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A chemical laser is a laser that obtains its energy from a chemical reaction. Chemical lasers can reach continuous wave output with power reaching to megawatt levels. They are used in industry for cutting and drilling. Common examples of chemical lasers are the chemical oxygen iodine laser (COIL), all gas-phase iodine laser (AGIL), and the hydrogen fluoride (HF) and deuterium fluoride (DF) lasers, both operating in the mid-infrared region. There is also a DF–CO2 laser (deuterium fluoride–carbon dioxide), which, like COIL, is a "transfer laser." The HF and DF lasers are unusual, in that there are several molecular energy transitions with sufficient energy to cross the threshold required for lasing. Since the molecules do not collide frequently enough to re-distribute the energy, several of these laser modes operate either simultaneously, or in extremely rapid succession, so that an HF or DF laser appears to operate simultaneously on several wavelengths unless a wavelength selection device is incorporated into the resonator. ==Origin of the CW chemical HF/DF laser== The possibility of the creation of infrared lasers based on the vibrationally excited products of a chemical reaction was first proposed by John Polanyi in 1961.〔 〕 A pulsed (although not chemical) laser was demonstrated by Jerome V. V. Kasper and George C. Pimentel in 1965.〔 〕 First, hydrogen chloride (HCl) was pumped optically so vigorously that the molecule disassociated and then re-combined, leaving it in an excited state suitable for a laser. Then hydrogen fluoride (HF) and deuterium fluoride (DF) were demonstrated. Pimentel went on to explore a DF-CO2 transfer laser. Although this work did not produce a purely chemical continuous wave laser, it paved the way by showing the viability of the chemical reaction as a pumping mechanism for a chemical laser. The continuous wave (CW) chemical HF laser was first demonstrated in 1969,〔 〕 and patented in 1972,〔 〕 by D. J. Spencer, T. A. Jacobs, H. Mirels and R. W. F. Gross at The Aerospace Corporation in El Segundo, California. This device used the mixing of adjacent streams of H2 and F, within an optical cavity, to create vibrationally-excited HF that lased. The atomic fluorine was provided by dissociation of SF6 gas using a DC electrical discharge. Later work at US Army, US Air Force, and US Navy contractor organizations (e.g. TRW) used a chemical reaction to provide the atomic fluorine, a concept included in the patent disclosure of Spencer et al.〔 The latter configuration obviated the need for electrical power and led to the development of high-power lasers for military applications. 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,〔 〕 the first numerical computer code solution〔 〕 and the first simplified model〔 〕 describing CW HF chemical laser performance. Chemical lasers stimulated the use of wave-optics calculations for resonator analysis. This work was pioneered by E. A. Sziklas (Pratt & Whitney) and A. E. Siegman (Stanford University).〔 〕〔 〕 Part I of their work dealt with Hermite-Gaussian Expansion and has received little use compared with Part II, which dealt with the Fast Fourier transform method, which is now a standard tool at United Technologies Corporation (SOQ), Lockheed Martin (LMWOC), SAIC (ACS), Boeing (OSSIM), tOSC, MZA (Wave Train), and OPCI. Most of these companies competed for contracts to build HF and DF lasers for DARPA, the US Air Force, the US Army, or the US Navy throughout the 1970s and 1980s. General Electric and Pratt & Whitney dropped out of the competition in the early 1980s leaving the field to Rocketdyne (now ironically part of Pratt & Whitney - although the laser organization remains today with Boeing) and TRW (now part of Northrop Grumman). Comprehensive chemical laser models were developed at SAIC by R. C. Wade,〔 〕 at TRW by C.-C. Shih, 〔 〕 by D. Bullock and M. E. Lainhart,〔 〕 and at Rocketdyne by D. A. Holmes and T. R. Waite.〔 〕 Of these, perhaps the most sophisticated was the CROQ code at TRW, outpacing the early work at Aerospace Corporation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chemical laser」の詳細全文を読む スポンサード リンク
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