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1

Parametric study of chemical oxygen iodine laser  

Microsoft Academic Search

An efficient chemical oxygen iodine laser system (COIL) intended for industrial applications was studied parametrically. Employing dilute hydrogen peroxide the system can operate stably at 1kW for 10 minutes with 23.6 percent chemical efficiency, achieving stable operation over 30 minutes at about 500 W under optimized conditions. The practicability of high trap temperature operation was certified, obtaining 800 W power

T. Sawano; S. Yoshida

1990-01-01

2

Chemical kinetics of discharge-driven oxygen-iodine lasers  

Microsoft Academic Search

Oxygen-iodine lasers that utilize electrical discharges to produce O2(a1Delta) are currently being developed. The discharge generators differ from those used in chemical oxygen-iodine lasers in that they produce significant amounts of atomic oxygen and traces of ozone. As a consequence of these differences, the chemical kinetics of the discharge laser are markedly different from those of a conventional chemical oxygen-iodine

Valeriy N. Azyazov; Ivan O. Antonov; Michael C. Heaven

2007-01-01

3

Systematic diagnostics of a chemical oxygen-iodine laser device  

Microsoft Academic Search

There are two kinds of diagnostics for chemical oxygen-iodine laser (COIL) system, laser device diagnostics and laser beam diagnostics. In this paper, we only discussed systematically the former. We divide them into several diagnostic subsystems such a flow diagnostic, oxygen-iodine flow mixing diagnostic, gain medium diagnostic and resonator diagnostic. In flow diagnostic, we selected some independent and easy-measured physical variables

Xiangwan Du; Jianxiang Wang

1998-01-01

4

Singlet delta oxygen generation for Chemical Oxygen-Iodine Lasers  

Microsoft Academic Search

The development of Chemical Oxygen-Iodine Lasers is based on the generation of singlet delta oxygen. To improve the overall efficiency of these lasers, it is necessary to increase the generator production and yield of singlet delta oxygen at low and high pressure, respectively, for subsonic and supersonic lasers. Furthermore, the water vapor content must be as low as possible. A

E. Georges; A. Mouthon; R. Barraud

1991-01-01

5

Plasma chemical oxygen-iodine laser: problems of development  

Microsoft Academic Search

Great success has been obtained in the R&D of a chemical oxygen-iodine laser (COIL) operating on the electronic transition of the iodine atom, which gets an excitation from the energy donor -singlet delta oxygen (SDO). The latter is normally produced in a chemical SDO generator using very toxic and dangerous chemicals, which puts a limit for civilian applications of COIL

Andrei A. Ionin; Anatoly P. Napartovich; Nikolai N. Yuryshev

2002-01-01

6

Spatial gain measurements in a chemical oxygen iodine laser (COIL)  

Microsoft Academic Search

The spatial distribution of small signal gain has been investigated on the RADICL device, a supersonic chemical oxygen-iodine laser (COIL). A frequency-stabilized, narrow linewidth diode laser system operating on the F=3?F=4 hyperfine levels of the (2 P1\\/2) to (2P3\\/2) spin-orbit transition in atomic iodine was used as a small signal probe. A peak gain of 1.2%\\/cm was measured along the

R. F. Tate; B. S. Hunt; C. A. Helms; K. A. Kruesdell; G. D. Hager

1995-01-01

7

Simplified chemical oxygen iodine laser (COIL) system model  

Microsoft Academic Search

An end-to-end system model has been developed to model the performance of a rotating disk reactor-based Chemical Oxygen Iodine Laser (COIL) system. The model consists of a system of nonlinear algebraic equations combined into modules by subsystem and is well suited for system trade studies and subsystem data analysis. The model treats the three main components of the COIL system

Peter G. Crowell; David N. Plummer

1993-01-01

8

Chemical kinetics of discharge-driven oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

Oxygen-iodine lasers that utilize electrical discharges to produce O II(a1?) are currently being developed. The discharge generators differ from those used in chemical oxygen-iodine lasers in that they produce significant amounts of atomic oxygen and traces of ozone. As a consequence of these differences, the chemical kinetics of the discharge laser are markedly different from those of a conventional chemical oxygen-iodine laser (COIL). The reactions of O with iodine include channels that are both beneficial and detrimental to the laser. The beneficial reactions result in the dissociation of I II while the detrimental processes cause direct and indirect removal of I(2P 1/2) (denoted I*, the upper level of the laser). We have examined kinetic processes relevant to the laser through studies of photo-initiated reactions in N IIO/CO II/I II mixtures. The reactions have been monitored using absorption spectroscopy, laser induced fluorescence and time-resolved emission spectroscopy. It has been established that deactivation of I* by O atoms is a critical energy loss process. We have determined a rate constant of (1.2+/-0.1)×10 -11 cm 3 s -1 for this reaction. As part of this effort the branching fraction for the formation of O II(a) from the reaction of O(1D) with N IIO was determined to be 0.38. This result has implications for lasers based on photolysis of O 3/N IIO/I II mixtures and the formation of O II(a) in the upper atmosphere.

Azyazov, Valeriy N.; Kabir, Md. Humayun; Antonov, Ivan O.; Heaven, Michael C.

2007-05-01

9

Advances in the Development of Chemical Oxygen-iodine Laser  

NASA Astrophysics Data System (ADS)

Results of three problems investigated on a Chemical Oxygen-Iodine Laser (COIL) in our laboratory are presented in connection with the advanced COIL development in the world. These problems concern: i) A gain modulation on the laser transition in iodine atom, I(2P1/2) - (2P3/2), by external magnetic field, and its utilization for a COIL output power stabilization, ii) An evaluation of the Einstein A-coefficient of singlet oxygen, O2(1 g), and its utilization in advanced diagnostics for O2(1? g) determination in COIL operation, iii) A chemically driven iodine atom delivery system for advanced COIL.

Kodymová, Jarmila; Špalek, Otomar; Jirásek, Vít; ?enský, Miroslav

2004-05-01

10

Overview on the chemical oxygen-iodine laser technology  

NASA Astrophysics Data System (ADS)

The "Chemical Oxygen-Iodine Laser" (COIL) has passed through a tremendous development from the first milliwatt to a multi-kilowatt power, and thus offered a great opportunity for investigations in the COIL technology based on a multidisciplinary science. This overview has been aimed at a demonstration of enormous endeavor of the international COIL community in the last years to bring this laser system soon to the end-users by a focusing on advanced concepts of the hardware design, improvement and scaling-up the existing facilities. The overall COIL technology is considered as a sequence of the coexistent technologies of main laser components with a mutual impact: a technology of the singlet oxygen generator, gasdynamic mixing and expansion nozzle, energy extraction and optical resonator, and the exhaust and pressure recovery system. Advanced concepts of the named technologies based on inherent supporting research disciplines - a computational modeling, kinetic studies and diagnostic techniques - are briefly described. A critical insight into the COIL performance via an energy flow, energy losses, power extraction, and a chemical efficiency of this laser system utilizes the established heuristic phenomenology. The paper ends with a reference to developed projects and suggested potential applications of the chemical oxygen-iodine laser technology.

Kodymová, Jarmila

2007-05-01

11

Advances in development of chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The contribution deals with three investigated problems on Chemical Oxygen-Iodine Laser (COIL) and utilization of the results in advanced COIL development and advanced techniques connected with the COIL. These problems are following i) A gain modulation on the laser transition in iodine atom, I(2P1/2)-(2P3/2), by an external magnetic field, and its utilization for the COIL output power stabilization, ii) The evaluation of the Einstein A-coefficient of singlet oxygen, O2(1?g), and utilization of this coefficient in the advanced diagnostics for O2(1?g) determination in a laser pumping, and iii) A development of the advanced COIL using a chemically driven iodine atom delivery system, and a confrontation of advantages of this system with disadvantages of conventional source of atomic iodine via dissociated molecular iodine. Examples of few recent experimental results are presented.

Kodymova, Jarmila

2004-06-01

12

Plasma chemical oxygen-iodine laser: problems of development  

NASA Astrophysics Data System (ADS)

Great success has been obtained in the R&D of a chemical oxygen-iodine laser (COIL) operating on the electronic transition of the iodine atom, which gets an excitation from the energy donor -singlet delta oxygen (SDO). The latter is normally produced in a chemical SDO generator using very toxic and dangerous chemicals, which puts a limit for civilian applications of COIL that is still a very unique apparatus. Totally new non-chemical SDO generator is needed to allow oxygen-iodine laser to achieve its full potential as a non-hazardous efficient source of high-power laser radiation. There was interest in producing SDO in electric discharge plasma since the 50's long before COIL appearing. The idea of using SDO as a donor for iodine laser was formulated in the 70's. However, the injection of iodine molecules into a low- pressure self-sustained discharge did not result in iodine lasing. One of the main factors that could prevent from lasing in many experiments is a rather high threshold yield approximately 15 percent at 300K, which is needed for obtaining an inversion population. An analysis of different attempts of producing SDO in different kinds of electric discharge plasma has been done which demonstrates that high yield at gas pressure of practical interest for modern COIL technology can be obtained only in non-self sustained electric discharge plasma. The reason is that the value of relatively low reduced electrical field strength E/N approximately 1E-16 V.cm2, which is an order of magnitude less than that for the self-sustained discharge, is extremely important for the efficient SDO production. Although different kinds of non-self sustained discharges can be used for SDO production, we got started experiments with e-beam sustained discharge in gas mixtures containing oxygen. High specific input energy up to approximately 3 - 5 kJ/ has been experimentally obtained. Theoretical calculations have been done for different experimental conditions indicating a feasibility of reasonable SDO yield. Experimental and theoretical research of self-sustained electric discharge in SDO produced in a chemical generator, which is very important for getting plasma-chemical kinetic data needed for an estimation of SDO yield, is also discussed.

Ionin, Andrei A.; Napartovich, Anatoly P.; Yuryshev, Nikolai N.

2002-05-01

13

Chemical oxygen iodine laser (COIL) technology and development  

NASA Astrophysics Data System (ADS)

In the late 1960's researchers realized that producing a population inversion in a moving medium could be used to generate high-energy laser beams. The first lasers to scale to the 10 kW size with good beam quality were supersonic flows of N2 - CO2, emitting radiation from the CO2 at 10.6 microns. In the 1970's gas dynamic CO2 lasers were scaled to hundreds of kilowatts and engineered into a KC-135 aircraft. This aircraft (The Airborne Laser Laboratory) was used to shoot down Sidewinder AIM-9B missiles in the early 1980"s. During this same time period (1970-1990) hydrogen fluoride and deuterium fluoride lasers were scaled to the MW scale in ground-based facilities. In 1978, the Iodine laser was invented at the Air Force Research Laboratory and scaled to the 100 kW level by the early 1990"s. Since the 60s, the DOD Chemical Laser development efforts have included CO2, CO, DF, HF, and Iodine. Currently, the DOD is developing DF, HF, and Iodine lasers, since CO2 and CO have wavelengths and diffraction limitations which make them less attractive for high energy weapons applications. The current military vision is to use chemical lasers to prove the principles and field ground and air mounted laser systems while attempting to develop weight efficient solid-state lasers at the high power levels for use in future Strategic and Tactical situations. This paper describes the evolution of Chemical Oxygen Iodine Lasers, their selection for use in the Airborne Laser (ABL), and the Advanced Tactical Laser (ATL). COIL was selected for these early applications because of its power scalability, its short wavelength, its atmospheric transmittance, and its excellent beam quality. The advantages and challenges are described, as well as some of the activities to improve magazine depth and logistics supportability. COIL lasers are also potentially applicable to mobile ground based applications, and future space based applications, but challenges exist. In addition, COIL is being considered for civil commercial applications in the US and overseas.

Duff, Edward A.; Truesdell, Keith A.

2004-09-01

14

Chemical generation of atomic iodine for chemical oxygen–iodine laser. I. Modelling of reaction systems  

Microsoft Academic Search

The mathematical modelling of reaction systems for chemical generation of atomic iodine is presented. This process is aimed to be applied in the chemical oxygen–iodine laser (COIL), where it can save a substantial part of energy of singlet oxygen and so increase the laser output power. In the suggested method, gaseous reactants for I atoms generation are admixed into the

V??t Jirásek; Otomar Špalek; Jarmila Kodymová; Miroslav ?enský

2001-01-01

15

A pulsed oxygen-iodine chemical laser initiated by an electrical discharge  

Microsoft Academic Search

The feasibility of a pulsed oxygen-iodine laser which can be initiated efficiently by low energy electrons is demonstrated for the first time. Electrical initiation was used to make an O2(1Delta)-CH3I-N2 mixture lase with an output energy of 130 mJ. Compared with the photoinitiated oxygen-iodine chemical laser, the efficiency of the electrical initiation is 350 times higher and the initiation device

Rongyao Zhang; Fang Chen; Xueqin Song; Qingzhou Xu; Changqing Huan; Zhuang Qi; Zhang Cunhao

1988-01-01

16

A pulsed oxygen-iodine chemical laser initiated by an electrical discharge  

NASA Astrophysics Data System (ADS)

The feasibility of a pulsed oxygen-iodine laser which can be initiated efficiently by low energy electrons is demonstrated for the first time. Electrical initiation was used to make an O2(1Delta)-CH3I-N2 mixture lase with an output energy of 130 mJ. Compared with the photoinitiated oxygen-iodine chemical laser, the efficiency of the electrical initiation is 350 times higher and the initiation device has a smaller volume.

Zhang, Rongyao; Chen, Fang; Song, Xueqin; Xu, Qingzhou; Huan, Changqing

1988-08-01

17

LASERS: A pulsed oxygen --- iodine chemical laser excited by a longitudinal electric discharge  

Microsoft Academic Search

The dependence of the energy parameters of an oxygen --- iodine chemical laser with a bulk generation of iodine atoms in a longitudinal electric discharge on the length of the discharge gap is studied for various discharge energies and voltages and various working mixture compositions (at constant oxygen and iodine pressures). Analyses of the results suggests that temperature effects account

Nikolai P. Vagin; Nikolai N. Yuryshev

2002-01-01

18

LASERS: Pulsed chemical oxygen --- iodine laser initiated by a transverse electric discharge  

Microsoft Academic Search

A pulsed chemical oxygen --- iodine laser with a volume production of atomic iodine in a pulsed transverse electric discharge is studied. An increase in the partial oxygen pressure was shown to increase the pulse energy with retention of the pulse duration. At the same time, an increase in the iodide pressure and the discharge energy shortens the pulse duration.

Nikolai P. Vagin; Nikolai N. Yuryshev

2001-01-01

19

COIL--Chemical Oxygen Iodine Laser: advances in development and applications  

Microsoft Academic Search

Advantageous features of Chemical Oxygen-Iodine Laser (COIL) for laser technologies have increased considerably activities of international COIL communities during past ten years. They have been focused on the advanced concepts of hardware designs of the COIL subsystems, and testing and scaling-up of existing laser facilities. Prospective special applications of COIL technology, both civil and military, have received a significant attention

Jarmila Kodymova

2005-01-01

20

Efficient chemical oxygen-iodine laser powered by a centrifugal bubble singlet oxygen generator  

NASA Astrophysics Data System (ADS)

Efficient production of singlet delta oxygen in a bubble singlet oxygen generator (BSOG) under the influence of centrifugal acceleration, 136g, has been obtained. An output power of 770W with chemical efficiency of 25.6% has been achieved in a small-scale, supersonic chemical oxygen-iodine laser supplied by the centrifugal BSOG. The ratio of the output power to the basic hydrogen peroxide volumetric flow rate was 4.3KJ/liter. Efficient chemical oxygen-iodine laser (COIL) operation with the centrifugal BSOG demonstrates the potential for mobile COIL applications.

Nikolaev, V. D.; Svistun, M. I.; Zagidullin, M. V.; Hager, G. D.

2005-06-01

21

Pulsed chemical oxygen—iodine laser with bulk formation of iodine atoms by an electric discharge  

Microsoft Academic Search

A preliminary investigation was made of a chemical oxygen—iodine laser with bulk formation of iodine atoms in an electric discharge. The output energy was comparable with that obtained for a photolysis variant of the laser, but the technical efficiency of the investigated discharge variant was much higher (91%). The pulse power (~100 kW) was approximately three orders of magnitude higher

Nikolai P Vagin; V S Pazyuk; Nikolai N Yuryshev

1995-01-01

22

LASERS: Pulsed chemical oxygen—iodine laser with bulk formation of iodine atoms by an electric discharge  

NASA Astrophysics Data System (ADS)

A preliminary investigation was made of a chemical oxygen—iodine laser with bulk formation of iodine atoms in an electric discharge. The output energy was comparable with that obtained for a photolysis variant of the laser, but the technical efficiency of the investigated discharge variant was much higher (91%). The pulse power (~100 kW) was approximately three orders of magnitude higher than the power of a cw chemical oxygen—iodine laser with the same chlorine flow rate.

Vagin, Nikolai P.; Pazyuk, V. S.; Yuryshev, Nikolai N.

1995-08-01

23

LASERS: A pulsed oxygeniodine chemical laser excited by a longitudinal electric discharge  

NASA Astrophysics Data System (ADS)

The dependence of the energy parameters of an oxygeniodine chemical laser with a bulk generation of iodine atoms in a longitudinal electric discharge on the length of the discharge gap is studied for various discharge energies and voltages and various working mixture compositions (at constant oxygen and iodine pressures). Analyses of the results suggests that temperature effects account for a twofold decrease in the specific energy yield for the lasing initiated by a longitudinal electric discharge compared to the photolytic initiation.

Vagin, Nikolai P.; Yuryshev, Nikolai N.

2002-07-01

24

LASERS: Pulsed chemical oxygeniodine laser initiated by a transverse electric discharge  

NASA Astrophysics Data System (ADS)

A pulsed chemical oxygeniodine laser with a volume production of atomic iodine in a pulsed transverse electric discharge is studied. An increase in the partial oxygen pressure was shown to increase the pulse energy with retention of the pulse duration. At the same time, an increase in the iodide pressure and the discharge energy shortens the pulse duration. Pulses with a duration of 6.5 ?s were obtained, which corresponds to a concentration of iodine atoms of 1.8 × 1015 cm-3. This concentration is close to the maximum concentration attained in studies of both cw and pulsed oxygen-iodine lasers. A specific energy output of 0.9 J litre-1 and a specific power of 75 kW litre-1 were obtained. The ways of increasing these parameters were indicated. It was found that SF6 is an efficient buffer gas favouring improvements in the energy pulse parameters.

Vagin, Nikolai P.; Yuryshev, Nikolai N.

2001-02-01

25

A pulsed oxygen - iodine chemical laser excited by a longitudinal electric discharge  

Microsoft Academic Search

The dependence of the energy parameters of an oxygen - iodine chemical laser with a bulk generation of iodine atoms in a longitudinal electric discharge on the length of the discharge gap is studied for various discharge energies and voltages and various working mixture compositions (at constant oxygen and iodine pressures). Analyses of the results suggests that temperature effects account

Nikolai P Vagin; Nikolai N Yuryshev

2002-01-01

26

Pulsed chemical oxygen - iodine laser initiated by a transverse electric discharge  

Microsoft Academic Search

A pulsed chemical oxygen - iodine laser with a volume production of atomic iodine in a pulsed transverse electric discharge is studied. An increase in the partial oxygen pressure was shown to increase the pulse energy with retention of the pulse duration. At the same time, an increase in the iodide pressure and the discharge energy shortens the pulse duration.

Nikolai P Vagin; Nikolai N Yuryshev

2001-01-01

27

Parametric studies of a small-scale supersonic chemical oxygen-iodine laser (COIL)  

Microsoft Academic Search

Parametric studies of the gain and the power of a small scale supersonic chemical oxygen- iodine laser are presented. The laser is of 5 cm long active medium, and utilizes a simple sparger-type O2(1(Delta) ) chemical generator and a medium size pumping system. A grid nozzle is used for iodine injection and supersonic expansion. 45 W of CW laser emission

Salman Rosenwaks; B. D. Barmashenko; A. Elior; E. Lebiush; I. Blyvas

1995-01-01

28

Two-dimensional gain measurements in a chemical oxygen-iodine laser (COIL) device  

Microsoft Academic Search

The spatial distribution of gain has been investigated on the Research Assessment and Device Improvement Chemical Laser, a supersonic chemical oxygen-iodine laser (COIL). A frequency-stabilized, narrow linewidth diode laser system operating on the F equals 3 yields F equals 4 hyperfine levels of the (2P1\\/2) to (2P3\\/2) spin-orbit transition in atomic iodine was used as a small signal probe. A

R. F. Tate; B. Scott Hunt; Gordon D. Hager; Charles A. Helms; Keith A. Truesdell

1995-01-01

29

Computational fluid dynamics methodologies for simulation of chemical oxygen-iodine laser flowfields  

Microsoft Academic Search

Simulation of chemical lasers such as the chemical oxygen-iodine laser (COIL) is of timely interest due to the recent acceleration of the airborne laser military research program and ongoing commercial development programs. As a part of these efforts, a 3-D COIL simulation model was developed based on the Computational Fluid Dynamics (CFD) code GASP which solves the conservative, finite-volume formulation

Timothy John Madden

1997-01-01

30

Chemical generation of atomic iodine for the chemical oxygen iodine laser. II. Experimental results  

NASA Astrophysics Data System (ADS)

A new method for the chemical generation of atomic iodine intended for use in a chemical oxygen-iodine laser (COIL) was investigated experimentally. The method is based on the fast reaction of hydrogen iodide with chemically produced chlorine atoms. Effects of the initial ratio of reactants and their mixing in a flow of nitrogen were investigated experimentally and interpreted by means of a computational model for the reaction system. The yield of iodine atoms in the nitrogen flow reached 70-100% under optimum experimental conditions. Gain was observed in preliminary experiments on the chemical generation of atomic iodine in a flow of singlet oxygen.

Špalek, Otomar; Jirásek, Vít.; ?enský, Miroslav; Kodymová, Jarmila; Jakubec, Ivo; Hager, Gordon D.

2002-08-01

31

Modeling of the chemical generation of atomic iodine in a chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The mathematical modeling of reaction systems for chemical generation of atomic iodine is presented. This process can be applied in the chemical oxygen-iodine laser (COIL), where it can save a substantial part of energy of singlet oxygen and so increase the laser output power. The parametric study of the production of atomic fluorine and subsequently atomic iodine in dependence on the pressure and dilution with inert gas was made. The calculation of the interaction between produced atomic iodine and singlet oxygen was made with four different mixing/reacting schemes.

Jirasek, Vit; Spalek, Otomar; Kodymova, Jarmila; Censky, Miroslav

2002-05-01

32

Pulse-periodic chemical oxygen-iodine laser with active medium formation by volumetric electric discharge  

Microsoft Academic Search

The paper describes a study of pulse-periodic operation of a chemical oxygen-iodine laser. The generator in use was of the jet type with high chlorine utilization degree (>=97%). Atomic iodine was released by dissociating methyl-iodide (CH3I) in volumetric electric discharge. Steady lasing was achieved at a repetition rate up to 30 Hz. The emission energy attained per individual pulse in

S. D. Velikanov; V. G. Gorelov; I. V. Gostev; Ye. V. Ireshev; V. V. Kalinovsky; I. A. Komissarov; V. V. Konovalov; I. V. Konovalov; V. N. Mikhalkin; V. D. Nikolaev; I. V. Sevryugin; A. V. Smirnov; R. E. Sobolev; L. N. Shornikov

2007-01-01

33

Studies of iodine dissociation in the chemical oxygen-iodine laser  

Microsoft Academic Search

The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied experimentally as a function of I2 flow rate. The measurements revealed that the number of consumed O2(1Delta) molecules per dissociated I2 molecule depends on the experimental conditions: it is 4.2 +\\/- 0.4 for typical conditions and I2 densities applied for the operation

V. Rybalkin; A. Katz; K. Waichman; D. Vingurt; Z. Dahan; B. D. Barmashenko; S. Rosenwaks

2007-01-01

34

Chemical generation of atomic iodine for chemical oxygen iodine laser. I. Modelling of reaction systems  

NASA Astrophysics Data System (ADS)

The mathematical modelling of reaction systems for chemical generation of atomic iodine is presented. This process is aimed to be applied in the chemical oxygen-iodine laser (COIL), where it can save a substantial part of energy of singlet oxygen and so increase the laser output power. In the suggested method, gaseous reactants for I atoms generation are admixed into the COIL primary gas flow containing singlet oxygen. Two reaction systems were proposed, based on the reaction of hydrogen iodide with chemically generated atomic fluorine or chlorine. It was found that the reaction path via Cl atoms better matches the experimental conditions of COIL with a yield of atomic iodine of up to 67%. As a result of modelling, a suitable reaction system and design of experimental arrangement for the effective production of atomic iodine in laser conditions were found.

Jirásek, Vít.; Špalek, Otomar; Kodymová, Jarmila; ?enský, Miroslav

2001-07-01

35

Nearly attaining the theoretical efficiency of supersonic chemical oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

Improving the chemical efficiency of the supersonic chemical oxygen-iodine laser (COIL) is a key issue for the design of devices for both defense and industrial applications. Efficiencies around 30% for the supersonic COIL have been the state of the art in the last decade. Here, we report the achievement of a record (40%) for the chemical efficiency of the supersonic COIL. More specifically, we show that by carefully studying and optimizing the operation of the chemical generator, the mixing of heavy and light molecules in the gas phase and the optical extraction efficiency, we have approached the theoretical limit for the chemical efficiency.

Rybalkin, V.; Katz, A.; Barmashenko, B. D.; Rosenwaks, S.

2004-12-01

36

Semi-gas kinetics model for performance modeling of flowing chemical oxygen-iodine lasers (COIL)  

NASA Astrophysics Data System (ADS)

A semi-gas kinetics (SGK) model for performance analyses of flowing chemical oxygen-iodine laser (COIL) is presented. In this model, the oxygen-iodine reaction gas flow is treated as a continuous medium, and the effect of thermal motions of particles of different laser energy levels on the performances of the COIL is included and the velocity distribution function equations are solved by using the double-parameter perturbational method. For a premixed flow, effects of different chemical reaction systems, different gain saturation models and temperature, pressure, yield of excited oxygen, iodine concentration and frequency-shift on the performances of the COIL are computed, and the calculated output power agrees well with the experimental data. The results indicate that the power extraction of the SGK model considering 21 reactions is close to those when only the reversible pumping reaction is considered, while different gain saturation, models and adjustable parameters greatly affect the output power, the optimal threshold gain range, and the length of power extraction.

Gao, Zhi; Hu, Limin; Shen, Yiqing

2004-05-01

37

A 33% efficient chemical oxygen-iodine laser with supersonic mixing of iodine and oxygen  

NASA Astrophysics Data System (ADS)

We report on a highly efficient supersonic chemical oxygen-iodine laser (COIL), with supersonic mixing of iodine and oxygen. Output power exceeding 0.5 kW with chemical efficiency of ˜33% was obtained in a 5-cm gain length for Cl2 flow rate of 17 mmole/s. A 33% efficiency is the highest reported chemical efficiency of any supersonic COIL. Comparison between different mixing schemes shows that, for supersonic mixing, the output power and chemical efficiency are about 20% higher than for transonic mixing scheme. The optimal conditions for the efficient operation are investigated.

Rybalkin, V.; Katz, A.; Barmashenko, B. D.; Rosenwaks, S.

2003-06-01

38

Chemical oxygen iodine laser (COIL) technology and development  

Microsoft Academic Search

In the late 1960's researchers realized that producing a population inversion in a moving medium could be used to generate high-energy laser beams. The first lasers to scale to the 10 kW size with good beam quality were supersonic flows of N2 - CO2, emitting radiation from the CO2 at 10.6 microns. In the 1970's gas dynamic CO2 lasers were

Edward A. Duff; Keith A. Truesdell

2004-01-01

39

Multikilowatt chemical oxygen-iodine laser with chemical generation of molecular iodine  

NASA Astrophysics Data System (ADS)

A multikilowatt chemical oxygen-iodine laser (COIL) using molecular iodine generated chemically as the iodine source was developed and tested. The COIL, with a gain length of 26.5cm, was energized by a square pipe-array jet singlet oxygen generator (JSOG), with a nozzle bank having a designed Mach number of 2.5. The JSOG, operating without a primary buffer gas, has a much better operation stability during basic hydrogen peroxide pumping circulations. Iodine injectors/nozzles made of polyimide were used. An output power of 7.8kW and a chemical efficiency of 24.5% were achieved with a chlorine flow rate of 353mmole/s.

Zhang, Yuelong; Sang, Fengting; Zhang, Peng; Jin, Yuqi; Fang, Benjie; Zhao, Weili; Chen, Fang; Li, Qingwei; Xu, Mingxiu

2007-07-01

40

LASERS: Pulsed chemical oxygen---iodine laser with bulk formation of iodine atoms by an electric discharge  

Microsoft Academic Search

A preliminary investigation was made of a chemical oxygen---iodine laser with bulk formation of iodine atoms in an electric discharge. The output energy was comparable with that obtained for a photolysis variant of the laser, but the technical efficiency of the investigated discharge variant was much higher (91%). The pulse power (~100 kW) was approximately three orders of magnitude higher

Nikolai P. Vagin; V. S. Pazyuk; Nikolai N. Yuryshev

1995-01-01

41

Power enhancement in chemical oxygen-iodine lasers by iodine predissociation via corona/glow discharge  

NASA Astrophysics Data System (ADS)

The gain and power in a supersonic chemical oxygen-iodine laser (COIL) are enhanced by applying dc corona/glow discharge in the transonic section of the secondary flow in the supersonic nozzle, dissociating I2 prior to its mixing with O2(?1). The loss of O2(?1) consumed for dissociation is thus reduced, and the consequent dissociation rate downstream of the discharge increases, resulting in up to 80% power enhancement. The implication of this method for COILs operating beyond the specific conditions reported here is assessed.

Katz, A.; Dahan, Z.; Rybalkin, V.; Waichman, K.; Barmashenko, B. D.; Rosenwaks, S.

2007-04-01

42

Plasma Excited Chemical-Oxygen-Iodine Lasers: Optimizing Injection and Mixing for Positive Gain  

Microsoft Academic Search

Chemical oxygen-iodine lasers achieve oscillation on the ^2P1\\/2->^2P3\\/2 transition of atomic iodine at 1.315 mum by a series of excitation transfers from O2(^1delta). In electrically plasma excited devices (eCOILs), O2(^1delta) is produced in a flowing plasma, typically He\\/O2, at a few to tens of Torr. The iodine is injected into the flow as a He\\/I2 mixture immediately upstream (or in)

Natalia Y. Babaeva; Luis A. Garcia; Ramesh A. Arakoni; Mark J. Kushner

2007-01-01

43

Test bed for a high throughput supersonic chemical oxygen - iodine laser  

SciTech Connect

The paper reports the development of a test bed for a chemical oxygen - iodine laser based on a high throughput jet flow singlet oxygen generator (JSOG). The system provides vertical singlet oxygen extraction followed by horizontal orientation of subsequent subsystems. This design enables the study of flow complexities and engineering aspects of a distributed weight system as an input for mobile and other platform-mounted systems developed for large scale power levels. The system under consideration is modular and consists of twin SOGs, plenum and supersonic nozzle modules, with the active medium produced in the laser cavity. The maximal chlorine flow rate for the laser is {approx}1.5 mole s{sup -1} achieving a typical chemical efficiency of about 18%. (lasers)

Singhal, Gaurav; Mainuddin; Rajesh, R; Varshney, A K; Dohare, R K; Kumar, Sanjeev; Singh, V K; Kumar, Ashwani; Verma, Avinash C; Arora, B S; Chaturvedi, M K; Tyagi, R K; Dawar, A L

2011-05-31

44

O2(^1delta) Production and Oxygen-Iodine Kinetics in Flowing Afterglows for Electrically Excited Chemical-Oxygen-Iodine Lasers  

Microsoft Academic Search

Chemical oxygen-iodine lasers (COILs) achieve oscillation on the ^2P1\\/2->^2P3\\/2 transition of atomic iodine at 1.315 mum by a series of excitation transfers from O2(^1delta). In electrically excited COILs, (eCOILs) the O2(^1delta) is produced in a flowing plasma, typically He\\/O2, at a few to tens of Torr. eCOILs additionally differ from conventional systems in the large amount of O atoms produced

Ramesh Arakoni; Natalie Y. Babaeva; Mark J. Kushner

2006-01-01

45

Development of the Chemical Oxygen-Iodine Laser (COIL) with chemical generation of atomic iodine  

NASA Astrophysics Data System (ADS)

This article addresses the development of a Chemical Oxygen-Iodine Laser (COIL) with alternative chemical ways of generating atomic iodine. Injection of atomic iodine as opposed to molecular iodine has the potential to improve the COIL efficiency. This paper describes two chemical methods for generating iodine atoms based on the gas phase reactions of hydrogen/deuterium iodide with fluorine or chlorine atoms, which are also produced chemically. Simplified one-dimensional gas dynamic modeling that describes the stream-wise profiles of species concentrations within both reaction systems is used to gain a theoretical understanding of both reaction systems under COIL conditions. The modeling results are used for the design of an experimental device and the interpretation of experimental data. The first experimental investigation studies the production of iodine atoms produced from reactions of Cl with HI. Atomic iodine yields of 70-100% in nitrogen are obtained, and the gain on the I(2P1/2)-I(2P3/2) transition in a flow of singlet oxygen is measured.

Kodymová, J.; Špalek, O.; Jirásek, V.; ?enský, M.; Hager, G. D.

46

Chemical oxygen-iodine laser with a centrifugal spray generator of singlet oxygen  

NASA Astrophysics Data System (ADS)

A chemical oxygen-iodine laser driven by the centrifugal spray generator of singlet oxygen was developed and experimentally studied. Modeling and experimental studies showed that the designed generator can produce singlet oxygen, O2(1?g), with a high efficiency (chlorine utilization 0.68 - 0.87 and O2(1?g) yield 0.35 - 0.7) even at very high generator pressures (25 - 70 kPa), which cannot be attained by other O2(1?g) generators. This high-pressure operation should be beneficial for a pressure recovery system of the laser. Another specific feature of the generator is a very high BHP utilization (0.24-0.6). The developed separator can effectively remove even small droplets (> 1 ?m) from gas at the generator exit. Preliminary experiments on the COIL driven the centrifugal spray generator provided the small signal gain up to 0.5 % cm-1.

Špalek, Otomar; Jirásek, Vít; ?enský, Miroslav; Kodymová, Jarmila

2010-09-01

47

Pulse-periodic chemical oxygen-iodine laser with active medium formation by volumetric electric discharge  

NASA Astrophysics Data System (ADS)

The paper describes a study of pulse-periodic operation of a chemical oxygen-iodine laser. The generator in use was of the jet type with high chlorine utilization degree (>=97%). Atomic iodine was released by dissociating methyl-iodide (CH 3I) in volumetric electric discharge. Steady lasing was achieved at a repetition rate up to 30 Hz. The emission energy attained per individual pulse in a train was 1.1 J at a pulse energy repeatability of (3÷5) % and a specific energy extraction from the active medium of 1.7 J/L. The lasing pulse duration depended on the concentration of methyl-iodide and the energy deposited into discharge. The minimal half-height duration of pulses was achieved as 10 ?m at a concentration of atomic iodine in the laser cavity ~1*10 15 cm -3.

Velikanov, S. D.; Gorelov, V. G.; Gostev, I. V.; Ireshev, Ye. V.; Kalinovsky, V. V.; Komissarov, I. A.; Konovalov, V. V.; Konovalov, I. V.; Mikhalkin, V. N.; Nikolaev, V. D.; Sevryugin, I. V.; Smirnov, A. V.; Sobolev, R. E.; Shornikov, L. N.

2007-05-01

48

High-efficiency chemical oxygen-iodine laser using a streamwise vortex generator  

NASA Astrophysics Data System (ADS)

A supersonic expansion nozzle has allowed us to achieve highly efficient operation of the supersonic mixing chemical oxygen-iodine laser (COIL). The nozzle's shape produced a rapid mixing of the primary and secondary flows. Made up of a series of thin alternating wedges placed adjacent to each other, the nozzle looks like the letter X when it is viewed from the side. Iodine is injected at the exit plane of the nozzle and is strongly entrained by the streamwise vortices generated by the nozzle. 599 W of output power with a chemical efficiency of 32.9% is obtained, values higher by a factor of 1.4 than those of the conventional COIL.

Endo, Masamori; Osaka, Tatsuo; Takeda, Shuzaburo

2004-04-01

49

Real-time data acquisition and control system for a chemical oxygen iodine laser  

NASA Astrophysics Data System (ADS)

A user-friendly data acquisition and control system (DACS) for a chemical oxygen-iodine laser (COIL) has been developed. The system is capable of handling 117 analogue/digital channels for performing various operations such as on-line acquisition, control, display, safety measures and status indication of various subsystems. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a COIL. The DACS system has been programmed using Advantech-GeniDAQ software. This software has also been used to convert the acquired data into graphical form. Using this DACS, more than 200 runs were given performed successfully.

Mainuddin; Tyagi, R. K.; Rajesh, R.; Singhal, Gaurav; Dawar, A. L.

2003-08-01

50

Singlet oxygen generators - the heart of chemical oxygen iodine lasers: past, present, and future  

NASA Astrophysics Data System (ADS)

Since the initial demonstration of chemical oxygen iodine lasers in 1977, researchers have realized that the heart of the COIL system is the singlet oxygen generator. This drives the performance of the system in terms of output power, mass efficiency, engineering complexity, reliability and maintainability. For this reason the singlet oxygen generator has been the focus of intense research and development efforts over the last 30 years. This paper reports on the history of singlet oxygen generators - starting with the simple sparger design used in the initial COIL demonstration and ending with current jet or droplet generators used in laboratories around the world. The relative performance of the different generator types will naturally lead to performance goals for the research efforts of the future.

Hewett, Kevin B.

2008-10-01

51

Phase retarder in chemical oxygen-iodine laser at 45-deg. incidence  

NASA Astrophysics Data System (ADS)

A phase retarder used in chemical oxygen-iodine laser (COIL) system has been fabricated by ion beam sputtering (IBS). When the incident angle is 45 deg. the reflectivity is about 99.9% from 1290 to 1340 nm and about 83.8% at 632.8 nm, and the phase retardance between the parallel and perpendicular polarization components is -92.8 deg. at 1315 nm. In order to get the influence of temperature on the phase retarder, six samples have been annealed from 523 to 648 K at interval of 25 K in air respectively, and the results show good temperature performance. With increasing temperature, phase retardance becomes smaller, and the variation is within 4 deg. at 1315 nm. At the same time, the variation maintains within +- 10 deg. for the incidence from 44 to 49 deg..

Wang, Fang; Huang, Jianbing; Wang, Yingjian; Fan, Zhengxiu

2006-02-01

52

Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen–iodine laser  

Microsoft Academic Search

The pulsed chemical oxygen–iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and

I V Kochetov; A P Napartovich; N P Vagin; N N Yuryshev

2009-01-01

53

Dissociation of I2 in chemical oxygen-iodine lasers: experiment, modeling, and pre-dissociation by electrical discharge  

Microsoft Academic Search

The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for

A. Katz; K. Waichman; Z. Dahan; V. Rybalkin; B. D. Barmashenko; S. Rosenwaks

2007-01-01

54

Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen-iodine laser  

Microsoft Academic Search

The pulsed chemical oxygen-iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and

I. V. Kochetov; A. P. Napartovich; N. P. Vagin; N. N. Yuryshev

2009-01-01

55

Chemical oxygen-iodine laser with atomic iodine generated via Cl or F atoms  

NASA Astrophysics Data System (ADS)

Two alternative chemical methods of atomic iodine generation for a chemical oxygen-iodine laser (COIL) were studied. These methods are based on fast reactions of gaseous hydrogen iodide with chemically produced chlorine and fluorine atoms. Both processes were studied first in small-scale reactors. A yield of atomic iodine in the Cl system and nitrogen (non-reactive) atmosphere exceeded 80%, while in the F system it was only up to 27% related to F2 or 50% related to HI. The process of atomic iodine generation via Cl atoms was employed in operation of the supersonic COIL. A laser power of 430 W at 40 mmol Cl2/s, and the small signal gain up to 0.4%/cm were attained. The proposed methods promise an increase in laser power, easier control of laser operation, and simpler iodine management in comparison with the conventional source of atomic iodine using I2. The experimental results obtained so far with this experimental arrangement did not proved yet increasing COIL chemical efficiency because some process quenching a part of singlet oxygen was indicated. Therefore a modified experimental set-up has been designed and prepared for further investigation.

Spalek, Otomar; Jirasek, Vit; Censky, Miroslav; Kodymova, Jarmila; Jakubec, Ivo; Hager, Gordon D.

2005-03-01

56

COIL--Chemical Oxygen Iodine Laser: advances in development and applications  

NASA Astrophysics Data System (ADS)

Advantageous features of Chemical Oxygen-Iodine Laser (COIL) for laser technologies have increased considerably activities of international COIL communities during past ten years. They have been focused on the advanced concepts of hardware designs of the COIL subsystems, and testing and scaling-up of existing laser facilities. Prospective special applications of COIL technology, both civil and military, have received a significant attention and gained concrete aims. The paper is introduced by a brief description of the COIL operation mechanism and key device subsystems. It deals then with presentation of some investigated advanced concepts of singlet oxygen generators, alternative methods for atomic iodine generation, a mixing and ejector nozzle design to downsize a pressure recovery system, and optical resonators for high power COIL systems. The advanced diagnostics and computational modeling are also mentioned as very useful tools for critical insight into the laser kinetics and fluid dynamics, supporting thus the COIL research. The recent progress in the COIL development moves this laser closer to the application projects that are also briefly presented.

Kodymova, Jarmila

2005-09-01

57

Parametric study of an efficient supersonic chemical oxygen-iodine laser\\/jet generator system operating without buffer gas  

Microsoft Academic Search

A detailed experimental study of an efficient supersonic chemical oxygen-iodine laser is presented. The laser is energized by a jet-type singlet oxygen generator, operated without primary buffer gas and applies simple nozzle geometry and transonic mixing of iodine and oxygen. Output power of 190 W with chemical efficiency of 18% was obtained in a 5-cm gain length for Cl2 flow

D. Furman; B. D. Barmashenko; S. Rosenwaks

1998-01-01

58

Numerical Simulation of Throat-mixing System for Supersonic Flow Chemical Oxygen-Iodine Laser  

NASA Astrophysics Data System (ADS)

Throat-mixing systems are proposed and assessed for the supersonic flow chemical oxygen-iodine laser (S-COIL). Three-dimensional, numerical simulation solving the governing equations of compressible gas flows together with chemical kinetics has been made for investigating the characteristics of the mixing condition and chemical reactions. The compressible Navier-Stokes equations and a chemical kinetic model encompassing 21 chemical reactions and 10 chemical species are solved by means of a full-implicit finite difference method. Two types of nozzles, a blade- and cylinder-type nozzles are adopted. The results show satisfactorily high values of the small signal gain coefficient G. The proposed throat-mixing system shows higher efficiency than the parallel mixing system. The blade-type nozzle is found to give 44% higher peak value of G than that of the parallel mixing system. It is also noted that the cylinder-type nozzle has superior ability than the parallel mixing system, in spite of its exceedingly simple structure.

Suzuki, Masataro; Suzuki, Takanori; Masuda, Wataru

59

An efficient supersonic chemical oxygen-iodine laser operating without buffer gas and with simple nozzle geometry  

Microsoft Academic Search

We report on an efficient supersonic chemical oxygen-iodine laser, energized by a jet-type singlet oxygen generator, operating without primary buffer gas and applying simple nozzle geometry and transonic mixing of iodine and oxygen. Output power of 177 W with chemical efficiency of 17% was obtained in a 5 cm gain length for Cl2 flow rate of 11 mmol\\/s. The power

D. Furman; B. D. Barmashenko; S. Rosenwaks

1997-01-01

60

Role of N2 molecules in pulse discharge production of I atoms for a pulsed chemical oxygen-iodine laser  

Microsoft Academic Search

A pulsed electric discharge is the most effective means to turn chemical oxygen-iodine laser (COIL) operation into the pulse mode by fast production of iodine atoms. Experimental studies and numerical simulations are performed on a pulsed COIL initiated by an electric discharge in a mixture CF3I : N2 : O2(3X) : O2(a 1Deltag) flowing out of a chemical singlet oxygen

I. V. Kochetov; A. P. Napartovich; N. P. Vagin; N. N. Yuryshev

2011-01-01

61

Pulsed oxygen-iodine chemical laser initiated by an electrical discharge  

SciTech Connect

This paper demonstrates for the first time the feasibility of an electrically initiated, pulsed oxygen-iodine laser which can be initiated efficiently by low energy electrons. By electrical initiation, an O/sub 2/(/sup 1/..delta..)--CH/sub 3/I--N/sub 2/ mixture has been made to lase with an output energy of 130 mJ. The efficiency of the electrical initiation is 350 times higher than that obtained with photo-initiation.

Zhang Rongyao; Chen Fang; Song Xueqin; Xu Qingzhou; Huan Changqing; Zhuang Qi; Zhang Cunhao

1988-08-01

62

Generation of atomic iodine via fluorine for chemical oxygen iodine laser  

NASA Astrophysics Data System (ADS)

A method of the chemical generation of atomic iodine for a chemical oxygen-iodine laser (COIL) using atomic fluorine as a reaction intermediate was studied experimentally. This method is based on the reaction between F 2 and NO providing F atoms, and the reaction of F with HI resulting in iodine atoms generation. Atomic iodine was produced with efficiency exceeding 40% relative to initial F 2 flow rate. This efficiency was nearly independent on pressure and total gas flow rate. The F atoms were stable in the reactor up to 2 ms. An optimum ratio of the reactants flow rates was F 2:NO:HI = 1:1:1. A rate constant of the reaction of F 2 with HI was determined. The numerical modelling showed that remaining HI and IF were probably consumed in their mutual reaction. The reaction system was found suitable for employing in a generator of atomic iodine with its subsequent injection into a supersonic nozzle of a COIL.

