Chemical laser

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A chemical laser is a laser that obtains its energy from a chemical reaction. Chemical lasers can achieve continuous wave output with power reaching to megawatt levels. They are used in industry for cutting and drilling, and in military as directed energy weapons. Common examples of chemical lasers are the chemical oxygen iodine laser (COIL), all gas-phase iodine laser (AGIL), and the hydrogen fluoride laser and deuterium fluoride laser, both operating in mid-infrared region. There is also a DF-CO laser (deuterium fluoride-carbon dioxide), which, like COIL, is a "transfer laser".

Origin of the CW chemical HF/DF laser

The continuous wave (CW) chemical HF laser was first demonstrated (1), and subsequently patented (2), by researchers at The Aerospace Corporation in El Segundo, California. This device used the mixing of adjacent supersonic streams of H2 and F, within an optical cavity, to create vibrationally excited HF which lased. The analysis of the HF laser performance is complicated due to the need to simultaneously consider the fluid dynamic mixing of adjacent supersonic streams, multiple non equilibrium chemical reactions and the interaction of the gain medium with the optical cavity. The researchers at The Aerospace Corporation developed the first exact analytic (flame sheet) solution (3), the first numerical computer code solution (4) and the first simplified model (5) describing chemical laser performance. Chemical rate information was obtained from reference (6).These studies provided parameters which define chemical laser performance and led to the design of efficient high power experimental CW HF laser devices. Power levels up to 10 kW were achieved by The Aerospace Corporation researchers. DF lasing was obtained by the substitution of D2 for H2. The TRW Systems Group in Redondo Beach, California, subsequently received US Air Force contracts to build higher power CW HF/DF lasers. Using a scaled up version of an Aerospace design, TRW achieved 100 kW power levels. This was followed by the MIRACL device that achieved megawatt power levels. The latter is believed to be the highest power continuous laser, of any type, developed to date (2007).

(Ref. 1). D. J. Spencer, T. A. Jacobs, H. Mirels and R. W. F. Gross, “ Continuous-Wave Chemical Laser,” International Journal of Chemical Kinetics, Vol. 1, No. 5, September 1969, pp. 493-494. (Ref. 2). D. J. Spencer, H. Mirels, T. A. Jacobs and R. W. F. Gross, “Continuous-Wave Chemical Laser,” US Patent No. 3,688,215, Aug. 29, 1972. (Ref. 3). R. Hofland and H. Mirels, “Flame Sheet Analysis of CW Diffusion Type Chemical Laser. 1 Uncoupled Radiation,” AIAA Journal, Vol. 10. No. 4, April 1972, pp. 420-428. (Ref. 4). W. S. King and H. Mirels, “ Numerical Study of a Diffusion Type Chemical Laser,” AIAA Journal, Vol. 10, No. 12, Dec. 1972, pp. 1647-1654. (Ref. 5). H. Mirels, R. Hofland and W. S. King, “ Simplified Model of CW Diffusion Type Chemical Laser,” 10th AIAA Aerospace Sciences Meeting, San Diego, Calif.,January 17-19, 1972. (Also AIAA Journal, Vol. 11. No. 2, February 1973, pp. 156=184.) (Ref. 6). N. Cohen, "A Review of Rate Coefficients for Reactions in the H2-F2 Laser System," TR-0172(2779)-2 Sept 1971. The Aerospace Corp., El Segundo, Ca.