 μm to 2.9…
- p. 61 …Multlmode Fiber Lasers
50kW Multimode
Output beam quality BPP-1 o
M"2-33
DC EDE…
- p. 62 …The resulting laser beam photon energy depends on the
electron energy, the undulator period, and (weakly…
- p. 63 UNCLASSIFIED/ /F8~ 8FFl&I.«1k WliEii a,.klf
electron beam
( \ I,:--- ■■>ti■--
undulator
)
resonator mirror
0…
- p. 64 …The superconducting accelerator gives good
efficiency and gradient while recirculation of the electron beam recovers beam…
- p. 65 UNCLASSIFIED/ /F&~ 8FFHiil.«1k 1!181! &••kY
- K"' 1.5.t
• Electron Beam:
- Photocathode injector creates…
- p. 66 …HIGH ENERGY LASER BEAM CONTROL
··costs could be reduced to as low as $20 per kg…
- p. 67 …The typical HEL beam control system includes:++ 1) a gimbaled
beam director, 2) tracking and pointing…
- p. 68 UNCLASSIFIED//F&II. &FFiii,111!! l!llili &HI!¥
A novel new HEL beam control architecture being…
- p. 69 …HEL Beam Pointer/Tracker (courtesy of the Directed Energy Professional
Society).
In summary, this new architecture…
- p. 70 …The BILL is a solid-state, kilowatt-class laser
that measures atmospheric conditions, allowing the beam…
- p. 71 …All of these HEL beam control innovations can be quickly adapted to laser propulsion
applications with…
- p. 72 …The entire Lightcraft launch
system is comprised of a ground, sea, or airborne laser beam generator…
- p. 73 …New beam
control devices and high-power optical train combinations have a resulting beam line
that…
- p. 75 …N. (1983), "Advanced Beamed-Energy and Field Propulsion Concepts,"
BDM/W-83-225-TR, BDM Corp…
- p. 76 …N. (2001), "World Record Flights of Beam-Riding Rocket Lightcraft:
Demonstration of 'Disruptive' Propulsion Technology," AIAA…
- p. 77 …of the 6 th Int'! Symposium on Beamed Energy
Propulsion, edited by C. R. Phipps, AIP…
UNCLASSIFIED/ il"9" 91"l"!e!lltt tl!IL 9HL I
An outline of the conceptual design features of the proposed 10 MW electron gun-driven
CO2/gas mixture laser is [29]:
• Scalability of total beam output power, beam combining concept.
• Power oscillator or master oscillator-power amplifier (MOPA) design.
• Unstable optical resonator cavity with grating and rotating mirrors beam-combine
techniques.
• Flow and gas handling system with blow down and exhaust to the atmosphere.
• Acoustics suppression with expansion horn downstream and anode muffler.
In this concept there are four separate laser transmitters each generating 2.5 MW
output beams that are combined into a single 10 MW output beam. The oscillator
parameters for each beam transmitter are [29]:
• Energy loading, Ep: Ep = 300 J (higher loadings at reduced gas temperature);
gain volume = 0.27 m 3 (x 4 lasers); A to K = 0.3 m; gain length = 3 m.
• Specific laser output = 65 J/1.
• Estimated extraction efficiency = 20%.
• Pulse repetition rate: 125 Hz@ 20μs.
• Laser power, P = 2.5 MW/beam x 4 beams = 10 MW.
• Laser energy per pulse = 18 kJ/beam x 4 beams = 72 kJ.
• Output wavelengths: 10.6 ~tm, 10.2 ~tm, 9.6 ~tm, and 9.3 μm (mixed).
• Gas mixture ratio (for N2:CO2:H2): 3:1:0.08.
• Gas pressure = 1.013 x 10 5 Pa (or 1 atmosphere).
• Flash factor= 1.3.
The optical resonator cavity and optical components specifications are [29]:
• Resonator type: confocal unstable with rotating mirrors beam combining.
• Magnification, M = 4.
• Cavity length, L = 36.5 m.
• Equivalent Fresnel number = 3.4.
• Cavity end mirrors radius of curvature: RMirror1 = 97.3 m (concave), RM1rror2 = 24.3
m (convex).
• Gain cell: volume= 0.3 x 0.3 x 3.0 m 3 , length= 3 m.
• Beam combine mirrors: 75 x 75 cm 2 flat (30 x 30 cm 2 apertures) @ f. = 10.59
~Lm.
• Low pressure hot cell: 0.3 to 0.5 GHz suppression near line center.
• Output scraper mirror: D = 0.075 m (taped).
See Figure 16 and Figure 17 for schematics of the power oscillator optics and the MOPA.
The laser operation requirements for the gas flow system are (see Figure 18) [29]:
• Flow System: blow down.
• Gain Section
• Cross-section, A= 0.3 m x 3.0 m = 0.9 m 2 .
• Volume, V = 0.3 m x 0.3 m x 3.0 m = 0.27 m 3 .
• Flow speed, u = SO m/sec (@ 125 Hz & flash factor= 1.3).
• Dynamic pressure, !'..P = 2000 Pa (or 0.02 atmospheres).
• Mass flow rate, Q = 60 kg/sec per module ( 45 m 3/sec std).
• Run time, t = 300 seconds
43
UNCLASSIFIED/;«F&lil 8FFI@Itllt 1!!191! SHLY