Jirásek, Vít; Špalek, Otomar; ?enský, Miroslav; Picková, Irena; Kodymová, Jarmila; Jakubec, Ivo

2007-04-01

63

Photolysis/Electrical Discharge Initiated Pulsed Chemical Oxygen-Iodine Lasers Using Alkyl Iodides As The Iodine Source  

NASA Astrophysics Data System (ADS)

A photolyzed 02(1?)-CH3I-N2 mixture was made to lase with an output energy of over 160 mJ per pulse. The utilization efficiency of the stored 02(1?) energy attains 12%. The evidence provided by our experiments confirms that the major contribution to the laser energy comes from the energy transferred from 02(1?) to the iodine atom. A comparison between 02(1?)-CH3I-N2 and 02(1?)-CF3I-N2 mixtures suggests that the laser performance is strongly affected by the molecular species of the iodides and the former exceeds the latter in many respects. It is also shown that N2 is as good a buffer gas as Ar in the pulsed chemical oxygen-iodine laser with respect to laser output. The paper also demonstrates for the first time the feasibility of an electrically initiated pulsed oxygen-iodine laser. It is confirmed that the reactions of the oxygen-iodine laser can be efficiently initiated by using low energy electrons. The electrical efficiency is 350 times higher than that obtained with iodide photolysis.

Zhang, Rongyao; Chen, Fang; Song, Xueqin; Xu, Qingzhou; Huan, Changqing; Zhuang, Qi; Zhang, Cunhao

1990-01-01

64

Photolysis/electrical discharge initiated pulsed chemical oxygen-iodine lasers using alkyl iodides as the iodine source  

NASA Astrophysics Data System (ADS)

A photolyzed O2(1-Delta)-CH3I-N2 mixture was made to lase with an output energy of over 160 mJ per pulse. The utilization efficiency of the stored O2(1-Delta) energy attains 12 percent. The evidence provided by these experiments confirms that the major contribution to the laser energy comes from the energy transferred from O2(1-Delta) to the iodine atom. A comparison between O2(1-Delta)-CH3I-N2 and O2(1-Delta)-CF3I-N2 mixtures suggests that the laser performance is strongly affected by the molecular species of the iodides and the former exceeds the latter in many respects. It is also shown that N2 is as good a buffer gas as Ar in the pulsed chemical oxygen-iodine laser with respect to laser output. The paper also demonstrates for the first time the feasibility of an electrically initiated pulsed oxygen-iodine laser. It is confirmed that the reactions of the oxygen-iodine laser can be efficiently initiated by using low energy electrons. The electrical efficiency is 350 times higher than that obtained with iodide photolysis.

Zhang, Rongyao; Chen, Fang; Song, Xueqin; Xu, Qingzhou; Huan, Changqing

1989-06-01

65

Spray generator of singlet oxygen for a chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A spray type of singlet oxygen generator for driving the Chemical Oxygen-Iodine Laser was developed. Singlet oxygen, O2(1?g), is generated by a fast reaction of chlorine with basic hydrogen peroxide solution in the form of a dense spray. A mathematical model of this reaction system showed that O2(1?g) can be generated in this system with a high yield (0.70-0.80), high utilization of chlorine (0.75-0.95), and effective utilization of liquid (0.36-0.54) at very high generator pressures (35-75 kPa). Experimental studies of this reaction system without an efficient separation of liquid proved an efficient O2(1?g) production characterized by a rather high product of chlorine utilization and O2(1?g) yield (0.4-0.9) at very high generator pressures (30-80 kPa). This pressure is much higher than the operation pressure used in other generators, which should be beneficial for a pressure recovery system of the COIL. These results provided the basis for designing a centrifugal spray generator with an efficient separation of liquid from the gas flow, which is the subject of the following paper.

Jirásek, V.; Hrubý, J.; Špalek, O.; ?enský, M.; Kodymová, J.

2010-09-01

66

Studies of iodine dissociation in the chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The dissociation of I II molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied experimentally as a function of I II flow rate. The measurements revealed that the number of consumed O II(1?) molecules per dissociated I II molecule depends on the experimental conditions: it is 4.2 +/- 0.4 for typical conditions and I II densities applied for the operation of the COIL, but increases at lower I II densities. In addition, a new method for dissociating I II prior to its mixing with O II(1?) and thus reducing the loss of O II(1?) is reported. The method is based on applying corona/glow electrical discharge in the transonic section of the secondary flow in the COIL supersonic nozzle. 1.7% of I II is dissociated by the discharge resulting in 70% power enhancement at rather high I II/O II ratio, 1.6%, close to the optimal value (~ 2.5%) for operation of COILs with supersonic mixing.

Rybalkin, V.; Katz, A.; Waichman, K.; Vingurt, D.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

2007-05-01

67

Plasma Excited Chemical-Oxygen-Iodine Lasers: Optimizing Injection and Mixing for Positive Gain  

NASA Astrophysics Data System (ADS)

Chemical oxygen-iodine lasers achieve oscillation on the ^2P1/2->^2P3/2 transition of atomic iodine at 1.315 ?m by a series of excitation transfers from O2(^1?). In electrically plasma excited devices (eCOILs), O2(^1?) is produced in a flowing plasma, typically He/O2, at a few to tens of Torr. The iodine is injected into the flow as a He/I2 mixture immediately upstream (or in) a supersonic nozzle. A small positive gain with I* limited to a narrow boundary layer near the wall indicates slow mixing when the I2 is injected from the wall. This results in low utilization of O2(^1?). In this paper we discuss results from 1- and 2-dimensional computational investigations of means to optimize gain in eCOILs by using different I2 injection strategies. It was found that due to the plasma generated distribution O2(^1?), placement of injectors closer to the axis significantly increased gain by facilitating complete O2(^1?)/I2 mixing. This is partly a function of the inlet flow of NO through the discharge which regulates the density of O atoms produced by electron impact dissociation of O2. By optimizing the nozzle dimensions, their location, and I2 and NO flow rates, the yield of O2(^1?) required to achieve positive gain can be minimized.

Babaeva, Natalia Y.; Garcia, Luis A.; Arakoni, Ramesh A.; Kushner, Mark J.

2007-10-01

68

Pulsed Chemical Oxygen Iodine Lasers Excited by Pulse Gas Discharge with the Assistance of Surface Sliding Discharge Pre-ionization  

Microsoft Academic Search

Continuous-wave chemical oxygen-iodine lasers (COILs) can be operated in a pulsed operation mode to obtain a higher peak power. The key point is to obtain a uniform and stable glow discharge in the mixture of singlet delta oxygen and iodide. We propose using an electrode system with the assistance of surface sliding pre-ionization to solve the problem of the stable

Li Guo-Fu; Yu Hai-Jun; Duo Li-Ping; Jin Yu-Qi; Wang Jian; Sang Feng-Ting; Wang De-Zhen

2012-01-01

69

LASERS: Highly efficient cw chemical oxygen—iodine laser with transsonic iodine injection and a nitrogen buffer gas  

NASA Astrophysics Data System (ADS)

Methods of increasing the efficiency of low-pressure chemical oxygen—iodine lasers (COILs) with transsonic injection of molecular iodine, in which nitrogen is used as a buffer gas, are studied. A two-layer gas-dynamic model is used for a parametric analysis of physicochemical processes occurring in the transsonic iodine injector and in the COIL resonator, including mixing and generation of radiation. The 3D-RANS computer simulation software is used to study the flow structures resulting from an injection of iodine-containing flow into the transsonic zone of the oxygen nozzle. Experiments with a 10-kW modified laser have resulted in a chemical efficiency of 31.5% for a lasing power of 13.5 kW. The results of experimental studies of the cryosorption COIL exhaust system are presented.

Boreysho, A. S.; Barkan, A. B.; Vasil'ev, D. N.; Evdokimov, I. M.; Savin, A. V.

2005-06-01

70

Chemical Oxygen-Iodine Laser Diluted by CO2/N2 Buffer Gases with a Cryosorption Vacuum Pump  

NASA Astrophysics Data System (ADS)

Experiments were carried out on a verti-chemical oxygen-iodine laser (COIL), which was designed for N2 and energized by a square-pipe jet singlet oxygen generator (JSOG). A cryosorption vacuum pump was used as the pressure recovery system for CO2 and N2 buffer gases. The output power with CO2 was 27.3% lower than that with N2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N2 in the continuous operation with a Cl2 flow rate of 155 mmol/s and a total flow rate of 430±3 mmol/s.

Xu, Mingxiu; Sang, Fengting; Jin, Yuqi; Fang, Benjie; Chen, Fang; Geng, Zicai; Li, Yongzhao

2008-11-01

71

Highly efficient cw chemical oxygen-iodine laser with transsonic iodine injection and a nitrogen buffer gas  

SciTech Connect

Methods of increasing the efficiency of low-pressure chemical oxygen-iodine lasers (COILs) with transsonic injection of molecular iodine, in which nitrogen is used as a buffer gas, are studied. A two-layer gas-dynamic model is used for a parametric analysis of physicochemical processes occurring in the transsonic iodine injector and in the COIL resonator, including mixing and generation of radiation. The 3D-RANS computer simulation software is used to study the flow structures resulting from an injection of iodine-containing flow into the transsonic zone of the oxygen nozzle. Experiments with a 10-kW modified laser have resulted in a chemical efficiency of 31.5% for a lasing power of 13.5 kW. The results of experimental studies of the cryosorption COIL exhaust system are presented. (lasers)

Boreysho, A S; Barkan, A B; Vasil'ev, D N; Evdokimov, I M; Savin, A V [D. F. Ustinov Voenmekh Baltic State Technical University, Laser Systems Ltd., St. Petersburg (Russian Federation)

2005-06-30

72

High-pressure gravity-independent singlet oxygen generator, laser nozzle, and iodine injection system for the chemical oxygen-iodine laser  

Microsoft Academic Search

A novel approach is outlined for a singlet oxygen generator (SOG), a laser minimum length nozzle (MLN), and an iodine injector system for a chemical oxygen-iodine laser (COIL). A unified approach, referred to as a SOG\\/MLN\\/I2 system, is partly based on past experimental work. For instance, the SOG concept stems from sparger technology and a KSY fesibility experiment. A MLN

George Emanuel

2004-01-01

73

How many O2(1?) molecules are consumed per dissociated I2 in chemical oxygen-iodine lasers?  

NASA Astrophysics Data System (ADS)

Direct measurements of the dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) as a function of I2 flow rate were carried out. This enabled us to determine the number of consumed O2(?1) molecules per dissociated I2 molecule. The number depends on the experimental conditions: it is 4.2±0.4 for typical conditions and I2 densities applied for the operation of the COIL, but increases at lower I2 densities. Possible dissociation mechanisms consistent with our results are discussed and the importance of dissociating I2 prior to its mixing with O2(?1) is stressed.

Rybalkin, V.; Katz, A.; Waichman, K.; Vingurt, D.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

2006-07-01

74

LASERS: Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygeniodine lasers  

NASA Astrophysics Data System (ADS)

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field. Additions of SF6 or N2 to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O2 to these mixtures has only an insignificant effect on the discharge stability. The possibility of SIVD initiation was modelled experimentally in a 1.5-L discharge volume. For the C4H9I:O2:SF6=0.083:0.25:0.67 mixture at a pressure of 72 Torr, the specific energy input into the discharge plasma ranged up to 130 J L-1 in this geometry. A conclusion was drawn that the SIVD is promising for the production of atomic iodine in the pulsed and repetitively pulsed operating regimes of a chemical oxygeniodine laser.

Belevtsev, A. A.; Kazantsev, S. Yu; Saifulin, A. V.; Firsov, K. N.

2003-06-01

75

Numerical analysis of spatial evolution of the small signal gain in a chemical oxygen–iodine laser operating without primary buffer gas  

Microsoft Academic Search

A chemical oxygen–iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic

Zongmin Hu; Zonglin Jiang; Rhoshin Myong; Taehwan Cho

2008-01-01

76

Role of N2 molecules in pulse discharge production of I atoms for a pulsed chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A pulsed electric discharge is the most effective means to turn chemical oxygen-iodine laser (COIL) operation into the pulse mode by fast production of iodine atoms. Experimental studies and numerical simulations are performed on a pulsed COIL initiated by an electric discharge in a mixture CF3I : N2 : O2(3X) : O2(a 1?g) flowing out of a chemical singlet oxygen generator. A transverse pulsed discharge is realized at various iodide pressures. The model comprises a system of kinetic equations for neutral and charged species, the electric circuit equation, the gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are repeatedly re-calculated by the electron Boltzmann equation solver when the plasma parameters are changed. The processes accounted for in the Boltzmann equation include direct and stepwise excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions and second-kind collisions. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. A conclusion is drawn about satisfactory agreement between the theory and the experiment.

Kochetov, I. V.; Napartovich, A. P.; Vagin, N. P.; Yuryshev, N. N.

2011-09-01

77

Pulsed Chemical Oxygen Iodine Lasers Excited by Pulse Gas Discharge with the Assistance of Surface Sliding Discharge Pre-ionization  

NASA Astrophysics Data System (ADS)

Continuous-wave chemical oxygen-iodine lasers (COILs) can be operated in a pulsed operation mode to obtain a higher peak power. The key point is to obtain a uniform and stable glow discharge in the mixture of singlet delta oxygen and iodide. We propose using an electrode system with the assistance of surface sliding pre-ionization to solve the problem of the stable glow discharge with a large aperture. The pre-ionization unit is symmetrically fixed on the plane of the cathode surface. A uniform and stable glow discharge is obtained in a mixture of iodide (such as CH3I) and nitrogen at the specific deposition energy of 4.5 J/L, pressure of 1.99-3.32 kPa, aperture size of 11 cm × 10 cm. The electrode system is applied in a pulsed COIL. Laser energy up to 4.4 J is obtained and the specific energy output is 2 J/L.

Li, Guo-Fu; Yu, Hai-Jun; Duo, Li-Ping; Jin, Yu-Qi; Wang, Jian; Sang, Feng-Ting; Wang, De-Zhen

2012-05-01

78

Toward understanding the dissociation of I2 in chemical oxygen-iodine lasers: Combined experimental and theoretical studies  

NASA Astrophysics Data System (ADS)

The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three-dimensional computational fluid dynamics calculations. The measurements, briefly reported in a recent paper [Rybalkin et al., Appl. Phys. Lett. 89, 021115 (2006)] and reanalyzed in detail here, revealed that the number N of consumed O2(a?g1) molecules per dissociated I2 molecule depends on the experimental conditions: it is 4.5±0.4 for typical conditions and I2 densities applied for optimal operation of the COIL but increases at lower I2 densities. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature, I2 dissociation fraction, and N at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven [AIAA J. 44, 1593 (2006)], where I2(A'?2u3), I2(A?1u3), and O2(a?g1,v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner III et al. [J. Phys. Chem. 87, 2348 (1983)], involving I(P1/22) and I2(X?g +1,v).

Waichman, K.; Rybalkin, V.; Katz, A.; Dahan, Z.; Barmashenko, B. D.; Rosenwaks, S.

2007-07-01

79

Dissociation of I II in chemical oxygen-iodine lasers: experiment, modeling, and pre-dissociation by electrical discharge  

NASA Astrophysics Data System (ADS)

The dissociation of I II molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature and I II dissociation fraction at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven (AIAA J. 44, 1593 (2006)), where I II(A' 3? 2u), I II(A 3? 1u) and O II(a1? g, v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner et al. (J. Phys. Chem. 87, 2348 (1983)), involving I(2P 1/2) and I II(X1? + g, v). In addition, we examined a new method for enhancement of the gain and power in a COIL by applying DC corona/glow discharge in the transonic section of the secondary flow in the supersonic nozzle, dissociating I II prior to its mixing with O II(1?). The loss of O II(1?) consumed for dissociation was thus reduced and the consequent dissociation rate downstream of the discharge increased, resulting in up to 80% power enhancement. The implication of this method for COILs operating beyond the specific conditions reported here is assessed.

Katz, A.; Waichman, K.; Dahan, Z.; Rybalkin, V.; Barmashenko, B. D.; Rosenwaks, S.

2007-06-01

80

Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The pulsed chemical oxygen-iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and charged species, electric circuit equation, gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are found by solving the electron Boltzmann equation, which is re-calculated in a course of computations when plasma parameters changed. The processes accounted for in the Boltzmann equation include excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions, second-kind collisions and stepwise excitation of molecules. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. Results of numerical simulations are compared with experimental laser pulse waveforms. It is concluded that there is satisfactory agreement between theory and the experiment. The prevailing mechanism of iodine atom formation from the CF3I donor in a very complex kinetic system of the COIL medium under pulse discharge conditions, based on their detailed numerical modelling and by comparing these results both with experimental results of other authors and their own experiments, is established. The dominant iodine atom production mechanism for conditions under study is the electron-impact dissociation of CF3I molecules. It was proved that in the conditions of the experiment the secondary chemical reactions with O atoms play an insignificant role.

Kochetov, I. V.; Napartovich, A. P.; Vagin, N. P.; Yuryshev, N. N.

2009-03-01

81

Development of the electric discharge oxygen-iodine laser  

Microsoft Academic Search

In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O2(a1Delta) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. Experimental studies over the past six years using electric

David L. Carroll; Joseph T. Verdeyen; Darren M. King; Andrew D. Palla; Julia K. Laystrom; Gabriel F. Benavides; Joseph W. Zimmerman; Brian S. Woodard; Wayne C. Solomon

2007-01-01

82

Development of the electric discharge oxygen-iodine laser  

Microsoft Academic Search

In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O2(a 1 ?) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O2(a 1 ?) generation system. Experimental studies over the past

David L. Carroll; Joseph T. Verdeyen; Darren M. King; Andrew D. Palla; Julia K. Laystrom; Gabriel F. Benavides; Joseph W. Zimmerman; Brian S. Woodard; Wayne C. Solomon

83

Novel concept of electric discharge oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A novel concept of discharge oxygen-iodine laser (DOIL) is presented. The supersonic DOIL includes a discharge singlet oxygen generator (DSOG) and discharge atomic iodine generator (DAIG). The operation of DSOG is based on a fast mixing of hybrid argon plasma jet of DC electric arc and RF discharge with a neutral molecular oxygen stream. The goal of our effort is achievement of DOIL oscillations by this new discharge technique, which should provide the singlet oxygen yields exceeding 30% at the total pressures higher than 10 torr. The DAIG operation is based on a cw/pulse RF discharge dissociation of iodine donors directly inside a laser iodine injector. This method substitutes the classic dissociation of molecular iodine by energy of singlet oxygen, which saves its energy for laser generation and so can increase the laser efficiency. The laser power could be thus enhanced by up to 25% if this method is employed in a chemical oxygen-iodine laser (COIL) operation, and even 3 times in DOIL without increase in the iodine laser pumping by singlet oxygen.

Schmiedberger, J.; Jirásek, V.; Kodymová, J.; Rohlena, K.

2009-08-01

84

High-pressure gravity-independent singlet oxygen generator, laser nozzle, and iodine injection system for the chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A novel approach is outlined for a singlet oxygen generator (SOG), a laser minimum length nozzle (MLN), and an iodine injector system for a chemical oxygen-iodine laser (COIL). A unified approach, referred to as a SOG/MLN/I2 system, is partly based on past experimental work. For instance, the SOG concept stems from sparger technology and a KSY fesibility experiment. A MLN with a curved sonic line is used for the laser nozzle, and slender struts are used for the injection, in the downstream direction, of iodine/helium vapor. The heated struts are located downstream of the nozzle's throat. The engineering logic behind the approach is discussed; it has a diversity of potential system benefits relative to current technology. These include a compact, scalable laser that can operate in space. The SOG operates at a significantly higher pressure with a high O2(1?) yield. In addition, basic hydrogen peroxide reconditioning is not required, a water vapor removal system is not required, and diluent may be unnecessary, although useful for pressure recovery. The impact on a COIL system in terms of power, efficiency, and pressure recovery is briefly assessed.

Emanuel, George

2004-09-01

85

Numerical analysis of spatial evolution of the small signal gain in a chemical oxygen iodine laser operating without primary buffer gas  

NASA Astrophysics Data System (ADS)

A chemical oxygen-iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic section. The results show that the molecular iodine fraction in the secondary flow has a notable effect on the spatial distribution of the small signal gain. The rich iodine condition produces some negative gain regions along the jet trajectory, while the lean iodine condition slows down the development of the gain in the streamwise direction. It is also found that the new configuration of an interleaving jet helps form a reasonable gain field under appropriate operation conditions.

Hu, Zongmin; Jiang, Zonglin; Myong, Rhoshin; Cho, Taehwan

2008-02-01

86

Direct Measurement of O(2)(a(1)D) and O(2)(X(3)?) in Chemical Oxygen-Iodine Lasers with use of Spontaneous Raman Imaging.  

PubMed

A spontaneous Raman imaging system (SRIS) has been developed that can monitor chemical oxygen-iodine laser (COIL) singlet oxygen generator (SOG) performance in real time. This system permits one to monitor directly the SOG performance by measuring O(2)(a(1)D) and O(2)(X(3)?) simultaneously with a single intensified CCD array at the exit of an imaging monochromator. We present the results from tests conducted on a 0.25-mol SOG using a prototype Raman system. Performance and validation of a highly sensitive SRIS that was designed and built specifically for SOG diagnostics are discussed. Detection and possible interferences of other species relevant to COIL devices such as I(2) and Cl(2) are investigated. PMID:18268680

Gylys, V T; Rubin, L F

1998-02-20

87

Problems of development of oxygen-iodine laser with electric discharge production of singlet delta oxygen  

Microsoft Academic Search

Great success has been obtained in the R&D of a chemical oxygen-iodine laser (COIL) operating on the electronic transition of the iodine atom, which gets an excitation from the energy donor -singlet delta oxygen (SDO). The latter is normally produced in a chemical SDO generator using very toxic and dangerous chemicals, which puts a limit for civilian applications of COIL

Andrei A. Ionin; Anatoly P. Napartovich; Nikolai N. Yuryshev

2002-01-01

88

40 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 36, NO. 1, JANUARY 2000 High-Performance Chemical OxygenIodine Laser  

E-print Network

­iodine laser (COIL), the Ver- tiCOIL device, was transferred from the Air Force Research Laboratory (AFRL-power VertiCOIL laser was measured with nitrogen diluent. New nozzle designs were investigated and implemented in qualitative agreement with the system design predictions of the Blaze II chemical laser model. Three

Carroll, David L.

89

Scaling of an Electric Discharge Excited Oxygen-Iodine Laser  

Microsoft Academic Search

Electric discharge excited oxygen-iodine laser apparatus has been scaled to increase the electric discharge volume and power, the laser mixture flow rate, and the gain path in the M=3 laser cavity. Specifically, singlet delta oxygen (SDO) generator discharge power has been increased at least up to 3.5 kW, laser mixture flow rate up to 0.5 mole\\/sec, and gain path up

John Bruzzese; Munetake Nishihara; Walter Lempert; J. William Rich; Igor Adamovich

2008-01-01

90

Advancement and problems of fullerene-oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The methods of improving the efficiency of a fullerene-oxygen-iodine laser are investigated. In the course of this research, we developed new fullerene coatings that possess better mechanical and radiative hardness, as well as higher efficiency of singlet oxygen generation. We show that, by using these coatings, the energy yield per unit volume of the active medium can be increased to 9 J/l, which is almost two times higher than the previous result. The energy efficiency of the laser can also be increased by a factor of nearly two. At the same time, several problems were revealed that hinder the further improvement of the laser efficiency and its long-term operation with stable parameters of the output radiation. We outline principal approaches to further optimization of the laser design that would help to overcome the negative factors and make it possible to create a fullerene-oxygen-iodine laser with high and stable parameters of the output radiation.

Grenishin, A. S.; Kiselev, V. M.; Kislyakov, I. M.; Pavlova, A. L.; Sosnov, E. N.

2010-01-01

91

Development of the electric discharge oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O II(a1?) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O II(a1?) generation system. Experimental studies over the past six years using electric discharges have demonstrated O II(a) yields greater than 20%, gain, and cw laser power. Several modeling studies have also been performed for ElectricOIL and similar systems. As the development of this type of iodine laser continues, the roles of oxygen atoms and NO/NO II are found to be very significant in both the discharge region and downstream of the discharge region. A series of O II(1?) emission, I* emission, O-atom titrations, gain, and O II(1?) yield, NO II* emission, and laser power measurements have been taken to explore the complex phenomena that are being observed. As the overall system is better understood improvements are being made in laser power and efficiency.

Carroll, David L.; Verdeyen, Joseph T.; King, Darren M.; Palla, Andrew D.; Laystrom, Julia K.; Benavides, Gabriel F.; Zimmerman, Joseph W.; Woodard, Brian S.; Solomon, Wayne C.

2007-05-01

92

The electric oxygen-iodine laser: Chemical kinetics of O2(a 1 ?) production and I(2P1\\/2) excitation in microwave discharge systems  

Microsoft Academic Search

Generation of singlet oxygen metastables, O2(a 1 ?), in an electric discharge plasma offers the potential for development of compact electric oxygen-iodine laser (EOIL) systems using a recyclable, all-gas-phase medium. The primary technical challenge for this concept is to develop a high-power, scalable electric discharge configuration that can produce high yields and flow rates of O2(a) to support I( 2

W. T. Rawlins; S. Lee; W. J. Kessler; D. B. Oakes; L. G. Piper; S. J. Davis

93

The electric oxygen-iodine laser: chemical kinetics of O2(a1Delta) production and I(2 P1\\/2) excitation in microwave discharge systems  

Microsoft Academic Search

Generation of singlet oxygen metastables, O2(a1Delta), in an electric discharge plasma offers the potential for development of compact electric oxygen-iodine laser (EOIL) systems using a recyclable, all-gas-phase medium. The primary technical challenge for this concept is to develop a high-power, scalable electric discharge configuration that can produce high yields and flow rates of O2(a) to support I(2P1\\/2->2P3\\/2) lasing at high

W. T. Rawlins; S. Lee; W. J. Kessler; D. B. Oakes; L. G. Piper; S. J. Davis

2006-01-01

94

Evolution of the electric discharge oxygen-iodine laser  

Microsoft Academic Search

Experiments and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O2(a) in a radio-frequency (RF) discharge in an O2\\/He\\/NO gas mixture. New discharge geometries have led to improvements in O2(a) production and efficiency. Further,

David L. Carroll; Gabriel F. Benavides; Joseph W. Zimmerman; Brian S. Woodard; Andrew D. Palla; Michael T. Day; Joseph T. Verdeyen; Wayne C. Solomon

2010-01-01

95

Comparing modeling and measurements of the output power in chemical oxygen-iodine lasers: A stringent test of I2 dissociation mechanisms  

NASA Astrophysics Data System (ADS)

A parametric study of the output power of supersonic chemical oxygen-iodine lasers (COILs) is carried out, applying a kinetic-fluid dynamics model calculations as well as an analytical model and comparing the results to experimental studies. The I2 dissociation mechanism recently suggested by Azyazov et al. [J. Chem. Phys. 130, 104306 (2009)], which was previously used for comparison of model calculations to measurements of the small signal gain [K. Waichman et al., J. Appl. Phys. 106, 063108 (2009)], is applied here for a similar, but more sensitive, comparison of the laser output power. The dependence of the power on iodine flow rate and on mirror transmission is studied for low and high pressure COILs, respectively. Good agreement between the calculated and measured power is obtained for both low and high pressure COILs only when the processes suggested by Azyazov et al. are included in the calculations. This is different from the situation for the gain where for high pressure COILs, the calculated values were insensitive to the assumed dissociation mechanism, although for low pressure the measurements were reproduced only by applying the Azyazov et al. mechanism. We believe that the results of the present work strongly support the application of this mechanism for modeling the COIL operation.

Waichman, K.; Barmashenko, B. D.; Rosenwaks, S.

2010-08-01

96

Numerical study of He/CF3I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH3I, CF3I, etc.) is the most efficient method for achieving the pulse operating mode of a chemical oxygen-iodine laser. In this paper, a one-dimensional fluid model is developed to study the characteristics of pulsed discharge in CF3I-He mixture. By solving continuity equation, momentum equation, Poisson equation, Boltzmann equation, and an electric circuit equation, the temporal evolution of discharge current density and various discharge products, especially the atomic iodine, are investigated. The dependence of iodine atom density on discharge parameters is also studied. The results show that iodine atom density increases with the pulsed width and pulsed voltage amplitude. The mixture ratio of CF3I and helium plays a more significant role in iodine atom production. For a constant voltage amplitude, there exists an optimal mixture ratio under which the maximum iodine atom concentration is achieved. The bigger the applied voltage amplitude is, the higher partial pressure of CF3I is needed to obtain the maximum iodine atom concentration.

Zhang, Jiao; Wang, Yanhui; Duo, Liping; Li, Guofu; Wang, Dezhen

2013-04-01

97

Numerical study of He/CF{sub 3}I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser  

SciTech Connect

The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH{sub 3}I, CF{sub 3}I, etc.) is the most efficient method for achieving the pulse operating mode of a chemical oxygen-iodine laser. In this paper, a one-dimensional fluid model is developed to study the characteristics of pulsed discharge in CF{sub 3}I-He mixture. By solving continuity equation, momentum equation, Poisson equation, Boltzmann equation, and an electric circuit equation, the temporal evolution of discharge current density and various discharge products, especially the atomic iodine, are investigated. The dependence of iodine atom density on discharge parameters is also studied. The results show that iodine atom density increases with the pulsed width and pulsed voltage amplitude. The mixture ratio of CF{sub 3}I and helium plays a more significant role in iodine atom production. For a constant voltage amplitude, there exists an optimal mixture ratio under which the maximum iodine atom concentration is achieved. The bigger the applied voltage amplitude is, the higher partial pressure of CF{sub 3}I is needed to obtain the maximum iodine atom concentration.

Zhang Jiao; Wang Yanhui; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Duo Liping; Li Guofu [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116024 (China)

2013-04-15

98

Novel concept of electric discharge oxygen-iodine laser  

Microsoft Academic Search

A novel concept of discharge oxygen-iodine laser (DOIL) is presented. The supersonic DOIL includes a discharge singlet oxygen\\u000a generator (DSOG) and discharge atomic iodine generator (DAIG). The operation of DSOG is based on a fast mixing of hybrid argon\\u000a plasma jet of DC electric arc and RF discharge with a neutral molecular oxygen stream. The goal of our effort is achievement

J. Schmiedberger; V. Jirásek; J. Kodymová; K. Rohlena

2009-01-01

99

Electric discharge oxygen-iodine laser: three decades from the idea to the laser development  

Microsoft Academic Search

The overview of experimental research aimed at the research and development of an electric discharge oxygen-iodine laser (DOIL) since the first negative attempt of launching a DOIL in the 1970's is presented. The problem is tightly connected with the development of singlet delta oxygen (SDO) electric generator, which could substitute in future for SDO chemical one used for a high-power

Andrey Ionin

2006-01-01

100

Electric discharge oxygen-iodine laser: three decades from the idea to the laser development.  

NASA Astrophysics Data System (ADS)

The overview of experimental research aimed at the research and development of an electric discharge oxygen-iodine laser (DOIL) since the first negative attempt of launching a DOIL in the 1970's is presented. The problem is tightly connected with the development of singlet delta oxygen (SDO) electric generator, which could substitute in future for SDO chemical one used for a high-power COIL resulting in the development of a high-power DOIL. The main experimental and theoretical efforts focused onto studying and understanding of physical processes, which could help in or prevent from achieving and exceeding the threshold SDO yield at partial oxygen pressure adequate for modern oxygen-iodine laser technology, are discussed. Quite recently obtained results on gain and output characteristics of DOIL, and some projects aimed at the development of high-power DOIL are discussed.

Ionin, Andrey

2006-10-01

101

The electric oxygen-iodine laser: chemical kinetics of O II(a1?) production and I(2 P 1/2) excitation in microwave discharge systems  

NASA Astrophysics Data System (ADS)

Generation of singlet oxygen metastables, O II(a1?), in an electric discharge plasma offers the potential for development of compact electric oxygen-iodine laser (EOIL) systems using a recyclable, all-gas-phase medium. The primary technical challenge for this concept is to develop a high-power, scalable electric discharge configuration that can produce high yields and flow rates of O II(a) to support I(2P 1/2->2P 3/2) lasing at high output power. This paper discusses the chemical kinetics of the generation of O II(a) and the excitation of I(2P 1/2) in discharge-flow reactors using microwave discharges at low power, 40-120 W, and moderate power, 1-2 kW. The relatively high E/N of the microwave discharge, coupled with the dilution of O II with Ar and/or He, leads to increased O II(a) production rates, resulting in O II(a) yields in the range 20-40%. At elevated power, the optimum O II(a) yield occurs at higher total flow rates, resulting in O II(a) flow rates as large as 1 mmole/s (~100 W of O II(a) in the flow) for 1 kW discharge power. We perform the reacting flow measurements using a comprehensive suite of optical emission and absorption diagnostics to monitor the absolute concentrations of O II(a), O II(b), O( 3P), I II, I(2P 3/2), I(2P 1/2), small-signal gain, and temperature. These measurements constrain the kinetics model of the system, and reveal the existence of new chemical loss mechanisms related to atomic oxygen. The results for O II(a) production at 1 kW have intriguing implications for the scaling of EOIL systems to high power.

Rawlins, W. T.; Lee, S.; Kessler, W. J.; Oakes, D. B.; Piper, L. G.; Davis, S. J.

2006-02-01

102

Systematic development of the electric discharge oxygen-iodine laser  

Microsoft Academic Search

Systematic experiments have led to continued improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased the discharge performance, supersonic cavity gain, and laser power output. Experimental investigations of radio-frequency (rf) and pulser-sustainer (ps) discharges in O2\\/He\\/NO mixtures in the pressure range of 10-50 Torr and power range of 0.1-2.0 kW have shown that O2(a1Delta) production is a

David L. Carroll; Gabriel F. Benavides; Joseph W. Zimmerman; Brian S. Woodard; Andrew D. Palla; Joseph T. Verdeyen; Wayne C. Solomon

2008-01-01

103

Overview of iodine generation for oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

A review of the methods for generation of iodine for oxygen-iodine lasers (OIL) is presented. The chemical and physical methods for production of both atomic (AI) and molecular (MI) iodine have been searched in order to improve the efficiency and/or technology of OILs. These trials were motivated by the estimations that a substantial part of singlet oxygen (SO) could be saved with these methods and the onset of the laser active medium will be accelerated. Vapour of MI can be generated by the evaporation of solid or pressurized liquid I2, or synthesized in situ by the reaction of Cl2 with either HI or CuI2. The chemical methods of generation of AI are based on the substitution of I atom in a molecule of HI or ICl by another halogen atom produced usually chemically. The discharge methods include the dissociation of various iodine compounds (organic iodides, I2, HI) in the RF, MW, DC-pulsed or DC-vortex stabilized discharge. Combined methods use discharge dissociation of molecules (H2, F2) to gain atoms which subsequently react to replace AI from the iodine compound. The chemical methods were quite successful in producing AI (up to the 100% yield), but the enhancement of the laser performance was not reported. The discharge methods had been subsequently improving and are today able to produce up to 0.4 mmol/s of AI at the RF power of 500 W. A substantial enhancement of the discharge- OIL performance (up to 40%) was reported. In the case of Chemical-OIL, the enhancement was reported only under the conditions of a low I2/O2 ratio, where the "standard" I2 dissociation by SO is slow. The small-signal gain up to 0.3 %/cm was achieved on the supersonic COIL using the HI dissociated in the RF discharge. Due to the complicated kinetics of the RI-I-I2-SO system and a strong coupling with the gas flow and mixing, the theoretical description of the problem is difficult. It, however, seems that we can expect the major improvement of the OIL performance for those systems, where the SO yield is rather low (DOIL) or for the high-pressure COIL, where the quenching processes are important and the shortage of the distance needed for the preparation of active media is essential.

Jirásek, Vít.

2012-01-01

104

Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen-iodine laser  

Microsoft Academic Search

Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CHI is used as the donor of atomic iodine. The fraction of iodine extracted from CHI in the generator is 50%. The optimal operation regimes are found in which 80%-90% of iodine contained in the output flow

V N Azyazov; M V Vorobev; A I Voronov; Nikolai V Kupryaev; P A Mikheev; N I Ufimtsev

2009-01-01

105

Photolysis\\/electrical discharge initiated pulsed chemical oxygen-iodine lasers using alkyl iodides as the iodine source  

Microsoft Academic Search

A photolyzed O2(1-Delta)-CH3I-N2 mixture was made to lase with an output energy of over 160 mJ per pulse. The utilization efficiency of the stored O2(1-Delta) energy attains 12 percent. The evidence provided by these experiments confirms that the major contribution to the laser energy comes from the energy transferred from O2(1-Delta) to the iodine atom. A comparison between O2(1-Delta)-CH3I-N2 and

Rongyao Zhang; Fang Chen; Xueqin Song; Qingzhou Xu; Changqing Huan

1989-01-01

106

Investigation of Axially Flowing He\\/O2 Plasmas for Oxygen-Iodine Lasers  

Microsoft Academic Search

Current trends in pumping chemical oxygen-iodine lasers (COIL) involve producing the O_2(^1Delta ) donor in axially flowing rf or pulsed electric discharges, thereby circumventing the hazards and complexity of conventional liquid-phase O_2(^1Delta ) production. Previous global-plug-flow modeling focused on developing reaction mechanisms and determining the specific energy deposition required to achieve high O_2(^1Delta ) yields. Recent experimental efforts have achieved

D. Shane Stafford; Mark J. Kushner

2004-01-01

107

The research on discharge oxygen iodine laser in Japan  

NASA Astrophysics Data System (ADS)

A decade has passed, since Discharge Oxygen Iodine Laser (DOIL) research started in our laboratory. Singlet delta oxygen production tests were carried out using RF discharge singlet oxygen generator of the first version (DSOG-1) in 1993. The maximum yield of 4.2% was achieved by DSOG-1. Efforts for improving RF-DSOG have been continuously carrying on and DSOG-5 is now under operation. The DSOG-5 consists of a jet nozzle having a diameter of 3 mm, an injector quarts nozzle of 2 mm diameter set inside the jet nozzle at coaxial position and a mixing slit nozzle with the height of 0.2 mm set surrounding the jet nozzle exit. High electric field is laid on inside surface of the jet nozzle by 200 W RF power source. The singlet delta oxygen is produced by energy transfer from Argon plasma which is produced in the jet nozzle. It is important for achieving high yield to have a good mixing of oxygen, blown from the slit nozzle and the quarts nozzle, with the Argon plasma. The yield of 24% was recorded when oxygen gas 110 sccm was mixed with 700 sccm Argon gas at the pressure 0.6 torr and the RF power 196 W. With a new laser system reinforced by a discharge iodine dissociation and a laser gas cooling device, oscillation tests were carried out in conjunction with the DSOG-5. Performance of the system was confirmed by an emission from excited iodine atoms which energy was transferred from the singlet delta oxygen. It is obvious that the new system gives a progress for the DOIL oscillation.

Fujii, Hiroo; Kihara, Yoshihumi; Funakoshi, Ryota; Okamura, Minoru; Schmiedberger, Josef

2004-09-01

108

Frequency-doubled pulsed chemical oxygen-iodine laser as an efficient pump source for high-power solid state lasers  

Microsoft Academic Search

Output laser parameters are enhanced significantly by using laser pumping. An excellent example is usage of laser diodes for solid-state laser pumping. Although there are permanent advances towards development of this technique, its application for laser systems of more than 100 J output requires time, significant effort and expense. I propose another pumping source based on a rather simple and

P. G. Kryukov

1995-01-01

109

Investigations of processes in a glow electrical discharge singlet-oxygen generator for oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Singlet oxygen (SO) concentration exceeding 20% is obtained in pure oxygen with the help of a glow-discharge singlet oxygen generator (DSOG). SO concentration exceeding 30% is obtained using homogeneous or heterogeneous catalysts at 0.5-1 Torr of pure oxygen. The possibility to develop an electrical discharge singlet oxygen generator for oxygen-iodine lasers, which is an alternative to a SO chemical generator is demonstrated.

Lodin, V. J.; Ikonnikov, V. C.; Sirotin, S. A.; Zhdanovich, S. I.; Savin, Yuri V.; Adamenkov, Yu. A.; Rogojnikov, Yu. K.

2005-03-01

110

Investigations of processes in a glow electrical discharge singlet-oxygen generator for oxygen-iodine laser  

Microsoft Academic Search

Singlet oxygen (SO) concentration exceeding 20% is obtained in pure oxygen with the help of a glow-discharge singlet oxygen generator (DSOG). SO concentration exceeding 30% is obtained using homogeneous or heterogeneous catalysts at 0.5-1 Torr of pure oxygen. The possibility to develop an electrical discharge singlet oxygen generator for oxygen-iodine lasers, which is an alternative to a SO chemical generator

V. J. Lodin; V. C. Ikonnikov; S. A. Sirotin; S. I. Zhdanovich; Yuri V. Savin; Yu. A. Adamenkov; Yu. K. Rogojnikov

2005-01-01

111

New concepts of the chemistry of electric-discharge oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

The chemistry of electric discharge driven oxygen iodine lasers (EOIL) has long been believed to have O2(a1?g) as the sole energy carrier for excitation of the lasing state I(2P1/2), and O(3P) as the primary quencher of this state. In many sets of experimental measurements over a wide range of conditions, we have observed persistent evidence to the contrary. In this paper, we review our experimental data base in both room-temperature discharge-flow measurements and EOIL reactor results, in comparison to model predictions and kinetics analysis, to identify the missing production and loss terms in the EOIL reaction mechanism. The analysis points to a significantly higher level of understanding of this energetic chemical system, which can support advanced concepts in power scaling investigations.

Rawlins, Wilson T.; Lee, Seonkyung; Hicks, Adam J.; Konen, Ian M.; Oakes, David B.; Plumb, Emily P.; Davis, Steven J.

2011-03-01

112

ELEMENTS OF LASER SETUPS: Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen---iodine laser  

Microsoft Academic Search

Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH3I is used as the donor of atomic iodine. The fraction of iodine extracted from CH3I in the generator is ~50%. The optimal operation regimes are found in which 80%---90% of iodine contained in the output flow

V. N. Azyazov; M. V. Vorob'ev; A. I. Voronov; Nikolai V. Kupryaev; P. A. Mikheev; N. I. Ufimtsev

2009-01-01

113

ELEMENTS OF LASER SETUPS: Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen—iodine laser  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH3I is used as the donor of atomic iodine. The fraction of iodine extracted from CH3I in the generator is ~50%. The optimal operation regimes are found in which 80%—90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%—30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was ~3%.

Azyazov, V. N.; Vorob'ev, M. V.; Voronov, A. I.; Kupryaev, Nikolai V.; Mikheev, P. A.; Ufimtsev, N. I.

2009-01-01

114

The research of Iodine pool pressure of chemical oxygen-iodine laser in non-equilibrium condition and its automatic control system design  

NASA Astrophysics Data System (ADS)

In the working process of chemical oxy-iodigenne laser(COIL), the change of iodine pool pressure is complicated. As a result, it causes some mis-judgements, such as the damage of heater and the leakage of iodine steam. Further more, when the heater electric circuit is in a single working status, and after the heater switch is on or off, there exists a buffer time for the stabilization of iodine pool pressure, which is a relatively long time, and the minimum buffer pressure exceeds to 19 torr . Of course, it increases the preparing time for steady operation of laser, and reduces the quality of laser beam. In this paper, we study the iodine pool pressure of COIL in non-equilibrium condition, and analyze the mutation and the serious buffer phenomenon of iodine steam pressure. At the same time, we design an automatic control system for iodine pool pressure, which consists of five modules, such as data collection, automatic control, manual control, heater electric circuit, and the setting and display of pressure. This system uses two kinds of heater electric circuits, in this way, the serious buffer phenomenon of iodine pool pressure is effectively avoided. As a result, the maximal buffer pressure reduces to 4 torr, this makes sure that the iodine steam pressure is suitable for the operation of COIL, which produces a good condition for the steady operation of laser system and an excellent laser output.

Zhou, Songqing; Qu, Pubo; Ren, Weiyan

2013-05-01

115

Problems of development of oxygen-iodine laser with electric discharge production of singlet delta oxygen  

NASA Astrophysics Data System (ADS)

Great success has been obtained in the R&D of a chemical oxygen-iodine laser (COIL) operating on the electronic transition of the iodine atom, which gets an excitation from the energy donor -singlet delta oxygen (SDO). The latter is normally produced in a chemical SDO generator using very toxic and dangerous chemicals, which puts a limit for civilian applications of COIL that is still a very unique apparatus. Totally new non-chemical SDO generator is needed to allow oxygen-iodine laser to achieve its full potential as a non-hazardous efficient source of high-power laser radiation. There was interest in producing SDO in electric discharge plasma since the 50's long before COIL appearing. The idea of using SDO as a donor for iodine laser was formulated in the 70's. However, the injection of iodine molecules into a low- pressure self-sustained discharge did not result in iodine lasing. One of the main factors that could prevent from lasing in many experiments is a rather high threshold yield ~15% at 300K, which is needed for obtaining an inversion population. An analysis of different attempts of producing SDO in different kinds of electric discharge plasma has been done which demonstrates that high yield at gas pressure of practical interest (p > 10 Torr) for modern COIL technology can be obtained only in non-self sustained electric discharge plasma. The reason is that the value of relatively low reduced electrical field strength E/N ~10-16 V.cm2, which is an order of magnitude less than that for the self-sustained discharge, is extremely important for the efficient SDO production. Although different kinds of non-self sustained discharges can be used for SDO production, we got started experiments with e-beam sustained discharge in gas mixtures containing oxygen. High specific input energy up to ~3 - 5 kJ/l. atm [O2] has been experimentally obtained. Theoretical calculations have been done for different experimental conditions indicating a feasibility of reasonable SDO yield. Experimental and theoretical research of self-sustained electric discharge in SDO produced in a chemical generator, which is very important for getting plasma-chemical kinetic data needed for an estimation of SDO yield, is also discussed.

Ionin, Andrei A.; Napartovich, Anatoly P.; Yuryshev, Nikolai N.

2002-09-01

116

Advanced chemical lasers  

NASA Astrophysics Data System (ADS)

A review of recent advances in chemical laser technology is presented. New technology and concepts related to the Chemical Oxygen Iodine Laser (COIL), All Gas-phase Iodine Laser (AGIL), and HF Overtone Laser are discussed.

Manke, Gerald C., II; Hewett, Kevin B.; Madden, Timothy J.; McCord, John E.; Wisniewski, Charles F.; Hager, Gordon D.

