COIL development in the USA

Truesdell, Keith A.; Helms, Charles A.; Hager, Gordon D.

doi:10.2514/6.1994-2421

Cited by 15 publications

(12 citation statements)

References 15 publications

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“…͑14͒. The flow conditions within the laser cavity are deduced by analysis and calculation of the RotoCOIL experiment 11,14 : The flow temperature T is 167K, the entrance pressure P is approximately 4 torr, the small signal gain g 0 ϭ 0.0068 cm…”

Section: Resultsmentioning

confidence: 99%

Performance Analyses of Flowing Chemical Oxygen-Iodine Laser

Zhi

2003

Appl. Opt.

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A modified simplified rate-equation model that utilizes the Voigt profile function and another gain saturation model deduced from the kinetic equations are presented for performance analyses of a flowing chemical oxygen-iodine laser. Both models are adapted to both the condition of homogeneous broadening and that of inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant. Effects of temperature and iodine density on the output power and on variations of output power, optical intensity, and saturation intensity with flow distance are presented as well. There are differences between results of two models, but both qualitatively agree with known results.

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Section: Resultsmentioning

confidence: 99%

Performance Analyses of Flowing Chemical Oxygen-Iodine Laser

Zhi

2003

Appl. Opt.

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“…I left the AFWL just as that device was coming on line; leaving Gordan Hager who we had just hired from Rocketdyne and Doug Loverro, an ex-student of mine from USAFA, with the problem of getting it to workwhich they did [26]. Gordan is still at the AFWL, although he is concentrating on his successful laser -the second electronic transition chemical laser, NCI-I.…”

Section: Early Coil Work At Afwl (1977 -1981)mentioning

confidence: 99%

“…Gordan Hager continued his innovative work by both frequency doubling [28]and Q-switching COIL [29]. The technical detail of COIL laser development can be found in the outstanding review by Keith Truesdell, Charlie Helms, and Gordon Hager [26]. Charlie Helms also did exceptional work on laser efficiency and mixing nozzles.…”

Section: An Explosion Of Researchmentioning

confidence: 99%

Historical perspective of COIL

McDermott

2002

Gas and Chemical Lasers and Intense Beam Applications III

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The oxygen-iodine laser was the first electronic transition chemical laser. It first lased 25 years ago at the Air Force Weapons Laboratory (now the Air Force Research Laboratory). The development started several years earlier and involved the support of many people in the laser community. I would like to describe the early thoughts, insights and even misconceptions that we had in the early days. I will also highlight the contributions of many of the people and organizations that contributed to the early development of the COIL laser. A Brief Background on 02( 1 Ag)Chemical sources of O2(Ag) have been known for many years. Mallet [1] first reported the red glow obtained when hypochlorite solution and hydrogen peroxide was mixed. The O2(Ag) molecule was first identified by Herzberg in the spectrum of the sun in 1934. Groh [2] mentions the red chemiluminescence obtained when gaseous chlorine or bromine is added to basic hydrogen peroxide. Later, Groh & Kirriman [3] mixed gaseous chlorine with KOH and hydrogen peroxide and proposed that the red glow is from two O2('Ag) molecules colliding. Later, Seliger [4] published the spectra of the hypochlorite -peroxide reaction in the red at 634 nm. For me, the seminal article on excited oxygen was Khan and Kasha [5]. Even though the chemical process that produced a metastable electronically excited species was known, the marriage of oxygen and iodine came in discharge studies. Iodine and O2(CAg)The reaction of iodine and discharged oxygen was first reported by Ogryzlo and his group [6]. They observed that when iodine was added to excited oxygen, a bright yellow glow was seen. This was recognized as 12 B state emission. They also observed a strong emission at 1.315 ýi, the iodine atom 2 P 1 / 2 2 P3/ 2 transition. The excitation of the iodine was attributed to the near resonant pumping by 02( 1 Ag) . The iodine atoms were thought to be formed by the dissociation of molecular iodine by O2(Tu). This work didn't attract the-attention of the laser community until later. In 1969, Elmer Ogryzlo went on sabbatical to Brian Thrush's laboratory in England. There he suggested the oxygen-iodine system as an interesting system for Thrush's graduate student, R. G. Derwent. The suggestion generated several papers [7], [8], [9], [10], and [11]. In their third paper, they suggested that an inversion could be achieved on the iodine atom 2 pv 2 -2 P 3 / 2 transition if a sufficient O2(Ag) fraction could be produced. Using the equilibrium constant for the energy pumping reaction, They showed a flow containing about 15% O2(OAg) could produce an inversion on the iodine 2 P 112 -2 P 3 / 2 transition. It was radical to propose an equilibrium as a pumping reaction -in a two level system terminating in the ground state! was looking for research projects of interest to the Air Force. I had visited the AFWL the previous year and met a number of the technical people there. In the summer of 1973, I began working on electronic transition chemical lasers. The initial funding for the effort was $1...

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“…It is well known that the performance characteristics of COIL can be improved significantly by gas cooling through supersonic expansion. Therefore, considerable effort has been exerted on the development of a supersonic flow chemical oxygen-iodine laser (S-COIL) (3) - (9) . The pulsed operation of S-COIL utilizing a Q-switch technique is desirable for certain applications in material processing, since a high peak power can be obtained.…”

Section: Introductionmentioning

confidence: 99%

“…The pulsed operation of S-COIL utilizing a Q-switch technique is desirable for certain applications in material processing, since a high peak power can be obtained. The Q-value is defined as Q = 2πνT p = 2πνU/(dU/dt) = 2πν(−L/clnr 1 r 2 ), (3) where ν, T p , U, t, L, c, and r i are the light frequency, the photon lifetime in a laser resonator, the light energy in the resonator, the time, the distance between mirrors, the light velocity, and the mirror reflectance, respectively. Qswitched operation, in which the Q-value is varied within a very short time for switching power on/off, is achieved using a mechanical chopper (10) or a heated I 2 cell (11) .…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Q-Switched Supersonic Flow Chemical Oxygen-Iodine Laser by Solving Time-Dependent Paraxial Wave Equation

Suzuki

Matsueda

Masuda

2006

JSME international journal. Ser. B, Fluids and thermal engineer

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The quality and power of an extracted beam from a Q-switched supersonic flow chemical oxygen-iodine laser have been investigated by numerical simulation. The flow system adopted in this study is the throat-mixing system proposed in a previous paper. Threedimensional calculation for optics is coupled with one-dimensional calculation for gas flow including chemical reactions. Both geometric and wave optics are calculated and compared to assess the effects of diffraction. Wave optics is calculated with a time-dependent paraxial wave equation. The results indicate that wave and geometric optics are qualitatively similar in the time-dependent behavior of beam power. Quantitatively, it is found that diffraction reduces the extracted power by 9%. It is also found from the spreading half-angle of the beam for wave optics that the beam quality at a maximum power is equivalent to that of a plane wave; however, it is lower than that of continuous extraction.

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COIL development in the USA

Cited by 15 publications

References 15 publications

Performance Analyses of Flowing Chemical Oxygen-Iodine Laser

Performance Analyses of Flowing Chemical Oxygen-Iodine Laser

Historical perspective of COIL

Numerical Simulation of Q-Switched Supersonic Flow Chemical Oxygen-Iodine Laser by Solving Time-Dependent Paraxial Wave Equation

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