2004-09-01

117

Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments  

NASA Astrophysics Data System (ADS)

In an electric discharge oxygen-iodine laser, laser action at 1315nm on the I(P1/22)?I(P3/22) transition of atomic iodine is obtained by a near resonant energy transfer from O2(a?1) which is produced using a low-pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the postdischarge kinetics which are not encountered in a classic purely chemical O2(a?1) generation system. Mixing effects are also present. In this paper we present postdischarge modeling results obtained using a modified version of the BLAZE-II gas laser code. A 28 species, 105 reaction chemical kinetic reaction set for the postdischarge kinetics is presented. Calculations were performed to ascertain the impact of a two stream mixing mechanism on the numerical model and to study gain as a function of reactant mass flow rates. The calculations were compared with experimental data. Agreement with experimental data was improved with the addition of new kinetics and the mixing mechanism.

Palla, Andrew D.; Carroll, David L.; Verdeyen, Joseph T.; Solomon, Wayne C.

2006-07-01

118

Continuous wave operation of a non-self-sustained electric discharge pumped oxygen-iodine laser  

Microsoft Academic Search

This letter discusses operation of an electric discharge excited oxygen-iodine laser using a high-pressure, non-self-sustained pulser-sustainer discharge. Small signal gain on the 1315 nm iodine atom transition and the laser output power are measured in the M=3 supersonic cavity downstream of the discharge section. In a 15% O2-85% He mixture, at a discharge pressure of 60 torr and discharge power

A. Hicks; Yu. G. Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich

2006-01-01

119

Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments  

Microsoft Academic Search

In an electric discharge oxygen-iodine laser, laser action at 1315 nm on the I(2P1\\/2)-->I(2P3\\/2) transition of atomic iodine is obtained by a near resonant energy transfer from O2(a 1Delta) which is produced using a low-pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the postdischarge kinetics which are not

Andrew D. Palla; David L. Carroll; Joseph T. Verdeyen; Wayne C. Solomon

2006-01-01

120

Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments  

Microsoft Academic Search

In an electric discharge oxygen-iodine laser, laser action at 1315 nm on the I(2P1?2)?I(2P3?2) transition of atomic iodine is obtained by a near resonant energy transfer from O2(a 1?) which is produced using a low-pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the postdischarge kinetics which are not

Andrew D. Palla; David L. Carroll; Joseph T. Verdeyen; Wayne C. Solomon

2006-01-01

121

Continuous wave operation of a non-self-sustained electric discharge pumped oxygen-iodine laser  

Microsoft Academic Search

This letter discusses operation of an electric discharge excited oxygen-iodine laser using a high-pressure, non-self-sustained pulser-sustainer discharge. Small signal gain on the 1315 nm iodine atom transition and the laser output power are measured in the M=3 supersonic cavity downstream of the discharge section. In a 15% O2–85% He mixture, at a discharge pressure of 60 torr and discharge power

A. Hicks; Yu. G. Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich

2006-01-01

122

Active medium gain study of electric-discharge oxygen-iodine laser  

Microsoft Academic Search

The paper reports on experimental studies of the active medium gain in supersonic electric-discharge oxygen-iodine laser (DOIL) based on traveling mw discharge. The measurements have included: absolute concentration, yield, and energy efficiency of production of SO in pure oxygen and oxygen-helium mixes at an oxygen partial pressure 3 to 15 Torr. For the gas flow to get rid of atomic

Yuriy Kolobyanin; Yuriy Adamenkov; Boris Vyskubenko; Leonid Goryachev; Sergey Ilyin; Anatoliy Kalashnik; Tatiana Rakhimova; Georgiy Rogozhnikov

2007-01-01

123

Recent Work on the Development of an Electric Discharge Oxygen Iodine Laser  

Microsoft Academic Search

Theoretical studies have indicated that sufficient fractions of O2( 1 ?) may be produced in an electrical discharge that will permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system in conjunction with injection of pre-dissociated iodine. Results of those studies along with more recent experimental results show that electric excitation is a very complicated process that must be investigated

D. L. Carroll; J. T. Verdeyen; D. M. King; B. Woodardb; L. Skorskib; W. C. Solomon

124

Electric generators of singlet delta oxygen for an oxygen-iodine laser  

Microsoft Academic Search

Experimental and theoretical research into electric generators of singlet delta oxygen (SDO) for an oxygen-iodine laser made\\u000a at the Lebedev Physics Institute and TRINITI is discussed. Breakdown and current-voltage characteristics of self-sustained\\u000a electric discharge in SDO were studied both experimentally and theoretically, indicating that SDO and pure oxygen have quite\\u000a different electric features. The electric properties and spectroscopy of an

A. A. Ionin; A. P. Napartovich; N. N. Yuryshev

2006-01-01

125

Recent work on the development of an electric discharge oxygen iodine laser  

Microsoft Academic Search

Theoretical studies have indicated that sufficient fractions of O2 (1Delta) may be produced in an electrical discharge that will permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system in conjunction with injection of pre-dissociated iodine. Results of those studies along with more recent experimental results show that electric excitation is a very complicated process that must be investigated with

David L. Carroll; J. T. Verdeyen; D. M. King; B. Woodard; L. Skorski; J. Zimmerman; W. C. Solomon

2003-01-01

126

New concepts of the chemistry of electric-discharge oxygen-iodine lasers  

Microsoft Academic Search

The chemistry of electric discharge driven oxygen iodine lasers (EOIL) has long been believed to have O2(a1▵g) as the sole energy carrier for excitation of the lasing state I(2P1\\/2), and O(3P) as the primary quencher of this state. In many sets of experimental measurements over a wide range of conditions, we have observed persistent evidence to the contrary. In this

Wilson T. Rawlins; Seonkyung Lee; Adam J. Hicks; Ian M. Konen; David B. Oakes; Emily P. Plumb; Steven J. Davis

2011-01-01

127

Investigation of Axially Flowing He/O2 Plasmas for Oxygen-Iodine Lasers  

NASA Astrophysics Data System (ADS)

Current trends in pumping chemical oxygen-iodine lasers (COIL) involve producing the O_2(^1? ) donor in axially flowing rf or pulsed electric discharges, thereby circumventing the hazards and complexity of conventional liquid-phase O_2(^1? ) production. Previous global-plug-flow modeling focused on developing reaction mechanisms and determining the specific energy deposition required to achieve high O_2(^1? ) yields. Recent experimental efforts have achieved positive laser gain with these energy depositions and have demonstrated the importance of upstream and downstream penetration of the plasma. In this work, we have examined the effects of axial transport (mass, momentum, and energy) on O_2(^1? ) yields in flowing He/O2 plasmas at a few to 10 Torr using a compressible 1D hydrodynamics and plasma kinetics model. Experimentally observed extension of short lived excited states upstream and downstream of the excitation zone is explained by electron thermal conduction and flow-induced extension of the plasma zone

Stafford, D. Shane; Kushner, Mark J.

2004-09-01

128

LASERS: Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygen --- iodine laser with a large active volume  

Microsoft Academic Search

Possibilities for increasing the active medium volume of a chemical oxygen --- iodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for

S. Yu Kazantsev; I. G. Kononov; S. V. Podlesnykh; K. N. Firsov

2010-01-01

129

O2(1?) and i(2p1\\/2) production in flowing afterglows for oxygen-iodine lasers: effect of no\\/no2 additives  

Microsoft Academic Search

Summary form only given. The chemical oxygen-iodine laser operates on the 1.315 mum I(1P12) rarr I(2P32) transition in atomic iodine; and is pumped by reactions between O2(1Delta) and molecular and atomic iodine. In electrically excited COIL lasers, (eCOIL), O2(1Delta) is produced in a plasma followed by injection of I2 in the afterglow containing the excited oxygen. The flowing afterglow additionally

R. A. Arakoni; N. Y. Babaeva; M. J. Kushner

2007-01-01

130

Mechanism of singlet oxygen deactivation in an electric discharge oxygeniodine laser  

NASA Astrophysics Data System (ADS)

We have determined the influence of the reaction of molecular singlet oxygen with a vibrationally excited ozone molecule O2(a 1?) + O3(?) ? 2O2 + O on the removal rate of O2(a 1?) in an electric-discharge-driven oxygeniodine laser. This reaction has been shown to be a major channel of O2(a 1?) loss at the output of an electric-discharge singlet oxygen generator. In addition, it can also contribute significantly to the loss of O2(a 1?) in the discharge region of the generator.

Azyazov, V. N.; Mikheyev, P. A.; Pershin, A. A.; Torbin, A. P.; Heaven, M. C.

2014-12-01

131

Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygen - iodine laser with a large active volume  

Microsoft Academic Search

Possibilities for increasing the active medium volume of a chemical oxygen - iodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for

S Yu Kazantsev; I G Kononov; S V Podlesnykh; K N Firsov

2010-01-01

132

Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygeniodine laser with a large active volume  

Microsoft Academic Search

Possibilities for increasing the active medium volume of a chemical oxygeniodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for

S Yu Kazantsev; I G Kononov; S V Podlesnykh; K N Firsov

2010-01-01

133

Continuous wave operation of a non-self-sustained electric discharge pumped oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

This letter discusses operation of an electric discharge excited oxygen-iodine laser using a high-pressure, non-self-sustained pulser-sustainer discharge. Small signal gain on the 1315nm iodine atom transition and the laser output power are measured in the M =3 supersonic cavity downstream of the discharge section. In a 15% O2-85% He mixture, at a discharge pressure of 60torr and discharge power of 1.5kW, the highest gain measured in the M =3 cavity is 0.022%/cm, at the flow temperature of T =100±10K. At these conditions, the laser output power is 0.28W.

Hicks, A.; Utkin, Yu. G.; Lempert, W. R.; Rich, J. W.; Adamovich, I. V.

2006-12-01

134

Oxygen Discharge and Post-Discharge Kinetics Experiments and Modeling for the Electric Oxygen-Iodine Laser System  

E-print Network

Oxygen Discharge and Post-Discharge Kinetics Experiments and Modeling for the Electric Oxygen a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels

Carroll, David L.

135

ACTIVE MEDIA: Analytic study of the chain dark decomposition reaction of iodides — atomic iodine donors — in the active medium of a pulsed chemical oxygen—iodine laser: 1. Criteria for the development of the branching chain dark decomposition reaction of iodides  

NASA Astrophysics Data System (ADS)

The scheme of chemical processes proceeding in the active medium of a pulsed chemical oxygen—iodine laser (COIL) is analysed. Based on the analysis performed, the complete system of differential equations corresponding to this scheme is replaced by a simplified system of equations describing in dimensionless variables the chain dark decomposition of iodides — atomic iodine donors, in the COIL active medium. The procedure solving this system is described, the basic parameters determining the development of the chain reaction are found and its specific time intervals are determined. The initial stage of the reaction is analysed and criteria for the development of the branching chain decomposition reaction of iodide in the COIL active medium are determined.

Andreeva, Tamara L.; Kuznetsova, S. V.; Maslov, Aleksandr I.; Sorokin, Vadim N.

2009-02-01

136

Gain Distribution and Output Power Measurements in a Scaled Electric Discharge Excited Oxygen-Iodine Laser1  

Microsoft Academic Search

Singlet delta oxygen (SDO) yield, gain in the supersonic cavity, and output power have been measured in a scaled-up electric discharge excited oxygen-iodine laser. The laser is using 5 kW transverse RF discharge operated at pressures of up to P0=90 torr to generate singlet delta oxygen in an oxygen-helium flow doped with NO. The total flow rate through the M=3

John R. Bruzzese; Adam C. Cole; Munetake Nishihara; Igor V. Adamovich

137

Gain and output power measurements in an electrically excited oxygen-iodine laser with a scaled discharge  

Microsoft Academic Search

Singlet delta oxygen (SDO) yield, small signal gain, and output power have been measured in a scaled electric discharge excited oxygen-iodine laser. Two different types of discharges have been used for SDO generation in O2-He-NO flows at pressures up to 90 Torr, crossed nanosecond pulser\\/dc sustainer discharge and capacitively coupled transverse RF discharge. The total flow rate through the laser

J. R. Bruzzese; A. Hicks; A. Erofeev; A. C. Cole; M. Nishihara; I. V. Adamovich

2010-01-01

138

Advances in the RF atomic iodine generator for oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Recent advances in the RF atomic iodine generator for oxygen-iodine lasers are presented. The generator is based on the RF discharge dissociation of a suitable iodine donor immediately before its injection to the flow of singlet oxygen. The discharge is ignited directly in the iodine injector, and the configuration is ready for the laser operation. The dissociation fraction was derived from the atomic iodine number density measured at a presupposed position of laser resonator. The dissociation fraction and the fraction of RF power spent on the dissociation (discharge dissociation efficiency) were measured for the following donors: CH3I, CF3I and HI. A significant improvement of the discharge stability was achieved by increasing the cross-sectional area of the exit injection holes and employing a tangential inlet of working gas into the discharge chamber. The flow rates 0.15 mmol/s and 0.19 mmol/s of produced atomic iodine were achieved using the HI and CF3I, respectively. The atomic iodine number density in the supersonic flow attained 4.22 × 1014 cm-3. The dissociation efficiency was substantially better for HI than for studied organic iodides.

Jirásek, Vít; Schmiedberger, Josef; ?enský, Miroslav; Kodymová, Jarmila

2010-09-01

139

Kinetics and scaling of gain and lasing in a 1-5 kW microwave discharge oxygen iodine laser  

Microsoft Academic Search

Scaling of Electric Oxygen-Iodine Laser (EOIL) systems to higher powers requires extension of electric discharge powers into the kW range and beyond, with high efficiency and singlet oxygen yield. This paper describes the implementation of a moderate-power (1 to 5 kW) microwave discharge at 30 to 70 Torr pressure in a supersonic flow reactor designed for systematic investigations of the

Wilson T. Rawlins; Seonkyung Lee; Adam J. Hicks; Ian M. Konen; Emily P. Plumb; David B. Oakes; Steven J. Davis

2010-01-01

140

O2(1?) production and gain in plasma pumped oxygen iodine lasers: consequences of NO and NO2 additives  

NASA Astrophysics Data System (ADS)

The 1.315 µm [I(2P1/2) ? I(2P3/2)] transition of atomic iodine in the chemical oxygen-iodine laser (COIL) is pumped by sequential reactions of I2 and I with O2(1?). In electrically pumped systems (eCOILs), electron impact excitation of O2 produces the O2(1?) and also produces O atoms through dissociative excitation. The O atoms, through reactions with I2, I(2P1/2) and I(2P3/2), lead to dissociation of I2, quenching of the upper laser level and removal of the lower laser level. While dissociating I2 is potentially beneficial, quenching of the upper laser level is detrimental and so management of the O atom density is necessary to maximize laser gain. In this regard, NO and NO2 additives have been used to manage the O atom density by cyclically reacting with O and I. In this paper, results from a computational investigation of eCOIL systems using plug flow and two-dimensional models are discussed where NO and NO2 additives are used. The system is a flowing plasma sustained in He/O2/NO mixtures with downstream injection of NO2 followed by injection of I2. We found that addition of NO and NO2 is effective in managing the density of O atoms and maximizing gain by minimizing quenching of the upper laser level. We found that by optimizing the additives, laser gain can be maximized even though O2(1?) densities may be lower due to the management of quenching and dissociation reactions.

Arakoni, Ramesh A.; Babaeva, Natalia Y.; Kushner, Mark J.

2007-08-01

141

Catalytic enhancement of singlet oxygen for hybrid electric discharge oxygen-iodine laser systems  

NASA Astrophysics Data System (ADS)

We are investigating catalytically enhanced production of singlet oxygen, O2(a1?g), observed by reaction of O2/He discharge effluents on an iodine oxide film surface in a microwave discharge-flow reactor at 320 K. We have previously reported a two-fold increase in the O2(a) yields by this process, and corresponding enhancement of I(2P1/2) excitation and small-signal gain upon injection of I2. In this paper we report further observations of the effects of elevated temperature up to 410 K, and correlations of the catalytically generated O2(a) with atomic oxygen over a large range of discharge-flow conditions. We have applied a diffusion-limited reaction rate model to extrapolate the catalytic reaction rates to the highpressure, fast-flow conditions of the subsonic plenum of a supersonic EOIL test reactor. Using the model and the flow reactor results, we have designed and implemented a first-generation catalytic module for the PSI supersonic MIDJet/EOIL reactor. We describe preliminary tests with this module for catalyst coating deposition and enhancement of the small-signal gain observed in the supersonic flow. The observed catalytic effect could significantly benefit the development of high-power electrically driven oxygen-iodine laser systems.

Rawlins, Wilson T.; Lee, Seonkyung; Hicks, Adam J.; Konen, Ian M.; Plumb, Emily P.; Davis, Steven J.

2010-02-01

142

Chemistry of I(2P1/2) excitation in a hybrid catalytic electric-discharge oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The chemistry of electric discharge driven oxygen iodine lasers (EOIL) has long been believed to have O2(a1?g) as the sole energy carrier for excitation of the lasing state I(2P1/2), and O(3P) as the primary quencher of this state. In many sets of experimental measurements over a wide range of conditions, we have observed persistent evidence to the contrary. In this paper, we examine comparisons of kinetics analysis and model predictions to experimental results from a supersonic EOIL research reactor. This analysis leads to identification of important additional production and loss terms for the lasing species, I(2P1/2), in the EOIL reaction mechanism. These mechanisms are also relevant to the catalytically enhanced EOIL excitation mechanism. Exploitation of this chemistry can lead to substantial increases in gain and power extraction efficiency in larger-scale EOIL systems. The analysis points to a significantly higher level of understanding of this energetic chemical system, which can support application of advanced concepts in power scaling investigations.

Rawlins, Wilson T.; Lee, Seonkyung; Davis, Steven J.

2012-03-01

143

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.  

PubMed

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics. PMID:17461557

Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

2007-07-26

144

LASERS: Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygeniodine laser with a large active volume  

NASA Astrophysics Data System (ADS)

Possibilities for increasing the active medium volume of a chemical oxygeniodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for CCOILs: low pressure of mixtures containing a strongly electronegative component, low voltage of discharge burning, low specific energy depositions, and long duration of the current pulse. An efficient electrode system is elaborated with the cathode based on an anisotropically-resistive material, which resulted in a stable discharge in the mixtures of iodide (CH3I, n-C3H7I, C2H5I) with oxygen and nitrogen at the specific energy depositions of ~5 J L-1, pressures of 10 — 25 Torr, and mixture volume of 2.5 L.

Kazantsev, S. Yu; Kononov, I. G.; Podlesnykh, S. V.; Firsov, K. N.

2010-08-01

145

Electron-beam sustained discharge in oxygen gas mixtures: singlet delta oxygen production for oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Electric properties and spectroscopy of an e-beam sustained discharge (EBSD) in oxygen and oxygen gas mixtures at gas pressure up to 100 Torr were experimentally studied. The pulsed discharge in pure oxygen and its mixtures with noble gases was shown to be very unstable and characterized by low input energy. When adding small amount of carbon monoxide or hydrogen, the electric stability of the discharge increases, specific input energy (SIE) per molecular component being more than order of magnitude higher and coming up to 6.5 kJ/(l atm) for gas mixture O2:Ar:CO = 1:1:0.1. The results of experiments on spectroscopy of the singlet delta oxygen O2(a1?g)(SDO) and O2(b1?g+) states in the EBSD are presented. The calibration of the optical scheme for measuring the SDO absolute concentration and yield using the detection of luminescence of the SDO going from a chemical SDO generator was done. The preliminary measurement of the SDO yield demonstrated that it was ~3% for the SIE of ~1 kJ/(l atm), which is close to the results of theoretical calculations for such a SIE. Theoretical calculations demonstrated that for the SIE of 6.5 kJ/(l atm) the SDO yield may reach ~20% exceeding its threshold value needed for oxygen-iodine laser operation at room temperature, although a part of the energy loaded into the EBSD goes into the vibrational energy of the molecular admixture, (which was experimentally demonstrated by launching a CO laser operating on an oxygen-rich mixture O2:Ar:CO = 1:1:0.1 and measuring its small-signal gain).

Frolov, Mikhail P.; Hager, Gordon D.; Ionin, Andrei A.; Klimachev, Yurii M.; Kochetov, Igor V.; Kotkov, Andrei A.; McIver, John K.; Napartovich, Anatolii P.; Podmar'kov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

2004-09-01

146

Three-block model of the kinetics of vibrationally excited I{sub 2}(X) molecules in the active media of oxygen - iodine lasers  

SciTech Connect

A three-block model of the kinetics of vibrationally excited I{sub 2}(X) molecules in the active media of chemical oxygen - iodine lasers is developed. Instead of the system of equations describing a change in the concentrations of I{sub 2}(X, u) (u=0 - 47) molecules, this model uses equations for the total concentrations of iodine molecules belonging to the blocks of vibrational levels with u {<=} 10, u = 11 - 24, and u {>=} 25. Effective deactivation rate constants of I{sub 2}(X, 11 {<=} u {<=} 24) molecules are found for laser media of different compositions. The results of calculations performed using the proposed model agree with experimental data and are close to the parameters calculated previously by using the total system of equations for populations of individual vibrational levels of I{sub 2}(X, u). (laser applications and other topics in quantum electronics)

Pichugin, S Yu [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation)

2012-09-30

147

Kinetics and scaling of gain and lasing in a 1-5 kW microwave discharge oxygen iodine laser  

NASA Astrophysics Data System (ADS)

Scaling of Electric Oxygen-Iodine Laser (EOIL) systems to higher powers requires extension of electric discharge powers into the kW range and beyond, with high efficiency and singlet oxygen yield. This paper describes the implementation of a moderate-power (1 to 5 kW) microwave discharge at 30 to 70 Torr pressure in a supersonic flow reactor designed for systematic investigations of the scaling of gain and lasing with power and flow conditions. The 2450 MHz microwave discharge is confined near the flow axis by a swirl flow. The discharge effluent, containing active species including O2(a1?), O(3P), and O3, passes through a 2-D flow duct equipped with a supersonic nozzle and cavity. I2 is injected upstream of the supersonic nozzle. The apparatus is water-cooled, and is modular to permit a variety of inlet, nozzle, and optical configurations. A comprehensive suite of optical emission and absorption diagnostics monitors the absolute concentrations of O2(a), O(3P), O3, I2, I(2P3/2), I(2P1/2), small-signal gain, and temperature in both the subsonic and supersonic flow streams. The experimental results include numerous observations of positive gain and lasing in supersonic flow, and the scaling of gain with a variety of flow and reaction rate conditions. The results are compared with kinetics modeling predictions to highlight key discrepancies as well as areas of agreement. The observed gains are generally lower than the predicted values, due in part to chemical kinetics effects and also due to mixing limitations specific to the reagent injection design. We discuss in detail the observed effects related to O-atom chemistry, and their import for scaling the gain to higher levels. We also will present initial beam quality measurements.

Rawlins, Wilson T.; Lee, Seonkyung; Hicks, Adam J.; Konen, Ian M.; Plumb, Emily P.; Oakes, David B.; Davis, Steven J.

2010-02-01

148

Effect of nitric oxide on gain and output power of a non-self-sustained electric discharge pumped oxygen-iodine laser  

Microsoft Academic Search

This letter discusses the effect of nitric oxide on gain and output power of a pulser-sustainer discharge excited oxygen iodine laser. Adding small amounts of NO to the laser mixture (a few hundreds of ppm) considerably increases gain and output power due to (i) O atom titration and resultant slower I* atom quenching and (ii) improved stability of the dc

A. Hicks; J. Bruzzese; W. R. Lempert; J. W. Rich; I. V. Adamovich

2007-01-01

149

Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments  

Microsoft Academic Search

which are not encountered in a classic purely chemical O2a 1 generation system. Mixing effects are also present. In this paper we present postdischarge modeling results obtained using a modified version of the BLAZE-II gas laser code. A 28 species, 105 reaction chemical kinetic reaction set for the postdischarge kinetics is presented. Calculations were performed to ascertain the impact of

Andrew D. Palla; David L. Carroll; Joseph T. Verdeyen; Wayne C. Solomon

2006-01-01

150

O2-I laser (Oxygen-iodine) mixing studies using LIF (Laser Induced Fluorescence)  

Microsoft Academic Search

Laser Induced Fluorescence (LIF) was incorporated to study the degree of mixing in two subsonic nozzle variations for the O2-I laser system. The studies were performed using a testbed version of COIL-IV, an O2-I laser. I2 was injected through the nozzles and excited with an Ar laser to produce fluorescence. The observed jet trajectories could then be compared to trajectories

Y. D. Jones; D. Plummer; L. D. Watkins; G. D. Hager

1987-01-01

151

2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen  

Microsoft Academic Search

The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge\\u000a and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain\\u000a are revealed. The simulation results

A. A. Chukalovsky; T. V. Rakhimova; K. S. Klopovsky; Yu. A. Mankelevich; O. V. Proshina

2011-01-01

152

Catalytic enhancement of singlet oxygen production and optical gain in electric discharge oxygen-iodine laser systems  

NASA Astrophysics Data System (ADS)

We are investigating catalytically enhanced production of singlet oxygen, O2(a1?g), observed by reaction of O2/He discharge effluents over an iodine oxide film surface in a microwave discharge-flow reactor at 320 K. We have previously reported a two-fold increase in the O2(a) yields by this process, and corresponding enhancement of I(2P1/2) excitation and small-signal gain upon injection of I2 and NO2. In this paper we review observed I* excitation behavior and correlations of the catalytically generated O2(a) with atomic oxygen over a large range of discharge-flow conditions to develop a conceptual reaction mechanism for the phenomena. We describe a first-generation catalytic module for the PSI supersonic MIDJet/EOIL reactor, and tests with this module for catalyst coating deposition and enhancement of the small-signal gain observed in the supersonic flow. The results present compelling evidence for catalytic production of vibrationally excited O2(X,v) and its participation in the I* excitation process. The observed catalytic effects could significantly benefit the development of high-power electrically driven oxygen-iodine laser systems.

Lee, Seonkyung; Rawlins, Wilson T.; Hicks, Adam J.; Konen, Ian M.; Plumb, Emily P.; Davis, Steven J.

2011-03-01

153

Advanced Gas Laser Experiments and Modeling D. L. Carroll1  

E-print Network

chemical and gas laser systems. Among these are the electric oxygen-iodine laser (ElectricOIL), the diode driven gas phase characteristics. II. The Electric Oxygen-Iodine Laser The electrically driven oxygen-iodine the discharge flow, (iii) the iodine injectors and injection region, (iv) the nozzle and laser cavity extraction

Carroll, David L.

154

Enhancement of electric oxygen-iodine laser performance using a rectangular discharge and longer gain length  

NASA Astrophysics Data System (ADS)

Herein the authors report on the demonstration of a 95% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine via a 50% increase in gain length, flow rates, and discharge power. O2(a ?1) is produced by a single radio-frequency-excited electric discharge sustained in an O2-He-NO gas mixture flowing through a rectangular geometry, and I(P21/2) is then pumped using energy transferred from O2(a ?1). A gain of 0.26% cm-1 was obtained and the total laser output power was 54.8 W.

Benavides, G. F.; Zimmerman, J. W.; Woodard, B. S.; Carroll, D. L.; Palla, A. D.; Day, M. T.; Verdeyen, J. T.; Solomon, W. C.

2009-11-01

155

Gain and continuous-wave laser power enhancement with a secondary discharge to predissociate molecular iodine in an electric oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Herein the authors report on the demonstration of a 50% enhancement in gain and 38% enhancement in continuous-wave laser power on the 1315nm transition of atomic iodine through the addition of a secondary discharge to predissociate the molecular iodine in an electric oxygen-iodine laser. In the primary discharge the O2(a?1) is produced by a radio-frequency-excited electric discharge sustained in an O2-He-NO gas mixture, and I(P1/22) is then pumped using energy transferred from O2(a?1). A gain of 0.10%cm-1 was obtained and the total laser output power was 6.2W.

Benavides, G. F.; Zimmerman, J. W.; Woodard, B. S.; Carroll, D. L.; Verdeyen, J. T.; Field, T. H.; Palla, A. D.; Solomon, W. C.

2008-01-01

156

Experimental Effects of Atomic Oxygen on the Development of an Electric Discharge Oxygen Iodine Laser  

Microsoft Academic Search

As the development of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region was found to be very significant. One of the largest uncertainties is the rate of quenching of I* by O atoms. We have taken a series of measurements of O 2 ( 1 ?) emission, I* emission, O-atom titrations, gain\\/absorption,

D. L. Carroll; J. T. Verdeyen; D. M. King; J. W. Zimmerman; J. K. Laystrom

157

Experimental effects of atomic oxygen on the development of an electric discharge oxygen iodine laser  

Microsoft Academic Search

As the development of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region was found to be very significant. One of the largest uncertainties is the rate of the quenching of I* by O atoms. We have taken a series of measurements of O2(1Delta) emission, I* emission, O-atom titrations, gain\\/absorption, and O2(1Delta) yield

David L. Carroll; Joseph T. Verdeyen; Darren M. King; J. W. Zimmerman; J. K. Laystrom; B. S. Woodard; G. F. Benavides; K. Kittell; Wayne C. Solomon

2005-01-01

158

Self-initiated volume discharge for production of atomic iodine in pulsed oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

This paper reports on investigating self-sustained volume discharge (SSVD) characteristics in CH3I, C3H7I, C4H9I, CF3I and their mixtures with SF6 and N2, employed as buffer gases, and with O2. The investigations performed in the plane-plane electrode system displaying high electric field edge enhancement have shown that in C3H7I, C4H9I and their mixtures with SF6, N2 and O2 SSVD is realized in the form of a self-initiated volume discharge (SIVD)- SSVD with no any preionization. Addition of SF6 or N2 in C3H7I, C4H9I leads to increasing the discharge stability, the latter being not adversely affected by addition of O2 in amounts of up to 300% of the iodide partial pressure. The fact that SSVD in C3H7I and C4H9I develops in the form of SIVD is indicative of these discharges to be promising for creation of high power pulsed and pulsed-periodic COIL. SIVD has been performed at total mixture pressures of up to 72 Torr and energy depositions of up to 130J/l in a volume of 1.5 l. The performed experimental modeling involving laser geometry of the discharge gap gives firm evidence that SIVD is promise for being used in creation of pulse and pulse-periodic COIL.

Belevtsev, Andrei A.; Firsov, Konstantin N.; Kazantsev, Sergey Y.; Saifulin, Alexei V.

2003-11-01

159

RF plasma jet generator of singlet delta oxygen and RF discharge pre-dissociation of iodine for oxygen-iodine laser at lowered temperature  

NASA Astrophysics Data System (ADS)

A new RF plasma jet generator (DSOG-5) of singlet oxygen has been developed for use in an oxygen-iodine laser. The plasma jet was produced in Al nozzles, which were fed by the radio-frequency (100 MHz) power of up to 200 W. The usual mode of operation was an energy transfer from Ar plasma jet to a neutral O2 gas stream. The yield of singlet delta oxygen was up to 24%. Iodine molecules were dissociated by 200 MHz RF discharge with the power of 60 W prior to injection into the mixing zone of laser. The pre-dissociation enhancement was up to 22% of iodine spontaneous emission intensity. Both the DSOG-5 and the RF iodine pre-dissociation were tested in laser experiments in a transverse flow Discharge Oxygen-Iodine Laser (DOIL). The effluent of DSOG-5 was cooled by liquid nitrogen to temperatures in the range 120-300 K. There was a temperature dependent loss of singlet delta oxygen on the walls. The singlet delta oxygen yield and the atomic iodine luminescence at the wavelength of 1315 nm were measured. The highest luminescence was achieved at pressures of ~1 Torr with the yield of 10-20%. Laser oscillations have not been achieved.

Schmiedberger, Josef; Fujii, Hiroo

2005-03-01

160

Modelling of COIL lasers  

Microsoft Academic Search

The modelling of chemical oxygen iodine lasers (COIL's) is discussed. A qualitative description of the system hardware elements and the major physical processes occurring in the laser is presented. Next, a steady one-dimensional model of the oxygen iodine laser system which includes the effects of area change, heat transfer, friction, mass injection and removal, changes in molecular weight and specific

D. H. Lewis Jr.; C. W. Clendening

1982-01-01

161

Design and operation of a supersonic flow cavity for a non-self-sustained electric discharge pumped oxygen iodine laser  

Microsoft Academic Search

The paper presents results of a high-pressure, non-self-sustained crossed discharge-M = 3 supersonic laser cavity operation. A stable and diffuse pulser-sustainer discharge in O2-He flows is generated at pressures of up to P0 = 120 Torr and discharge powers of up to 2.1 kW. The reduced electric field in the dc sustainer discharge ranges from 0.6 × 10-16 to 1.2

A. Hicks; S. Tirupathi; N. Jiang; Yu Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich

2007-01-01

162

Analysis of rate constants for oxygen-iodine active media  

Microsoft Academic Search

To work out specific laser system, to optimize their operating conditions it is necessary to have a complete description of the kinetic processes in active media and exact values of the reactions rate constants. The detailed study of process kinetics in COIL were discussed in a number of papers and a review on the rate constants at oxygen-iodine media has

Yu. A. Kulagin; V. N. Yarygina

1996-01-01

163

O{sub 2}(a {sup 1}DELTA{sub g}) production in flowing Ar-O{sub 2} surface-wave microwave discharges: Possible use for oxygen-iodine laser excitation  

SciTech Connect

Herein we present the calculations conducted on an Ar-O{sub 2} surface-wave microwave discharge and its afterglow, and show that this system can be effectively used for the oxygen-iodine laser excitation. It is demonstrated that at pressures higher than 10 mbar O{sub 2}(a) yields higher than the threshold yield required for positive gain can be achieved along the afterglow. Additionally, the density of O({sup 3}P) atoms, which can quench the I({sup 2}P{sub 1/2}) excited state, can be tuned to the desired level.

Guerra, Vasco [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Kutasi, Kinga [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Sa, Paulo A. [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisboa, Portugal and Departamento de Engenharia Fisica, Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto (Portugal)

2010-02-15

164

AIAA Plasmadynamics and Lasers Conference 5-8 June 2006, San Francisco, California  

E-print Network

system parameters. I. Introduction The classical chemical oxygen iodine laser (COIL) system1 employs to improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased37 th AIAA Plasmadynamics and Lasers Conference 5-8 June 2006, San Francisco, California AIAA 2006

Carroll, David L.

165

Scaling of plasma sources for O2(1?) generation for chemical oxygen-iodine lasers  

Microsoft Academic Search

Summary form only given. In this paper, results from a computational investigation of the scaling of O2(1?) generation in electric discharges sustained in rare gas\\/O2 mixtures at pressure of a few to 10 s Torr will be discussed. Global, 1-dimensional and 2-dimensional plasma dynamics models were used in this study. Typical configurations use remote flowing cw plasma sources which are

D. Shane Stafford; M. J. Kushner

2004-01-01

166

Electrochemical regeneration of basic hydrogen peroxide for chemical oxygen iodine laser  

NASA Astrophysics Data System (ADS)

A 3.6M basic hydrogen peroxide solution is electrochemically regenerated. The apparatus was originally developed for electrolytic H2O2 production, generating dilute (<0.2M) BHP for paper manufacturing. To suppress decomposition by various mechanisms, they are identified and quantified. Both caffeine and peracetic acid are found effective to suppress autodecomposition. Theoretical prediction of the current efficiency is made to find an optimum operational condition. A BHP of 3.614M is regenerated to 3.657M with a current efficiency of 67%.

Endo, Masamori; Hano, Masami; Wakita, Syuhei; Uno, Masaharu; Takeda, Shuzaburo

2005-03-01

167

Gain and continuous-wave laser oscillation on the 1315 nm atomic iodine transition pumped by an air-helium electric discharge  

E-print Network

American Institute of Physics. DOI: 10.1063/1.2957678 The classical chemical oxygen iodine laser COIL re investigations into an electrically driven oxygen-iodine laser ElectricOIL that was demonstrated by Carroll et alGain and continuous-wave laser oscillation on the 1315 nm atomic iodine transition pumped by an air

Carroll, David L.

168

Proceedings of the International Conference on Lasers 2000, eds. V.J. Corcoran and T.A. Corcoran, STS Press, McLean VA, 2001, pp. 265-272.  

E-print Network

oxygen-iodine laser (COIL) singlet oxygen generator (SOG) based on discharge excitation of molecular the O2(1 S) concentrations. I. INTRODUCTION The classical chemical oxygen-iodine laser (COIL) operates by electrical means. A new kind of continuous wave COIL device is proposed: an Electrically assisted Chemical

Carroll, David L.

169

Oxygen-iodine active medium with external production of iodine in a DC glow discharge  

NASA Astrophysics Data System (ADS)

Experiments with a flow cell apparatus imitating conditions of oxygen-iodine laser, equipped with a chemical jet singlet oxygen generator and an electric discharge iodine generator have been performed. I II and CH 3I in the flow of Ar were used as atomic iodine precursors. The distributions of the electronically excited species along the flow were examined detecting their optical emissions. A straightforward comparison of two methods of oxygen-iodine medium production - conventional, by means of I II dissociation in the singlet oxygen flow and with iodine atoms produced externally in the electric discharge - was performed. It was found that stored electron energy lifetime had been about 30% longer, when iodine was produced from CH 3I in the discharge, compared to the conventional I II dissociation in the singlet oxygen flow. It was observed that maximums of the I(2P 1/2) and I II(B) concentrations had shifted to the nozzle plane, when I II in Ar carrier was subjected to the glow discharge, pointing to a nearly twofold increase in the I II dissociation rate. Contrary to the known results for low iodine and singlet oxygen concentrations, squared dependence of the amplitude of the I II(B) luminescence maximum with I(2P 1/2) concentration was observed in the dissociation region for both methods of iodine production.

Mikheyev, Pavel A.; Azyazov, Valeriy N.; Mezhenin, Adrew V.; Ufimtsev, Nikolay I.; Shepelenko, Alexander A.; Voronov, Anatoly I.; Kupryaev, Nikolay V.; Pichugin, Sergey Yu.; Vorobyov, Mikhail V.

2007-05-01

170

Proceedings of the XI International Symposium on Gas Flow and Chemical Lasers and High Power Laser Conference, Edinburgh, UK 25-30 August 1996, SPIE Vol. 3092, ed. H.J. Baker, pp. 758-763 (1997).  

E-print Network

for the atomic iodine laser transition of interest. A block diagram of a typical COIL system is illustrated-5776 ABSTRACT A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel. Cut depths are compared with existing COIL and CO2 laser cutting data. COIL cuts carbon steel and stainless steel

Carroll, David L.

171

Short Wavelength Chemical Laser (SWCL) Workshop  

NASA Astrophysics Data System (ADS)

The workshop was held for the purpose of identifying the government's interest in SWCL technology, reviewing past and present efforts in this area and presenting the government's plans for a new thrust in SWCL source development. In addition, the workshop was to provide a forum for interaction between members of the Strategic Defense Initiation Organization (SDIO) and the 6.1 agencies with the technical community in order to create an enthusiastic response to the SWCL thrust and to generate new concepts as well as to involve new participants in this technically challenging area. This document contains abstracts of papers presented at the workshops. Some of the topics discussed in the sessions include: HF Lasers - What have we learned?; Chemical Oxygen Iodine Laser Review; Why So FEw Chemical Lasers?; Approach to Efficient Short-Wavelength Chemical Lasers; Metal/Oxidizer Systems; Pyrotechnic Systems; Metastable State Production; Metastable Transfer Systems; Energy Exchange Mechanisms.

Watt, W.

1984-12-01

172

AIAA Plasmadynamics and Lasers Conference 6-9 June 2005, Toronto, Ontario Canada  

E-print Network

. Introduction HE classic chemical oxygen-iodine laser (COIL) system1 operates on the I(2 P1/2) I(2 P336 th AIAA Plasmadynamics and Lasers Conference 6-9 June 2005, Toronto, Ontario Canada AIAA 2005 In an electric discharge Oxygen-Iodine laser (ElectricOIL), laser action at 1315 nm on the I(2 P1/2) I(2 P3

Carroll, David L.

173

LASERS: Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen --- iodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A. A. Belevtsev; S. Yu Kazantsev; A. V. Saifulin; K. N. Firsov

2003-01-01

174

Numerical simulation of the mixing kinetics of an iodine-containing flow and the oxygen flow excited in the electric-discharge oxygen-iodine laser  

Microsoft Academic Search

A parametric analysis has been carried out to discover how the concentration of atomic oxygen in the O2: O2 (1?g): O flow and the degree of predissociation and concentration of molecular iodine in the I2: He mixture affect the temperature regime and the formation of the inverse population at the atomic iodine laser transition\\u000a at elevated pressures of P =

A. A. Chukalovsky; K. S. Klopovsky; T. V. Rakhimova

2008-01-01

175

Proceedings of the XIII International Symposium on Gas Flow and Chemical Lasers and High Power Laser Conference, Florence, Italy 18-22 September 2000, The Int. Soc. for Opt. Eng. Vol. 4184, P.O. Box 10, Bellingham, WA 98227-0010, pp. 40-44.  

E-print Network

generator technologies are needed to allow chemical oxygen-iodine laser (COIL) systems to achieve their full 10, Bellingham, WA 98227-0010, pp. 40-44. ElectriCOIL: An Advanced Chemical Iodine Laser Concept attributes. Preliminary analysis and modeling of the ElectriCOIL system concept is presented. ElectriCOIL

Carroll, David L.

176

Singlet oxygen generator for a solar powered chemically pumped iodine laser. Final Report  

Microsoft Academic Search

The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by

Busch

1984-01-01

177

Chemical lasers  

NASA Astrophysics Data System (ADS)

Fundamental properties of chemical lasers are presented and principal systems described in the nonclassified literature are reviewed. The fundamentals of the production of inversion in molecular gases by chemical processes are discussed. Iodine, HF, and DF lasers are described. The chemical reaction in the pulsed chemical HF and DF lasers is introduced by a transverse electrical discharge. In spite of the high dissociation energy and the electronegative properties which are unfavorable for a stable discharge regime, SF6 is used as fluorine source for safety reasons. The pulse energies reach 26 J in agreement with estimated values. The advantage of the present system is that is can also operate as CO2 laser in the TEA mode. The radiation of DF lasers is particularly interesting for military near-Earth applications because of its good transmission properties in the atmosphere.

Hugenschmidt, M.; Wey, J.

1985-05-01

178

Numerical simulation of supersonic-flow chemical oxygen-iodine laser with high Mach-number ramp-nozzle array  

NASA Astrophysics Data System (ADS)

The characteristics of mixing between two flows of oxygen and iodine, having different Mach numbers, are numerically examined with the intention of improving the pressure recovery of the exhaust gas of supersonic-flow COIL. Supersonic, parallel mixing system with ramp nozzle array is adopted. The nozzle array has unevenly-piled shape, which is expected to generate vortices and enhance mixing. Three-dimensional, compressible Navier-Stokes equations are solved by means of full-implicit finite difference method. The flow fields are calculated for three types of nozzles, namely, ramp nozzle, symmetric ramp nozzle, and symmetric swept-ramp nozzle. The results indicate that the symmetric swept-ramp nozzle has the best performance.

Suzuki, Masataro; Ito, Kenichi; Masuda, Wataru

2005-03-01

179

Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygeniodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A A Belevtsev; S Yu Kazantsev; A V Saifulin; K N Firsov

2003-01-01

180

Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen - iodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (CHI, CHI) and in their mixtures with SF, N, and O in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A A Belevtsev; S Yu Kazantsev; A V Saifulin; K N Firsov

2003-01-01

181

Pressure recovery devices for supersonic COIL lasers  

Microsoft Academic Search

The basic challenge in the design of a pressure recovery system for a supersonic gas laser arises from the fact that the cavity pressure is quite low: 50 - 70 torr for a CO2 gasdynamic laser (GDL) and as low as 4 torr for a chemical oxygen-iodine laser (COIL) system. The purpose of the pressure recovery system is to increase

Robert F. Walter; Robert A. O'Leary

1993-01-01

182

Volume 170, number 5,6 CHEMICAL PHYSICS LETTERS 20 July 1990 Nature of the red emission  

E-print Network

in the chemical oxygen iodine laser (COIL) system. The O2(`4) isproduced by bubbling Cl, through an alkaline) Recently, Yoshida et al. [41 reported a new visible chemical laser using a subsonic COIL system for observing enhanced red emissions in the COIL laser system. mm long by 200 mm wide by 45 mm high. The stream

Zare, Richard N.

183

Diagnosis of the spot and drift of a cw-COIL laser beam  

Microsoft Academic Search

A dynamic spot diagnostic system has been developed to quantitatively measure the instability of a continuous-wave chemical oxygen iodine laser (CW-COIL). The system can measure the real time changes in drift, vibration of low frequency, intensity profile and spot diameter for the CW- COIL laser beam. The cause that induces the instability of laser beam was tentatively analyzed in this

Chunyan Wang; Jianheng Zhao; Yonghua Yuan; Xufa Liu; Changling Liu

1997-01-01

184

Proceedings of the International Conference on Lasers '99, ed. V.J. Corcoran, STS Press, McLean VA, 2000, pp. 69-77. ADVANCED MIXING NOZZLE CONCEPTS FOR COIL  

E-print Network

-iodine laser (COIL) that will significantly improve the chemical efficiency of such systems. It is believed are needed to allow chemical oxygen-iodine laser (COIL) systems to achieve their full potential as efficient will have major implications for the military programs as well as evolving industrial COIL systems. Research

Carroll, David L.

185

Laser welding with high power lasers combining system  

Microsoft Academic Search

We have developed the high power laser beam combining system with the 10kW class chemical oxygen-iodine laser (COIL) of wavelength 1.315µm and the 6kW class Nd:YAG laser of wavelength 1.064µm. The characteristic of the beam propagation, the combining beam quality and the optics were evaluated. The combining beam providing power was up to over 16kW. The combining beam was used

Mikio Muro; Tokuhiro Nakabayashi; Yoshiaki Hayakawa; Fumio Wani; Kozo Yasuda; Fumisato Mifune; Kouichi Yoshida

2000-01-01

186

High-power COIL and YAG laser welding  

Microsoft Academic Search

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 mm wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW Chemical Oxygen-Iodine Laser (COIL). The average power of

Fumio Wani; Tokuhiro Nakabayashi; Akiyoshi Hayakawa; Sachio Suzuki; Kozu Yasuda

2002-01-01

187

High-power COIL and Nd:YAG laser welding  

Microsoft Academic Search

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 µm wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW class Chemical Oxygen-Iodine Laser (COIL) beams of 6

Fumio Wani; T. Nakabayashi; A. Hayakawa; S. Suzuki; K. Yasuda

2003-01-01

188

Singlet oxygen generator for a solar powered chemically pumped iodine laser  

NASA Technical Reports Server (NTRS)

The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by means of an electrical discharge through the conductive indium oxide coating. The evolution of singlet-delta oxygen was determined by measuring the dimol emission signal at 634 nm. Comparison of the measured signal with an analytic model leads to two main conclusions: virtually all the oxygen being evolved is in the singlet-delta state and in the gas phase, and there is no significant quenching other than energy pooling on the time scale of the experiment (approximately 10 msec). The use of solid phase endoperoxide as a singlet-delta oxygen generator for an oxygen-iodine laser appears promising.

Busch, G. E.

1984-01-01

189

Laser research at the Institute of Physics AS CR  

Microsoft Academic Search

Laser research at the Institute of Physics of the Academy of Sciences of Czech Republic covers both the development of advanced pulsed high-power laser systems, the iodine and x-ray in particular, and their applications in science and technology. The COIL laboratory with a small chemical oxygen-iodine laser facility participates in the worldwide effort to develop a competitive quasi-steady laser device

Karel Jungwirth

2005-01-01

190

Excimer laser chemical problems  

SciTech Connect

Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.

Tennant, R.; Peterson, N.

1982-01-01

191

Kinetics of the electrical discharge pumped oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A systematic study of microwave discharges at 2.45 GHz has been performed through the pressure range of sustainable electric discharges in pure oxygen flows of 2 to 10 Torr. A corresponding study of 13.56 MHz has also been performed at pressures of 2, 4, and 7 Torr. Optical emissions from O2( a),O2(b), and O-atoms have been measured from the center of a microwave discharge. Discharge residence times from 0.1 to 5 ms have been reported, establishing that gas temperatures arrive at stationary values within the first 0.3 ms upon entering the discharge region. The O2(b) emissions, with a spectral resolution of 0.01 nm, have been used to measure the temperature of the gas, which typically reaches a steady-state of 1,200 K. A theoretical description of the gas heating is fit to measured temperatures, which determines that the fraction of discharge energy coupled into gas heating is 17 +/- 2%. The yield of O2( a) comes to steady-state at all pressures within 1 ms of entering the discharge region. The interpretation of the measured yield, using a streamlined, nearly analytic model, cast new light on the kinetics within the electric discharge. The pseudo-first order quenching rate of O2 (a) ranges from 6,000 1/s for microwave discharges to 600 1/s for radio frequency (RF) discharges, independent of gas pressure and flow rate. The slower decay rate for the RF discharge corresponds with a considerably lower ionization rate. The observations are consistent with a second order reaction channel that is dependent on both the electron and molecular oxygen ground state concentrations. Destruction of the O2 (b) state by direct impact with electrons or atomic oxygen does not adequately describe the observed behavior of O2( a). The role of vibrationally excited ground state oxygen is explored and provides a plausible destruction mechanism.

Lange, Matthew A.

192

Lasers in chemical processing  

SciTech Connect

The high cost of laser energy is the crucial issue in any potential laser-processing application. It is expensive relative to other forms of energy and to most bulk chemicals. We show those factors that have previously frustrated attempts to find commercially viable laser-induced processes for the production of materials. Having identified the general criteria to be satisfied by an economically successful laser process and shown how these imply the laser-system requirements, we present a status report on the uranium laser isotope separation (LIS) program at the Lawrence Livermore National Laboratory (LLNL).

Davis, J.I.

1982-04-15

193

AIAA Plasmadynamics and Lasers Conference 6-9 June 2005, Toronto, Ontario Canada  

E-print Network

The classic chemical oxygen-iodine laser (COIL) system1 operates on the I(2 P1/2) I(2 P3/2) [hereafter with the ElectricOIL Laser System D. L. Carroll,1 J. T. Verdeyen,2 D. M. King,3 J. W. Zimmerman,4 J. K. Laystrom,4,7,8,10 indicated that such a system could produce a viable laser. Recently Carroll et al.11,12 reported direct

Carroll, David L.

194

Progress report on the development of a repetitively pulsed frequency-shifted COIL laser  

NASA Astrophysics Data System (ADS)

This paper summarizes recent progress that has occurred in several research areas related to the development of a repetitively-pulsed, frequency-shifted chemical oxygen iodine laser (COIL). COIL gain- switch experiments at 10 kHz pulse rates are described using a novel solid state pulsed magnetic field system. Raman conversion experiments in hydrogen using a pulsed photolytic iodine laser as a COIL surrogate are also described.

Hager, Gordon D.; Anderson, Brian T.; Kendrick, Kip R.; Tate, Ralph F.; Helms, Charles A.; Adler, Richard J.; Fisher, Charles H.; Brown, Andrew J.; Plummer, David N.

2000-08-01

195

Progress report on the development of a repetitively pulsed frequency-shifted COIL laser  

Microsoft Academic Search

This paper summarizes recent progress that has occurred in several research areas related to the development of a repetitively-pulsed, frequency-shifted chemical oxygen iodine laser (COIL). COIL gain- switch experiments at 10 kHz pulse rates are described using a novel solid state pulsed magnetic field system. Raman conversion experiments in hydrogen using a pulsed photolytic iodine laser as a COIL surrogate

Gordon D. Hager; Brian T. Anderson; Kip R. Kendrick; Ralph F. Tate; Charles A. Helms; Richard J. Adler; Charles H. Fisher; Andrew J. Brown; David N. Plummer

2000-01-01

196

Computational Issues in Analysis and Design of Chemical-Laser Flow-Fields  

NASA Astrophysics Data System (ADS)

In support of the Air Force's airborne laser (ABL) development program. state-of-the-art CFD analysis and design methods have been extended to include the physical models important in chemical oxygen-iodine laser (COIL) systems. The three-dimensional COIL simulation model is based on the CFD flow solver GASP v4 which solves the conservative, finite-volume formulation of the Navier-Stokes equations with general thermo-chemistry. The COIL design software is based on the continuous sensitivity equation method (CSEM) and AeroSoft's flow-field sensitivity solver. SENSE. Extensions to GASP and SENSE include a COIL chemistry mechanism, a multicomponent diffusion model with pressure terms, and coupling with a laser optics resonator module based on the geometric ray-tracing method. In addition, GASP has been modified to include a water-vapor condensation model and a COIL surface catalysis model Simulations have been performed for the RADICL research laser for both power-on and power-off conditions.

Eppard, W. M.; Cliff, Eugene M.

2002-09-01

197

Development of safe infrared gas lasers  

NASA Astrophysics Data System (ADS)

Infrared gas lasers find application in numerous civil and military areas. Such lasers are therefore being developed at different institutions around the world. However, the development of chemical infrared gas lasers such as chemical oxygen iodine lasers (COIL) involves the use of several hazardous chemicals. In order to exploit full potential of these lasers, one must take diligent care of the safety issues associated with the handling of these chemicals and the involved processes. The present paper discusses the safety aspects to be taken into account in the development of these infrared gas lasers including various detection sensors working in conjunction with a customized data acquisition system loaded with safety interlocks for safe operation. The developed safety schemes may also be implemented for CO2 gas dynamic laser (GDL) and hydrogen fluoride-deuterium fluoride (HF-DF) Laser.

Mainuddin; Singhal, Gaurav; Tyagi, R. K.; Maini, A. K.

2013-04-01

198

Chemical laser systems: An engineering approach. Volume 1: Chemical laser analysis program  

Microsoft Academic Search

The Chemical Laser Analysis Program presented in this report is a computer program for the rapid, parametric evaluation of high energy, chemical laser systems, including the combustion chemistry, laser devices gas dynamics, various diffuser-ejector pressure recovery subsystems, and system volume\\/mass estimates. The program does not calculate specific laser power but relies on experimental data for scaling information. The FORTRAN EXTENDED

C. D. Mikkelsen; B. J. Walker

1979-01-01

199

Chemical laser systems: an engineering approach. Volume I. Chemical laser analysis program. Technical report  

Microsoft Academic Search

The Chemical Laser Analysis Program presented in this report is a computer program for the rapid, parametric evaluation of high energy, chemical laser systems including the combustion chemistry, laser devices gas dynamics, various diffuser-ejector pressure recovery subsystems, and system volume\\/mass estimates. The program does not calculate specific laser power but relies on experimental data for scaling information. The FORTRAN EXTENDED

C. D. Mikkelsen; B. J. Walker

1979-01-01

200

Catalytic enhancement of singlet oxygen for hybrid electric discharge oxygen-iodine laser systems  

Microsoft Academic Search

We are investigating catalytically enhanced production of singlet oxygen, O2(a1▵g), observed by reaction of O2\\/He discharge effluents on an iodine oxide film surface in a microwave discharge-flow reactor at 320 K. We have previously reported a two-fold increase in the O2(a) yields by this process, and corresponding enhancement of I(2P1\\/2) excitation and small-signal gain upon injection of I2. In this

Wilson T. Rawlins; Seonkyung Lee; Adam J. Hicks; Ian M. Konen; Emily P. Plumb; Steven J. Davis

2010-01-01

201

Gain measurements in a non-self-sustained electric discharge pumped oxygen-iodine laser cavity  

Microsoft Academic Search

The paper presents results of singlet delta oxygen yield (SDO) measurements in a high-pressure, non-self-sustained discharge and small signal gain measurements on the 1315 nm iodine atom transition in the M=3 supersonic cavity downstream of the discharge. The results demonstrate operation of a stable pulser-sustainer discharge in O2-He flows at pressures of up to 120 torr and discharge powers of

A. Hicks; K. Fredrickson; S. Tirupathi; Y. G. Utkin; W. R. Lempert; J. W. Rich; I. V. Adamovich; K. L. Galbally-Kinney; W. J. Kessler; W. T. Rawlins; P. A. Mulhall; S. J. Davis

2007-01-01

202

Gain Measurements in a Non-Self-Sustained Electric Discharge Pumped Oxygen-Iodine Laser Cavity  

Microsoft Academic Search

The paper presents results of singlet delta oxygen (SDO) yield measurements in a high-pressure, non-self-sustained crossed discharge and small signal gain measurement on the iodine atom transition in the M=3 supersonic cavity downstream of the discharge. The results demonstrate operation of a stable and diffuse crossed discharge in O2 -- He mixtures at pressures of up to P0=120 torr and

Igor Adamovich; Adam Hicks; Yurii Utkin; Walter Lempert; J. William Rich

2006-01-01

203

COIL with supersonic injection of chemically produced atomic iodine  

NASA Astrophysics Data System (ADS)

An advanced Chemical Oxygen-Iodine Laser (COIL) using the chemical generation of atomic iodine was studied. Atomic iodine is produced by the reaction of atomic chlorine with hydrogen iodide (HI) in two separated reactors tightly attached to the supersonic laser cavity. The iodine-contained mixture is injected to the flow of singlet oxygen by means of the supersonic orifices located 5 mm downstream the nozzle throat. The atomic iodine number density in the laser cavity up to 1.2 x 10 15 cm -3 and a small-signal gain up to 0.35 %/cm were achieved. An rather high quenching of singlet oxygen by HI caused that the attained laser power was low. The results of small signal gain and the laser power are compared with the previous system including the mixing of reactants upstream the nozzle throat.

Jirásek, Vít; Špalek, Otomar; ?enský, Miroslav; Kodymová, Jarmila; Picková, Irena; Jakubec, Ivo

2007-05-01

204

Chemically-Assisted Pulsed Laser-Ramjet  

SciTech Connect

A preliminary study of a chemically-assisted pulsed laser-ramjet was conducted, in which chemical propellant such as a gaseous hydrogen/air mixture was utilized and detonated with a focused laser beam in order to obtain a higher impulse compared to the case only using lasers. CFD analysis of internal conical-nozzle flows and experimental measurements including impulse measurement were conducted to evaluate effects of chemical reaction on thrust performance improvement. From the results, a significant improvement in the thrust performances was confirmed with addition of a small amount of hydrogen to propellant air, or in chemically-augmented operation.

Horisawa, Hideyuki; Kaneko, Tomoki; Tamada, Kazunobu [Department of Aeronautics and Astronautics, Tokai University, Hiratsuka, Kanagawa, 259-1292 (Japan)

2010-10-13

205

Chemical stabilization of laser dyes  

NASA Astrophysics Data System (ADS)

Coumarin laser dyes upon excitation degrade to produce products which absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. The roles of singlet oxygen and excitation intensity on dye degradation were explored. Singlet oxygen is formed but its reactions with the dye do not appear to be a major cause of dye laser output deterioration. High light intensity results in dye sensitized, solvent oligomerization to yield materials which interfere with dye stimulated emission. 1, 4-Diazabicyclo2,2,2octane (DABCO)inhibits this oligomerization.

Koch, Tad H.

1987-05-01

206

Surface discharge photoinitiation of pulsed chemical lasers  

NASA Astrophysics Data System (ADS)

This report summarizes the work carried out under the contract entitled Surface Discharge (SD) Photoinitiation Pulsed Chemical Lasers. This work consisted of technical analyzes, memos, and on-site test support. We considered SD design issues for both pulsed chemical lasers and photodissociation iodine lasers. Due to the similarity in the absorption band, the requirements on the SD light source are very similar. The SD systems can be utilized for either type of laser. Both rectangular and cylindrical SD configurations were analyzed. The cylindrical configuration is simpler, provides direct ultraviolet coupling into the laser medium, is smaller and lighter, and is better for voltage stand-off in multiple module configurations. But the impedance matching between the electrical circuit and the SD plasma is more difficult with the cylindrical geometry, unless small diameter cavities can be employed. A cylindrical configuration is preferred if the laser energy density is high enough for the diameter to be less than about 10 cm. A single rectangular SD module was tested for the first time at high voltage and worked very well. The four module system was integrated into the laser and SD tests conducted. Laser operation both in the DF-CO2 mode at 10.6 microns and the DF mode at about 3.8 microns were investigated. This is the first time an SD has been used in this configuration to produce laser energy outputs at the levels achieved. A weight scaling analysis of the pulsed power system was undertaken to support the application of this laser system. The pulsed power system will weigh 50 to 100 lbs, and provide 10 to 100 shots at repetition rates of less then 1 Hz. We concluded that the most practical approach to producing efficient ultraviolet emission from the SD at the short pulses needed for photoinitiation, and on the SD areas needed for the laser operation, employs a single capacitor bank rather than a pulser-sustainer approach.

1992-10-01

207

A spectroscopic study of CW chemical lasers.  

NASA Technical Reports Server (NTRS)

A subsonic transverse-flow chemical laser has been instrumented to permit measurements of vibration-rotation state populations and laser output spectra under flow conditions typical of present CW hydrogen halide laser operation. Measurements are presented for the F + HI, F + HBr, F + CH4, F + HCl, F + H2, Cl + HI, and Cl + HBr atom-exchange reaction systems. CW operation was found to be characterized by relatively modest departures from Maxwell-Boltzmann vibrational energy distributions at all stages of reaction in contrast to pulsed operation based on similar reactions.

Rosen, D. I.; Sileo, R. N.; Cool, T. A.

1973-01-01

208

*cuaerospace@cuaerospace.com; phone 217-333-8274; fax 217-244-7757; http://cuaerospace.com; CU Aerospace, 2004 S. Wright St. Ext., Urbana, IL, 61801; **wsolomon@uiuc.edu; phone 217-244-7646; fax 217-244-0720; http://www.aae.uiuc.edu;  

E-print Network

Work on the Development of an Electric Discharge Oxygen Iodine Laser D. L. Carroll*a , J. T. Verdeyen discharge oxygen-iodine laser (ElectriCOIL) system in conjunction with injection of pre-dissociated iodine The classic chemical oxygen-iodine laser (COIL) [McDermott, 1978] operates on the electronic transition

Carroll, David L.

209

ElectricOIL discharge and post-discharge kinetics experiments and modeling  

E-print Network

/helium/nitric-oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic of ozone in the downstream kinetics. Keywords: oxygen-iodine laser, ElectricOIL, DOIL, oxygen kinetics, singlet-delta oxygen, NOx kinetics 1. INTRODUCTION The classical chemical oxygen-iodine laser first

Carroll, David L.

210

Improved production of O2(a1 ) in transverse radio-frequency  

E-print Network

). Since this first reporting of a viable electric discharge-driven oxygen-iodine laser system (called EOIL favorable conditions for application to an electric oxygen-iodine laser (EOIL). As pressure is increased performance dependence on various parameters. 1. INTRODUCTION The classical chemical oxygen-iodine laser first

Carroll, David L.

211

Atomic fluorine source for chemical lasers  

NASA Astrophysics Data System (ADS)

We present results from the early development of an F atom source appropriate for HF and AGIL chemical laser research. The system uses high power microwaves to produce a high enthalpy plasma that thermally dissociates molecular species such as SF6 and F2. Results of the characterization of the flow are presented.

Davis, Steven J.; Oakes, David B.; Read, Michael E.; Gelb, Alan H.

2002-05-01

212

Remote Chemical Detection using Quantum Cascade Lasers  

SciTech Connect

The Infrared Technologies Program at the Pacific Northwest National Laboratory (PNNL) is focused on the science and technology of remote and in-situ chemical sensors for detecting proliferation and countering terrorism. The program is focusing on the infrared detection of gaseous species including chemical warfare agents and gases associated with the production of chemical and nuclear weapons. Several sensors under development are based on miniature infrared quantum cascade (QC) lasers constructed of semiconductor material. The QC laser is unique in that by simply changing the thickness of the semiconductor layers, the laser's wavelength can be changed to target molecular absorption features of specific chemicals. For remote sensing over long optical paths, QC lasers are applied to remote areas using the differential-absorption LIDAR technique. Using a single laser, this technique can easily monitor large areas that would require a large network of point sensors. The original remote sensing configuration, suitable for laboratory applications, consisted of an optical table, laser, beam expander, telescope, mirror, and various supporting electronic and optical components. Recently, PNNL began development of a ruggedized version to conduct experiments in real-world conditions. To reduce the effects of thermal distortion, the system had to be operated from within a large, well insulated, temperature-controlled trailer. The optical breadboard was attached to 4 shock-mounts to reduce shock and vibrational loads to the optical set-up during transport. A custom jacking system using electromechanical actuators was designed to affix the optical table directly to the ground through penetrations in the trailer floor. The jacking system allows remote sensing at longer ranges (up to 5 km) by eliminating jitter caused by wind or personnel movement within the trailer. A computer-controlled gimbal-mounted mirror was added to allow the laser beam to be accurately pointed in both the vertical and horizontal plane. Mechanical tests and finite element analysis were undertaken to verify that the gimbal drives and mounting hardware had sufficient capacity to handle the inertia of the large 22-inch diameter mirror while maintaining adequate mirror flatness. This paper will provide an overview of the remote chemical detection system and will describe innovative optical mechanical solutions developed to overcome several alignment and stability issues.

Hatchell, Brian K.; Harper, Warren W.; Gervais, Kevin L.

2006-02-01

213

Laser enhanced chemical reaction studies  

NASA Astrophysics Data System (ADS)

The relaxation of vibrationally excited pyrazine (E = 40,640/cm) by collisions which populate the high J tail (J = 58-82) of the vibrationless ground state (00(exp 0)0) of CO2 has been studied using tunable infrared diode lasers to probe the scattered CO2 molecules. The nascent rotational populations and translational recoil velocities for a series of rotational states in the high J tail of the 00(exp 0)0 level of CO2 were measured at five collision cell temperatures: 243, 263, 298, 339, and 364 K. Both the rate constants describing these V-R/T processes and the translational temperatures describing the recoiling CO2 molecules exhibit a very weak positive temperature dependence indicating that the high energy CO2 molecules must originate from near the center of the pre-collision energy distribution. Quantitative estimates of the actual amount of energy transferred in collisions between CO2 and vibrationally excited pyrazine, based on an angular momentum and translational energy exponential gap model of the cross section, indicate that delta E(total) can be as large as 7090/cm (approximately 20 kcal/mol). These experiments offer compelling evidence that these energy transfer events can indeed be classified as supercollisions since they involve unusually large, single collision energy transfer magnitudes; and despite their relative infrequency, they play a most important role in the collisional deactivation of vibrationally excited pyrazine by a CO2 bath.

214

A electroionization chemical hydrogen-iodine laser  

NASA Astrophysics Data System (ADS)

The feasibility of creating a hydrogen-iodine laser with an electroionization excitation capability which operates at the 2P(1/2)-2P(3/2) magnetodipole transition in atomic iodine (lambda = 1.315 microns) is studied. The atomic iodine needed for the H2-Ar:I2 mixture can be obtained in the electric-discharge-induced fast chemical reaction H + I2 yields HI + I. Based on the analysis of the basic processes and the calculation of the electron-distribution function, a numerical simulation of a similar laser is carried out. It is shown that the specific energy input required for the development of the hydrogen-iodine laser is sufficiently high (about 250-300 J/l atm) and that the mixture has an optimum with regard to energy input and initial temperature.

Bel'Diugin, I. M.; Stepanov, A. A.; Shcheglov, V. A.; Vysotskii, Iu. P.

1987-02-01

215

Chemically assisted laser ablation ICP mass spectrometry.  

PubMed

A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis. PMID:12553756

Hirata, Takafumi

2003-01-15

216

Efficient electric-discharge HCl chemical laser  

Microsoft Academic Search

The development of a pulsed electric-discharge chemical laser utilizing vibrational–rotational transitions in an HCl molecule (? = 3.7–4.1 ?m) and having record-high values of the pulse energy (EHCl = 0.4 J) and electrical efficiency (?HCl ? 30%) is reported. Lasing was observed simultaneously due to transitions in the HF molecule (? = 2.6–3.1 ?m) with EHF = 0.9 J and

Evgenii B Gordon; V I Matyushenko; P B Repin; V D Sizov

1990-01-01

217

A electroionization chemical hydrogen-iodine laser  

Microsoft Academic Search

The feasibility of creating a hydrogen-iodine laser with an electroionization excitation capability which operates at the 2P(1\\/2)-2P(3\\/2) magnetodipole transition in atomic iodine (lambda = 1.315 microns) is studied. The atomic iodine needed for the H2-Ar:I2 mixture can be obtained in the electric-discharge-induced fast chemical reaction H + I2 yields HI + I. Based on the analysis of the basic processes

I. M. Bel'Diugin; A. A. Stepanov; V. A. Shcheglov; Iu. P. Vysotskii

1987-01-01

218

Industrial COIL systems--part 1: laser beam delivery by fiber  

Microsoft Academic Search

First results of experimental and theoretical investigations related to an industrial application of oxygen-iodine laser (COIL) are reported. A developed calculative model determines a transmission factor of a laser emission at a set wavelength depending on the waveguide parameters, focusing system characteristics, and laser emission intensity angular distribution. Carried out investigations concerned with delivery of a laser emission power up

Sergey P. Ilyin; Vladimir V. Buzoverya; Anatoly A. Adamenkov; Victor V. Bakshin; Valentin I. Efremov; David G. Kochiev; Yuriy V. Kolobyanin; Vladimir B. Moiseev; Boris A. Vyskubenko

2005-01-01

219

High-power COIL and Nd:YAG laser welding  

NASA Astrophysics Data System (ADS)

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 ?m wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW class Chemical Oxygen-Iodine Laser (COIL) beams of 6 kW Nd:YAG laser and COIL are combined in a coaxial beam and its maximum average power is 19 kW. The third laser beam, 4 kW Nd:YAG laser beam, is added obliquely from the same side of workpiece or oppositely from the reverse one. The effects of various welding parameters were investigated, such as the laser power, pulse modulation, and so on. As a result of the welding test with the 6 kW Nd:YAG laser, it was clarified that the pulse wave (PW) has good efficiency of deeper penetration at low welding speed. When the combined beam with CW COIL and PW Nd:YAG laser was used, 20 mm penetration on the stainless steel could be achieved at a welding speed of 1 m/min. By adding the third laser beam, the both side welding on 30mm thickness plate could be achieved.

Wani, Fumio; Nakabayashi, T.; Hayakawa, A.; Suzuki, S.; Yasuda, K.

2003-11-01

220

Properties of O2(1?)-I(2P1/2) laser medium with a dc glow discharge iodine atom generator  

NASA Astrophysics Data System (ADS)

Experiments were carried out in a flow cell apparatus under conditions corresponding to those of a typical oxygen-iodine laser. The cell was equipped with a chemical jet type singlet oxygen generator and an electric discharge for the production of iodine atoms. The properties of the discharge generator and the active medium were studied using laser-induced fluorescence and emission spectroscopy. I2 or CH3I entrained in a carrier flow of Ar were used as atomic iodine precursors. About 50% of the iodine contained in CH3I molecules was extracted in the generator. 2.6% of the electric power loaded into the discharge was used in CH3I dissociation. Right after the discharge 80%-90% of the iodine flow consisted of atoms. However, due to recombination during transport, only 20%-50% of atoms remained at the point of injection into the oxygen flow. A straightforward comparison of two methods of oxygen-iodine medium production—conventional, by means of I2 dissociation in the singlet oxygen flow and with iodine atoms produced externally in the electric discharge—was performed. It was found that the lifetime for the energy stored in singlet oxygen was about 30% longer, when atomic iodine was produced from CH3I in the discharge, as compared to the conventional chemical dissociation of I2 in the singlet oxygen flow.

Mikheyev, Pavel A.; Azyazov, Valeriy N.

2008-12-01

221

Mid-IR semiconductor lasers for chemical sensing  

NASA Technical Reports Server (NTRS)

The development of mid-IR semiconductor diode lasers based on type-II interband cascade structures is presented. How these diode lasers can be developed to meet the requirements in chemical sensing applications is discussed.

Hill, C. J.; Yang, R. Q.

2003-01-01

222

Remote Chemical Sensing Using Quantum Cascade Lasers  

SciTech Connect

Spectroscopic chemical sensing research at Pacific Northwest National Laboratory (PNNL) is focused on developing advanced sensors for detecting the production of nuclear, chemical, or biological weapons; use of chemical weapons; or the presence of explosives, firearms, narcotics, or other contraband of significance to homeland security in airports, cargo terminals, public buildings, or other sensitive locations. For most of these missions, the signature chemicals are expected to occur in very low concentrations, and in mixture with ambient air or airborne waste streams that contain large numbers of other species that may interfere with spectroscopic detection, or be mistaken for signatures of illicit activity. PNNL’s emphasis is therefore on developing remote and sampling sensors with extreme sensitivity, and resistance to interferents, or selectivity. PNNL’s research activities include: 1. Identification of signature chemicals and quantification of their spectral characteristics, 2. Identification and development of laser and other technologies that enable breakthroughs in sensitivity and selectivity, 3. Development of promising sensing techniques through experimentation and modeling the physical phenomenology and practical engineering limitations affecting their performance, and 4. Development and testing of data collection methods and analysis algorithms. Close coordination of all aspects of the research is important to ensure that all parts are focused on productive avenues of investigation. Close coordination of experimental development and numerical modeling is particularly important because the theoretical component provides understanding and predictive capability, while the experiments validate calculations and ensure that all phenomena and engineering limitations are considered.

Harper, Warren W.; Schultz, John F.

2003-01-30

223

Laser-based sensors for chemical detection  

NASA Astrophysics Data System (ADS)

Stand-off detection of hazardous materials ensures that the responder is located at a safe distance from the suspected source. Remote detection and identification of hazardous materials can be accomplished using a highly sensitive and portable device, at significant distances downwind from the source or the threat. Optical sensing methods, in particular infrared absorption spectroscopy combined with quantum cascade lasers (QCLs), are highly suited for the detection of chemical substances since they enable rapid detection and are amenable for autonomous operation in a compact and rugged package. This talk will discuss the sensor systems developed at Pacific Northwest National Laboratory and will discuss the progress to reduce the size and power while maintaining sensitivity to enable stand-off detection of multiple chemicals.

Myers, Tanya L.; Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Schiffern, John T.; Cannon, Bret D.

2010-04-01

224

Laser-based Sensors for Chemical Detection  

SciTech Connect

Stand-off detection of hazardous materials ensures that the responder is located at a safe distance from the suspected source. Remote detection and identification of hazardous materials can be accomplished using a highly sensitive and portable device, at significant distances downwind from the source or the threat. Optical sensing methods, in particular infrared absorption spectroscopy combined with quantum cascade lasers (QCLs), are highly suited for the detection of chemical substances since they enable rapid detection and are amenable for autonomous operation in a compact and rugged package. This talk will discuss the sensor systems developed at Pacific Northwest National Laboratory and will discuss the progress to reduce the size and power while maintaining sensitivity to enable stand-off detection of multiple chemicals.

Myers, Tanya L.; Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Schiffern, John T.; Cannon, Bret D.

2010-05-10

225

Industrial COIL systems--part 2: gas-laser cutting  

Microsoft Academic Search

First results of experimental and theoretical investigations concerning an industrial application of oxygen-iodine laser (COIL) are reported. The dependencies of the largest cut depth on the laser emission power, cut width and rate, and kind of processing gas (oxygen or nitrogen) were determined for carbon and stainless steels, and aluminium alloys. A developed simple engineering model determines parameters of separating

Yury V. Kolobyanin; Il'ya A. Bulatkin; Vladimir V. Kalinovskiy; Vladimir V. Konovalov; Vladimir B. Moiseev; Victor D. Nickolaev; Lev N. Shornikov; Roman E. Sobolev; Boris A. Vyskubenko

2005-01-01

226

Chemical generation of atomic iodine for a COIL via atomic fluorine  

NASA Astrophysics Data System (ADS)

Results of experimental investigation of the chemical generation of atomic iodine for a Chemical Oxygen-Iodine Laser (COIL) are presented. The work was focused on the reaction system with atomic fluorine as an intermediate species produced by the chemical way from gaseous reactants. At the first step, atomic fluorine is produced in reaction of molecular fluorine with nitrogen oxide. Then F atoms react with gaseous hydrogen iodide producing atomic iodine. The efficiency of this two-step process was studied thoroughly in dependence on mixing conditions, flow rate of reacting gases and pressure in the reactor. The results obtained on the small-scale device under experimental conditions simulating pressure and flow conditions in a COIL show that atomic iodine is generated by this alternative, advantageous method with rather high concentrations sufficient for operation of the supersonic COIL.

Censky, Miroslav; Spalek, Otomar; Jirasek, Vit; Kodymova, Jarmila; Jakubec, Ivo

2004-05-01

227

Influence of nitrogen oxides on singlet delta oxygen production in pulsed electric discharge for oxygen-iodine laser  

Microsoft Academic Search

Experimental and theoretical study of influence of nitrogen oxides NO and NO2 admixtures in oxygen containing gas mixture excited by pulsed electron-beam sustained discharge on input energy and time behavior of singlet delta oxygen (SDO) luminescence was carried out. Temperature dependence of the constant of SDO relaxation by unexcited molecular oxygen was estimated.

A. A. Ionin; Yu. M. Klimachev; A. A. Kotkov; A. Yu. Kozlov; I. V. Kochetov; A. P. Napartovich; O. A. Rulev; L. V. Seleznev; D. V. Sinitsyn; N. P. Vagin; N. N. Yuryshev

2008-01-01

228

Influence of nitrogen oxides on singlet delta oxygen production in pulsed discharge for electric discharge oxygen-iodine laser  

Microsoft Academic Search

Influence of nitrogen oxides NO and NO2 on specific input energy (SIE) and time behavior of singlet delta oxygen (SDO) luminescence excited by pulsed e-beam sustained discharge in oxygen was experimentally and theoretically studied. NO and NO2 addition into oxygen results in a small increase and a decrease of SIE, respectively. Addition of 0.1-0.3 percent of nitrogen oxides was experimentally

Andrey Ionin; Yurii Klimachev; Andrey Kozlov; Andrey Kotkov; Igor Kochetov; Anatoly Napartovich; Oleg Rulev; Leonid Seleznev; Dmitry Sinitsyn; Nikolay Vagin; Nikolay Yurushev

2008-01-01

229

Electron-beam sustained discharge in oxygen gas mixtures: singlet delta oxygen production for oxygen-iodine laser  

Microsoft Academic Search

Electric properties and spectroscopy of an e-beam sustained discharge (EBSD) in oxygen and oxygen gas mixtures at gas pressure up to 100 Torr were experimentally studied. The pulsed discharge in pure oxygen and its mixtures with noble gases was shown to be very unstable and characterized by low input energy. When adding small amount of carbon monoxide or hydrogen, the

Mikhail P. Frolov; Gordon D. Hager; Andrei A. Ionin; Yurii M. Klimachev; Igor V. Kochetov; Andrei A. Kotkov; John K. McIver; Anatolii P. Napartovich; Yurii P. Podmar'kov; Leonid V. Seleznev; Dmitrii V. Sinitsyn; Nikolai P. Vagin; Nikolay N. Yuryshev

2004-01-01

230

Catalytic enhancement of singlet oxygen production and optical gain in electric discharge oxygen-iodine laser systems  

Microsoft Academic Search

We are investigating catalytically enhanced production of singlet oxygen, O2(a1▵g), observed by reaction of O2\\/He discharge effluents over an iodine oxide film surface in a microwave discharge-flow reactor at 320 K. We have previously reported a two-fold increase in the O2(a) yields by this process, and corresponding enhancement of I(2P1\\/2) excitation and small-signal gain upon injection of I2 and NO2.

Seonkyung Lee; Wilson T. Rawlins; Adam J. Hicks; Ian M. Konen; Emily P. Plumb; Steven J. Davis

2011-01-01

231

Laser research at the Institute of Physics AS CR  

NASA Astrophysics Data System (ADS)

Laser research at the Institute of Physics of the Academy of Sciences of Czech Republic covers both the development of advanced pulsed high-power laser systems, the iodine and x-ray in particular, and their applications in science and technology. The COIL laboratory with a small chemical oxygen-iodine laser facility participates in the worldwide effort to develop a competitive quasi-steady laser device for industrial and military applications. In the new laboratory SOFIA a unique hybrid laser system consisting of a commercial crystal oscillator and iodine power amplifiers (SOFIA = Solid State Oscillator Followed by Iodine Amplifiers) has been developed. It is used as a pump of parametric amplifiers in a pilot OPCPA experiment. Our largest laboratory, the PALS Research Centre operated jointly with the Institute of Plasma Physics AS CR, is open to external users, offering them the beam time of the TW/ns iodine laser system PALS (Prague Asterix Laser System). Several tens of experimental projects have been performed at PALS since September 2000, aimed e.g. at various applications of plasma XUV sources, QSS plasma XUV lasers, laser ion sources, and laser-induced shock waves. An overview of the research programmes of all the three laboratories is given in the paper.

Jungwirth, Karel

2005-03-01

232

Atmospheric propagation properties of various laser systems  

NASA Astrophysics Data System (ADS)

Atmospheric propagation properties of various laser systems, including diode pumped alkali lasers (DPALs) and the Chemical Oxygen Iodine Laser (COIL), are of importance. However, there appears to be a lack of highly accurate transmission characteristics of these systems associated with their operating conditions. In this study laser propagation of the rubidium-based DPAL and the COIL has been simulated utilizing integrated cavity output spectroscopy. This technique allowed for the simulation of laser propagation approaching distances of 3 kilometers on a test stand only 35 cm long. The spectral output from these simulations was compared to the HITRAN database with excellent agreement. The spectral prole and proximity of the laser line to the atmospheric absorbers is shown. These low pressure spectral proles were then extrapolated to higher pressures using an in-house hyperne model. These models allowed for the comparison of proposed systems and their output spectral prole. The diode pumped rubidium laser at pressures under an atmosphere has been shown to interact with only one water absorption feature, but at pressures approaching 7 atmospheres the D1 transition may interact with more than 6 water lines depending on resonator considerations. Additionally, a low pressure system may have some slight control of the overlap of the output prole with the water line by changing the buer gases.

Pitz, Greg A.; Glass, Sara; Kamer, Brian; Klennert, Wade L.; Hostutler, David A.

2012-06-01

233

FRONTIERS ARTICLE Quantum cascade lasers in chemical physics  

E-print Network

FRONTIERS ARTICLE Quantum cascade lasers in chemical physics Robert F. Curl a,*, Federico Capasso b their first demonstration, quantum cascade lasers have become the most useful sources of tunable mid applications of quantum cascade lasers to infrared spectroscopy. We foresee the potential application

234

Remote chemical sensing with quantum cascade lasers  

SciTech Connect

A trailer based sensor system has been developed for remote chemical sensing applications. The sensor uses quantum cascade lasers (QCL) that operate in the long wave infrared. The QCL is operated continuous wave, and its wavelength is both ramped over a molecular absorption feature and frequency modulated. Lock-in techniques are used to recover weak laser return signals. Field experiments have monitored ambient water vapor and small quantities of nitrous oxide, tetrafluoroethane (R134a), and hydrogen sulfide released as atmospheric plumes. Round trip path lengths up to 10 km were obtained using a retro-reflector. Atmospheric turbulence was found to be the dominating noise source. It causes intensity fluctuations in the received power, which can significantly degrade the sensor performance. Unique properties associated with QCLs enabled single beam normalization techniques to be implemented thus reducing the impact that turbulence has on experimental signal to noise. Weighted data averaging was additionally used to increase the signal to noise of data traces. Absorbance sensitivities as low as {approx}1 x 10{sup -4} could be achieved with 5 seconds of data averaging, even under high turbulence conditions.

Harper, Warren W.; Strasburg, Jana D.

2004-10-15

235

High-power COIL and YAG laser welding  

NASA Astrophysics Data System (ADS)

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 mm wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW Chemical Oxygen-Iodine Laser (COIL). The average power of the combined beam is up to over 20 kW. The effects of various welding parameters were investigated, such as the laser power, pulse modulation, and so on. The 10 kW COIL has a very good beam quality which is 64 mm.mrad. The beam spot diameter is 0.48 mm at the focal point. On the contrary the beam quality of Nd:YAG laser is worse, but it has the function of pulse modulation which the COIL dose not have. As a result of the welding test with the 6 kW Nd:YAG laser, it was clarified that the pulse wave (PW) has good efficiency of deeper penetration at low welding speed. When the combined beam with CW COIL and PW Nd:YAG laser was used, 20 mm penetration on the stainless steel could be achieved at a welding speed of 1 m/min.

Wani, Fumio; Nakabayashi, Tokuhiro; Hayakawa, Akiyoshi; Suzuki, Sachio; Yasuda, Kozu

2002-05-01

236

Remote Chemical Sensing Using Quantum Cascade Lasers  

SciTech Connect

Research done by the IR sensors team at PNNL is focused on developing advanced spectroscopic methods for detecting signatures of nuclear, chemical, biological and explosives weapons or weapons production. The sensors we develop fall into two categories: remote sensors that can be operated at distances ranging from 150 m to 10 km, and point sensors that are used for in-situ inspection and detection. FY03 has seen an explosion in FM DIAL progress with the net result being solid confirmation that FM DIAL is a technique capable of remote chemical monitoring in a wide variety of venues. For example, FM DIAL was used to detect a small plume of hydrogen sulfide, a candidate CW agent, released in the desert environment of the Hanford 200 Area site. These experiments were conducted over a range of physical conditions including outside temperatures ranging from 70 F to 105 F and turbulence conditions ranging from quiescent to chaotic. We are now rapidly developing the information needed to design prototype FM DIAL systems that are optimized for specific applications that include scenarios such as fixed position stand-off detection and mobile UAV mounted remote monitoring. Just as an example, in FY04 we will use FM DIAL to detect both in-facility and outdoor release of enriched UF6. The rapid progress in FM DIAL research made in FY03 is attributed to several advances. First, final construction of a custom-designed trailer allowed the instrument to be housed in a mobile temperature-controlled environment. This allowed the experiment to be transported to several locations so that data could be collected under a range of physical conditions. This has led to a better understanding of a variety of experimental noise sources. With this knowledge, we have been able to implement several changes in the way the FM DIAL data is collected and processed, with the net result being a drastic improvement in our confidence of analyte concentration measurement and an improvement i n the instrument detection limit. The range of chemicals detectable by FM DIAL has also been extended. Prior to FY03 only water and nitrous oxide (N2O) had been seen. Experiments on extending the tuning range of the quantum cascade laser (QCL) currently used in the experiments demonstrate that many more species are now accessible including H2S, C2F4H2, and CH4. We additionally demonstrated that FM DIAL measurements can be made using short wave infrared (SWIR) telecommunications lasers. While measurements made using these components are noisier because turbulence and particulate matter cause more interference in this spectral region, monitoring in this region enables larger species to be detected simply because these lasers have a greater tuning range. In addition, SWIR monitoring also allows for the detection of second-row hydride species such as HF and HCl, which are important nuclear and CWA proliferation signatures.

Harper, Warren W.; Strasburg, Jana D.; Aker, Pam M.; Schultz, John F.

2004-01-20

237

Thick plate welding with Nd:YAG laser and COIL  

NASA Astrophysics Data System (ADS)

In the field of heavy industries, many products are made of thick metal parts. Nd:YAG laser has been recently developed up to 10 kW. Nd:YAG laser has the characteristics of the optical fiber transmittance and the good absorption by the metal surface, so that it is expected to apply Nd:YAG laser to thick plate welding. This study presents the thick plate welding with Nd:YAG laser and COIL (Chemical Oxygen-Iodine Laser). We have developed a coaxial beam combining system with beams of Nd:YAG laser and COIL. The maximum average power of the combined beam was 19 kW. Welding tests of 304 stainless steel plates were carried out. The effects of various welding parameters were investigated, such as the laser power and pulse modulation. As a result, it was clarified that the pulse wave has good efficiency of deeper penetration as compared to continuous wave at low welding speed. When the combined beam was used, 20 mm penetration depth on the stainless steel could be obtained in high aspect ratio at welding speed of 1m/min. When the combined beams and another Nd:YAG laser beam whose power was 4 kW were used, both side welding on 30 mm thickness plate could be achieved.

Nakabayashi, Tokuhiro; Wani, Fumio; Hayakawa, Akiyoshi; Suzuki, Sachio; Yasuda, Kozo

2003-03-01

238

Laser cutting with chemical reaction assist  

DOEpatents

A method is described for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation. 1 figure.

Gettemy, D.J.

1992-11-17

239

Synchronization: from pendulum clocks to chaotic lasers and chemical oscillators  

E-print Network

Synchronization: from pendulum clocks to chaotic lasers and chemical oscillators MICHAEL ROSENBLUM Christiaan Huygens reported on his observation of synchronization of two pendulum clocks which he had briefly described in his memoirs Horologium Oscillatorium (The Pendulum Clock, or Geome- trical

Potsdam, Universität

240

Laser-induced chemical etching of silicon in chlorine atmosphere  

Microsoft Academic Search

Laser-induced chemical etching of single-crystalline (100) Si in Cl2 atmosphere has been investigated for continuous Ar+ and Kr+ laser irradiation at around 351 nm, and at 457.9, 488.0, 514.5, and 647.1 nm. For laser irradiances below 105 W\\/cm2 the etching mechanism is non-thermal, and is based on photo-generated electron-hole pairs within the Si surface and Cl atoms produced within the

P. Mogyorósi; K. Piglmayer; R. Kullmer; D. Bäuerle

1988-01-01

241

Investigation of jet curtains for chemical laser application  

Microsoft Academic Search

A method is presented for passively containing reacting gas within the cavity of a chemical laser using a combination of cavity wall displacement and jet curtains. Suggesting several advantages over the matched pressure approach, the concept was evaluated in an application to a DF laser using the hydraulic analogy. Analyses were made to determine the flow characteristics of the confined

S. Boraas

1978-01-01

242

Laser micromachining of chemically altered polymers  

SciTech Connect

During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposals, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emissino lines, e.g. 351, 308 and 248 nm lines of excimer lasers. The authors show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are no redeposited ablation products or surface modifications of the polymer after ablation.

Lippert, T.

1998-08-01

243

Developments in Theoretical and Applied Mechanics, Vol. XVIII, eds. H. Wilson, R. Batra, C. Bert, A. Davis R. Schapery, D. Stewart, and F. Swinson, School of Engineering, The University of Alabama, 1996, pp. 411-424.  

E-print Network

associated with the operation of chemical oxygen- iodine laser (COIL) systems. While there are numerous COIL) technique for optimizing the performance of a laser system (chemical, solid-state, or gaseous). The effects. The typical chemical oxygen-iodine laser (COIL) utilizes an energy transfer from the singlet delta excited

Carroll, David L.

244

Project LOCOST: Laser or Chemical Hybrid Orbital Space Transport  

NASA Technical Reports Server (NTRS)

A potential mission in the late 1990s is the servicing of spacecraft assets located in GEO. The Geosynchronous Operations Support Center (GeoShack) will be supported by a space transfer vehicle based at the Space Station (SS). The vehicle will transport cargo between the SS and the GeoShack. A proposed unmanned, laser or chemical hybrid orbital space transfer vehicle (LOCOST) can be used to efficiently transfer cargo between the two orbits. A preliminary design shows that an unmanned, laser/chemical hybrid vehicle results in the fuel savings needed while still providing fast trip times. The LOCOST vehicle receives a 12 MW laser beam from one Earth orbiting, solar pumped, iodide Laser Power Station (LPS). Two Energy Relay Units (ERU) provide laser beam support during periods of line-of-sight blockage by the Earth. The baseline mission specifies a 13 day round trip transfer time. The ship's configuration consist of an optical train, one hydrogen laser engine, two chemical engines, a 18 m by 29 m box truss, a mission-flexible payload module, and propellant tanks. Overall vehicle dry mass is 8,000 kg. Outbound cargo mass is 20,000 kg, and inbound cargo mass is 6,000 kg. The baseline mission needs 93,000 kg of propellants to complete the scenario. Fully fueled, outbound mission mass is 121,000 kg. A regeneratively cooled, single plasma, laser engine design producing a maximum of 768 N of thrust is utilized along with two traditional chemical engines. The payload module is designed to hold 40,000 kg of cargo, though the baseline mission specifies less. A proposed design of a laser/chemical hybrid vehicle provides a trip time and propellant efficient means to transport cargo from the SS to a GeoShack. Its unique, hybrid propulsion system provides safety through redundancy, allows baseline missions to be efficiently executed, while still allowing for the possibility of larger cargo transfers.

Dixon, Alan; Kost, Alicia; Lampshire, Gregory; Larsen, Rob; Monahan, Bob; Wright, Geoff

1990-01-01

245

carroll@cuaerospace.com; phone 1-217-333-8274; fax 1-217-244-7757; http://cuaerospace.com; CU Aerospace, 60 Hazelwood Dr., Champaign, IL 61820.  

E-print Network

to the system. Keywords: DOIL, EOIL, chemical oxygen-iodine laser, COIL, ElectriCOIL, RF excitation of oxygen, singlet-delta oxygen 1. INTRODUCTION The classic chemical oxygen-iodine laser (COIL) system [Mc; Stafford, 2003] that indicate that such a system should produce a viable laser. A number of papers have

Carroll, David L.

246

Production of Singlet Oxygen within a Flow Discharge  

Microsoft Academic Search

The Airborne laser program is an Air Force sponsored program to place a laser on the battle field for use as a tactical weapon. The chemical oxygen iodine laser offers the powers necessary for this weapons application, but it requires significant logistical support. The goal of this current research program is to demonstrate an oxygen-iodine laser with electrical discharge production

Matthew Lange; Greg Pitz; Glen Perram

2008-01-01

247

Comparison of Laser Chemical Processing and LaserMicroJet for structuring and cutting silicon substrates  

NASA Astrophysics Data System (ADS)

This paper deals with the development of a new cutting method for thin silicon solar wafers with liquid-jet-guided lasers (LaserMicroJet®, LMJ, and Laser Chemical Processing, LCP). Several laser systems with different wavelengths were tested to find the optimum laser system and processing parameters in terms of efficient material removal and deep laser cutting. Water and potassium hydroxide were used as carrier liquids to enhance laser ablation. The ablation efficiency was defined as a target parameter and experimentally determined by performing single laser grooves. It is demonstrated that the ablation process of LMJ is mainly affected by silicon melting and then removing by the liquid-jet momentum for single laser grooves. Best result for deep laser grooves is achieved if evaporation dominates the ablation process. Better surface quality referred to laser-induced crystalline damage is presented for a cut wafer with LMJ in comparison to a standard multiwire slurry saw. This shows a great potential of wafering with liquid-jet-guided lasers although no optimal liquid media was used.

Hopman, Sybille; Fell, Andreas; Mayer, Kuno; Mesec, Matthias; Rodofili, Andreas; Kray, Daniel

2009-06-01

248

Space-based chemical lasers for ballistic missile defense  

NASA Astrophysics Data System (ADS)

A space-based laser (SBL), currently under development as a follow-on technology by the Ballistic Missile Defense Organization, is described. A constellation of several orbiting laser platforms (hydrogen fluoride chemical lasers at 2.7 microns) is capable of providing continuous theater or global coverage against ballistic missile threats. The SBL platforms destroy ballistic missiles early in the boost phase, before they can release submunitions, chaff, or decoys, and ensuring that the resulting debris falls far from defended territory. The system is expected to be operational in the 2008 time frame.

Wildt, Daniel R.; Lissit, Scott A.

1993-07-01

249

Laser-chemical finishing of micro forming tools  

NASA Astrophysics Data System (ADS)

In this contribution, we report on a laser-chemical removal method for precise machining of micro forming tools. Thereby, a focused machining laser beam is guided coaxially to an etchant jet stream. Since the material removal is caused by laser-induced chemical reactions using this method, machining is achieved at low laser powers. Hence, material stressing involving micro cracks and further parasitic effects can be avoided. Due to these advantages, this method offers a suitable technique for the finishing of precision micro tools. Several experiments have been performed at rotary swaging jaws made of Stellite 21 in order to chamfer the edged transition section between the operating sphere and the tool flank. The influence of both different laser powers and work piece traverse speeds has been investigated. For this purpose, several parallel laser paths were applied along the edged transition section when varying the process parameters. Here, the incident laser beam is subjected to different angles of incidence. Due to reflection effects, the process parameters have to be matched with respect to the particular angle of incidence during the machining. In this vein, the edged transition section of rotary swaging jaws was chamfered at radii in the range of 120 ?m.

Stephen, Andreas; Gerhard, Christoph; Vollertsen, Frank

2011-03-01

250

Laser studies of chemical reaction and collision processes  

SciTech Connect

This work has concentrated on several interrelated projects in the area of laser photochemistry and photophysics which impinge on a variety of questions in combustion chemistry and general chemical kinetics. Infrared diode laser probes of the quenching of molecules with {open_quotes}chemically significant{close_quotes} amounts of energy in which the energy transferred to the quencher has, for the first time, been separated into its vibrational, rotational, and translational components. Probes of quantum state distributions and velocity profiles for atomic fragments produced in photodissociation reactions have been explored for iodine chloride.

Flynn, G. [Columbia Univ., New York, NY (United States)

1993-12-01

251

Premixed cw Electric-Discharge CO Chemical Lasers  

Microsoft Academic Search

cw lasing has been observed by discharging premixed CS2&sngbnd;O2. The spectral distribution of the output suggests a chemical-pumping mechanism. Additional observations on CS2 + O2 flames indicate the possibility of a flame laser.

C. J. Ultee

1971-01-01

252

Photonic metamaterials by direct laser writing and silver chemical vapour  

E-print Network

LETTERS Photonic metamaterials by direct laser writing and silver chemical vapour deposition online: 11 May 2008; doi:10.1038/nmat2197 Metamaterials are artificial materials that--unlike natural metamaterials4,5 has been fabricated by electron-beam lithography and evaporation of metal films, both of which

253

Remote Chemical Sensing Using Quantum Cascade Lasers  

Microsoft Academic Search

Research done by the IR sensors team at PNNL is focused on developing advanced spectroscopic methods for detecting signatures of nuclear, chemical, biological and explosives weapons or weapons production. The sensors we develop fall into two categories: remote sensors that can be operated at distances ranging from 150 m to 10 km, and point sensors that are used for in-situ

Warren W. Harper; Jana D. Strasburg; Pam M. Aker; John F. Schultz

2004-01-01

254

... production in flowing He/O2 plasmas. II. Two-dimensional modeling Ramesh Arakonia  

E-print Network

In conventional chemical oxygen-iodine lasers COIL the 1.315 m transition in atomic iodine is pumped by a sequence system. Due to the thermodynamic and power loading requirements, the plasma in eCOIL systems is sustained high effi- ciency and potential for multikilowatt cw power.1­6 The chemical oxygen-iodine laser COIL

Kushner, Mark

255

wsolomon@uiuc.edu; phone 1-217-244-7646; fax 1-217-244-0720; http://www.aae.uiuc.edu; Univ. of Illinois, 306 Talbot Lab, 104 S. Wright St., Urbana, IL 61801.  

E-print Network

. Electrodynamic modeling of the ElectriCOIL system Joseph W. Zimmermana , Lawrence W. Skorskia , Wayne C. Solomon oscillation of a chemical oxygen-iodine laser system in conjunction with injection of pre-dissociated iodine temperatures. Keywords: ElectriCOIL, COIL, chemical oxygen iodine laser, electric discharge modeling 1

Carroll, David L.

256

wsolomon@uiuc.edu; phone 1-217-244-7646; fax 1-217-244-0720; http://www.aae.uiuc.edu; Univ. of Illinois, 306 Talbot Lab, 104 S. Wright St., Urbana, IL 61801.  

E-print Network

COIL, COIL, chemical oxygen iodine laser, electric discharge modeling 1. INTRODUCTION The classic chemical permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system, possibly in conjunction studies have indicated that fractions of O2(1 D) can be produced in an electrical discharge that may

Carroll, David L.

257

Continuous graded cavity for unstable resonator laser diodes by laser-assisted chemical etching  

Microsoft Academic Search

A method to photo-etch n-type epitaxially grown GaAs to produce an approximately parabolic cross sectioned channel, has been developed by using laser-assisted chemical etching. Such cavity was later successfully used to create an unstable resonator, for a high-power semiconductor laser with a degree of coherence up to twice the diffraction limit. We show recent experimental results, where channels up to

Salvador Guel Sandoval; Stephen D. Hersee; Alan H. Paxton; John G. McInerney

1996-01-01

258

Laser-induced chemical-vapor deposition of copper with a cw CO2 laser  

Microsoft Academic Search

The kinetics of the thermal deposition of copper film by decomposing bis-(pivaloyl- trifluoroacetonate) copper(II) [Cu(pta)2] is reported. A cw CO2 laser is used to heat a quartz substrate, on which chemical-vapor deposition of copper takes place. The deposition rate is measured insitu by monitoring the transmittance of the copper film with a He-Ne laser. The deposition rates are determined as

Dun-Min Mao; Zhong-Kao Jin; Qi-Zong Qin

1992-01-01

259

An efficient electric-discharge chemical HCl laser  

Microsoft Academic Search

An electric-discharge pulsed chemical laser based on vibration-rotational transitions in the HCl molecule in SF6:H2:Cl2 active-medium mixtures is described. The HCl-laser exhibits a record-high pulse energy, E(HCl), of 0.4 J and an electric efficiency, eta(HCl), of 30 percent, as well as emission due to HF-molecule transitions (2.6-3.1 microns), with an E(HF) of 0.9 J and an eta(HF) of about 60

E. B. Gordon; V. I. Matiushenko; P. B. Repin; V. D. Sizov

1990-01-01

260

Molecular dispersion spectroscopy – new capabilities in laser chemical sensing  

PubMed Central

Laser spectroscopic techniques suitable for molecular dispersion sensing enable new applications and strategies in chemical detection. This paper discusses the current state-of-the art and provides an overview of recently developed chirped laser dispersion spectroscopy (CLaDS) based techniques. CLaDS and its derivatives allow for quantitative spectroscopy of trace-gases and enable new capabilities such as extended dynamic range of concentration measurements, high immunity to photodetected intensity fluctuations, or capability of direct processing of spectroscopic signals in optical domain. Several experimental configurations based on quantum cascade lasers and examples of molecular spectroscopic data are presented to demonstrate capabilities of molecular dispersion spectroscopy in the mid-infrared spectral region. PMID:22809459

Nikodem, Michal; Wysocki, Gerard

2012-01-01

261

ARTICLES: Electron-beam-controlled chemical hydrogen-iodine laser  

NASA Astrophysics Data System (ADS)

A study is made of the feasibility of constructing a hydrogen-iodine laser with electron-beam-controlled excitation, emitting as a result of the 2P1/2?2P3/2 magnetic-dipole transition in atomic iodine (? = 1.315 ?). The necessary iodine atoms are produced in an H2-Ar-I2 mixture as a result of a fast chemical reaction H + I2?HI + I initiated by an electric discharge. An analysis of the main processes combined with a calculation of the distribution function of electrons is used in a numerical modeling of such a laser. It is found that the specific input energy required in a hydrogen-laser is fairly high, 250-300 J·liter-1·atm-1, and that there are optimal values of this input energy and of the initial temperature of the mixture.

Bel'dyugin, Igor'M.; Vysotski?, Yu P.; Stepanov, A. A.; Shcheglov, V. A.

1987-02-01

262

ARTICLES: Electron-beam-controlled chemical hydrogen-iodine laser  

Microsoft Academic Search

A study is made of the feasibility of constructing a hydrogen-iodine laser with electron-beam-controlled excitation, emitting as a result of the 2P1\\/2-->2P3\\/2 magnetic-dipole transition in atomic iodine (lambda = 1.315 mu). The necessary iodine atoms are produced in an H2-Ar-I2 mixture as a result of a fast chemical reaction H + I2-->HI + I initiated by an electric discharge. An

Igor'M. Bel'dyugin; Yu P. Vysotskii; A. A. Stepanov; V. A. Shcheglov

1987-01-01

263

BRIEF COMMUNICATIONS: Efficient electric-discharge HCl chemical laser  

Microsoft Academic Search

The development of a pulsed electric-discharge chemical laser utilizing vibrational-rotational transitions in an HCl molecule (lambda = 3.7-4.1 mum) and having record-high values of the pulse energy (EHCl = 0.4 J) and electrical efficiency (etaHCl approx 30%) is reported. Lasing was observed simultaneously due to transitions in the HF molecule (lambda = 2.6-3.1 mum) with EHF = 0.9 J and

Evgenii B. Gordon; V. I. Matyushenko; P. B. Repin; V. D. Sizov

1990-01-01

264

Electron-beam-controlled chemical hydrogen–iodine laser  

Microsoft Academic Search

A study is made of the feasibility of constructing a hydrogen–iodine laser with electron-beam-controlled excitation, emitting as a result of the 2P1\\/2?2P3\\/2 magnetic-dipole transition in atomic iodine (? = 1.315 ?). The necessary iodine atoms are produced in an H2–Ar–I2 mixture as a result of a fast chemical reaction H + I2?HI + I initiated by an electric discharge. An

Igor M Beldyugin; Yu P Vysotski?; A A Stepanov; V A Shcheglov

1987-01-01

265

Gain anisotropy in low-pressure chemical lasers. Technical report  

SciTech Connect

Continuous-wave (cw) chemical lasers are frequently operated at pressures of the order of 1 Torr to achieve efficient lasing. At these pressures, the medium is inhomogeneously (Doppler) broadened, and the line shape (gain coefficient versus frequency), under power on operation, is a function of the viewing angle. For example, when viewed along the optical-resonator axis, the line shape may have holes because of the radiation field; when viewed from a direction orthogonal to the resonator axis, it is free of holes. This anisotropy of the gain medium is the subject of this study. The purpose is to aid in the experimental validation of numerical cw chemical laser codes wherein the line shape, as viewed along the resonator axis, is predicted, and experimental measurements of power on gain are made from an orthogonal direction. In the first portion of this study, general expressions for line shape are deduced. These expressions are then applied to determine both the axial and orthogonal gain distribution in a low-pressure multimode cw chemical laser with a Fabry-Perot (F-P) resonator.

Mirels

1986-04-15

266

Space-Based Chemical Lasers in strategic defense  

SciTech Connect

The Strategic Defense Initiative Organization (SDIO) has made significant progress in developing Space-Based chemical Laser (SBL) technologies and in studying the SBLs global defense capability. In this mission, a constellation of several orbiting laser platforms provides continuous global defense by intercepting threatening missiles in their boost phase, including short range ballistic missiles (SRBMs). An optional smaller constellation provides defense against launches from the low and midlatitude regions. In addition, SBLs have utility in other important related missions such as surveillance, air defense and discrimination. The hardware necessary to build such a system has been developed to the point where it is mature and ready for demonstration in space. Advances have been made in each of the following major areas of the SBL: laser device; optics/beam control; beam pointing; ATP (acquisition, tracking and pointing); uncooled optics; and laser lethality. Integration of the key laser and beam control technologies is now occurring in the ground-based ALI experiment, and a space demonstration experiment, Star LITE, is in the planning and concept development phase.

Wildt, D. (SDIO, Washington, DC (United States))

1992-07-01

267

Discharge Generation of Atomic Iodine  

Microsoft Academic Search

In this article we describe our new experimental device for generation of atomic iodine in discharge. This device will be a part of the COIL (chemical oxygen-iodine laser) and also DOIL (discharge oxygen-iodine laser) system. There are three main tasks which must be solved for a successful COIL operation: generation of atomic iodine, generation of singlet oxygen (excited oxygen molecule)

I. Pickova; V. Jirasek; J. Schmiedberger

2007-01-01

268

Improved production of O2(a1 ) in capacitively-coupled radio-  

E-print Network

to an electric oxygen- iodine laser (EOIL). At lower pressures, improvements in yield are observed when The classical chemical oxygen-iodine laser first reported by McDermott1 operates on the electronic transition electric discharges for O2(a) production to pump iodine for lasing, but were unable to obtain positive gain

Carroll, David L.

269

Effect of excimer laser irradiation on crystallinity and chemical bonding of biodegradable polymer  

E-print Network

Effect of excimer laser irradiation on crystallinity and chemical bonding of biodegradable polymer: Biodegradable polymer Poly(L-lactic acid) Laser irradiation Chemical modification Crystallinity Radical mobility is favorable for surface treatment. The effects of excimer laser irradiation on the surface morphology

Yao, Y. Lawrence

270

Production of radioactive Ag ion beams with a chemically selective laser ion source  

NASA Astrophysics Data System (ADS)

We have developed a chemically selective laser ion source at the CERN-ISOLDE facility in order to study neutron-rich Ag nuclides. A pulsed laser system with high repetition rate has been used based on high-power copper-vapour pump lasers and dye lasers. With this source significant reductions of the isobaric background has been achieved.

Jading, Y.; Catherall, R.; Jokinen, A.; Jonsson, O. C.; Kugler, E.; Lettry, J.; Ravn, H. L.; Tengblad, O.; Kautzsch, T.; Klöckl, I.; Kratz, K.-L.; Scheerer, F.; Fedoseyev, V. N.; Mishin, V. I.; van Duppen, P.; Wöhr, A.; Walters, W. B.

1996-04-01

271

Quantum cascade laser based standoff photoacoustic chemical detection.  

PubMed

Standoff chemical detection with a distance of more than 41 feet using photoacoustic effect and quantum cascade laser (QCL) operated at relatively low power, less than 40 mW, is demonstrated for the first time. The option of using QCL provides the advantages of easy tuning and modulation besides the benefit of compact size, light weight and low power consumption. The standoff detection signal can be calibrated as a function of different parameters such as laser pulse energy, gas vapor concentration and detection distance. The results yield good agreements with theoretical model. Techniques to obtain even longer detection distance and achieve outdoor operations are in the process of implementation and their projection is discussed. PMID:21997036

Chen, Xing; Cheng, Liwei; Guo, Dingkai; Kostov, Yordan; Choa, Fow-Sen

2011-10-10

272

Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics  

SciTech Connect

This project has comprised laser flame diagnostic experiments, chemical kinetics measurements, and low pressure flame studies. Collisional quenching has been investigated for several systems: the OH radical, by H{sub 2}0 in low pressure flames; the rotational level dependence for NH, including measurements to J=24; and of NH{sub 2} at room temperature. Transition probability measurements for bands involving v{prime} = 2 and 3 of the A-X system of OH were measured in a flame. Laser-induced fluorescence of vinyl radicals was unsuccessfully attempted. RRKM and transition state theory calculations were performed on the OH + C{sub 2}H{sub 4} reaction, on the t-butyl radical + HX; and transition state theory has been applied to a series of bond scission reactions. OH concentrations were measured quantitatively in low pressure H{sub 2}/N{sub 2}O and H{sub 2}/O{sub 2} flames, and the ability to determine spatially precise flame temperatures accurately using OH laser-induced fluorescence was studied.

Crosley, D.R.

1992-09-01

273

Free-Electron Lasers, Thermal Diffusion, Chemical Kinetics, and Surgery  

NASA Astrophysics Data System (ADS)

Experiments demonstrate that the Mark-III FEL is a particularly effective tool for etching soft matter with remarkably little damage surrounding the site when tuned to wavelengths near 6.45 microns. Based on these observatons, human neuorsurgical and ophthalmic procedures were developed and have been performed successfully. A thermodynamic model was proposed to account for the wavelength dependence; however, the dynamics have not been well understood. We have theoretically investigated thermal diffusion and chemical kinetics in a system of alternating layers of protein and water as heated by a Mark-III FEL. The model is representative of cornea and the exposure conditions are comparable to previous experimental FEL investigations. A substantial temperature enhancement develops in the surface layer on the ten-nanosecond time scale. We consider the onset of both the helix-coil transition and chemical bond breaking of collagen in terms of the thermal, chemical, and structural properties of the system as well as laser wavelength and pulse structure.

Edwards, Glenn; Hutson, M. Shane

2001-11-01

274

Recent results in the development of a chemical way of atomic iodine generation for a COIL  

NASA Astrophysics Data System (ADS)

The results of theoretical and experimental investigation of gas phase chemical generation of atomic iodine, I(2P3/2), for stimulated emission in chemical oxygen-iodine laser (COIL) are presented. The method of I atoms generation employs a principal reaction X+HI implies I(2P3/2)+HX, where X equals F or Cl. A computational modeling was based on the 1D flow development exploring the chemical processes within the reaction systems, and was aimed at the theoretical understanding of the two complex reaction systems and finding out which is better applicable for conditions in COIL. The results of modeling were further used for a design of the device and conditions during the experimental investigation, and for an interpretation of the experimental results. The experimental work has been done, for the present, on the atomic iodine generation via Cl atoms. A high yield of atomic iodine of 70% to 100% (related to the initial HI flow rate) was attained in a flow of nitrogen. Gain was observed in preliminary experiments on the chemical generation of atomic iodine in a flow of singlet oxygen.

Kodymova, Jarmila; Spalek, Otomar; Jirasek, Vit; Censky, Miroslav; Hager, Gordon D.

2002-09-01

275

Evaluation of vaned diffuser performance applicable to chemical laser pressure recovery systems  

Microsoft Academic Search

In order to operate weapon-level chemical lasers, such as DF or COIL, or test articles, such as the Alpha HF chemical laser, in the atmosphere it is necessary to recover as much of the velocity component of the flow and convert it to pressure as possible. This conversion is accomplished through diffusers which decelerate the flow from supersonic to near

Robert Acebal

1994-01-01

276

Laser assisted chemical vapor deposition synthesis of carbon nanotubes and their characterization  

E-print Network

to determine a suitable manufacturing process. To date, carbon nanotubes have been synthesized in relativelyLaser assisted chemical vapor deposition synthesis of carbon nanotubes and their characterization S of carbon nanotubes using the laser assisted chemical vapor deposition process was studied to determine

Wang, Zhong L.

277

Quantum cascade laser development efforts for implementation into chemical and remote sensing systems  

Microsoft Academic Search

Quantum cascade laser (QCL) offer many desirable attributes as mid-infrared laser sources for chemical and remote sensing. Some key advantages are a narrow linewidth, wide bandwidth current modulation characteristics and moderate tunability (15 cm-1). Combined, these characteristics allow for applications to a wide variety of chemical and remote sensing techniques such as wavelength and frequency modulation based detection techniques, cavity

Michael D. Wojcik; Tanya L. Myers; Matthew S. Taubman; Bret D. Cannon; Bryan T. Broocks; Trinesha Mosely

2004-01-01

278

Microchemical systems for singlet oxygen generation  

E-print Network

Chemical Oxygen-Iodine Lasers (COIL) are a technology of interest for industrial and military audiences. COILs are flowing gas lasers where the gain medium of iodine atoms is collisionally pumped by singlet delta oxygen ...

Hill, Tyrone F. (Tyrone Frank), 1980-

2008-01-01

279

Laser Chemical Vapor Deposition of Titanium Nitride and Process Diagnostics with Laser-Induced Fluorescence Spectroscopy.  

NASA Astrophysics Data System (ADS)

TiN films have been deposited on Ti-6Al-4V substrates by a cw CO_2 laser chemical vapor deposition (LCVD) process with TiCl_4, H_2, and N_2. Pulsed dye laser induced fluorescence (LIF) spectroscopy is used to obtain transient gas phase Ti atomic concentration above the substrate. Multi-wavelength pyrometry is applied to measure the surface temperature during deposition. Film thickness profiles are obtained by stylus profilometry, and film compositions are analyzed by Auger Electron Spectroscopy (AES). Very high film growth rates are found in the order of 1 mum/sec. The dependencies of the film growth rate on partial pressure ratio N _2:H_2, TiCl _4 partial pressure, total chamber pressure, and laser power are studied, and empirical relationships between the growth rate and TiCl_4, H_2, and N_2 partial pressures are established. The results suggest that the deposition is mainly due to chemical reactions on the substrate surface that is initiated by laser heating. The time change of Ti atomic concentration above the center of the deposition area measured by LIF is found to behave in the same way as the film thickness when experimental conditions are varied. Therefore, the LIF signal can be used as an in situ diagnostic tool for process monitoring and control. Possible surface reaction pathways and the rate-controlling steps are suggested. The apparent activation energy is found to be (115.0 +/- 10.7) kJ/mol for a substrate center temperature of 1339 K to 1515 K, a total pressure of 600 Torr, a partial pressure ratio N_2:H_2 of 3:1, and a TiCl_4 partial pressure of 27 Torr. AES analyses indicate that all the TiN _{rm x} films are in the range x = 0.8 +/- 0.1, with one exception of x = 0.6 for the lowest total pressure (Total = 100 Torr, N_2:H_2 = 3:1, TiCl_4 = 27 Torr, Laser Power = 400 W). Films are obtained with Cl atomic concentration as low as <0.5%, and O and C atomic concentrations as low as <1%. Finally, suggestions are made for improved numerical modeling based on the new findings.

Chen, Xiangli

280

Numerical analysis on the beam quality improvements of high power chemical laser system with water cooled mirrors  

Microsoft Academic Search

Chemical laser is one of the most widely used high power infrared sources. Thermal deformation of mirrors in a resonator is a key factor which hinders the improvement of the beam quality in high power chemical lasers, and it has been a matter of the utmost concern in the design of high power chemical laser systems. Water-cooled technique is one

Kai Han; Bin Li; Xiao-Jun Xu

2011-01-01

281

Metal film deposition by laser breakdown chemical vapor deposition  

SciTech Connect

Dielectric breakdown of gas mixtures can be used to deposit homogeneous thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas phase nucleation and particle formation. Using a pulsed CO/sub 2/ laser operating at 10.6 microns where there is no significant resonant absorption in any of the source gases, we have succeeded in depositing homogeneous films from several gas phase precursors by gas phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls and tungsten from the hexafluoride have been examined to date. In each case the gas precursor is buffered to reduce the partial pressure of the reactants and to induce breakdown. The films are spectrally reflective and uniform over a large area. Films have been characterized by Auger electron spectroscopy, x-ray diffraction, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed x-ray diffraction analysis of these films yields a very small domain size (approx. 50 A) consistent with rapid quenching from the gas phase reaction zone. This analysis also shows nickel carbide formation consistent with the temperature of the reaction zone and the Auger electron spectroscopy results which show some carbon and oxygen incorporation (8% and 1% respectively). Gas phase transport and condensation of the molybdenum carbonyl results in substantial carbon and oxygen contamination of the molybdenum films requiring heated substrates, a requirement not consistent with the goals of the program to maximize the quench rate of the deposition. Results from tungsten deposition experiments representing a reduction chemistry instead of the decomposition chemistry involved in the carbonyl experiments are also reported.

Jervis, T.R.

1985-01-01

282

Laser Applications to Chemical, Security, and Environmental Analysis: introduction to the feature issue  

SciTech Connect

This Applied Optics feature issue on Laser Applications to Chemical, Security,and Environmental Analysis (LACSEA) highlights papers presented at theLACSEA 2006 Tenth Topical Meeting sponsored by the Optical Society ofAmerica.

Dreizler, Andreas; Fried, Alan; Gord, James R

2007-07-01

283

Optimization of an External Cavity Quantum Cascade Laser for Chemical Sensing Applications  

SciTech Connect

We describe and characterize an external cavity quantum cascade laser designed for detection of multiple airborne chemicals, and used with a compact astigmatic Herriott cell for sensing of acetone and hydrogen peroxide.

Phillips, Mark C.; Bernacki, Bruce E.; Taubman, Matthew S.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

2010-03-01

284

Observation of high laser gain at 703 nm in a new chemical system  

Microsoft Academic Search

Results are presented on gain measurements in a new chemical laser system demonstrating positive gain in the visible spectral region. It is shown that visible stimulated emission is due to a metastable O4 complex produced in a sequence of reactions generally employed in a high power iodine laser (COIL). A maximum positive gain of 2.8 percent was measured at 703

Sanichiro Yoshida; Manabu Taniwaki; Tatsuo Sawano; Kouki Shimizu; Tomoo Fujioka

1989-01-01

285

Laser power effects on the Raman spectrum of isolated diamond chemical vapor deposition particles  

Microsoft Academic Search

In the present work the effect of incident laser power on the Raman spectra of diamond isolated particles and continuous films deposited on silicon and glassy carbon (GC) substrates by the chemical vapor deposition method is investigated. It is shown that the Raman line position measured for diamond particles shifts to lower wave numbers as a function of incident laser

A. Laikhtman; A. Hoffman

1997-01-01

286

Fast infrared chemical imaging with a quantum cascade laser.  

PubMed

Infrared (IR) spectroscopic imaging systems are a powerful tool for visualizing molecular microstructure of a sample without the need for dyes or stains. Table-top Fourier transform infrared (FT-IR) imaging spectrometers, the current established technology, can record broadband spectral data efficiently but requires scanning the entire spectrum with a low throughput source. The advent of high-intensity, broadly tunable quantum cascade lasers (QCL) has now accelerated IR imaging but results in a fundamentally different type of instrument and approach, namely, discrete frequency IR (DF-IR) spectral imaging. While the higher intensity of the source provides a higher signal per channel, the absence of spectral multiplexing also provides new opportunities and challenges. Here, we couple a rapidly tunable QCL with a high performance microscope equipped with a cooled focal plane array (FPA) detector. Our optical system is conceptualized to provide optimal performance based on recent theory and design rules for high-definition (HD) IR imaging. Multiple QCL units are multiplexed together to provide spectral coverage across the fingerprint region (776.9 to 1904.4 cm(-1)) in our DF-IR microscope capable of broad spectral coverage, wide-field detection, and diffraction-limited spectral imaging. We demonstrate that the spectral and spatial fidelity of this system is at least as good as the best FT-IR imaging systems. Our configuration provides a speedup for equivalent spectral signal-to-noise ratio (SNR) compared to the best spectral quality from a high-performance linear array system that has 10-fold larger pixels. Compared to the fastest available HD FT-IR imaging system, we demonstrate scanning of large tissue microarrays (TMA) in 3-orders of magnitude smaller time per essential spectral frequency. These advances offer new opportunities for high throughput IR chemical imaging, especially for the measurement of cells and tissues. PMID:25474546

Yeh, Kevin; Kenkel, Seth; Liu, Jui-Nung; Bhargava, Rohit

2015-01-01

287

Quantum Cascade Laser Development Efforts for Implementation into Chemical and Remote Sensing Systems  

SciTech Connect

Quantum cascade lasers (QCL) offer many desirable attributes as mid-infrared laser sources for chemical and remote sensing. Some key advantages are a narrow linewidth, wide bandwidth current modulation characteristics and moderate tunability (15 cm-1). Combined, these characteristics allow for applications to a wide variety of chemical and remote sensing techniques such as wavelength and frequency modulation based detection techniques, cavity enhanced point sensors as well as techniques such as LIDAR and DIAL. This paper will describe laser development efforts to enhance QCL frequency stabilization and QCL injection locking and to develop robust external cavity QCL designs.

Wojcik, Michael D.; Myers, Tanya L.; Taubman, Matthew S.; Cannon, Bret D.; Broocks, Bryan T.; Mosely, Trinesha

2004-12-01

288

Time and wavelength domain algorithms for chemical analysis by laser radar  

NASA Technical Reports Server (NTRS)

Laser-induced fluorescence (LIF) is a promising technique for laser radar applications. Laser radar using LIF has already been applied to algae blooms and oil slicks. Laser radar using LIF has great potential for remote chemical analysis because LIF spectra are extremely sensitive to chemical composition. However, most samples in the real world contain mixtures of fluorescing components, not merely individual components. Multicomponent analysis of laser radar returns from mixtures is often difficult because LIF spectra from solids and liquids are very broad and devoid of line structure. Therefore, algorithms for interpreting LIF spectra from laser radar returns must be able to analyze spectra that overlap in multicomponent systems. This paper analyzes the possibility of using factor analysis-rank annihilation (FARA) to analyze emission-time matrices (ETM) from laser radar returns instead of excitation-emission matrices (EEM). The authors here define ETM as matrices where the rows (or columns) are emission spectra at fixed times and the columns (or rows) are temporal profiles for fixed emission wavelengths. Laser radar usually uses pulsed lasers for ranging purposes, which are suitable for measuring temporal profiles. Laser radar targets are hard instead of diffuse; that is, a definite surface emits the fluorescence instead of an extended volume. A hard target would not broaden the temporal profiles as would a diffuse target. Both fluorescence lifetimes and emission spectra are sensitive to chemical composition. Therefore, temporal profiles can be used instead of excitation spectra in FARA analysis of laser radar returns. The resulting laser radar returns would be ETM instead of EEM.

Rosen, David L.; Gillespie, James B.

1992-01-01

289

Simulation of a two-frequency cw chemical HF-HBr laser  

SciTech Connect

An autonomous cw chemical HF-HBr laser emitting simultaneously at {approx}2.7 {mu}m (HF molecules) and {approx}4.2 {mu}m (HBr molecules) is studied numerically by using complete Navier-Stokes equations. It is shown that the output power of the HBr laser per unit area of the nozzle array can achieve {approx}20 W cm{sup -2} for the laser region length {approx}20 cm. The relation between the radiation intensities emitted by HF and HBr molecules is controlled by diluting the secondary fuel by bromine. (lasers)

Aleksandrov, B P; Katorgin, B I; Stepanov, A A [Open Joint-Stock Company, V. P. Glushko Energomash Research and Production Assocation, Khimki-1, Moscow region (Russian Federation)

2008-10-31

290

Effects of translational and rotational nonequilibrium on c-w chemical-laser performance. Technical report  

SciTech Connect

A previous model used to describe continuous-wave (c-w) chemical laser performance is generalized to include rotational as well as translational nonequilibrium. The resultant equations are simplified by the realistic assumption that translational and rotational relaxation rates are fast compared with convection, chemical pumping, and collisional deactivation rates. As a consequence, translational and rotational relaxation rates are in equilibrium with stimulated emission. The resultant system of equations is independent of rotational relaxation. An amplifier solution is presented that predicts saturation effects in accord with experiments. Fabry-Perot oscillator solutions are also presented for a multiline saturated laser and for a partly saturated single-lien laser. These present results provide a base for simplification of numerical codes. It is concluded that a resonable first estimate for c-w chemical laser performance can be obtained by assuming rotational equilibrium and translational nonequilibrium.

Mirels, H.

1988-03-01

291

Analysis of nonlinear chemically reactive flow characteristic of high energy laser systems  

Microsoft Academic Search

This paper is concerned with the mechanics and computation of the performance of a high energy chemical laser of the HF type. The analysis requires solving the viscous, compressible supersonic flow equations which are coupled to the chemical and optical characteristics of the flowing gas media. A finite element method is chosen for performing the computation. The physical system simulated

T. J. Chung; G. R. Karr

1980-01-01

292

Laser micromachined and laminated microchannel components for chemical sensors and heat transfer applications  

Microsoft Academic Search

The fabrication of microchannel chemical sensors with seven laminated individual functional modules is described. The sensors, used to detect chromium in nuclear and chemical waste streams, were fabricated using laser micromachining, bulk silicon micromachining, photolithographic techniques, sputter coating deposition, and anodic and adhesive bonding processes. The size of the sensor was 2 cm by 2.2 cm, with a total thickness

Peter M. Martin; Wendy D. Bennett; D. J. Hammerstrom; John W. Johnston; Dean W. Matson

1997-01-01

293

A Diode Laser Chemical Sensor Utilizing an Oxidized Lower Cladding Layer for High Sensitivity  

E-print Network

A Diode Laser Chemical Sensor Utilizing an Oxidized Lower Cladding Layer for High Sensitivity Chad@engineering.ucsb.edu Tel: 805.893.7065 Abstract: We demonstrate a novel chemical sensor incorporating a symmetrically-clad clad, and have tight optical confinement [4]. Symmetrically clad dielectric waveguides have been

Coldren, Larry A.

294

CO2 laser scribe of chemically strengthened glass with high surface compressive stress  

NASA Astrophysics Data System (ADS)

Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

Li, Xinghua; Vaddi, Butchi R.

2011-03-01

295

Predictions of Chemical Species via Diode Laser Spectroscopy  

NASA Technical Reports Server (NTRS)

A technique to predict temperature and chemical species in flames from absorbance measurement of one chemical species is presented. Predicted temperature and mole fractions of methane and water agreed well with measured and published results.

Chen, Shin-Juh; Silver, Joel A.; Dahm, Werner J. A.; Piltch, Nancy D.; Salzman, Jack (Technical Monitor)

2001-01-01

296

Synthesis of carbon nanotubes by laser-assisted alcohol chemical vapor deposition  

NASA Astrophysics Data System (ADS)

A laser-assisted alcohol chemical vapor deposition (CVD) process was carried out on a quartz substrate without a thick absorption layer, as a result of which, the substrate retained its transparency. The thickness of the carbon nanotube (CNT) film grown with 120 s of laser irradiation was 16.6 ?m, which was three orders of magnitude thicker than the CNT film grown without laser irradiation. The area of growth enhancement was nearly the same size as the laser spot, which implies that this method can be used for position-controlled CNT growth. In addition, the laser-assisted method can be used to decrease the process temperature. Raman spectra also showed the enhancement of CNT growth from the higher signal intensity of the G and D bands from the laser-irradiated sample.

Akahane, Kouichi; Yamamomto, Naokatsu; Maeda, Makoto; Takai, Hiroshi; Nakamura, Shin-ichi; Yamaguchi, Hiroshi; Sotobayashi, Hideyuki

2014-02-01

297

Results of investigations of overtone supersonic cw chemical HF lasers  

Microsoft Academic Search

Overtone supersonic cw HF laser with power density of about 8 kW is developed. Efficiency of the laser relative to emission of the main tone is about 40%. Coefficient of active medium gain measured by the technique of calibrated losses is (5.5 divided by 7.8)(DOT)10-4 cm-1. Designed wavelength- discriminating mirrors operated at power density of about 40 kW\\/cm2 (90 kW\\/cm2

I. A. Fedorov; S. V. Konkin; V. K. Rebone; M. A. Rotinyan; Yu. P. Maksimov; A. A. Belyaev; Oleg B. Danilov; Aleksandr P. Zhevlakov

1998-01-01

298

IR LASER BASED CHEMICAL SENSOR FOR THE COOPERATIVE MONITORING PROGRAM  

SciTech Connect

The purpose of this project was to investigate the device properties of the quantum cascade laser (QCL), a type of laser invented at Bell Laboratories, Lucent Technologies in the device physics research lab of Dr. Federico Capasso and more specifically to determine the remote sensing capability of this device. The PI and Stevens Institute of Technology collaborated with Dr. Capasso and Bell Laboratories to carry out this research project. The QCL is a unique laser source capable of generating laser radiation in the middle-infrared spectral region that overlaps the most important molecular absorption bands. With appropriate modulation techniques it is possible to use the laser to measure the concentration of many molecules of interest to the remote sensing community. In addition, the mid-IR emission wavelength is well suited to atmospheric transmission as mid-IR experiences much less scattering due to dust and fog. At the onset of this project little was known about several key device performance parameters of this family of lasers and the NNSA supported research enabled them to determine values of several of these characteristics.

Edward A Whitaker

2005-08-08

299

Progress toward realization of a KW-class EOIL laser  

NASA Astrophysics Data System (ADS)

The electric oxygen iodine laser (EOIL) offers a vastly more practical, implementable, and safer alternative to its predecessor, the chemical oxygen iodine laser (COIL), particularly for airborne or other mobile military applications. Despite its promise and after 25 years effort, numerous laboratories around the world have not succeeded in providing the known basic physical requirements needed to electrically convert O II into O II(a1?)with the fractional yields and efficiencies needed to make a practical laser. Hence, as of this date, the world record power generated from an EOIL device is only 6.5 watts. In this paper, a 30% conversion from O II into O II(a1?) operating at substantial oxygen mass flow rates (0.090 moles O II/sec at 50 torr) and 40% electrical efficiency is reported. The O II(a1?) flow stream being produced carries 2400 watts. Gain measurements are currently in progress, to be followed shortly by power extraction. Current conditions imply that initial power extraction could push beyond 1 KW. Efforts to date have failed to generate substantial laser power because critical criteria have not been met. In order to achieve good O II(a1?) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O II while efficiently removing the waste heat energy from the generator so that less than a few hundred degrees Kelvin rise occurs due to gas heating. The generator must be excited by an electric field on the order of 10 Td. This is far below glow potential; hence, a fully externally sustained plasma generation technique is required. Ionization is supplied by means of applying short (tens of nanosecond) pulses to the O II(a1?) generator at 50,000 PPS, which are on the order of ten times breakdown potential. This enables a quasi-steady adjustable DC current to flow through the generator, being conducted by application of a DC, 10 to 14 Td pump E-field. This field is also independently tunable. The result is that up to 180 KJ/mole O II gets imparted to the gas by means of the ~6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O II(b1?) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O II to O II(a1?) has been achieved. Fortuitously, neither excited O atom production nor O II(b1?) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O II(a1?) line. Energy normally partitioned to O II(b1?) and apparently O atoms now feeds into O II(a1?) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I II disassociating mixing section - then subsequently a 20 cm transverse M = 2.5 laser channel - has been coupled to the O II(a1?) generator. The effects of titrating NO, NO II, etc. to scavenge O atoms and O 3 atoms is under current investigation. Laser power extraction will commence after having optimized all parameters to achieve maximum gain.

Hill, Alan E.

2008-02-01

300

Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing  

DOEpatents

Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

Taubman, Matthew S; Phillips, Mark C

2014-03-18

301

OPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERING University of New Mexico  

E-print Network

SSL laser systems. SSL, fiber lasers and ultrashort lasers (USL) will be discusses. A unique thermal Iodine Laser (PIL) and Chemical-Oxygen Iodine Laser (COIL), greatly improved their HEL performance made in High Energy Laser (HEL) technology using both chemical reactions and electrical discharge

New Mexico, University of

302

OPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERINGOPTICAL SCIENCE & ENGINEERING University of New Mexico  

E-print Network

SSL laser systems. SSL, fiber lasers and ultrashort lasers (USL) will be discusses. A unique thermal Iodine Laser (PIL) and Chemical-Oxygen Iodine Laser (COIL), greatly improved their HEL performance advances made in High Energy Laser (HEL) technology using both chemical reactions and electrical discharge

New Mexico, University of

303

Ultrasensitive standoff chemical sensing based on nonlinear multi-photon laser wave-mixing spectroscopy  

NASA Astrophysics Data System (ADS)

Nonlinear multi-photon laser wave mixing is presented as an ultrasensitive optical detection method for chem/bio agents in thin films and gas- and liquid-phase samples. Laser wave mixing is an unusually sensitive optical absorption-based detection method that offers significant inherent advantages including excellent sensitivity, small sample requirements, short optical path lengths, high spatial resolution, high spectral resolution and standoff remote detection capability. Wave mixing can detect trace amounts of chemicals even when using micrometer-thin samples, and hence, it can be conveniently interfaced to fibers, microarrays, microfluidic systems, lab-on-a-chip, capillary electrophoresis and other capillary- or fiber-based chemical separation systems. The wave-mixing signal is generated instantaneously as the two input laser beams intersect inside the analyte of interest. Laser excitation wavelengths can be tuned to detect multiple chemicals in their native form since wave mixing can detect both fluorescing and non-fluorescing samples at parts-pertrillion or better detection sensitivity levels. The wave-mixing signal is a laser-like coherent beam, and hence, it allows reliable and effective remote sensing of chemicals. Sensitive wave-mixing detectors offer many potential applications including sensitive detection of biomarkers, early detection of diseases, sensitive monitoring of environmental samples, and reliable detection of hazardous chem/bio agents with a standoff detection capability.

Gregerson, Marc; Hetu, Marcel; Iwabuchi, Manna; Jimenez, Jorge; Warren, Ashley; Tong, William G.

2012-10-01

304

LDRD final report on high power broadly tunable Mid-IR quantum cascade lasers for improved chemical species detection.  

SciTech Connect

The goal of our project was to examine a novel quantum cascade laser design that should inherently increase the output power of the laser while simultaneously providing a broad tuning range. Such a laser source enables multiple chemical species identification with a single laser and/or very broad frequency coverage with a small number of different lasers, thus reducing the size and cost of laser based chemical detection systems. In our design concept, the discrete states in quantum cascade lasers are replaced by minibands made of multiple closely spaced electron levels. To facilitate the arduous task of designing miniband-to-miniband quantum cascade lasers, we developed a program that works in conjunction with our existing modeling software to completely automate the design process. Laser designs were grown, characterized, and iterated. The details of the automated design program and the measurement results are summarized in this report.

Wanke, Michael Clement; Hudgens, James J.; Fuller, Charles T.; Samora, Sally; Klem, John Frederick; Young, Erik W.

2006-01-01

305

Initiation of the emission of chemical gas lasers by neutron fluxes  

NASA Astrophysics Data System (ADS)

The possibility of initiating chemical lasers through a nuclear reaction is examined, and the required threshold density of a neutron flux is determined. In particular, attention is given to the conditions of lasing using UF6-H2, UF6-H2-F2, and UF6-D2-F2-CO2 mixtures in the case of a branched chain reaction. The possibility of chemical laser initiation using UF-containing mixtures, without any external neutron source, is demonstrated for the case where the total mass of the UF6 gas containing enriched uranium exceeds the critical mass.

Basov, N. G.; Molchanov, A. G.; Oraevskii, A. N.

306

Chemical-specific imaging of shallowly buried objects using femtosecond laser pulses.  

PubMed

We demonstrate that objects buried in sand (1 to 4 mm deep) may be selectively imaged according to their chemical composition through spectral analysis of the laser-induced breakdown signal. The signal is generated by loosely focused femtosecond laser pulses having energies ranging from 0.5 to 2.5 mJ. We determine the depth from which a spectral signal may be measured as a function of pulse energy. Having in mind applications to remote sensing, chemical-specific imaging of shallowly buried objects may find use in various fields ranging from space exploration to landmine detection. PMID:23852190

Strycker, B D; Wang, K; Springer, M; Sokolov, A V

2013-07-10

307

Pulsed laser evaporation of boron/carbon pellets: Infrared spectra and quantum chemical structures and frequencies for BCp  

E-print Network

Pulsed laser evaporation of boron/carbon pellets: Infrared spectra and quantum chemical structures March 1993) Pulsed laser evaporation of pellets pressed from boron and graphite powder gave a new 1 by pulsed laser evaporation3 and the formation of small carbon clusters including C3, Cs , Cg, and C

Martin, Jan M.L.

308

Open-air laser-induced chemical vapor deposition of silicon carbide coatings  

Microsoft Academic Search

This study demonstrates the open-air deposition of amorphous hydrogenated silicon carbide (a-SiC:H) by laser-induced chemical vapor deposition (LCVD) using an enclosureless (open-air) reactor system. Films are deposited on fused quartz substrates using the precursor gas trimethylsilane (TrMS). Based on Auger electron spectroscopy (AES), Fourier transform infrared absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the film's chemical composition and microstructure

Christopher J. Jensen; Wilson K. S. Chiu

2006-01-01

309

Chemical Changes Associated with Increased Acid Resistance of Er:YAG Laser Irradiated Enamel  

PubMed Central

Background. An increase in the acid resistance of dental enamel, as well as morphological and structural changes produced by Er:YAG laser irradiation, has been reported. Purpose. To evaluate the chemical changes associated with acid resistance of enamel treated with Er:YAG laser. Methods. Forty-eight enamel samples were divided into 4 groups (n = 12). Group I (control); Groups II, III, and IV were irradiated with Er:YAG at 100?mJ (12.7?J/cm2), 200?mJ (25.5?J/cm2), and 300?mJ (38.2?J/cm2), respectively. Results. There were significant differences in composition of irradiated groups (with the exception of chlorine) and in the amount of calcium released. Conclusions. Chemical changes associated with an increase in acid resistance of enamel treated with Er:YAG laser showed a clear postirradiation pattern characterized by a decrease in C at.% and an increase in O, P, and Ca at.% and no changes in Cl at.%. An increased Ca/P ratio after Er:YAG laser irradiation was associated with the use of higher laser energy densities. Chemical changes produced by acid dissolution showed a similar trend among experimental groups. Stable or increased Ca/P ratio after acid dissolution was observed in the irradiated groups, with reduction of Ca released into the acid solution. PMID:24600327

Olea-Mejía, Oscar Fernando; García-Fabila, María Magdalena; Rodríguez-Vilchis, Laura Emma; Sánchez-Flores, Ignacio; Centeno-Pedraza, Claudia

2014-01-01

310

Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis  

SciTech Connect

Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting to the formation of sub-30 nm craters. Laser Induced Breakdown Spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full-with-at-half-maximum) was possible, which are among the smallest ever reported for femtosecond LIBS.

Zormpa, Vasileia; Mao, Xianglei; Russo, Richard E.

2010-02-02

311

LIBS and LITE Emission Based Laser Remote Sensing of Chemical Species and Enhanced Modeling of Atmospheric Absorption  

Microsoft Academic Search

Laser-Induced Breakdown spectroscopy (LIBS) and Laser-Induced Thermal Emission (LITE) emission based laser remote sensing were investigated with the application to the remote measurements of trace chemical species. In particular, UVvisible LIBS and Mid-IR LITE systems were developed and measurements of remote targets and chemical surfaces were studied. The propagation through the atmosphere of the multi-wavelength backscattered LIBS and LITE optical

Dzianis V. Pliutau

2010-01-01

312

Overview of the SDI (Strategic Defense Initiative) Program in short wavelength chemical lasers  

SciTech Connect

Advanced chemical lasers promise to be effective space-based weapons against responsive threats. In this program, we are developing both CW and pulsed concepts for achieving this goal. Certain approaches may also be appropriate as ground-based weapons and fusion drivers. 12 refs., 1 fig., 5 tabs.

Jones, C.R.

1988-01-01

313

Monte Carlo simulation of laser induced chemical vapor deposition Yehuda Zeiri, Uzi Atzmony, and Joseph Bloch  

E-print Network

Monte Carlo simulation of laser induced chemical vapor deposition Yehuda Zeiri, Uzi Atzmony 21 September 1989; accepted for publication 30 November 1990) We have used a Monte Carlo method developed a Monte Carlo procedure which was used to simulate the LICVD process. The beam inten- sities used

Zeiri, Yehuda

314

Combined Effects of Laser Irradiation and Chemical Inhibitors on the Dissolution of Dental Enamel  

Microsoft Academic Search

It has previously been shown that the susceptibility of human teeth to acid dissolution can be reduced by the presence of various chemical agents in the dissolution medium or by pretreatment of the teeth with laser irradiation. Now synergism between these two approaches to improving acid resistance has been demonstrated. Extracted human teeth were irradiated with a continuous-wave carbon dioxide

J. L. Fox; D. Yu; M. Otsuka; W. I. Higuchi; J. Wong; G. Powell

1992-01-01

315

Effect of sample compositions on chemical analysis using matrix-assisted laser desorption ionization mass spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption ionization (MALDI) is an effective ionization technique for mass spectrometry. It take advantages of some unique properties of certain organic chemicals to provide entrapment, isolation, vaporization, and ionization of the analyte of interest. While the main application of the MALDI technique is currently in the area of biological molecule analysis, it is possible to use this technique

David Schriemer; Yuqin Dai; Liang Li

1996-01-01

316

Effects of chemical kinetics of the performance of the atomic iodine laser system  

NASA Astrophysics Data System (ADS)

Model calculations show that chemical reactions which take place in the active medium of a photolytically pumped iodine laser limit the efficiency with which pump photons are utilized and convert significant amounts of the starting material RI to the unwanted by-products R2 and I2. Laser- and RF-discharge-based methods for regenerating starting materials from by-products are evaluated experimentally. For economical operation of large iodine laser systems, CF3I is presently the best starting material, and a pulsed RF-discharge technique is presently the best one for chemical regeneration. The absorbed energy required to regenerate one CF3I molecule using pulsed RF-discharge techniques is 5.8 eV.

Fisk, G. A.; Truby, F. K.

1980-01-01

317

Generation of cavitation luminescence by laser-induced exothermic chemical reaction  

NASA Astrophysics Data System (ADS)

Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxide concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.

Jung Park, Han; Diebold, Gerald J.

2013-08-01

318

Facilities: NHMFL 9.4 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Citation: Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry  

E-print Network

: Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry for Analysis of atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/ LIAD-CI) source. The laser a powerful new approach for the analysis of saturated hydrocarbon mixtures: atmospheric pressure laser

Weston, Ken

319

Chlorine monofluoride-hydrogen electric discharge chemical laser  

Microsoft Academic Search

The lasing characteristics of a ClF-H2-M mixture with short pulsed initiation of chemical reactions in a transverse electrical gas discharge are investigated. Experiments were conducted on a setup incorporating a discharge chamber in an optical cavity, two pulse power sources, a synchronization unit, a gas injection and evaluation system, and a system to record the energy, pulse shape and spectral

V. B. Kolovskiy; S. A. Drobakha; G. P. Zhitneva; G. A. Abakumov; A. P. Simonov

1986-01-01

320

Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics  

SciTech Connect

We have made a detailed study of the care that must be taken to correctly measure OH radical concentrations in flames. A large part of these studies has concerned collisional quenching of hydride radical species (OH, NH, and NH{sub 2}), in particular the dependence upon rotational level and collision velocity (temperature). The results on OH and NH have shown unique and interesting behavior from the viewpoint of fundamental molecular dynamics, pointing to quenching often governed by collisions on an anisotropic, attractive surface, whereas NH{sub 2} quenching appears to depend on state-mixing considerations, not dynamic control. This state-specific behavior of these small, theoretically tractable hydrides has direct ramifications for quantitative flame diagnostics. Our other effort in the diagnostic area has been repeated but unsuccessful searches for laser induced fluorescence in the vinyl radical.

Crosley, D.R.

1991-01-22

321

Characterizing effects and benefits of beam defocus on high energy laser performance under thermal blooming and turbulence conditions for air-to-ground engagements  

NASA Astrophysics Data System (ADS)

This dissertation makes contributions towards knowledge of optimizing of laser weapon performance when operating in the air-to-ground (ATG) regime in thermal blooming conditions. Wave optics modeling techniques were used to represent laser weapon performance in a high fidelity sense to allow progress to be made toward improving lower-fidelity scaling laws that can be used in systems level analysis which has need for better representations of thermal blooming. Chemical-oxygen iodine laser (COIL) based weapon systems that operate near the ground will experience thermal blooming due to atmospheric absorption if output power is sufficiently high. The thermal lens in the ATG case is predominantly in the far-field of the optical system which puts the problem outside the envelope for most classical phase correction techniques. Focusing the laser beyond the target (defocus) in the air-to-ground regime is shown to improve irradiance at the target and can be thought of as reducing the thermal blooming distortion number, ND, rather than phase correction. Improvement is shown in a baseline scenario presented and all variations from it explored herein. The Breaux ND is examined for potential use in a defocus scaling law, and a correction factor due to Smith (1977), developed for a different context, is proposed to address deficiencies. Optimal defocus settings and expected improvement are presented as a function of Breaux ND. Also, the generally negative interaction between turbulence and thermal blooming is investigated and shown to further limit performance potential of ATG laser weapons. This negative interaction can impact the weapon design trade space and operational methods for minimizing the interaction and thermal blooming are explored in a case study.

Long, Scott N.

2008-10-01

322

Chemical and microstructural transformations in lithium iron phosphate battery electrodes following pulsed laser exposure  

NASA Astrophysics Data System (ADS)

Multi-layer lithium iron phosphate (LFP) battery electrodes are exposed to nanosecond pulsed laser radiation of wavelength 1064 nm. Test parameters are chosen to achieve characteristic interaction types ranging from partial incision of the active coating layers only to complete penetration of the electrodes with high visual cut quality. Raman spectroscopy is performed on unexposed regions and at points approaching each incision, highlighting changes in chemical composition and microstructure in the heat affected zone (HAZ). Thermogravimetric analysis is performed on the unexposed electrode active materials to distinguish the development of compositional changes under conditions of slow heating below the melting and sublimation temperatures. A brief theoretical description of the physical phenomena taking place during laser exposure is provided in terms of direct ablation during each laser pulse and vaporization or thermal degradation due to conductive heat transfer on a much longer time-scale, with characteristics of the HAZ reported in terms of these changes. For all laser exposures carried out in the study, chemical and microstructural changes are limited to the visible HAZ. Some degree of oxidation and LFP olivine phase degradation is observed in the cathode, while the polycrystalline graphite structure becomes less ordered in the anode. Where complete penetration is achieved, melting of the cathode active layer and combustion of the anode active layer take place near the cut edge due to thermal conduction from the metallic conductive layers. The presented results provide insight into the effects of laser processing on LFP electrode integrity.

Lutey, Adrian H. A.; Fiorini, Maurizio; Fortunato, Alessandro; Ascari, Alessandro

2014-12-01

323

Development of a new laser heating system for thin film growth by chemical vapor deposition  

NASA Astrophysics Data System (ADS)

We have developed a new laser heating system for thin film growth by chemical vapor deposition (CVD). A collimated beam from a high-power continuous-wave 808 nm semiconductor laser was directly introduced into a CVD growth chamber without an optical fiber. The light path of the heating laser inside the chamber was isolated mechanically from the growth area by bellows to protect the optics from film coating. Three types of heat absorbers, (10 × 10 × 2 mm3) consisting of SiC, Ni/NiOx, or pyrolytic graphite covered with pyrolytic BN (PG/PBN), located at the backside of the substrate, were tested for heating performance. It was confirmed that the substrate temperature could reach higher than 1500 °C in vacuum when a PG/PBN absorber was used. A wide-range temperature response between 400 °C and 1000 °C was achieved at high heating and cooling rates. Although the thermal energy loss increased in a H2 gas ambient due to the higher thermal conductivity, temperatures up to 1000°C were achieved even in 200 Torr H2. We have demonstrated the capabilities of this laser heating system by growing ZnO films by metalorganic chemical vapor deposition. The growth mode of ZnO films was changed from columnar to lateral growth by repeated temperature modulation in this laser heating system, and consequently atomically smooth epitaxial ZnO films were successfully grown on an a-plane sapphire substrate.

Fujimoto, Eiji; Sumiya, Masatomo; Ohnishi, Tsuyoshi; Lippmaa, Mikk; Takeguchi, Masaki; Koinuma, Hideomi; Matsumoto, Yuji

2012-09-01

324

Laser Microdissection and Atmospheric Pressure Chemical Ionization Mass Spectrometry Coupled for Multimodal Imaging  

SciTech Connect

This paper describes the coupling of ambient laser ablation surface sampling, accomplished using a laser capture microdissection system, with atmospheric pressure chemical ionization mass spectrometry for high spatial resolution multimodal imaging. A commercial laser capture microdissection system was placed in close proximity to a modified ion source of a mass spectrometer designed to allow for sampling of laser ablated material via a transfer tube directly into the ionization region. Rhodamine 6G dye of red sharpie ink in a laser etched pattern as well as cholesterol and phosphatidylcholine in a cerebellum mouse brain thin tissue section were identified and imaged from full scan mass spectra. A minimal spot diameter of 8 m was achieved using the 10X microscope cutting objective with a lateral oversampling pixel resolution of about 3.7 m. Distinguishing between features approximately 13 m apart in a cerebellum mouse brain thin tissue section was demonstrated in a multimodal fashion including co-registered optical and mass spectral chemical images.

Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

2013-01-01

325

Chemical etch effects on laser-induced surface damage growth in fused silica  

NASA Astrophysics Data System (ADS)

We investigated chemical etching as a possible means to mitigate the growth of UV laser-induced surface damage on fused silica. The intent of this work is to examine the growth behavior of existing damage sites that have been processed to remove the UV absorbing, thermo-chemically modified material within the affected area. The study involved chemical etching of laser-induced surface damage sites on fused silica substrates, characterizing the etched sites using scanning electron microscopy (SEM) and laser fluorescence, and testing the growth behavior of the etched sites upon illumination with multiple pulses of 351- nm laser light. The results show that damage sites that have been etched to depths greater than about 9 micrometers have about a 40% chance for zero growth with 1000 shots at fluences of 6.8-9.4 J/cm2. For the etched sites that grow, the growth rates are consistent with those for non-etched sites. There is a weak dependence of the total fluorescence emission with the etch depth of a site, but the total fluorescence intensity from an etched site is not well correlated with the propensity of the site to grow. Deep wet etching shows some promise for mitigating damage growth in fused silica, but fluorescence does not seem to be a good indicator of successful mitigation.

Hrubesh, Lawrence W.; Norton, Mary A.; Molander, William A.; Wegner, Paul J.; Staggs, Michael C.; Demos, Stavros G.; Britten, Jerald A.; Summers, Leslie J.; Lindsey, Edward F.; Kozlowski, Mark R.

2001-04-01

326

BRIEF COMMUNICATIONS: High-efficiency electric-discharge chemical H2-F2 laser  

Microsoft Academic Search

An investigation was made of a chemical H2-F2 laser with electric-discharge initiation. A mixture of the F2:O2:SF6:H2 = 5:1:3:2 composition (pSigma = 84 Torr) was used to generate laser radiation of El = 5.8 J energy and the physical efficiency was etaph = 240%. The corresponding parameters for an SF2-free gas mixture of the F2:O2:He:H2 = 10:2:30:2.5 composition (pSigma =

Evgenii B. Gordon; V. V. Gorokhov; V. I. Matyushenko; V. I. Karelin; A. I. Pavlovskii; P. B. Repin; V. D. Sizov

1986-01-01

327

Physics of a ballistic missile defense - The chemical laser boost-phase defense  

NASA Technical Reports Server (NTRS)

The basic physics involved in proposals to use a chemical laser based on satellites for a boost-phase defense are investigated. After a brief consideration of simple physical conditions for the defense, a calculation of an equation for the number of satellites needed for the defense is made along with some typical values of this for possible future conditions for the defense. Basic energy and power requirements for the defense are determined. A sumary is made of probable minimum conditions that must be achieved for laser power, targeting accuracy, number of satellites, and total sources for power needed.

Grabbe, Crockett L.

1988-01-01

328

Excimer laser induced surface chemical modification of polytetrafluoroethylene  

NASA Astrophysics Data System (ADS)

Polytetrafluoroethylene has a notoriously non adhesive and non reactive character. Its successful surface photochemical modification was performed by irradiating the polytetrafluoroethylene/liquid triethylamine interface with an ArF excimer laser ( ?=193 nm). Due to the photochemical treatment the polytetrafluoroethylene surface became more hydrophilic. The water receding contact angle decreased from 94° to 43°. The reaction cross section was determined from the decrease of the contact angles. It was found to be as high as 6.4×10 -18 cm 2. XPS measurements evidenced the removal of fluorine from the polytetrafluoroethylene, incorporation of alkyl carbon and nitrogen. Photochemical dissociation path of the triethylamine makes probable that it bonded to the fluoropolymer backbone via the ?-carbon atom of an ethyl group. A radical, or a photoinduced electron transfer mechanism was suggested to describe this reaction. A selective area electroless plating of silver was performed after pretreating the sample with patterned photomodification. The increased adhesion of the sample was proved by gluing with epoxy resin. As a result of the surface modification the tensile strength of gluing increased by 210× and reached 24% of the value characteristic for the bulk material.

Révész, K.; Hopp, B.; Bor, Z.

1997-02-01

329

Latest developments toward the demonstration of a KW-class EOIL laser  

NASA Astrophysics Data System (ADS)

The electric oxygen iodine laser (EOIL) offers a vastly more practical, implementable, and safer alternative to its predecessor, the chemical oxygen iodine laser (COIL), particularly for airborne or other mobile military applications. Despite its promise and after 25 years effort, numerous laboratories around the world have not succeeded in providing the known basic physical requirements needed to electrically convert O2 into O2(a1?) with the fractional yields and efficiencies needed to make a practical laser. Hence, as of this date, the world record power generated from an EOIL device is only 6.5 watts. In this paper, a 30% conversion from O2 into O2(a1?) operating at substantial oxygen mass flow rates (0.090 moles O2/sec at 50 torr) and 40% electrical efficiency is reported. The O2(a1?) flow stream being produced carries 2400 watts. Gain measurements are currently in progress, to be followed shortly by power extraction. Current conditions imply that initial power extraction could push beyond 1 KW. Efforts to date have failed to generate substantial laser power because critical criteria have not been met. In order to achieve good O2(a1?) fractional yield, it is normally mandatory to impart on the order of 100 KJ/mole O2 while efficiently removing the waste heat energy from the generator so that less than a few hundred degrees Kelvin rise occurs due to gas heating. The generator must be excited by an electric field on the order of 10 Td. This is far below glow potential; hence, a fully externally sustained plasma generation technique is required. Ionization is supplied by means of applying short (tens of nanosecond) pulses to the O2(a1?) generator at 50,000 PPS, which are on the order of ten times breakdown potential. This enables a quasi-steady adjustable DC current to flow through the generator, being conducted by application of a DC, 10 to 14 Td pump E-field. This field is independently tunable. The result is that up to 180 KJ/mole O2 gets imparted to the gas by means of the 6 KW sub-breakdown pump field, while another 2700 watts is applied to the controlled avalanche field. The generator consists of 24 each, 1 cm diameter tubes that are submerged in rapidly circulating cold fluorinert. Heat is efficiently removed so that that the gas temperature, initially 273°K, raises only by 125°K, as evidenced by spectrographic analysis of the fine structure of O2(b1?) at lower pressure. Since all necessary conditions have been met, a 30% conversion rate of O2 to O2(a1?) has been achieved. Fortuitously, neither excited O atom production nor O2(b1?) production is visible in the spectra of the higher pressure, best yield runs. Essentially all other spectral lines are dwarfed in comparison the O2(a1?) line. Energy normally partitioned to O2(b1?) and apparently O atoms now feeds into O2(a1?) directly, enabling electrical efficiency to exceed 40%. As a continuation of this work, an I2 disassociating mixing section - then subsequently a 20 cm transverse M = 2.5 laser channel - has been coupled to the O2(a1?) generator. The effects of titrating NO, NO2, etc. to scavenge O atoms and O3 atoms is under current investigation. Laser power extraction will commence after having optimized all parameters to achieve maximum gain. Power extraction has been delayed due to substantial mechanical equipment failure; however, the apparatus has now been fully restored. Also, several modes of potential discharge instabilities peculiar to high O2(a1?) concentrations have been discovered. These phenomenon and their means of prevention will be discussed.

Hill, Alan E.

2008-05-01

330

The impact of several atomic and molecular laser spectroscopic techniques for chemical analysis  

NASA Astrophysics Data System (ADS)

Several laser-based methods, namely laser induced fluorescence, laser enhanced ionisation and thermal lensing spectrophotometry are discussed with respect to their capabilities of approaching the extremely high detection sensitivity which is nowadays required in many fields of application, notably in high purity materials, in biomedicine and in the nuclear industry. The discussion is restricted to atomisers operated at atmospheric pressure, i.e., combustion flames, plasmas and graphite furnaces. It is shown that the analytical limit of detection can be in the range of femtograms and that double-resonance excitation possesses significant advantages over single-resonance excitation, both in terms of signal-to-noise ratio and spectral selectivity. In addition, the combination of the fluorescence and ionisation techniques represents a remarkable diagnostic tool. In the nuclear field, the suitability of the technique of thermal lensing for the direct determination and chemical speciation of very low levels of uranium in water is discussed.

Omenetto, N.

1988-07-01

331

Chemical taggant detection and analysis by laser-induced breakdown spectroscopy  

SciTech Connect

A commercially available chemical identification taggant that imparts a unique elemental fingerprint to any object and can be analytically distinguished from billions of possible combinations has been developed. The liquid tag is easily applied and, once dry, can be removed and analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to determine the combination of elements present in the sample. The current study investigates the use of laser-induced breakdown spectroscopy (LIBS) as an alternative, and perhaps more practical, analysis scheme to LA-ICP-MS for this taggant. LIBS provides excellent discrimination potential, sensitivity, and repeatability of analysis for up to 17 rare-earth elements using a Nd:YAG 266 nm or 1064 nm laser and an intensified CCD detector.

Wise, Steven H.; Almirall, Jose R

2008-11-01

332

Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy  

SciTech Connect

We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8–16 min. Mixture of metastable oxides like InAsO{sub 4,} As{sub 2}O{sub 3} are formed upon oxidation, which are reflected as sharp Raman peaks at ?240–254 and 180–200?cm{sup ?1}. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka [Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

2014-07-07

333

Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8-16 min. Mixture of metastable oxides like InAsO4, As2O3 are formed upon oxidation, which are reflected as sharp Raman peaks at ˜240-254 and 180-200 cm-1. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka

2014-07-01

334

Laser chemical vapor deposition of TiN dots: A comparison of theoretical and experimental results  

NASA Astrophysics Data System (ADS)

A mathematical model for the concentration profile of TiCl4 at the top surface of an Incoloy 800H substrate placed inside a laser chemical vapor deposition (LCVD) reactor is developed by using the three-dimensional transient mass diffusion equation. The model is used for studying the spatial variation of the thickness of TiN dots deposited by LCVD, using a CO2 laser and a reactive atmosphere consisting of TiCl4, N2, and H2. By assuming that the chemical reaction is first-order with respect to TiCl4, and that the sticking coefficient of TiN at the substrate surface is temperature dependent, the deposited TiN film is found to have a volcanic profile under certain conditions, which is in good agreement with experimental results.

Conde, O.; Kar, A.; Mazumder, J.

1992-07-01

335

Influence of exothermic chemical reactions on laser-induced shock waves.  

PubMed

Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time. PMID:25182866

Gottfried, Jennifer L

2014-10-21

336

Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors  

NASA Astrophysics Data System (ADS)

One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of ?-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO2 laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO3 and SrTiO3 can be formed from corresponding mixtures of ?-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.

Winterer, Markus; Srdic, Vladimir V.; Djenadic, Ruzica; Kompch, Alexander; Weirich, Thomas E.

2007-12-01

337

BRIEF COMMUNICATIONS: Electric-discharge chemical laser utilizing a mixture of chlorine monofluoride with hydrogen  

Microsoft Academic Search

A determination was made of the energy, spectrum, and duration of emission of radiation generated as a result of vibrational-rotational transitions in HF and HCl molecules in a chemical laser utilizing ClF-H2-He mixtures and subjected to short-pulse initiation of the pump reactions by a transverse electric discharge preceded by photopreionization. When the total energy of the output radiation pulses due

V. B. Kolovskii; S. A. Drobakha; G. P. Zhitneva; G. A. Abakumov; Alexander P. Simonov

1984-01-01

338

A high-efficiency electric-discharge H2-F2 chemical laser  

Microsoft Academic Search

The paper presents the results of investigations of an electric-discharge-initiated H2-F2 chemical laser. The F2: O2: SF6: H2 = 5:1:3:2 mixture (pressure = 84 mm Hg) yielded a lasing energy of 5.8 J, the physical efficiency being 240 percent. In an F2: O2: He: H2 = 10:2:30:2.5 mixture (pressure = 340 mm Hg) in which the SF6 gas is absent,

E. B. Gordon; V. V. Gorokhov; V. I. Matiushenko; V. I. Karelin; A. I. Pavlovskii

1986-01-01

339

Electric-discharge chemical laser utilizing a mixture of chlorine monofluoride with hydrogen  

Microsoft Academic Search

A determination was made of the energy, spectrum, and duration of emission of radiation generated as a result of vibrational-rotational transitions in HF and HCl molecules in a chemical laser utilizing ClF–H2–He mixtures and subjected to short-pulse initiation of the pump reactions by a transverse electric discharge preceded by photopreionization. When the total energy of the output radiation pulses due

V. B. Kolovskii; S. A. Drobakha; G. P. Zhitneva; G. A. Abakumov; Alexander P Simonov

1984-01-01

340

Laser skin resurfacing, chemical peels, and other cutaneous treatments of the brow and upper lid.  

PubMed

The focus of this article is treatments of the brow and upper lid, in the context of appreciating their relationship to the forehead and periorbital complex to best evaluate and treat. This material is focused on treatments designed to stimulate collagen synthesis, as well as improve fine lines, wrinkles, and overall appearance of the skin, by mechanical dermabrasion, application of chemical peels, laser surgery, and treatment with energy devices including radiofrequency and focused ultrasound. PMID:23186758

Brauer, Jeremy A; Patel, Utpal; Hale, Elizabeth K

2013-01-01

341

COIL recent developments in Dalian  

Microsoft Academic Search

The chemical oxygen iodine laser (COIL) is the first CW chemical laser utilizing electronic transitions and it is most attractive short wavelength chemical laser system with very good scalable ability, excellent beam quality, high efficiency, great energy storage density, narrow emission line and good transfer performance in optical fibers at present which can lead to various potential applications in industrial

Yang Bailing

1999-01-01

342

Active coherent laser spectrometer for remote detection and identification of chemicals  

NASA Astrophysics Data System (ADS)

Currently, there exists a capability gap for the remote detection and identification of threat chemicals. We report here on the development of an Active Coherent Laser Spectrometer (ACLaS) operating in the thermal infrared and capable of multi-species stand-off detection of chemicals at sub ppm.m levels. A bench top prototype of the instrument has been developed using distributed feedback mid-infrared quantum cascade lasers as spectroscopic sources. The instrument provides active eye-safe illumination of a topographic target and subsequent spectroscopic analysis through optical heterodyne detection of the diffuse backscattered field. Chemical selectivity is provided by the combination of the narrow laser spectral bandwidth (typically < 2 MHz) and frequency tunability that allows the recording of the full absorption spectrum of any species within the instrument line of sight. Stand-off detection at distances up to 12 m has been demonstrated on light molecules such as H2O, CH4 and N2O. A physical model of the stand-off detection scenario including ro-vibrational molecular absorption parameters was used in conjunction with a fitting algorithm to retrieve quantitative mixing ratio information on multiple absorbers.

MacLeod, Neil A.; Weidmann, Damien

2012-10-01

343

On the role of chemical reactions in initiating ultraviolet laser ablation in poly(methyl methacrylate)  

SciTech Connect

The role of chemical reactions is investigated versus the thermal and mechanical processes occurring in a polymer substrate during irradiation by a laser pulse and subsequent ablation. Molecular dynamics simulations with an embedded Monte Carlo based reaction scheme were used to study ultraviolet ablation of poly(methyl methacrylate) at 157 nm. We discuss the onset of ablation, the mechanisms leading to ablation, and the role of stress relaxation of the polymer matrix during ablation. Laser induced heating and chemical decomposition of the polymer substrate are considered as ablation pathways. It is shown that heating the substrate can set off ablation via mechanical failure of the material only for very short laser pulses. For longer pulses, the mechanism of ejection is thermally driven limited by the critical number of bonds broken in the substrate. Alternatively, if the photon energy goes towards direct bond breaking, it initiates chemical reactions, polymer unzipping, and formation of gaseous products, leading to a nearly complete decomposition of the top layers of substrates. The ejection of small molecules has a hollowing out effect on the weakly connected substrates which can lead to lift-off of larger chunks. Excessive pressure buildup upon the creation of gaseous molecules does not lead to enhanced yield. The larger clusters are thermally ejected, and an entrainment of larger polymer fragments in gaseous molecules is not observed.

Prasad, Manish; Conforti, Patrick F.; Garrison, Barbara J. [Department of Chemistry, 104 Chemistry Building, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2007-05-15

344

Photothermal laser fabrication of micro- and nanostructured chemical templates for directed protein immobilization.  

PubMed

Photothermal patterning of poly(ethylene glycol) terminated organic monolayers on surface-oxidized silicon substrates is carried out using a microfocused beam of a CW laser operated at a wavelength of 532 nm. Trichlorosilane and trimethoxysilane precursors are used for coating. Monolayers from trimethoxysilane precursors show negligible unspecific protein adsorption in the background, i.e., provide platforms of superior protein repellency. Laser patterning results in decomposition of the monolayers and yields chemical templates for directed immobilization of proteins at predefined positions. Characterization is carried out via complementary analytical methods including fluorescence microscopy, atomic force microscopy, and scanning electron microscopy. Appropriate labeling techniques (fluorescent markers and gold clusters) and substrates (native and thermally oxidized silicon substrates) are chosen in order to facilitate identification of protein adsorption and ensure high sensitivity and selectivity. Variation of the laser parameters at a 1/e(2) spot diameter of 2.8 ?m allows for fabrication of protein binding domains with diameters on the micrometer and nanometer length scale. Minimum domain sizes are about 300 nm. In addition to unspecific protein adsorption on as-patterned monolayers, biotin-streptavidin coupling chemistry is exploited for specific protein binding. This approach represents a novel facile laser-based means for fabrication of protein micro- and nanopatterns. The routine is readily applicable to femtosecond laser processing of glass substrates for the fabrication of transparent templates. PMID:25397891

Schröter, Anja; Franzka, Steffen; Hartmann, Nils

2014-12-16

345

Electric discharge repetitively pulsed HF\\/DF chemical laser operating on the mixture F2 + H2 (D2)  

Microsoft Academic Search

The HF\\/DF pulsed chemical lasers, operating on the unchain mixtures SF6 + H2 (D2), have rather low efficiency and relatively small number of lines in a radiation spectrum. The application fluorine-hydrogen (deuterium) mixtures allows to raise many times the specific energy characteristics of the laser and number of lines in a radiation spectrum, that potentially makes such a laser as

C. A. Kutumov; E. A. Klimuk; Georgiy A. Troshchinenko

1998-01-01

346

Volume 164, number 4 CHEMICAL PHYSICS LETTERS 15 December 1989 TUNABLE FAR INFRARED LASER SPECTROSCOPY OF ULTRACOLD FREE RADICALS  

E-print Network

Volume 164, number 4 CHEMICAL PHYSICS LETTERS 15 December 1989 TUNABLE FAR INFRARED LASER subsequently probed by a tunable far infrared laser. A detection limit of lo* mole- cules/cm3 for light at the study of very- short-lived radicals and of clusters containing free radicals in the far infrared (FIR

Cohen, Ronald C.

347

Potential phase control of chromium oxide thin films prepared by laser-initiated organometallic chemical vapor deposition  

E-print Network

Potential phase control of chromium oxide thin films prepared by laser-initiated organometallic used laser-initiated chemical vapor deposition to grow the chromium oxide thin films through chromium oxide CrO2 with Tc 397 K Ref. 5 has been predicted to be half metallic metallic for one spin

Idzerda, Yves

348

Laser micromachined and laminated microchannel components for chemical sensors and heat transfer applications  

NASA Astrophysics Data System (ADS)

The fabrication of microchannel chemical sensors with seven laminated individual functional modules is described. The sensors, used to detect chromium in nuclear and chemical waste streams, were fabricated using laser micromachining, bulk silicon micromachining, photolithographic techniques, sputter coating deposition, and anodic and adhesive bonding processes. The size of the sensor was 2 cm by 2.2 cm, with a total thickness of 2.2 cm. It consisted of two or more reservoir modules to hold the liquids being evaluate, two or more micropump modules to pump the liquids through the sensor, a chemical mixing module, a reaction module, and a sensor module with electrical circuitry for connection to external measurement equipment. The fluids were directed through the layers by interconnecting flow channels. The reservoir modules were fabricated by machining Pyrex and anodic bonding to silicon. The chemical mixing module was fabricated by wet etching Pyrex and anodic bonding to silicon. The reaction module contained a serpentine 200- micrometers -wide channel, and was formed by laser micromachining polyimide. The first prototype of this sensor employed external micropumps, while the second prototype will use off-the-shelf piezoelectric micropumps. The detector layer consisted of iridium, silver, and platinum sensor pads connected to gold contact strips. The modules were joined using adhesive bonding, and an electrostatic technique was used for silicon-Pyrex bonding.

Martin, Peter M.; Bennett, Wendy D.; Hammerstrom, D. J.; Johnston, John W.; Matson, Dean W.

1997-09-01

349

CONTROL OF LASER RADIATION PARAMETERS: Influence of the cavity losses on the energy and spectral characteristics of a pulsed chemical chain-reaction HF (DF) laser  

NASA Astrophysics Data System (ADS)

The dependences of the energy and spectral characteristics of the radiation of a pulsed photoinitiated chemical chain-reaction HF (DF) laser, operating at atmospheric pressure, on the optical cavity parameters were investigated. The maximum specific output energies of the HF and DF chain lasers (53 and 43 J litre-1) and their fullest spectra (47 and 83 lines, respectively) were similar when the unsaturated gain exceeded the threshold by a factor greater than 50. An analysis was made of how the energy and spectrum of the radiation of the HF (DF) laser were influenced by the spatiotemporal inhomogeneity of the initiation and of the course of the chemical chain reaction. There was a marked effect of the CO2 molecules in the active medium and in the air filling part of the volume of the complex cavity of the DF laser on its efficiency and emission spectrum.

Azarov, M. A.; Aleksandrov, Boris S.; Drozdov, V. A.; Troshchinenko, G. A.

2000-01-01

350

Use of the spatial phase of a focused laser beam to yield mechanistic information about photo-induced chemical reactions  

NASA Astrophysics Data System (ADS)

Two-pathway quantum mechanical interference was used to control the photoionization and photodissociation of a number of polyatomic molecules. The phase lag between different pairs of products obtained from acetone and dimethyl sulfide was altered by translating the focus of the laser beam along an axis normal to the molecular beam axis. This effect was derived quantitatively from the spatial Gouy phase of the laser beam. Details of the chemical reaction mechanisms were deduced from the channel phase lags, obtained when the laser was focused on the axis of the molecular beam, and from the variation of the phase lag produced by axial translation of the laser focus.

Barge, V. J.; Hu, Z.; Gordon, R. J.

2009-10-01

351

Laser-induced shock wave removal of chemical-mechanical polishing slurries from silicon wafers  

NASA Astrophysics Data System (ADS)

A new dry cleaning methodology named laser-induced shock cleaning has been applied to remove the chemical-mechanical polishing (CMP) slurries from silicon wafer surfaces. After CMP process using the slurries, the slurry particles should be removed from the surface in order to avoid the circuit failure and enhance the yield. The well-distributed remaining silica particles were attempted to remove from the surface by using laser-induced plasma shock waves. In order to evaluate the cleaning performance quantitatively, the number of particles on the wafer surfaces were measured by surface scanner before and after cleaning. It was found that most of the silica particles on the wafer surface were removed after the treatment of laser-induced shock waves. The average removal efficiency of the particles was 99% over. It was found that cleaning performance is strongly dependent on a gap distance between laser focus and the surface and a suitable control of the gap is crucial for the successful removal of the particles.

Lee, J. M.; Cho, S. H.; Park, J. G.; Lee, S. H.; Han, Y. P.; Kim, S. Y.

2003-02-01

352

IR and UV laser-induced chemical vapor deposition: Chemical mechanism for a-Si:H and Cr (O,C) film formation  

NASA Astrophysics Data System (ADS)

The characteristic features of laser-induced chemical vapor deposition in the parallel and perpendicular laser beam/surface configurations are discussed. Low temperature chemical processing with directed and spatially localized energy deposition in the system is investigated. Results obtained for the deposition of hydrogenated amorphous silicon (a-Si:H) films in the parallel configuration employing CO 2 and KrFlasers and SiH 4 and Si 2H 6 as precursors are presented. As a second example, the growth of oxygen- and carbon-containing chromium films Cr(O,C) from chromium hexacarbonyl as the precursor using cw and pulse uv lasers is discussed. The chemical pathways leasing to film formation are investigated in detail.

Hess, Peter

353

Volume 112, number 2 CHEMICAL PHYSICS LETTERS 30 November 1984 PICOSECOND LASER STUDIES OF THE EFFEC?S OF REACTANTS  

E-print Network

Volume 112, number 2 CHEMICAL PHYSICS LETTERS 30 November 1984 PICOSECOND LASER STUDIES-triplet enera splitting changes from 1400 to 950 cm-l in going from iso- octane to acetonitrile. The polarity. Because the chemistry 111 #12;Volume 112, number 2 CHEMICAL PHYSICS LEl-l-ERS 30 November 1984

Eisenthal, Kenneth B.

354

Colour and chemical changes of the lime wood surface due to CO2 laser thermal modification  

NASA Astrophysics Data System (ADS)

We studied colour and main wood components changes of lime wood caused by CO2 laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO2 laser beam (wavelength of 10.6 ?m) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm-2) lightness (?L*) decrease and increase of the total colour difference (?E*) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

Kubovský, Ivan; Ka?ík, František

2014-12-01

355

Laser chemistry’ synthesis, physicochemical properties, and chemical processing of nanostructured carbon foams  

PubMed Central

Laser ablation of selected coordination complexes can lead to the production of metal-carbon hybrid materials, whose composition and structure can be tailored by suitably choosing the chemical composition of the irradiated targets. This ‘laser chemistry’ approach, initially applied by our group to the synthesis of P-containing nanostructured carbon foams (NCFs) from triphenylphosphine-based Au and Cu compounds, is broadened in this study to the production of other metal-NCFs and P-free NCFs. Thus, our results show that P-free coordination compounds and commercial organic precursors can act as efficient carbon source for the growth of NCFs. Physicochemical characterization reveals that NCFs are low-density mesoporous materials with relatively low specific surface areas and thermally stable in air up to around 600°C. Moreover, NCFs disperse well in a variety of solvents and can be successfully chemically processed to enable their handling and provide NCF-containing biocomposite fibers by a wet-chemical spinning process. These promising results may open new and interesting avenues toward the use of NCFs for technological applications. PMID:23679938

2013-01-01

356

`Laser chemistry' synthesis, physicochemical properties, and chemical processing of nanostructured carbon foams  

NASA Astrophysics Data System (ADS)

Laser ablation of selected coordination complexes can lead to the production of metal-carbon hybrid materials, whose composition and structure can be tailored by suitably choosing the chemical composition of the irradiated targets. This `laser chemistry' approach, initially applied by our group to the synthesis of P-containing nanostructured carbon foams (NCFs) from triphenylphosphine-based Au and Cu compounds, is broadened in this study to the production of other metal-NCFs and P-free NCFs. Thus, our results show that P-free coordination compounds and commercial organic precursors can act as efficient carbon source for the growth of NCFs. Physicochemical characterization reveals that NCFs are low-density mesoporous materials with relatively low specific surface areas and thermally stable in air up to around 600°C. Moreover, NCFs disperse well in a variety of solvents and can be successfully chemically processed to enable their handling and provide NCF-containing biocomposite fibers by a wet-chemical spinning process. These promising results may open new and interesting avenues toward the use of NCFs for technological applications.

Seral-Ascaso, Andrés; Garriga, Rosa; Sanjuán, María Luisa; Razal, Joselito M.; Lahoz, Ruth; Laguna, Mariano; de la Fuente, Germán F.; Muñoz, Edgar

2013-05-01

357

Design and Investigation of a Hybrid Optical Resonator for Medium Energy COIL  

Microsoft Academic Search

High brightness laser radiation of chemical oxygen iodine lasers (COIL) requires reso- nator types especially adapted to low gain medium and rectangular cavity geometry. For medium energy class lasers, those resonators suffer from small magnification numbers and therefore often imply sophisticated optical concepts. Selected solutions should not inhibit the demands of a field deployment of the laser system. Outside the

Karin M. Gruenewald; Juergen Handke; Thomas Hall; Frank Duschek

358

Industrial COIL systems--part 2: gas-laser cutting  

NASA Astrophysics Data System (ADS)

First results of experimental and theoretical investigations concerning an industrial application of oxygen-iodine laser (COIL) are reported. The dependencies of the largest cut depth on the laser emission power, cut width and rate, and kind of processing gas (oxygen or nitrogen) were determined for carbon and stainless steels, and aluminium alloys. A developed simple engineering model determines parameters of separating gas-laser cutting of metals allowing for principal channels of heat loss: warming, melting, material evaporation and heat conductivity, convection and radiant heat exchange. It was shown that when oxygen is applied as a processing gas it is necessary to take into account the additional heat emanation that is usually about 10% of the material oxidation energy. A good agreement between calculative and experimental data was obtained.

Kolobyanin, Yury V.; Bulatkin, Il'ya A.; Kalinovskiy, Vladimir V.; Konovalov, Vladimir V.; Moiseev, Vladimir B.; Nickolaev, Victor D.; Shornikov, Lev N.; Sobolev, Roman E.; Vyskubenko, Boris A.

2005-03-01

359

Microstructure of metastable metallic alloy films produced by laser breakdown chemical vapor deposition and ion implantation  

SciTech Connect

Thin films produced by laser breakdown chemical vapor deposition from nickel and iron carbonyls and by implanting Ni foils with varying levels of C have been characterized by transmission electron microscopy. Decomposition of Ni(CO)/sub 4/ produces polycrystalline films of fcc Ni and metastable ordered hexagonal Ni/sub 3/C. This metastable phase is identical to that produced by gas carburization, rapid solidification of Ni-C melts, and ion implantation of C into Ni at low concentrations. Increasing the H/sub 2/ content in the gas mixture during laser deposition reduces the grain size of the films significantly with grain sizes smaller than 10 nanometers produced. Laser decomposition of Fe(CO)/sub 5/ produces films with islands of fcc gamma-Fe and finely dispersed metastable Fe/sub 3/C (Cementite). In addition, the ferrous oxides Fe/sub 2/O/sub 3/ and Fe/sub 3/O/sub 4/ were found in these samples. Implants of C into pure Ni foils at 77/sup 0/K and at a concentration of 35 at. % produced amorphous layers. Implants at the same dose at room temperature did not produce amorphous layers.

Menon, S.K.; Jervis, T.R.; Nastasi, M.

1986-01-01

360

Laser-micromachined and laminated microfluidic components for miniaturized thermal, chemical, and biological systems  

NASA Astrophysics Data System (ADS)

Microchannel microfluidic components are being developed for heat transfer, chemical reactor, chemical analysis, and biological analytical applications. Specific applications include chemical sensing, DNA replication, blood analysis, capillary electrophoresis, fuel cell reactors, high temperature chemical reactors, heat pumps, combustors, and fuel processors. Two general types of component architectures have been developed and the fabrication processes defined. All involve a lamination scheme using plastic, ceramic, or metal laminates, as opposed to planar components. The first type is a stacked architecture that utilizes functionality built in each layer, with fluid flow interconnects between layers. Each layer of the laminate has specific microchannel geometry, and performs a specific function. Polymeric materials are used primarily. Fabrication processes used are laser micromachining, wet and dry etching, and coating deposition. the laminates can also be micromolded plastics. The second architecture employs laminates to form internal microchannels and interconnects. Materials include ceramic tapes and high temperature metals. Catalysts can be placed in the microchannels. Fabrication processes used are diffusion bonding, ceramic bonding and firing, photochemical etching, and electrochemical micromachining. Bonding, thus sealing, the laminates is an important issue. Process conditions have been develop to reduce distortion of the laminates and to hermetically seal the components.

Martin, Peter M.; Matson, Dean W.; Bennett, Wendy D.; Stewart, Donald C.; Lin, Yuehe

1999-03-01

361

Chemical models for simulating single-walled nanotube production in arc vaporization and laser ablation processes  

NASA Technical Reports Server (NTRS)

Chemical kinetic models for the nucleation and growth of clusters and single-walled carbon nanotube (SWNT) growth are developed for numerical simulations of the production of SWNTs. Two models that involve evaporation and condensation of carbon and metal catalysts, a full model involving all carbon clusters up to C80, and a reduced model are discussed. The full model is based on a fullerene model, but nickel and carbon/nickel cluster reactions are added to form SWNTs from soot and fullerenes. The full model has a large number of species--so large that to incorporate them into a flow field computation for simulating laser ablation and arc processes requires that they be simplified. The model is reduced by defining large clusters that represent many various sized clusters. Comparisons are given between these models for cases that may be applicable to arc and laser ablation production. Solutions to the system of chemical rate equations of these models for a ramped temperature profile show that production of various species, including SWNTs, agree to within about 50% for a fast ramp, and within 10% for a slower temperature decay time.

Scott, Carl D.

2004-01-01

362

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser.  

PubMed

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T; Thomas, Richard D; Larsson, Mats; Richter, Robert; Prince, Kevin C; Bozek, John D; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N; Tashiro, Motomichi; Ehara, Masahiro

2011-10-11

363

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser  

PubMed Central

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

2011-01-01

364

Direct spatiotemporal analysis of femtosecond laser-induced plasma-mediated chemical reactions  

NASA Astrophysics Data System (ADS)

Localized, micron to millimetre-scale plasmas resulting from the fleeting interaction between ultrashort laser pulses and matter have been studied extensively in inert atmospheres. In spite of recent interest in reactive plasmas as a nanofabrication tool, ultrashort pulsed laser ablation in reactive gas atmospheres has undergone little study. In this study, we develop a methodology combining time-resolved optical emission spectroscopy and spectrally filtered time-gated fast photography to directly observe and analyse plasma-mediated chemical reactions that occur when laser ablation is performed in reactive gases. Specifically, we compare the ablation of silicon dioxide in an atmosphere of xenon difluoride gas to its ablation in nitrogen and xenon atmospheres. We show that when xenon difluoride molecules are collisionally driven into an excited state by the silicon plasma produced during laser-induced decomposition of the solid substrate, the gas undergoes dissociation. The resulting fluorine radicals react spontaneously with the silicon plasma to produce volatile fluorinated silicon compounds. In particular, mass spectroscopy shows that the primary reaction byproduct is SiF2 with small amounts of SiF and SiF4. The high spatial and temporal resolution of our methodology reveals a slowly expanding plume having an atomic silicon core with a XeF? shell that persists for less than 300 ns. As the silicon is fluorinated, the optical emission due to excited silicon is quenched. The absence of a silicon signal after 300 ns establishes this as the upper limit of the reaction lifetime given the conditions of the experiment.

Straw, Marcus; Randolph, Steven

2014-03-01

365

In Situ Chemical Composition Measurements of Planetary Surfaces with a Laser Ablation Mass Spectrometer  

NASA Astrophysics Data System (ADS)

The knowledge of the chemical composition of moons, comets, asteroids or other planetary bodies is of particular importance for the investigation of the origin and evolution of the Solar System. For cosmochemistry, the elemental and isotopic composition of the surface material is essential information to investigate origin, differentiation and evolution processes of the body and therefore the history of our Solar System [1]. We show that the use of laser-based mass spectrometers is essential in such research because of their high sensitivity in the ppm range and their capability for quantitative elemental and isotopic analysis. A miniaturised Laser Ablation Time-of-Flight Mass Spectrometer (LMS) was developed in our group to study the elemental composition of solid samples [2]. The instrument's small size and light weight make it suitable for an application on a space mission to determine the elemental composition of a planetary surface for example [3]. Meteorites offer the excellent possibility to study extraterrestrial material in the laboratory. To demonstrate the sensitivity and functionality of the LMS instrument, a sample of the Allende meteorite has been investigated with a high spatial resolution. The LMS measurements allowed investigations of the elemental abundances in the Allende meteorite and detailed studies of the mineralogy and volatility [4]. These approaches can be of considerable interest for in situ investigation of grains and inhomogeneous materials with high sensitivity on a planetary surface. [1] Wurz, P., Whitby, J., Managadze, G., 2009, Laser Mass Spectrometry in Planetary Science, AIP Conf. Proc. CP1144, 70-75. [2] Tulej, M., Riedo, A., Iakovleva, M., Wurz, P., 2012, Int. J. Spec., On Applicability of a Miniaturized Laser Ablation Time of Flight Mass Spectrometer for Trace Element Measurements, article ID 234949. [3] Riedo, A., Bieler, A., Neuland, M., Tulej, M., Wurz, P., 2012, Performance evaluation of a miniature laser ablation time-of-flight mass spectrometer designed for in-situ investigations in planetary space research, J. Mass Spectrom., in press. [4] Neuland, M.B., Meyer, S., Mezger, K., Riedo, A., Tulej, M., Wurz, P., Probing the Allende meteorite with a miniature Laser-Ablation Mass Analyser for space application, Planetary and Space Science, Special Issue: Terrestrial Planets II, submitted

Brigitte Neuland, Maike; Riedo, Andreas; Meyer, Stefan; Mezger, Klaus; Tulej, Marek; Wurz, Peter

2013-04-01

366

An infrared free-electron laser for the Chemical Dynamics Research Laboratory. Design report  

SciTech Connect

This document describes a free-electron laser (FEL) proposed as part of the Chemical Dynamics Research Laboratory (CDRL), a user facility that also incorporates several advanced lasers of conventional design and two beamlines for the ALS. The FEL itself addresses the needs of the chemical sciences community for a high-brightness, tunable source covering a broad region of the infrared spectrum -- from 3 to 50 {mu}m. All of these sources, together with a variety of sophisticated experimental stations, will be housed in a new building to be located adjacent to the ALS. The radiation sources can be synchronized to permit powerful two-color, pump-probe experiments that will further our fundamental understanding of chemical dynamics at the molecular level, especially those aspects relevant to practical issues in combustion chemistry. The technical approach adopted in this design makes use of superconducting radiofrequency (SCRF) accelerating structures. The primary motivation for adopting this approach was to meet the user requirement for wavelength stability equal to one part in 10{sup 4}. Previous studies concluded that a wavelength stability of only one part in 10{sup 3} could be achieved with currently available room-temperature technology. In addition, the superconducting design operates in a continuous-wave (cw) mode and hence offers considerably higher average optical output power. It also allows for various pulse-gating configurations that will permit simultaneous multiuser operations. A summary of the comparative performance attainable with room-temperature and superconducting designs is given. The FEL described in this report provides a continuous train of 30-ps micropulses, with 100{mu}J of optical energy per micropulse, at a repetition rate of 6.1 MHz. The device can also deliver pulses at a cw repetition rate of 12.2 MHz, with a peak power of 50 {mu}J per micropulse. 70 ref.

Vaughan, D. [comp.

1992-04-01

367

An infrared free-electron laser for the Chemical Dynamics Research Laboratory  

SciTech Connect

This document describes a free-electron laser (FEL) proposed as part of the Chemical Dynamics Research Laboratory (CDRL), a user facility that also incorporates several advanced lasers of conventional design and two beamlines for the ALS. The FEL itself addresses the needs of the chemical sciences community for a high-brightness, tunable source covering a broad region of the infrared spectrum -- from 3 to 50 {mu}m. All of these sources, together with a variety of sophisticated experimental stations, will be housed in a new building to be located adjacent to the ALS. The radiation sources can be synchronized to permit powerful two-color, pump-probe experiments that will further our fundamental understanding of chemical dynamics at the molecular level, especially those aspects relevant to practical issues in combustion chemistry. The technical approach adopted in this design makes use of superconducting radiofrequency (SCRF) accelerating structures. The primary motivation for adopting this approach was to meet the user requirement for wavelength stability equal to one part in 10{sup 4}. Previous studies concluded that a wavelength stability of only one part in 10{sup 3} could be achieved with currently available room-temperature technology. In addition, the superconducting design operates in a continuous-wave (cw) mode and hence offers considerably higher average optical output power. It also allows for various pulse-gating configurations that will permit simultaneous multiuser operations. A summary of the comparative performance attainable with room-temperature and superconducting designs is given. The FEL described in this report provides a continuous train of 30-ps micropulses, with 100{mu}J of optical energy per micropulse, at a repetition rate of 6.1 MHz. The device can also deliver pulses at a cw repetition rate of 12.2 MHz, with a peak power of 50 {mu}J per micropulse. 70 ref.

Vaughan, D. (comp.)

1992-04-01

368

Characterization of electron-deficient chemical bonding of diborane with attosecond electron wavepacket dynamics and laser response  

NASA Astrophysics Data System (ADS)

We report a theoretical study of non-adiabatic electrons-nuclei coupled dynamics of diborane H 2BH 2BH 2 under several types of short pulse lasers. This molecule is known to have particularly interesting geometrical and electronic structures, which originate from the electron-deficient chemical bondings. We revisit the chemical bonding of diborane from the view point of electron wavepacket dynamics coupled with nuclear motions, and attempt to probe the characteristics of it by examining its response to intense laser fields. We study in the following three aspects, (i) bond formation of diborane by collision between two monoboranes, (ii) attosecond electron wavepacket dynamics in the ground state and first excited state by circularly polarized laser pulse, and (iii) induced fragmentation back to monoborane molecules by linearly polarized laser. The wave lengths of two types of laser field employed are 200 nm (in UV range) and 800 nm (in IR range), and we track the dynamics from hundreds of attoseconds up to few tens of femtoseconds. To this end, we apply the ab initio semiclassical Ehrenfest theory, into which the classical vector potential of a laser field is introduced. Basic features of the non-adiabatic response of electrons to the laser fields is elucidated in this scheme. To analyze the electronic wavepackets thus obtained, we figure out bond order density that is a spatial distribution of the bond order and bond order flux density arising only from the bonding regions, and so on. Main findings in this work are: (i) dimerization of monoboranes to diborane is so efficient that even intense laser is hard to prevent it; (ii) collective motions of electron flux emerge in the central BHHB bonding area in response to the circularly polarized laser fields; (iii) laser polarization with the direction of central two BH bonding vector is efficient for the cleavage of BH 3-BH 3; and (iv) nuclear derivative coupling plays a critical role in the field induced fragmentation dynamics.

Yonehara, Takehiro; Takatsuka, Kazuo

2009-12-01

369

High rate, large area laser-assisted chemical vapor deposition of nickel from nickel carbonyl  

NASA Astrophysics Data System (ADS)

High-power diode lasers (HPDL) are being increasingly used in industrial applications. Deposition of nickel from nickel carbonyl (Ni(CO)4 ) precursor by laser-induced chemical vapor deposition (CVD) was studied with emphasis on achieving high deposition rates. An HPDL system was used to provide a novel energy source facilitating a simple and compact design of the energy delivery system. Nickel deposits on complex, 3-dimensional polyurethane foam substrates were prepared and characterized. The resulting "nickel foam" represents a novel material of high porosity (>95% by volume) finding uses, among others, in the production of rechargeable battery and fuel cell electrodes and as a specialty high-temperature filtration medium. Deposition rates up to ˜19 mum/min were achieved by optimizing the gas precursor flow pattern and energy delivery to the substrate surface using a 480W diode laser. Factors affecting the transition from purely heterogeneous decomposition to a combined hetero- and homogeneous decomposition of nickel carbonyl were studied. High quality, uniform 3-D deposits produced at a rate more than ten times higher than in commercial processes were obtained by careful balance of mass transport (gas flow) and energy delivery (laser power). Cross-flow of the gases through the porous substrate was found to be essential in facilitating mass transport and for obtaining uniform deposits at high rates. When controlling the process in a transient regime (near the onset of homogenous decomposition), unique morphology features formed as part of the deposits, including textured surface with pyramid-shape crystallites, spherical and non-spherical particles and filaments. Operating the laser in a pulsed mode produced smooth, nano-crystalline deposits with sub-100 nm grains. The effect of H2S, a commonly used additive in nickel carbonyl CVD, was studied using both polyurethane and nickel foam substrates. H2S was shown to improve the substrate coverage and deposit uniformity in tests with polyurethane substrate, however, it was found to have no effect in improving the overall deposition rate compared to H2S-free deposition process. Deposition on other selected substrates, such as ultra-fine polymer foam, carbon nanofoam and multi-wall carbon nanotubes, was demonstrated. The HPDL system shows good promise for large-scale industrial application as the cost of HPDL energy continues to decrease.

Paserin, Vlad

370

JOURNAL DE PHYSIQUE IV Colloque C4, supplement au Journal de Physique III, Volume 4, avril 1994 C4-743  

E-print Network

-743 Experimental and theoretical study of a high-power c.w. chemical oxygen iodine laser(COIL) Y. LOUVET, D A theoretical analysis of a kilowatt class COIL system has been performed in order to explain its output power. Introduction A high power kilowatt class COIL has been developed at ONERA /l/. During laser tests, the laser

Paris-Sud XI, Université de

371

Properties of aluminum oxide thin films deposited by pulsed laser deposition and plasma enhanced chemical vapor deposition  

Microsoft Academic Search

The chemical, structural, mechanical and optical properties of thin aluminum oxide films deposited at room temperature (RT) and 800 °C on (100) Si and Si–SiO2 substrates by pulsed laser deposition and plasma enhanced chemical vapor deposition are investigated and compared. All films are smooth and near stoichiometric aluminum oxide. RT films are amorphous, whereas ? type nano-crystallized structures are pointed out

C. Cibert; H. Hidalgo; C. Champeaux; P. Tristant; C. Tixier; J. Desmaison; A. Catherinot

2008-01-01

372

Luminescence properties of SiO{sub x}N{sub y} irradiated by IR laser 808 nm: The role of Si quantum dots and Si chemical environment  

SciTech Connect

We investigated optical, structural, and chemical properties of SiO{sub x}N{sub y} layers irradiated by CW IR laser during a time lapse of few milliseconds. We observed tunable photoluminescence signal at room temperature in the range 750-950 nm, without Si/SiO{sub 2} phase separation, depending on the IR laser power irradiation. Furthermore, no photoluminescence signal was recorded when the IR laser power density was high enough to promote phase separation forming Si quantum dots. By chemical analysis the source of the luminescence signal has been identified in a change of silicon chemical environment induced by IR laser annealing inside the amorphous matrix.

Ruggeri, Rosa; Neri, Fortunato [Dipartimento di Fisica della Materia e Ingegneria Elettronica, Universita di Messina, Salita, Sperone 31, 98166 Messina (Italy); Sciuto, Antonella; Privitera, Vittorio; Spinella, Corrado; Mannino, Giovanni [CNR-IMM, Strada VIII no 5, Zona Industriale, 95121 Catania (Italy)

2012-01-23

373

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield  

NASA Astrophysics Data System (ADS)

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (~18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts (~1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving ~6.5 kJ L-1 atm-1 per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O2 : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O2(a1?g) and O2(b1?g+), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O2(a1?g) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value ~3% for W ~ 1.0 kJ L-1 atm-1 is in agreement with the theoretical estimate. Theoretical calculations performed for W ~ 6.5 kJ L-1 atm-1 at a fixed temperature show that the singlet-oxygen yield may be ~20%, which is higher than the value required to achieve the lasing threshold in an oxygen—iodine laser at room temperature.

Vagin, Nikolai P.; Ionin, Andrei A.; Klimachev, Yu M.; Kotkov, A. A.; Kochetov, Igor'V.; Napartovich, A. P.; Podmar'kov, Yu P.; Seleznev, L. V.; Sinitsyn, D. V.; Frolov, M. P.; Hager, G. D.; Yuryshev, Nikolai N.

2004-09-01

374

Experimental study of continuous wave hydrogen-fluoride chemical laser overtone performance  

NASA Astrophysics Data System (ADS)

The overtone lasing performance of the supersonic continuous wave hydrogen-fluoride chemical laser at the University of Illinois at Urbana-Champaign was optimized by the same set of flow rates that optimized the fundamental performance. When the absorption/scattering losses of the mirrors were taken into account, an overtone efficiency (the ratio of overtone power to maximum fundamental power for the same flow conditions) of 70-90 percent was achieved. The overtone efficiency was a strong function of medium saturation. There was no significant change in overtone power and efficiency as the mode volume increased. However, there was an increase in the number of lasing lines and a shift to higher rotational (J) lines. Overtone performance was as sensitive to cavity pressure as fundamental performance was. There was no significant change in overtone efficiency when the method of helium injection was changed.

Carroll, D. L.; Sentman, L. H.; Theodoropoulos, P. T.; Waldo, R. E.; Gordon, S. J.

1993-04-01

375

In situ chemical imaging of lithiated tungsten using laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Lithium conditioning can significantly improve the plasma confinement of EAST tokamak by reducing the amount of hydrogen and impurities recycled from the wall, but the details of this mechanism and approaches that reduce the concentrations of hydrogen and impurities recycle still remain unclear. In this paper, we studied lithiated tungsten via a cascaded-arc plasma simulator. An in situ laser-induced breakdown spectroscopy (LIBS) diagnostic system has been developed to chemically image the three-dimensional distribution of lithium and impurities on the surface of lithiated tungsten co-deposition layer for the first time. The results indicate that lithium has a strong ability to draw hydrogen and oxygen. The impurity components from the co-deposition processes present more intensity on the surface of co-deposition layer. This work improves the understanding of lithiated tungsten mechanism and is useful for using LIBS as a wall-diagnostic technique for EAST.

Li, Cong; Wu, Xingwei; Zhang, Chenfei; Ding, Hongbin; Hu, Jiansheng; Luo, Guang-Nan

2014-09-01

376

Theoretical analysis of dynamic chemical imaging with lasers using high-order harmonic generation  

SciTech Connect

We report theoretical investigations of the tomographic procedure suggested by Itatani et al. [Nature (London) 432, 867 (2004)] for reconstructing highest occupied molecular orbitals (HOMOs) using high-order harmonic generation (HHG). Due to the limited range of harmonics from the plateau region, we found that even under the most favorable assumptions, it is still very difficult to obtain accurate HOMO wave functions using the tomographic procedure, but the symmetry of the HOMOs and the internuclear separation between the atoms can be accurately extracted, especially when lasers of longer wavelengths are used to generate the HHG. Since the tomographic procedure relies on approximating the continuum wave functions in the recombination process by plane waves, the method can no longer be applied upon the improvement of the theory. For future chemical imaging with lasers, we suggest that one may want to focus on how to extract the positions of atoms in molecules instead, by developing an iterative method such that the theoretically calculated macroscopic HHG spectra can best fit the experimental HHG data.

Van-Hoang Le [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, University of Pedagogy, 280 An Duong Vuong, Ward 5, Ho Chi Minh City (Viet Nam); Anh-Thu Le; Xie Ruihua; Lin, C. D. [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States)

2007-07-15

377

A modular architecture for multi-channel external cavity quantum cascade laser-based chemical sensors: a systems approach  

SciTech Connect

A multi-channel laser-based chemical sensor platform is presented, in which a modular architecture allows the exchange of complete sensor channels without disruption to overall operation. Each sensor channel contains custom optical and electronics packages, which can be selected to access laser wavelengths, interaction path lengths and modulation techniques optimal for a given application or mission. Although intended primarily to accommodate mid-infrared (MIR) external cavity quantum cascade lasers (ECQCLs)and astigmatic Herriott cells, channels using visible or near infrared (NIR) lasers or other gas cell architectures can also be used, making this a truly versatile platform. Analog and digital resources have been carefully chosen to facilitate small footprint, rapid spectral scanning, ow-noise signal recovery, failsafe autonomous operation, and in-situ chemometric data analysis, storage and transmission. Results from the demonstration of a two-channel version of this platform are also presented.

Taubman, Matthew S.; Myers, Tanya L.; Bernacki, Bruce E.; Stahl, Robert D.; Cannon, Bret D.; Schiffern, John T.; Phillips, Mark C.

2012-04-01

378

Emission of a pulsed purely rotational transition chemical H{sub 2}-F{sub 2} laser  

SciTech Connect

The possibility of obtaining efficient emission at purely rotational transitions of HF molecules in a pulsed chemical hydrogen fluoride laser is studied theoretically. The operation of a H{sub 2}-F{sub 2} laser with a gas pressure of 1.1 atm emitting at the v, j {yields} v, j - 1 (v = 1 - 6, j = 10 - 14) transitions is simulated taking into account resonance VR processes. The total specific laser energy release calculated over all the vibrational levels is 5.5 J L{sup -1} on purely rotational transitions at {lambda}{approx}17 {mu}m (j = 14), 3.5 J L{sup -1} at {lambda}{approx}18.5 {mu}m (j = 13), and 2.5 J L{sup -1} at {lambda}{approx}20 {mu}m (j = 12). (lasers and amplifiers)

Molevich, N E; Pichugin, S Yu [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2008-04-30

379

Synthesis of nanostructured carbon materials by open-air laser-induced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Elemental carbon in the sp2 hybridization state can form a great variety of graphitic and amorphous structures. Carbon nanotube is a well-known form of graphitic carbon that has remarkable mechanical, electronic and electrochemical properties with applications ranging from reinforced composite materials to micro-scale electronic devices. Pyrolytic carbon film with turbostratic structure is a form of amorphous carbon that possesses excellent barrier properties against diffusion of moisture and hydrogen, and is used as hermetic coating for optical fibers operating under harsh environments. Current deposition techniques for these novel carbon materials are limited in production rate, quality and reproducibility, thereby restricting their usage for advanced applications. In this dissertation, an open-air laser-induced chemical vapor deposition technique is proposed and investigated for the rapid growth of high quality carbon nanotubes and nanometer thick pyrolytic carbon films. The first part of the thesis focuses on the open-air synthesis of carbon nanotubes on stationary and moving fused quartz substrates. The second part will study the deposition of pyrolytic carbon film on various optical components including optical fibers. Optical microscopy, high-resolution transmission and scanning electron microscopy, Raman and Auger electron spectroscopy, as well as x-ray energy-dispersive spectrometry, scanning white-light interferometry and thermal pyrometry are used to investigate the deposition rate, morphology, microstructure and chemical composition of the deposited carbon materials.

Kwok, Kinghong

380

Femtosecond laser pulses for chemical-free embryonic and mesenchymal stem cell differentiation  

NASA Astrophysics Data System (ADS)

Owing to their self renewal and pluripotency properties, stem cells can efficiently advance current therapies in tissue regeneration and/or engineering. Under appropriate culture conditions in vitro, pluripotent stem cells can be primed to differentiate into any cell type some examples including neural, cardiac and blood cells. However, there still remains a pressing necessity to answer the biological questions concerning how stem cell renewal and how differentiation programs are operated and regulated at the genetic level. In stem cell research, an urgent requirement on experimental procedures allowing non-invasive, marker-free observation of growth, proliferation and stability of living stem cells under physiological conditions exists. Femtosecond (fs) laser pulses have been reported to non-invasively deliver exogenous materials, including foreign genetic species into both multipotent and pluripotent stem cells successfully. Through this multi-photon facilitated technique, directly administering fs laser pulses onto the cell plasma membrane induces transient submicrometer holes, thereby promoting cytosolic uptake of the surrounding extracellular matter. To display a chemical-free cell transfection procedure that utilises micro-litre scale volumes of reagents, we report for the first time on 70 % transfection efficiency in ES-E14TG2a cells using the enhanced green fluorescing protein (EGFP) DNA plasmid. We also show how varying the average power output during optical transfection influences cell viability, proliferation and cytotoxicity in embryonic stem cells. The impact of utilizing objective lenses of different numerical aperture (NA) on the optical transfection efficiency in ES-E14TG2a cells is presented. Finally, we report on embryonic and mesenchymal stem cell differentiation. The produced specialized cell types could thereafter be characterized and used for cell based therapies.

Mthunzi, Patience; Dholakia, Kishan; Gunn-Moore, Frank

2011-10-01

381

High-efficiency photoinitiated chemical D/sub 2/--F/sub 2/--CO/sub 2/ laser  

SciTech Connect

An investigation was made of a photoinitiated chemical D/sub 2/--F/sub 2/--CO/sub 2/ laser. When the mixture composition was D/sub 2/:F/sub 2/:CO/sub 2/:He = 1:5.5:4:9.5 ((O/sub 2/)/(F/sub 2/) = 0.03, p = 1 atm) and the degree of initiation was ..delta..(F/sub 2/)/(F/sub 2/) = 0.05%, the specific output energy was 37 J/liter, which corresponded to a technical laser efficiency of 18%.

Bashkin, A.S.; Vagin, N.P.; Kulakov, L.V.; Oraevskii, A.N.; Podmar'kov, Y.P.; Porodinkov, O.E.; Prishchepa, M.I.; Yuryshev, N.N.

1982-03-01

382

XeCl laser controlled chemical etching of aluminum in chlorine gas  

Microsoft Academic Search

The 308 nm XeCl laser assisted etching process of thin Al metal films on Si substrate in Cl2 gas was investigated. Etch rates were measured versus the laser fluence on the sample, the laser repetition rate, the Cl2 pressure and the sample temperature. Irradiation experiments under vacuum of films which were previously exposed to Cl2, and laser assisted etching in

G. Koren; F. Ho; J. J. Ritsko

1986-01-01

383

JOURNAL DE PHYSIQUE IV Colloque C7,slipplBmentau Journal de Physique111,Vol. 1,dbembre 1991  

E-print Network

-iodine laser (COIL) using magnetic modulation of gain is presented. An experimental verification of feasibility. Introduction A Chemical Oxygen-Iodine Laser (COIL) can generate kilowatt output powers in the CW regime is produced from molecular iodine. The third method used for the COIL system is a Q-switching technique

Paris-Sud XI, Université de

384

Measurement of molecular electronic ground state oxygen O2(3Sigma) in COIL device  

Microsoft Academic Search

The improvement of the efficiency of singlet oxygen generators (SOG) in chemical oxygen iodine lasers (COIL) is still a key component for optimizing the performance of these lasers. Important parameters for the SOG operation are the utilization of chlorine and the singlet oxygen yield. In this work, the singlet oxygen yield is examined by two different methods: the absorption spectroscopy

Frank R. Duschek; Karin M. Gruenewald; Juergen Handke; Wolfgang O. Schall

2005-01-01

385

Recent results of iodine and water diagnostics in supersonic COIL  

Microsoft Academic Search

Water vapor measurements at DLRs supersonic chemical oxygen iodine laser (COIL) have been carried out applying a tunable diode laser system. During a typical hot flow of 8 s, the water molar flow rate increases from 35 mmol\\/s to 85 mmol\\/s. Simultaneous measurements in the subsonic and supersonic region showed that about 10 percent of water in front of the

Frank R. Duschek; Karin M. Gruenewald; Willy L. Bohn

2000-01-01

386

COIL-related activities in the Czech Republic  

Microsoft Academic Search

This presentation is an historical overview of the activities related to the Chemical Oxygen- Iodine Laser conducted in the Czech Republic. It includes small scale basic research, both the experimental and the theoretical, with a view to particular topics of this laser system in the cw and the pulsed regime of generation.

Jarmila Kodymova; Otomar Spalek; Karel Rohlena; Jaroslav Beranek

1996-01-01

387

JOURNALDE PHYSIQUEIV ColloqueC7, suppl6ment au Journal de Physique 111,Vol. 1, dhmbre 1991  

E-print Network

power o f at least one kilowatt i s expected. 1 - Introduction The chemical oxygen iodine laser (COIL and optical f i b e r transmission properties(3) . The COIL systems are interesting f o r many industrial, m i, a rectangular duct laser cavity, an iodine heater and injector system, a l i q u i d nitrogen trap and a group o

Boyer, Edmond

388

Important kinetic effects in the hybrid ElectricOIL system Joseph W. Zimmermana,b  

E-print Network

transfer from O2(a1 ) produced using a low­pressure electric discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds purely chemical O2(a1 ) generation system. In this paper, the discharge species output for laser

Carroll, David L.

389

Chemical decomposition of urinary stones during holmium-laser lithotripsy: II. Evidence for photothermal breakdown  

Microsoft Academic Search

Because of the greater than or equal to 250 microsecond pulsewidth emitted by the Ho:YAG laser used in clinical lithotripsy, it is unlikely that stress confinement occurs within the irradiated stones. Experimental data supports a thermal mechanism for Ho:YAG laser stone ablation. Stone fragmentation occurs soon after the onset of the laser pulse, is uncorrelated to cavitation bubble formation or

Randolph D. Glickman; Joel M. Teichman; George J. Vassar; Susan E. Weintraub; Kin Foong Chan; Thomas Joshua Pfefer; Ashley J. Welch

1999-01-01

390

Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry  

PubMed Central

Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. Four APCI reagent systems were tested: the traditionally used mixture of methanol and water, neat benzene, neat carbon disulfide, and nitrogen gas (no liquid reagent). The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar amount of fragmentation was observed for these reagents. When the experiment was performed without a liquid reagent(nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to form stable molecular ions. PMID:21472571

Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

2010-01-01

391

Data Analysis of Multi-Laser Standoff Spectral identification of chemical and biological compounds  

SciTech Connect

With the availability of tunable broadband coherent sources that emit mid-infrared radiation with well-defined beam characteristics, spectroscopies that were traditionally not practical for standoff detection1 or for develop- ment of miniaturized infrared detectors2, 3 have renewed interest. While obtaining compositional information for objects from a distance remains a major challenge in chemical and biological sensing, recently we demonstrated that capitalizing on mid-infrared excitation of target molecules by using quantum cascade lasers and invoking a pump probe scheme can provide spectral fingerprints of substances from a variable standoff distance.3 However, the standoff data is typically associated with random fluctuations that can corrupt the fine spectral features and useful data. To process the data from standoff experiments toward better recognition we consider and apply two types of denoising techniques, namely, spectral analysis and Karhunen-Loeve Transform (KLT). Using these techniques, infrared spectral data have been effectively improved. The result of the analysis illustrates that KLT can be adapted as a powerful data denoising tool for the presented pump-probe infrared standoff spectroscopy.

Farahi, R H [ORNL; Zaharov, Viktor [ORNL; Tetard, Laurene [ORNL; Thundat, Thomas George [ORNL; Passian, Ali [ORNL

2013-01-01

392

Chemical mapping of tulobuterol in transdermal tapes using microscopic laser Raman spectroscopy.  

PubMed

Microscopic Laser Raman Spectroscopy and Mapping (MLRSM) technique was used to investigate the distribution of tulobuterol (TBR) crystals in transdermal tapes. TBR is one of suitable compounds for the transdermal pharmaceuticals because it has high permeability into skin. In case of TBR transdermal tapes, some commercial products also contain TBR crystals in order to control a release rate from a matrix. Therefore, the presence of TBR crystals in the matrix is a critical factor for quality assurance of this type of TDDS tapes. The model tapes prepared here employed two kinds of matrices, i.e., rubber or acrylic, which are generally used for transdermal pharmaceuticals. TBR crystals in the matrix were observed by MLRSM. Accurate observation of the distribution of TBR in the tapes was achieved by creating a Raman chemical map based on detecting unique TBR peak in each pixel. Moreover, differences in the growth of TBR crystals in the two kinds of matrices were detected by microscopic observation. MLRSM also enabled the detection of TBR crystals in commercial products. The present findings suggest that Raman micro-spectroscopic analysis would be very useful for verifying and/or assessing the quality of transdermal pharmaceuticals in development, as well as for manufacturing process control. PMID:19348338

Sakamoto, T; Matsubara, T; Sasakura, D; Takada, Y; Fujimaki, Y; Aida, K; Miura, T; Terahara, T; Higo, N; Kawanishi, T; Hiyama, Y

2009-03-01

393

Coupled molecular dynamics-Monte Carlo model to study the role of chemical processes during laser ablation of polymeric materials  

SciTech Connect

The coarse grained chemical reaction model is enhanced to build a molecular dynamics (MD) simulation framework with an embedded Monte Carlo (MC) based reaction scheme. The MC scheme utilizes predetermined reaction chemistry, energetics, and rate kinetics of materials to incorporate chemical reactions occurring in a substrate into the MD simulation. The kinetics information is utilized to set the probabilities for the types of reactions to perform based on radical survival times and reaction rates. Implementing a reaction involves changing the reactants species types which alters their interaction potentials and thus produces the required energy change. We discuss the application of this method to study the initiation of ultraviolet laser ablation in poly(methyl methacrylate). The use of this scheme enables the modeling of all possible photoexcitation pathways in the polymer. It also permits a direct study of the role of thermal, mechanical, and chemical processes that can set off ablation. We demonstrate that the role of laser induced heating, thermomechanical stresses, pressure wave formation and relaxation, and thermochemical decomposition of the polymer substrate can be investigated directly by suitably choosing the potential energy and chemical reaction energy landscape. The results highlight the usefulness of such a modeling approach by showing that various processes in polymer ablation are intricately linked leading to the transformation of the substrate and its ejection. The method, in principle, can be utilized to study systems where chemical reactions are expected to play a dominant role or interact strongly with other physical processes.

Prasad, Manish; Conforti, Patrick F.; Garrison, Barbara J. [Department of Chemistry, 104 Chemistry Building, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2007-08-28

394

A Study on Fractional Erbium Glass Laser Therapy Versus Chemical Peeling for the Treatment of Melasma in Female Patients  

PubMed Central

Introduction: Melasma is a commonly acquired hypermelanosis and a common dermatologic skin disease that occurs on sun-exposed areas of face. Aims: To assess the efficacy and safety of non-ablative 1,550 nm Erbium glass fractional laser therapy and compare results with those obtained with chemical peeling. Materials and Methods: We selected 30 patients of melasma aged between 20 years and 50 years for the study. The patients were divided into two groups of 15 patients each. Group I patients were subjected to four sessions of 1,550 nm Erbium glass non-ablative fractional laser at 3 weeks interval. In group II patients, four sessions of chemical peeling with 70% glycolic acid was performed. Results: After 12 weeks of treatment, percentage reduction in Melasma Area and Severity Index (MASI) score was seen in 62.9% in the laser group and 58.7% in the peels group. Conclusion: It was observed that 1,550 nm fractional laser is as effective as 70% glycolic acid peel in reducing MASI score in patients with melasma. PMID:24163531

Puri, Neerja

2013-01-01

395

Volume 141,number 4 CHEMICAL PHYSICS LETTERS I3 November 1987 TUNABLE FAR-INFRARED LASER SPECTROSCOPY IN A PLANAR SUPERSONIC JET  

E-print Network

Volume 141,number 4 CHEMICAL PHYSICS LETTERS I3 November 1987 TUNABLE FAR-INFRARED LASER 23.6 cm-' from P(23) to R(17), in a continuous planar jet expansion using a tunable far-infrared der Waals molecules. Mid-infrared laser spectroscopy of van der Waals clusters generated in a pulsed

Cohen, Ronald C.

396

Kinetic and microstructural study of titanium nitride deposited by laser chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Titanium nitride (TiN) films were deposited onto Ti-6Al-4V substrates by laser chemical vapor deposition using a cw COsb2 laser and TiClsb4,\\ Nsb2, and Hsb2 reactant gases. In-situ laser induced fluorescence (LIF) and multi-wavelength pyrometry determined relative titanium gas phase atomic number density and deposition temperature, respectively. Deposited films were yellow to gold in color. Transmission electron microscopy on one sample revealed a face-centered cubic structure with a lattice parameter (0.4237 nm) expected for TiN. Auger electron spectroscopy found substoichiometric compositions with a N/Ti ratio between 0.7 and 0.9. Variables decreasing grain size (lower temperature, higher TiClsb4 input) decreased the N/Ti ratio. Higher Nsb2 input increased stoichiometry, while larger Hsb2 input decreased stoichiometry. The deposit substoichiometry is believed to be caused by diffusion of nitrogen through TiN grain boundaries to the titanium alloy substrate. The morphology starts as a dense polycrystalline structure evolving into a columnar structure having facets or nodules at the surface with crystallite sizes ranging from 10-1000 nm. TiClsb4 input had a inverse correlation with crystallite size, while Nsb2:Hsb2 ratio had minimal effect; the crystallite size (G) varied exponentially with temperature (T) for a given irradiation time, i.e., G = C exp (-28000/T), with constant C reflecting substrate roughness and gas composition. Microhardness tests revealed substrate contributions; nevertheless, films appeared to have a minimum hardness of 2000 Hsbv. The deposition apparent activation energy was calculated as 122 ± 9 kJ/mole using growth rates measured by film height and 117 ± 23 kJ/mole using growth rates measured by LIF signals. This puts the process in the surface kinetic growth regime over the temperature range 1370-1610 K. Above Nsb2 and Hsb2 levels of 1.25% and below TiClsb4 input of 4.5%, the growth rate has a half-order dependence on nitrogen and a linear dependence on hydrogen and is approximated by$r = {{kPsb{TiClsb4}Psb{Hsb2}Psbsp{Nsb2}{1/2}exp?ft({{-}Esb{a}/ {RT}right)}/{1 + Psb{Ar}}}}.Since nitrogen positively affects growth rate (when added to a TiClsb4+Hsb2 mixture), stepwise reduction of TiClsb4 to Ti by hydrogen does not occur. NHsb{x} complexes are clearly involved in the growth mechanism; a likely combination of rate determining steps is the formation of NH and the initial reduction of TiClsb4$ by hydrogen.

Egland, Keith Maynard

397

Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds  

NASA Astrophysics Data System (ADS)

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were 35 m for dimethyl methylphosphonate (DMMP) detection and 60, 90 and 140 m for cyclohexane detection. The prototype systems consisted of a Raman spectrometer equipped with a CCD detector (for CW measurements) and an I-CCD camera with time-gated electronics (for pulsed laser measurements), a reflecting telescope, a fiber optic assembly, a single-line CW laser source (514.5, 488.0, 351.1 and 363.8 nm) and a frequency-doubled single frequency Nd:YAG 532 nm laser (5 ns pulses at 10 Hz). The telescope was coupled to the spectrograph using an optical fiber, and filters were used to reject laser radiation and Rayleigh scattering. Two quartz convex lenses were used to collimate the light from the telescope from which the telescope-focusing eyepiece was removed, and direct it to the fiber optic assembly. To test the standoff sensing system, the Raman Telescope was used in the detection of liquid TIC: benzene, chlorobenzene, toluene, carbon tetrachloride, cyclohexane and carbon disulfide. Other compounds studied were CWAS: dimethylmethyl phosphonate, 2-chloroethyl ethyl sulfide and 2-(butylamino)-ethanethiol. Relative Raman scattering cross sections of liquid CWAS were measured using single-line sources at 532.0, 488.0, 363.8 and 351.1 nm. Samples were placed in glass and quartz vials at the standoff distances from the telescope for the Remote Raman measurements. The mass of DMMP present in water solutions was also quantified as part of the system performance tests.

Ortiz-Rivera, William; Pacheco-Londoño, Leonardo C.; Hernández-Rivera, Samuel P.

2010-09-01

398

Stabilization, Injection and Control of Quantum Cascade Lasers, and Their Appli-cation to Chemical Sensing in the Infrared  

SciTech Connect

Quantum cascade lasers (QCLs) are a relatively new type of semiconductor laser operating in the mid- to long-wave infrared. These monopolar multilayered quantum well structures can be fabricated to operate anywhere between 3.5 microns and 20 microns, which includes the molecular fingerprint region of the in-frared. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present. Frequency stabilization and injection locking increase the utility of QCLs. We present results of locking quantum cascade lasers to optical cavities, achieving relative linewidths down to 5.6 Hz. We report injec-tion locking of one distributed feedback grating QCL with light from a similar QCL, demonstrating capture ranges of up to ±500 MHz, and suppression of amplitude modulation by up to 49 dB. We also present various cavity-enhanced chemical sensors employing the frequency stabilization techniques developed, in-cluding the resonant sideband technique known as Nice-Ohms. Sensitivities of 9.7 x 10-11 cm-1 Hz-1/2 have been achieved in nitrous oxide.

Taubman, Matthew S.; Myers, Tanya L.; Cannon, Bret D.; Williams, Richard M.

2004-12-01

399

Excimer laser-assisted chemical process for formation of hydrophobic surface of Si (001)  

NASA Astrophysics Data System (ADS)

Silicon (Si) wettability is one of the important parameters in the development of Si-based biosensing and lab-on-chip devices. We report on UV laser induced hydrophobicity of Si (001) wafers immersed in methanol during the irradiation with an ArF excimer laser. The irradiation with 800 pulses of the laser operating at 65 mJ/cm2 allowed to significantly increase the hydrophobicity of investigated samples as characterized by the static contact angle change from 77° to 103°. Owing to the irradiation with relatively low laser fluence, no measurable change in surface morphology of the irradiated samples has been observed with atomic force microscopy measurements. The nature of the hydrophobic surface of investigated samples is consistent with X-ray photoelectron spectroscopy analysis that indicates formation of Si-O-CH3 bonds on the surface of the laser-irradiated material.

Liu, Neng; Hassen, Walid M.; Dubowski, Jan J.

2014-10-01

400

System and method for laser assisted sample transfer to solution for chemical analysis  

DOEpatents

A system and method for laser desorption of an analyte from a specimen and capturing of the analyte in a suspended solvent to form a testing solution are described. The method can include providing a specimen supported by a desorption region of a specimen stage and desorbing an analyte from a target site of the specimen with a laser beam centered at a radiation wavelength (.lamda.). The desorption region is transparent to the radiation wavelength (.lamda.) and the sampling probe and a laser source emitting the laser beam are on opposite sides of a primary surface of the specimen stage. The system can also be arranged where the laser source and the sampling probe are on the same side of a primary surface of the specimen stage. The testing solution can then be analyzed using an analytical instrument or undergo further processing.

Van Berkel, Gary J; Kertesz, Vilmos

2014-01-28

401

A microfluidic dye laser fabricated by nanoimprint lithography in a highly transparent and chemically resistant cyclo-olefin copolymer (COC)  

NASA Astrophysics Data System (ADS)

We present a polymer-based, microfluidic dye laser suitable for integration into polymer- or silicon-based lab-on-a-chip systems. The laser is fabricated by nanoimprint lithography (NIL) in cyclo-olefin copolymer (COC). The polymer device consists of microfluidic channels, with sizes ranging from several mm down to a few µm, and integrated optical waveguides to couple the light out of the structure, all fabricated in one single NIL step and with approximately 10 nm roughness. COC is a highly transparent, chemically resistant thermoplastic polymer optimal for the integration of microfluidic systems with optical elements. Rhodamine 6G dissolved in ethanol is used as an active medium in the laser, and the resonator is based on multiple reflections from a periodic structure of 16 µm wide, parallel microfluidic channels. Lasing from the device is observed at 577 nm, when optically pumped with a frequency doubled Nd:YAG laser emitting at 532 nm, where Rhodamine 6G has its absorption maximum.

Nilsson, Daniel; Balslev, Søren; Kristensen, Anders

2005-02-01

402

Influence of pulse duration on the doping quality in laser chemical processing (LCP)—a simulative approach  

NASA Astrophysics Data System (ADS)

The laser chemical processing (LCP) technique for the local doping of crystalline silicon solar cells is investigated. Here, a liquid jet containing a dopant source acts as a waveguide for pulsed laser light, which results in the melting and subsequent doping of the silicon surface. Typical LCP pulse durations are in the 15 ns range, giving satisfactory results for specific parameter settings. While great potential is assumed to exist, optimization of the pulse duration has until now not been deeply investigated, because it is hard to change this parameter in laser systems. Therefore, this paper accesses the influence of the pulse duration by a simulative approach. The model includes optics, thermodynamics, and melt dynamics induced by the liquid jet and dopant diffusion into the silicon melt. It is solved by coupling our existing finite differences Matlab-code LCPSim with the commercial fluid flow solver Ansys Fluent. Simulations of axial symmetric single pulses were performed for pulse durations ranging from 15 ns to 500 ns. Detailed results are given, which show that for longer pulse durations lateral heat conduction significantly homogenizes the inhomogeneous dopant distribution caused by the speckled intensity profile within the liquid jet cross section. The melt expulsion by the liquid jet is low enough that a sufficiently doped layer remains after full resolidification for all pulse durations. Last, temperature gradients are evaluated to give an indication on the amount of laser damage induced by thermal stress.

Fell, Andreas; Granek, Filip

2013-03-01

403

Photo-chemical study and optical properties of microtips self- written on vertical laser diodes using NIR photo-polymerization.  

PubMed

Near infra-red (NIR) self-guided photo-polymerization is investigated in the context of micro-optics photo-fabrication on VCSELs (Vertical-Cavity Surface Emitting Lasers). We present the optimized process we have developed to allow for a collective fabrication on III-V devices wafers under real-time optical monitoring. The influence of photo-chemical parameters on final micro-elements dimensions is studied for two types of single mode 760 nm VCSELs. The difference of the resulting tip shape between the two lasers is due to the strong differences of their emissions, as they are nicely reproduced by the computed near-field profiles. The tip shapes are also compared to those produced by the light emitted by an optical fiber and differences with VCSEL tips are discussed. Also the VCSEL characteristics with fabricated tips are discussed and found in good agreement with optical modeling. PMID:23037442

Barat, D; Bardinal, V; Dika, I; Soppera, O; Debernardi, P; Rumyantseva, A; Reig, B; Renault, M; Camps, T; Bruyant, A; Doucet, J B; Malval, J P; Daran, E

2012-09-24

404

Passively mode-locked fiber laser by using monolayer chemical vapor deposition of graphene on D-shaped fiber.  

PubMed

We demonstrate a monolayer graphene saturable absorber (SA) based on D-shaped fiber for operation of the mode-locked fiber laser. The monolayer graphene is grown by chemical vapor deposition (CVD) on Cu substrate and transferred onto the polymer, and then covered with D-shaped fiber, which allows light-graphene interaction via the evanescent field of the fiber. Due to the side-coupled interaction, the length of graphene is long enough to avoid optical power-induced thermal damage. Using such a graphene-based SA, stable mode-locked solitons with 4.5 nm spectral bandwidth and 713 fs pulsewidth at the 1563 nm wavelength have been obtained under 280 mW pump power. The influence of total cavity dispersion on the optical spectrum and pulse is also investigated by adding different lengths of single-mode fiber in the laser cavity. PMID:24921867

Chen, Tao; Liao, Changrui; Wang, D N; Wang, Yiping

2014-05-01

405

Thermal diffusion and chemical kinetics in laminar biomaterial due to heating by a free-electron laser.  

PubMed

We have theoretically investigated the role of thermal diffusion and chemical kinetics as a possible dynamic explanation for the preferential ablative properties of infrared radiation from a free-electron laser (FEL). The model is based on a laminar system composed of alternating layers of protein and saline. We have compared exposure to 3 microm where water is the main absorber and 6.45 microm where both water and protein absorb. The picosecond pulses of the superpulse are treated as a train of impulses. We find that the heating rates are sufficient to superheat the outer saline layers on the nanosecond time scale, leading to explosive vaporization. We also find that competition between the layer-specific heating rates and thermal diffusion results in a wavelength-dependent separation in layer temperatures. We consider the onset of both chemical bond breaking and the helix-coil transition of protein prior to vaporization in terms of the thermal, chemical, and structural properties of the system as well as laser wavelength and pulse structure. There is no evidence for thermal bond breaking on these time scales. At 6.45 microm, but not 3 microm, there is evidence for a significant helix-coil transition. While the native protein is ductile, the denatured protein exhibits brittle fracture. This model provides a dynamic mechanism to account for the preferential ablative properties observed with FEL radiation tuned near 6.45 microm. PMID:12188758

Hutson, M Shane; Hauger, Susanne A; Edwards, Glenn

2002-06-01

406

Laser-induced destruction of toxic chemicals contained in waste water. Report on Phase 1  

SciTech Connect

The feasibility of using laser radiation to remove toxic species from waste water was investigated. Benzene, phenol, and chlorobenzene were selected as representative of the aromatic groups typically encountered in common toxic substances. These species were introduced in water in concentrations ranging from 1 to 100 ppm and irradiated with 100 mJ energy pulsed from an excimer laser: the parent aromatic species were readily destroyed. Energy inputs required to destroy a mole of each of the species were deduced, and the required energy input for chlorobenzene was found to be significantly lower than for benzene. Laser radiation may be effective in removing toxic species from water.

Galimore, R.; Porter, J.H.; Sharma, P.K.

1983-04-01

407

High-power supersonic chemical lasers: gas-dynamic problems of operation of mobile systems with PRS  

NASA Astrophysics Data System (ADS)

Supersonic chemical lasers, such as HF /DF and COIL, have always been in the focus of special interest as the most powerful sources of continuous wave generation. Presently, autonomous mobile laser complexes (both air- and landbased) are being developed on the basis of SCL [1-3]. It is commonly accepted that SCL appeared, conditionally speaking, at the crossroads of a number of sciences: of physics - quantum electronics and physical kinetics; chemistry - combustion theory and chemical kinetics; classic optics - theory of resonators, aero-optics, and gas dynamics (there is a supersonic flow in the SCL channel). Due to this fact, all tasks and problems which could be resolved in the course of SCL development have complex character and could be considered as the next stage of complexity in comparison with the well known similar tasks which had been considered earlier. This is why they should be resolved anew with consideration of the specific aspects of the SCL processes. This is true for the gas-dynamic problems: new parameter areas, non-traditional channel geometry, consideration of new phenomena, etc.Supersonic chemical lasers, such as HF /DF and COIL, have always been in the focus of special interest as the most powerful sources of continuous wave generation. Presently, autonomous mobile laser complexes (both air- and landbased) are being developed on the basis of SCL [1-3]. It is commonly accepted that SCL appeared, conditionally speaking, at the crossroads of a number of sciences: of physics - quantum electronics and physical kinetics; chemistry - combustion theory and chemical kinetics; classic optics - theory of resonators, aero-optics, and gas dynamics (there is a supersonic flow in the SCL channel). Due to this fact, all tasks and problems which could be resolved in the course of SCL development have complex character and could be considered as the next stage of complexity in comparison with the well known similar tasks which had been considered earlier. This is why they should be resolved anew with consideration of the specific aspects of the SCL processes. This is true for the gas-dynamic problems: new parameter areas, non-traditional channel geometry, consideration of new phenomena, etc.

Boreysho, A. S.; Malkov, V. M.; Savin, A. V.

2008-10-01

408

Identification of vapor-phase chemical warfare agent simulants and rocket fuels using laser-induced breakdown spectroscopy  

SciTech Connect

Application of laser-induced breakdown spectroscopy (LIBS) to the identification of security threats is a growing area of research. This work presents LIBS spectra of vapor-phase chemical warfare agent simulants and typical rocket fuels. A large dataset of spectra was acquired using a variety of gas mixtures and background pressures and processed using partial least squares analysis. The five compounds studied were identified with a 99% success rate by the best method. The temporal behavior of the emission lines as a function of chamber pressure and gas mixture was also investigated, revealing some interesting trends that merit further study.

Stearns, Jaime A.; McElman, Sarah E.; Dodd, James A.

2010-05-01

409

High beam quality COIL with hybrid resonators  

NASA Astrophysics Data System (ADS)

For a 10kW-class Chemical Oxygen Iodine Laser (COIL), negative and positive branch hybrid resonators are investigated in theory and experiment. Calculations from Fresnel-Kirchhoff theory predict a nearly diffraction limited beam quality in the unstable direction. Theory is verified by measurements with a 2D-camera system in the far field.

Handke, Jürgen; Hall, Thomas; Duschek, Frank; Grünewald, Karin

2007-05-01

410

Modelling coil with iodine atoms produced by pulsed electric discharge  

Microsoft Academic Search

The pulse mode of operation of the chemical oxygen iodine laser (COIL) is attractive for a large body of new applications. Pulsed electric discharge is most effective to turn COIL operation into the pulse mode by instant production of iodine atoms. Numerical model is developed for simulations of the pulsed COIL initiated by electric discharge. The model comprises a system

A. P. Napartovich; I. V. Kochetov; N. P. Vagin; N. N. Yuryshev

2007-01-01

411

Experimental modeling the active medium of a pulsed DOIL with volume generation of iodine atoms  

NASA Astrophysics Data System (ADS)

The active medium of a pulsed DOIL with volume generation of iodine atoms was experimentally simulated using the chemical generator of singlet oxygen and MW discharge to understand the feasibility of a pulsed oxygen-iodine laser with electrical generator of singlet oxygen.

Yuryshev, N. N.; Vagin, N. P.

2008-10-01

412

Combustion Research Program: Flame studies, laser diagnostics, and chemical kinetics. Final report, 15 July 1987--15 June 1992  

SciTech Connect

This project has comprised laser flame diagnostic experiments, chemical kinetics measurements, and low pressure flame studies. Collisional quenching has been investigated for several systems: the OH radical, by H{sub 2}0 in low pressure flames; the rotational level dependence for NH, including measurements to J=24; and of NH{sub 2} at room temperature. Transition probability measurements for bands involving v{prime} = 2 and 3 of the A-X system of OH were measured in a flame. Laser-induced fluorescence of vinyl radicals was unsuccessfully attempted. RRKM and transition state theory calculations were performed on the OH + C{sub 2}H{sub 4} reaction, on the t-butyl radical + HX; and transition state theory has been applied to a series of bond scission reactions. OH concentrations were measured quantitatively in low pressure H{sub 2}/N{sub 2}O and H{sub 2}/O{sub 2} flames, and the ability to determine spatially precise flame temperatures accurately using OH laser-induced fluorescence was studied.

Crosley, D.R.

1992-09-01

413

Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150°C  

NASA Astrophysics Data System (ADS)

Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200°C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200°C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150°C. We employed various buffer layers, such as silicon nitride (SiNX) and silicon dioxide (SiO2), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,?=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiNX buffer layer is wider than SiO2 and the maximum grain size slightly increased.

Park, Joong-Hyun; Han, Sang-Myeon; Park, Sang-Geun; Han, Min-Koo; Shin, Moon-Young

2006-09-01

414

Development of Efficient Mid-IR Interband Cascade Lasers for Chemical Sensing  

NASA Technical Reports Server (NTRS)

Significant progress has been made: Above room temperature (up to 350K) pulsed operation has been demonstrated. CW operation temperature has been raised up to 237 K. DFB IC lasers have been applied for the detection of trace gases such as CH4, HCl, and H2CO. Devices have been operated continuously over several hundred hours without degradation. Main challenge remains for many potential applications of ICLs. CW operation at room temperature and above with significant output powers. There is still significant room for improvement: Laser design and material quality - many parameters have not been optimized. Device fabrication and thermal management (passivation, better mounting, etc.). Significantly higher output power can be achieved with laser arrays.

Yang, Rui Q.; Hill, Cory J.; Yang, Baohua; Qiu, Yueming; Jan, Darrell

2006-01-01

415

Systems and methods for laser assisted sample transfer to solution for chemical analysis  

SciTech Connect

Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

Van Berkel, Gary J.; Kertesz, Vilmos; Ovchinnikova, Olga S.

2014-06-03

416

Systems and methods for laser assisted sample transfer to solution for chemical analysis  

DOEpatents

Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

Van Berkel, Gary J; Kertesz, Vilmos; Ovchinnikova, Olga S

2013-08-27

417

Hexagonal Truncated Pyramidal Light Emitting Diodes through Wafer Bonding of ZnO to GaN, Laser Lift-off, and Photo Chemical Etching  

Microsoft Academic Search

We report on a hexagonal pyramidal light emitting diodes (LEDs) produced by direct wafer bonding of a metal organic chemical vapor deposition (MOCVD) grown GaN LED on sapphire to a n-type ZnO wafer, laser lift off, and photochemical etching of the nitrogen face of the GaN LED. Laser lift off was used to remove the sapphire of the GaN wafer,

Daniel B. Thompson; Akihiko Murai; Michael Iza; Stuart Brinkley; Steven P. DenBaars; Umesh K. Mishra; Shuji Nakamura

2008-01-01

418

Photo-chemical etching on silicon-carbide by using KrF excimer laser and Xe{sub 2}* excimer lamp  

SciTech Connect

Silicon-carbide (SiC) has excellent refractivity in the range of soft X-ray and is well-used as a diffraction grating for Synchrotron-radiation (SR) light. This material has a high melting point, hardness and chemical stability. Therefore, etching of the material by chemical or physical methods is very difficult. The authors reported a photo-chemical etching method in which a SiC surface is placed in NF{sub 3} laser light of 248 nm perpendicularly on the sample surface. The Xe{sub 2}* excimer lamp light are employed for NF{sub 3} gas decomposition, and KrF laser light used for excitation on the sample surface. This photochemical etching reaction are detected by XPS, QMS and FTIR measurements. This method achieved 0.18 {angstrom}/shot in etching efficiency, and became maximum approximately 7 times as high as ArF laser light for photodecomposition.

Hasegawa, K.; Murahara, M. [Tokai Univ., Hiratsuka, Kanagawa (Japan)

1996-12-31

419

CO2 laser scribe of chemically strengthened glass with high surface compressive stress  

Microsoft Academic Search

Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute.

Xinghua Li; Butchi R. Vaddi

2011-01-01

420

Scanning Diode Laser Desorption Thin-Layer Chromatography Coupled with Atmospheric Pressure Chemical Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Continuous wave diode laser is applied for desorption of an analyte from a porous surface of a thin-layer plate covered with a graphite suspension. The thermally desorbed analyte molecules are ionized in the gas phase by a corona discharge at atmospheric pressure. Therefore, both essential processes - the desorption and the ionization of analyte molecules, which are often performed in one step - are separated. Reserpine was chosen as model analyte, which is often used for specification of mass spectrometers. No fragmentation was observed because of efficient collisional cooling under atmospheric pressure. The influence of diode laser power and the composition of the graphite suspension were investigated, and a primary optimization was performed. An interface to allow online qualitative and quantitative full plate detection and analysis of compounds separated by thin-layer chromatography is presented.

Peng, Song; Ahlmann, Norman; Edler, Michael; Franzke, Joachim

421

BRIEF COMMUNICATIONS: Electric-discharge chemical HF laser operating at a high pulse repetition frequency  

Microsoft Academic Search

Stimulated emission was obtained from an HF laser at atmospheric pressure as a result of the H2 + F2 chain reaction initiated in a reagent in a stream by a volume transverse electric discharge with ultraviolet preionization by a spark radiation source. The pulse repetition frequency attained in this system was 1 kHz and the output energy was 9 mJ

S. F. Zhuravlev; V. G. Karel'skii; Yu I. Kozlov; V. K. Orlov; A. K. Piskunov; Yu V. Romanenko; Yu I. Shcherbakov

1981-01-01

422

Chemical decomposition of urinary stones during holmium-laser lithotripsy: I. Lack of a photomechanical effect  

Microsoft Academic Search

The Ho:YAG laser commonly used for clinical lithotripsy of urinary stones typically emits 250-microsecond pulses at a wavelength of 2.12 micrometer and repetition rates of up to 10 Hz. This pulse duration is longer than the time required for a pressure wave to propagate beyond the optical penetration depth of this wavelength in water. Fast-flash photography was used to study

Kin Foong Chan; George J. Vassar; Thomas Joshua Pfefer; Joel M. Teichman; Randolph D. Glickman; Susan E. Weintraub; Ashley J. Welch

1999-01-01

423

Kr/sup +/ laser-induced chemical vapor deposition of W  

SciTech Connect

Kr/sup +/ laser-induced pyrolytic direct writing of W stripes by H/sub 2/ reduction of WF/sub 6/ has been investigated. The reproducibility of the process and the morphology and electrical properties of deposits depend heavily on the partial pressures of both WF/sub 6/ and H/sub 2/; the best results have been obtained with p(WF/sub 6/) = 5 mbar and 100 mbarless than or equal top(H/sub 2/)less than or equal to800 mbar. For a laser focus of 2w/sub 0/ = 7 ..mu..m and laser powers between 30 and 200 mW, the widths of stripes varied between 1.5 and 15 ..mu..m with corresponding thicknesses between 0.1 to 3 ..mu..m. The width of stripes is independent of the scanning speed within the range 20 ..mu..m/sless than or equal toV/sub s/ less than or equal to400 ..mu..m/s. The electrical resistivities of these stripes were about a factor of 1.3--2.3 larger than the bulk value.

Zhang, G.Q.; Szoerenyi, T.; Baeuerle, D.

1987-07-15

424

Roughening Hexagonal Surface Morphology on Laser Lift-Off (LLO) N-Face GaN with Simple Photo-Enhanced Chemical Wet Etching  

Microsoft Academic Search

A photo-enhanced chemical wet etching technique is presented to form a roughened surface morphology with hexagonal symmetry on laser lift-off (LLO) N-face GaN grown by metalorganic chemical vapor deposition (MOCVD). An aqueous solution of KOH was used as etch electrolyte. The etched surface showed cones with hexagonal pyramid structures bound by \\\\{10\\\\bar{1}\\\\bar{1}\\\\} facets. A detailed analysis of the etch rates

Yan Gao; Tetsuo Fujii; Rajat Sharma; Kenji Fujito; Steven P. Denbaars; Shuji Nakamura; Evelyn L. Hu

2004-01-01

425

Application of a widely electrically tunable diode laser to chemical gas sensing with quartz-enhanced photoacoustic spectroscopy  

NASA Astrophysics Data System (ADS)

A near-infrared diode laser with sample-grating distributed Bragg reflectors was used as a widely tunable spectroscopic source for multispecies chemical sensing. Quartz-enhanced photoacoustic spectroscopy was utilized to obtain high absorption sensitivity in a compact gas cell. CO2, H2O, C2H2, and NH3 were monitored. A noise equivalent sensitivity of 8×10^-9 cm^-1 W^-1 Hz^-1/2 for NH3 detection was achieved, which corresponds to a NH3 mixing ratio of 4.4 parts in 10^6 by volume (ppmv) with a 1-s time constant and available 5.2-mW optical power in the gas cell.

Weidmann, Damien; Kosterev, Anatoliy A.; Tittel, Frank K.; Ryan, Neil; McDonald, David

2004-08-01

426

Increasing the output power of single 808-nm laser diodes using diamond submounts produced by microwave plasma chemical vapour deposition  

SciTech Connect

We have designed and fabricated submounts from synthetic diamond grown by microwave plasma chemical vapour deposition and developed an economical process for metallising such submounts. Laser diode chips having an 808-nm emission wavelength, 3-mm-long cavity and 130-mm-wide stripe contact were mounted on copper heat sinks with the use of diamond submounts differing in quality. The devices were tested for more than 150 h in continuous mode at an output power of 8 W on diamond with a thermal conductivity of 700 W m{sup -1} K{sup -1}, and no changes in their output power were detected. On diamond with a thermal conductivity of 1600 W m{sup -1} K{sup -1}, stable cw operation for 24 h at an output power of 12 W was demonstrated. (letters)

Ashkinazi, E E; Bezotosnyi, V V; Bondarev, Vadim Yu; Kovalenko, V I; Konov, Vitalii I; Krokhin, Oleg N; Oleshchenko, V A; Pevtsov, Valerii F; Popov, Yurii M; Popovich, A F; Ral'chenko, Viktor G; Cheshev, E A

2012-11-30

427

Volume 154, number 5 CHEMICAL PHYSICS LETTERS 3 February 1989 A SOLID STATE RARE GAS HALIDE LASER: XeF IN CRYSTALLINE ARGON  

E-print Network

Volume 154, number 5 CHEMICAL PHYSICS LETTERS 3 February 1989 A SOLID STATE RARE GAS HALIDE LASER, is representative of the large family of solid state rare gas halide exciplexes which contains members suitable gases [4]. Most pertinent to the present are their solid state results. They showed that rare gas solids

Apkarian, V. Ara

428

Combining Transmission Geometry Laser Ablation and a Non Contact Continuous Flow Surface Sampling Probe/Electrospray Emitter for Mass Spectrometry-Based Chemical Imaging  

SciTech Connect

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and on to the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 m in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 m.

Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

2011-01-01

429

CO-CATALYTIC ABSORPTION LAYERS FOR CONTROLLED LASER-INDUCED CHEMICAL VAPOR DEPOSITION OF CARBON NANOTUBES  

E-print Network

CVD, i.e. conventional global substrate back heating, to investigate the influence of the Ta support layer thickness on the solid-state reduction27 of the initially oxidized Fe catalyst (from transport/storage in ambient air), and hence... laser heating is beyond the scope of this study, we can apply simple models to rationalize the experimentally observed absorption layer thickness dependencies. The following heat flux equation can be applied: #14;#15; #14;#16; #17; #14; #14;#16; #18...

Michaelis, F.B.; Weatherup, R.S.; Bayer, B.C.; Bock, M.C.D; Sugime, H.; Caneva, S.; Robertson, J.; Baumberg, J.J.; Hofmann, S.

2014-02-24

430

Stability and performance of CDRL-FEL (Chemical Dynamics Research Laboratory-Free Electron Laser)  

SciTech Connect

We study the performance of a proposed infrared free electron laser at Lawrence Berkeley Laboratory, which would be a user facility and therefore has a unique set of requirements in intensity, spectrum and stability. The output performance in intensity and spectrum, and methods to optimize the performance, are studied in detail. The effect of the electron beam fluctuation on FEL stability is carefully evaluated to set a tolerance for the accelerator design. Use of intracavity gratings is studied as a means of further improving the spectral purity and stability. 19 refs., 12 figs., 2 tabs.

Kim, K.J.; Xie, M.

1990-11-01

431

Droplet shattering, vaporization and recondensation in cloud clearing with long pulse infrared chemical lasers  

SciTech Connect

Results of experimental attempts to produce an optically clear channel in a water cloud by evaporating the cloud droplets with a CO{sub 2} laser are presented. Using scattered light it is possible to visualize the clear channel produced. Measurements of the fraction of power transmitted through the channel at visible wavelengths give insight into the clearing mechanisms. The present data suggest that the water droplets explode in the process of clearing. A theoretical explanation of why this should occur is presented and predictions of the onset of droplet explosions are made. 4 refs., 5 figs.

Caramana, E.J.; Kindel, J.L.; Morse, R.L.; Quigley, G.P.; Webster, R.B.; York, G.W.

1990-01-01

432

Laser fluorescence studies of the chemical interactions of sodium species with sulfur bearing fuels  

NASA Technical Reports Server (NTRS)

By using a large matrix of fuel rich and fuel lean H2/O2/N2 and fuel rich C2H2/O2/N2 flames, the behavior of sodium and its interactions with sulfur at high temperatures was extensively characterized. OH concentrations were measured for each flame using the previously validated laser induced fluorescence technique. Sodium atomic concentrations were obtained by the saturated laser fluorescence method. Measurements were made in the absence and presence of up to 2% sulfur. In oxygen rich systems sodium is depleted by NaO2 and NaOH formation. The relative amounts of each are controlled by the degree of nonequilibration of the flame radicals and by the temperature. The bond strength of NaO2 was established. For the first time, a complete understanding of the complex behavior of sodium in fuel lean H2/O2 flames has emerged and computer modeling has permitted various rate constants of Na, NaO2 and NaOH reactions to be approximately fixed.

Steinberg, M.; Schofield, K.

1983-01-01

433

Chemical composition of ZrC thin films grown by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

ZrC films were grown on (1 0 0) Si substrates by the pulsed laser deposition (PLD) technique using a KrF excimer laser working at 40 Hz. The nominal substrate temperature during depositions was set at 300 °C and the cooling rate was 5 °C/min. X-ray diffraction investigations showed that films deposited under residual vacuum or under 2 × 10 -3 Pa of CH 4 atmosphere were crystalline, exhibiting a (2 0 0)-axis texture, while those deposited under 2 × 10 -2 Pa of CH 4 atmosphere were found to be equiaxed and with smaller grain size. The surface elemental composition of as-deposited films, analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), showed the usual high oxygen contamination of carbides. Once the topmost 2-4 nm region was removed, the oxygen concentration rapidly decreased, down to around 3-8% only in bulk. Simulations of the X-ray reflectivity (XRR) curves indicated a smooth surface morphology, with roughness values below 1 nm (rms) and films density values of around 6.30-6.45 g/cm 3, very close to the bulk density. The growth rate, estimated from thickness measurements by XRR was around 8.25 nm/min. Nanoindentation results showed for the best quality ZrC films a hardness of 27.6 GPa and a reduced modulus of 228 GPa.

Craciun, D.; Socol, G.; Stefan, N.; Bourne, G.; Craciun, V.

2009-03-01

434

Preparation, characterisation and optimisation of lithium battery anodes consisting of silicon synthesised using Laser assisted Chemical Vapour Pyrolysis  

NASA Astrophysics Data System (ADS)

Suitability of silicon prepared using Laser assisted Chemical Vapour Pyrolysis (LaCVP) as a potential anode material in lithium batteries is systematically investigated. Its compositional, morphological, physical-chemical and electrochemical properties are compared to a current benchmark commercial silicon. Important differences in particle size and particle composition are found which, as shown, affect critically the rheological properties of the corresponding electrode slurries. In order to overcome the rheological problems of prepared nanosilicon, we introduce and optimise a spraying method instead of using the usual casting technique for slurry application. Interestingly, the optimised electrodes show similar electrochemical performance, regardless of the particle size or composition of nanosilicon. This unexpected result is explained by the unusually high resistance of electrochemical wiring in silicon-based electrodes (about 60 Ohm per 1 mg cm-2 of active material loading). Despite that, the optimised material still shows a capacity up to 1200 mA h g-1 at a relatively high loading of 1.6 mg cm-2 and after 20 cycles. On the other hand, by decreasing the loading to below ca. 0.9 mg cm-2 the wiring problems are effectively overcome and capacities close to theoretical values can be obtained.

Veliscek, Ziga; Perse, Lidija Slemenik; Dominko, Robert; Kelder, Erik; Gaberscek, Miran

2015-01-01

435

Design and Performance of a Sensor System for Detection of Multiple Chemicals Using an External Cavity Quantum Cascade Laser  

SciTech Connect

We describe the performance of a sensor system designed for simultaneous detection of multiple chemicals with both broad and narrow absorption features. The sensor system consists of a broadly tunable external cavity quantum cascade laser (ECQCL), multi-pass Herriott cell, and custom low-noise electronics. The ECQCL features a rapid wavelength tuning rate of 2265 cm 1/s (15660 nm/s) over its tuning range of 1150-1270 cm 1 (7.87-8.70 ?m), which permits detection of molecules with broad absorption features and dynamic concentrations, while the 0.2 cm-1 spectral resolution of the ECQCL system allows measurement of small molecules with atmospherically broadened absorption lines. High-speed amplitude modulation and low-noise electronics are used to improve the ECQCL performance for direct absorption measurements. We demonstrate simultaneous detection of Freon-134a (1,1,1,2-tetrafluoroethane), ammonia (NH3), and nitrous oxide (N2O) at low-ppb concentrations in field measurements of atmospheric chemical releases from a point source.

Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

2010-01-23

436

Exploring the nanoworld with terahertz and infrared laser spectrometers and chemical nanoscopes  

Microsoft Academic Search

Research on biomolecules, proteins, and living cells requires extremely sensitive spectrometers to harvest the response from precious, small quantity samples. Exploring the large biological parameter space of different mutations, concentrations, pH-values and temperatures demands fast data acquisition and high signal-to-noise ratios for satisfying statistics. We developed terahertz and infrared spectrometers to facilitate the study of biological samples. A chemical nanoscope

E. Briindermann

2007-01-01

437

GaN-based LEDs with air voids prepared by laser scribing and chemical etching  

NASA Astrophysics Data System (ADS)

The authors report the formation of air-voids at GaN/cone-shaped-patterned-sapphire-substrate interface by laser scribing and lateral etching with one-step growth. With 5 and 20 min lateral etching, it was found that pyramid-like airvoid was formed with an average height of 0.98 and 1.9 ?m, respectively, on top of each corn of the substrate. It was also found that we can enhance output power of GaN-based light-emitting diodes by 6.6 and 11.5%, respectively, by immersing the wafer in a mixture of H3PO4 and H2SO4 solution at 220°C for 5 and 20 min, respectively.

Chang, S. J.

2012-03-01

438

Mitigation of organic laser damage precursors from chemical processing of fused silica.  

PubMed

Increases in the laser damage threshold of fused silica have been driven by the successive elimination of near-surface damage precursors such as polishing residue, fractures, and inorganic salts. In this work, we show that trace impurities in ultrapure water used to process fused silica optics may be responsible for the formation of carbonaceous deposits. We use surrogate materials to show that organic compounds precipitated onto fused silica surfaces form discrete damage precursors. Following a standard etching process, solvent-free oxidative decomposition using oxygen plasma or high-temperature thermal treatments in air reduced the total density of damage precursors to as low as <50 cm-2. Finally, we show that inorganic compounds are more likely to cause damage when they are tightly adhered to a surface, which may explain why high-temperature thermal treatments have been historically unsuccessful at removing extrinsic damage precursors from fused silica. PMID:25606889

Baxamusa, S; Miller, P E; Wong, L; Steele, R; Shen, N; Bude, J

2014-12-01

439

Industrial COIL systems--part 1: laser beam delivery by fiber  

NASA Astrophysics Data System (ADS)

First results of experimental and theoretical investigations related to an industrial application of oxygen-iodine laser (COIL) are reported. A developed calculative model determines a transmission factor of a laser emission at a set wavelength depending on the waveguide parameters, focusing system characteristics, and laser emission intensity angular distribution. Carried out investigations concerned with delivery of a laser emission power up to 1.6 kW via industrial quartz waveguides of 0.8- and 1 -mm- diameters and 3 and 10 meters long. It was shown that at optimal parameters of the delivery system the waveguide transmission is virtually independent of the diameter and bending radius and is equal to 0.90+/-0.02, which is in a good agreement with calculative results. The spatial distribution of the laser intensity at the waveguide input and output was measured. The far-field divergence at the 90%-level of the power was shown to increase approximately by 4 times when the laser emission is propagated through a quartz waveguide with a 800-mkm-diameter core and 3 m long.

Ilyin, Sergey P.; Buzoverya, Vladimir V.; Adamenkov, Anatoly A.; Bakshin, Victor V.; Efremov, Valentin I.; Kochiev, David G.; Kolobyanin, Yuriy V.; Moiseev, Vladimir B.; Vyskubenko, Boris A.

2005-03-01

440

Ternary molybdenum cluster sulfides: electrochemical and chemical behavior of in situ pulsed laser deposited thin films  

NASA Astrophysics Data System (ADS)

The electrochemical deinsertions and insertions in recently synthesised PLD molybdenum cluster sulfide films are presented. We prove that Cu xMo 6S 8 can be electrochemically converted to Mo 6S 8. The copper, cadmium, zinc and lead intercalation performed by electrochemistry on deintercalated films has succeeded. During this study, we also report that the use of a chemical process allows the formation of PbMo 6S 8 and SnMo 6S 8 thin films, that means that the intercalation of large cations is effective like the one of small cations.

Kaidi, Z.; Boulanger, C.; Lecuire, J. M.; Lemée, N.; Guilloux-Viry, M.; Perrin, A.

1999-10-01

441

High-rate deposition of YBa2Cu3O7-? high-temperature superconducting films by IR-laser-assisted chemical vapor deposition  

NASA Astrophysics Data System (ADS)

We applied an infrared- (IR-) laser-assisted chemical vapor deposition technique to YBa2Cu3O7-? (YBCO) film fabrication in order to enhance the deposition rate to one suitable for commercial applications. IR-laser illumination during deposition effectively suppressed outgrowth of a-axis oriented grains, which strongly diminish the film’s current-carrying capacity. As a result, high-performance YBCO films with critical current densities of greater than 1 × 106 A cm-2 were successfully obtained at high deposition rates of up to 58 ?m h-1 (˜1 ?m min-1) by this method.

Miyata, S.; Matsuse, K.; Ibi, A.; Izumi, T.; Shiohara, Y.; Goto, T.

2013-04-01

442

Comparison of silver nanoparticles confined in nanoporous silica prepared by chemical synthesis and by ultra-short pulsed laser ablation in liquid  

NASA Astrophysics Data System (ADS)

Hexagonally ordered mesoporous silica materials, MCM-41 and SBA-15, have been synthesized and loaded with Ag nanoparticles, utilizing both chemical synthesis and ultra-short pulsed laser ablation in liquid. In laser ablation, a silver target, immersed in aqueous suspension of ordered mesoporous silica SBA-15, was irradiated by ultra-short laser pulses to generate silver nanoparticles. For comparison, samples of similar silver contents were prepared either by incorporating silver into the SBA-15 during a hydrothermal synthesis or by introducing silver in MCM-41 by template ion-exchange. Samples were characterized by XRD, N2 physisorption, TEM and UV-vis spectroscopy. All preparations contained significant amount of 5-50 nm size silver agglomerates on the outer surface of the silica particles. The laser ablation process did not cause significant destruction of the SBA-15 structure and metallic silver (Ag0) nanoparticles were mainly generated. It is demonstrated that by laser ablation in aqueous silica suspension smaller and more uniform metallic silver particles can be produced and loaded on the surface of the silica support than by synthesis procedures. Catalytic properties of the samples have been tested in the total oxidation of toluene. Because of its favorable Ag dispersity, the Ag/SBA-15 catalyst, generated by the laser ablation method, had better catalytic stability and, relative to its Ag load, higher activity than the conventional Ag/SBA-15 preparations.

Szegedi, Á.; Popova, M.; Valyon, J.; Guarnaccio, A.; De Stefanis, A.; De Bonis, A.; Orlando, S.; Sansone, M.; Teghil, R.; Santagata, A.

2014-10-01

443

Laser enhanced chemical reaction studies. Technical report, January 1, 1994--February 28, 1995  

SciTech Connect

The relaxation of vibrationally excited pyrazine (E=40,640 cm{sup -1}) by collisions which populate the high J tail (J=58-82) of the vibrationless ground state (00{sup 0}0) of CO{sub 2} has been studied using tunable infrared diode lasers to probe the scattered CO{sub 2} molecules. The nascent rotational populations and translational recoil velocities for a series of rotational states in the high J tail of the 00{sup 0}0 level of CO{sub 2} were measured at five collision cell temperatures: 243, 263, 298, 339, and 364 K. Both the rate constants describing these V-R/T processes and the translational temperatures describing the recoiling CO{sub 2} molecules exhibit a very weak positive temperature dependence indicating that the high energy CO{sub 2} molecules must originate from near the center of the pre-collision energy distribution. Quantitative estimates of the actual amount of energy transferred in collisions between CO{sub 2} and vibrationally excited pyrazine, based on an angular momentum and translational energy exponential gap model of the cross section, indicate that {triangle}E{sub total} can be as large as 7090 cm{sup -1} ({approximately}20 kcal/mol). These experiments offer compelling evidence that these energy transfer events can indeed be classified as supercollisions since they involve unusually large, single collision energy transfer magnitudes; and despite their relative infrequency, they play a most important role in the collisional deactivation of vibrationally excited pyrazine by a CO{sub 2} bath.

NONE

1995-07-01

444

Observation of whispering gallery modes in the mid-Infrared with a Quantum Cascade Laser: possible applications to nanoliter chemical  

E-print Network

) of a CaF2 ball resonator is demonstrated at 4.5 micron with a pulsed Quantum Cascade laser. A prism in that range, and finally CW QCL sources are still far from as popular as telecom CW diode lasers The schematic of the setup is given in Figure 1. A Quantum Cascade (QC) Distributed Feedback (DFB) pulsed laser

Jensen, Grant J.

445

582 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 38, NO. 6, JUNE 2002 Chemical Sensors Based on Quantum Cascade Lasers  

E-print Network

on Quantum Cascade Lasers Anatoliy A. Kosterev and Frank K. Tittel, Fellow, IEEE Invited Paper Abstract spectroscopy. Index Terms--Infrared spectroscopy, quantum cascade lasers, trace gas detection. I. INTRODUCTION of detectable molecules. The advance of quantum cascade (QC) lasers fabricated by band structure engineering

446

High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

447

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers  

NASA Technical Reports Server (NTRS)

The design and chemical synthesis of new media for solar pumped iodine molecule lasers are explored. In an effort to prepare an iodo fluorocarbon compound absorbing strongly at 300 nm or above, the synthesis of perfluoro allylic iodides was investigated. These compounds furnish especially stable allylic radicals upon photodissociation. The desired red shift is anticipated in the absorption maximum could correlate with increasing radical stability. This expectation was based upon the analysis, previously reported, of the structures and absorption maxima of compounds studied earlier. A previously unknown substance was prepared, a prototypical target molecule, perfluoro-3-iodocyclopent-1-ene. It was obtained by reaction of perfluorocyclopentene with sulfur trioxide under the influence of antimony pentafluoride catalyst, followed by treatment of the resulting allylic fluorosulfonate with sodium iodide in sulfoland solvent. Preliminary data indicate that the absorption maximum for the iodo fluorocarbon is not shifted significantly to longer wavelength. It is not certain whether this result reflects an unexpected influence of the cyclic structure upon the position of the absorption maximum.

Shiner, C. S.

1986-01-01

448

A hyphenated optical trap capillary electrophoresis laser induced native fluorescence system for single-cell chemical analysis.  

PubMed

Single-cell measurements allow a unique glimpse into cell-to-cell heterogeneity; even small changes in selected cells can have a profound impact on an organism's physiology. Here an integrated approach to single-cell chemical sampling and assay are described. Capillary electrophoresis (CE) with laser-induced native fluorescence (LINF) has the sensitivity to characterize natively fluorescent indoles and catechols within individual cells. While the separation and detection approaches are well established, the sampling and injection of individually selected cells requires new approaches. We describe an optimized system that interfaces a single-beam optical trap with CE and multichannel LINF detection. A cell is localized within the trap and then the capillary inlet is positioned near the cell using a computer-controlled micromanipulator. Hydrodynamic injection allows cell lysis to occur within the capillary inlet, followed by the CE separation and LINF detection. The use of multiple emission wavelengths allows improved analyte identification based on differences in analyte fluorescence emission profiles and migration time. The system enables injections of individual rat pinealocytes and quantification of their endogenous indoles, including serotonin, N-acetyl-serotonin, 5-hydroxyindole-3-acetic acid, tryptophol and others. The amounts detected in individual cells incubated in 5-hydroxytryptophan ranged from 10(-14) mol to 10(-16) mol, an order of magnitude higher than observed in untreated pinealocytes. PMID:22543409

Cecala, Christine; Rubakhin, Stanislav S; Mitchell, Jennifer W; Gillette, Martha U; Sweedler, Jonathan V

2012-07-01

449

Periodic nanostructuring of Er/Yb-codoped IOG1 phosphate glass by using ultraviolet laser-assisted selective chemical etching  

SciTech Connect

The patterning of submicron period ({approx_equal}500 nm) Bragg reflectors in the Er/Yb-codoped IOG1 Schott, phosphate glass is demonstrated. A high yield patterning technique is presented, wherein high volume damage is induced into the glass matrix by exposure to intense ultraviolet 213 nm, 150 ps Nd:YAG laser radiation and, subsequently, a chemical development in potassium hydroxide (KOH)/ethylenediamine tetra-acetic acid (EDTA) aqueous solution selectively etches the exposed areas. The electronic changes induced by the 213 nm ultraviolet irradiation are examined by employing spectrophotometric measurements, while an estimation of the refractive index changes recorded is provided by applying Kramers-Kronig transformation to the absorption change data. In addition, real time diffraction efficiency measurements were obtained during the formation of the volume damage grating. After the exposure, the growth of the relief grating pattern in time was measured at fixed time intervals and the dependence of the grating depth on the etching time and exposure conditions is presented. The gratings fabricated are examined by atomic and scanning electron microscopies to reveal the relief topology of the structures. Gratings with average depth of 120 nm and excellent surface quality were fabricated by exposing the IOG1 phosphate glass to 36 000 pulses of 208 mJ/cm{sup 2} energy density, followed by developing in the KOH/EDTA agent for 6 min.

Pappas, C.; Pissadakis, S. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vasilika Vouton, P.O. Box 1527, Heraklion 71 110 (Greece)

2006-12-01

450

CO2 laser-based differential absorption lidar system for range-resolved and long-range detection of chemical vapor plumes  

NASA Astrophysics Data System (ADS)

A dual CO2 laser-based differential absorption lidar (DIAL) system has been constructed and demonstrated for range-resolved mapping of chemical vapor plumes. The system acquires high range resolution through the use of plasma-shutter pulse clippers that extinguish the nitrogen tail of the CO2-laser output. A programmable servomotor-driven scanner allows full hemispherical coverage of the interrogated field. A high-speed direct-detection receiver subsystem is used to gather, process, and display vapor-concentration data in near real time. Data demonstrating range-resolved detection of low concentrations of chemical plumes from ranges of 1 to 2 km are presented. In the column-content detection mode, trace levels of secondary vapors from various organophosphate liquids were monitored. Detection of an SF6 vapor plume released 16 km from the DIAL system is also adduced.

Carlisle, Clinton B.; van der Laan, Jan E.; Carr, Lewis W.; Adam, Philippe; Chiaroni, Jean-Pierre

1995-09-01

451

Chemical Peeling  

MedlinePLUS

... the skin heals can cause unwanted side effects ranging from infection to scarring. If you have any ... Tanzi EL and Alster TS. “Skin Resurfacing: Ablative Lasers, Chemical Peels, and Dermabrasion.” In: Wolff K, Goldsmith ...

452

Laser combustion analysis of ? 34S of sulfosalt minerals . determination of the fractionation systematics and some crystal-chemical considerations  

NASA Astrophysics Data System (ADS)

Laser sulfur combustion in the presence of O 2 is the most commonly used method of in situ sulfur isotope analysis. Previous workers indicated that a small but reproducible fractionation of 34S/ 32S exists between the product SO 2 gas and the mineral. The magnitude of this fractionation varies with bond strength, as reflected in Gibbs free energy of formation at 298.15K. The correction factors are known for common sulfides and anhydrite but not, hitherto, for stibnite and the sulfosalt minerals, which are important constituents of many classes of ore deposits. We present the correction factors for the following chemically and crystallographically well-characterized minerals: stibnite (weighted mean = -1.2‰), bournonite (+0.6‰), tetrahedrite (+1.3‰), and boulangerite (+1.4‰). The Gibbs free energies of formation of these phases have been approximated by the sulfide summation method, and the correlation of ?G 2980 with the correction factor for the sulfosalts fits well with the trend previously established for simple sulfides. There is an excellent correlation between the fractionation factor and mineral composition, a parameter that does result in bond strength variations (e.g., mol fraction of PbS in sulfosalts), allowing estimation of the correction factors for simple intermediate compositions. Finally, bond strength also varies with variation in interatomic distances, and we have, therefore, investigated the behaviour of stibnite, a strongly anisotropic mineral. Our results indicate that there is a significant variation in fractionation factor, depending on crystal orientation. The fractionation factor along the prismatic b-axis, which displays the strongest chemical bonds (as monitored by the shortest bond lengths), is more negative (-1.7‰) than along the other crystallographic directions (-0.7 to -1.0‰), which is in full agreement with theoretical predictions. We demonstrate the application of the technique in unravelling source- and process-related sulfur isotope systematics in two hydrothermal vein systems in the classic mining area of the NE Rhenish Massif, both studies requiring resolution beyond the scale of conventional sulfur isotope analysis.

Wagner, Thomas; Boyce, Adrian J.; Fallick, Anthony E.

2002-09-01

453

Investigation by laser induced breakdown spectroscopy, X-ray fluorescence and X-ray powder diffraction of the chemical composition of white clay ceramic tiles from Veliki Preslav  

NASA Astrophysics Data System (ADS)

The paper presents the results of the application of laser induced breakdown spectroscopy, X-ray fluorescence spectrometry, and X-ray powder diffraction in assessing the chemical and phase composition of white clay decorative ceramic tiles from the medieval archaeological site of Veliki Preslav, a Bulgarian capital in the period 893-972 AC, well-known for its original ceramic production. Numerous white clay ceramic tiles with highly varied decoration, produced for wall decoration of city's churches and palaces, were found during the archaeological excavations in the old capital. The examination of fourteen ceramic tiles discovered in one of the city's monasteries is aimed at characterization of the chemical profile of the white-clay decorative ceramics produced in Veliki Preslav. Combining different methods and comparing the obtained results provides complementary information regarding the white-clay ceramic production in Veliki Preslav and complete chemical characterization of the examined artefacts.

Blagoev, K.; Grozeva, M.; Malcheva, G.; Neykova, S.

2013-01-01

454

Lasers '87; Proceedings of the Tenth International Conference on Lasers and Applications, Lake Tahoe, NV, Dec. 7-11, 1987  

NASA Astrophysics Data System (ADS)

Various papers on lasers are presented. The general topics addressed include: laser physics and theory, VUV and X-ray lasers, excimer lasers, chemical lasers, nuclear pumped lasers, blue-green and metal-vapor lasers, dye lasers, solid-state lasers, semiconductor and diode lasers, CO2 lasers, FIR lasers, ultrafast phenomena, nonlinear phenomena, wave mixing and dynamic gratings, and phase conjugation. Also considered are: laser radars and remote sensing, adaptive optics and propagation, imaging, fiber optics, laser spectroscopy, laser dyes, lasers in medicine, optical devices and measuring technique, laser industrial applications, lasers in strategic defense.

Duarte, F. J.

455

Production of Singlet Oxygen within a Flow Discharge  

NASA Astrophysics Data System (ADS)

The Airborne laser program is an Air Force sponsored program to place a laser on the battle field for use as a tactical weapon. The chemical oxygen iodine laser offers the powers necessary for this weapons application, but it requires significant logistical support. The goal of this current research program is to demonstrate an oxygen-iodine laser with electrical discharge production of singlet oxygen. Optical diagnostics have been applied to microwave and radio frequency discharges within a pure oxygen flow. The O2(a) emissions within a discharge are complicated by atomic oxygen emission requiring care in determining gas concentrations from optically measured emissions. Thermal effects also complicate optical emissions. The inclusion of vibrationally excited oxygen as a quencher of the O2(a) state appears to be the limiting rate for production of O2(a) within the electric discharge conditions studied in this research.

Lange, Matthew; Pitz, Greg; Perram, Glen

2008-10-01

456

Hexagonal Truncated Pyramidal Light Emitting Diodes through Wafer Bonding of ZnO to GaN, Laser Lift-off, and Photo Chemical Etching  

NASA Astrophysics Data System (ADS)

We report on a hexagonal pyramidal light emitting diodes (LEDs) produced by direct wafer bonding of a metal organic chemical vapor deposition (MOCVD) grown GaN LED on sapphire to a n-type ZnO wafer, laser lift off, and photochemical etching of the nitrogen face of the GaN LED. Laser lift off was used to remove the sapphire of the GaN wafer, exposing the Nitrogen face for roughening, in the form of microcones, as well as allowing deposition of metal contacts to the nitrogen face of the GaN LED. Contacts to the ZnO allow for the creation of a vertical current path. Selective etching was used to form truncated hexagonal pyramids of the ZnO.

Thompson, Daniel B.; Murai, Akihiko; Iza, Michael; Brinkley, Stuart; DenBaars, Steven P.; Mishra, Umesh K.; Nakamura, Shuji

2008-05-01

457

Design of Laser Based Monitoring Systems for Compliance Management of Odorous and Hazardous Air Pollutants in Selected Chemical Industrial Estates at Hyderabad, India  

NASA Astrophysics Data System (ADS)

Industrialization can no longer sustain without internalization of the concerns of the receiving environment and land-use. Increased awareness and public pressure, coupled with regulatory instruments and bodies exert constant pressure on industries to control their emissions to a level acceptable to the receiving environment. However, when a group of industries come-up together as an industrial estate, the cumulative impacts of all the industries together often challenges the expected/desired quality of receiving environment, requiring stringent pollution control and monitoring measures. Laser remote sensing techniques provide powerful tools for environmental monitoring. These methods provide range resolved measurements of concentrations of various gaseous pollutants and suspended particulate matter (SPM) not only in the path of the beam but over the entire area. A three dimensional mapping of the pollutants and their dispersal can be estimated using the laser remote sensing methods on a continuous basis. Laser Radar (Lidar) systems are the measurements technology used in the laser remote sensing methods. Differential absorption lidar (DIAL) and Raman Lidar technologies have proved to be very useful for remote sensing of air pollutants. DIAL and Raman lidar systems can be applied for range resolved measurements of molecules like SO2, NO2, O3 Hg, CO, C2H4, H2O, CH4, hydrocarbons etc. in real time on a continuous basis. This paper describes the design details of the DAIL and Raman lidar techniques for measurement of various hazardous air pollutants which are being released into the atmosphere by the chemical industries operating in the Bachupally industrial Estate area at Hyderabad, India. The relative merits of the two techniques have been studied and the minimum concentration of pollutants that can be measured using these systems are presented. A dispersion model of the air pollutants in the selected chemical industrial estates at Hyderabad has been developed.

Sudhakar, P.; Kalavathi, P.; Ramakrishna Rao, D.; Satyanarayna, M.

2014-12-01

458

Chemical, morphological and accumulation phenomena in ultrashort-pulse laser ablation of TiN in air  

Microsoft Academic Search

.   Ultrashort-pulse laser ablation (?=130 fs, ?=800 nm, repetition rate 2–20 Hz) of titanium nitride was investigated for laser\\u000a fluences between 0.3 and 4.5 J\\/cm2 using the direct focusing technique in air. The influence of the laser pulse number and the peak fluence was investigated\\u000a by means of several surface analytical techniques (optical microscopy, dynamic friction atomic force microscopy, scanning\\u000a Auger electron microscopy and

J. Bonse; H. Sturm; D. Schmidt; W. Kautek

2000-01-01

459

Femtosecond-laser-produced low-density plasmas in transparent biological media: a tool for the creation of chemical, thermal, and thermomechanical effects below the optical breakdown threshold  

NASA Astrophysics Data System (ADS)

The irradiance threshold for femtosecond optical breakdown in aqueous media is approximately equals 1.0x1013W cm-2. At the breakdown threshold, a plasma with a free electron density of about 1021cm-3 is generated, and the energy density in the breakdown region is sufficiently high to cause the formation of a bubble which can be experimentally observed. We found previously that plasmas with a free electron density <1021cm-3 are formed also in a fairly large irradiance range below the breakdown threshold. The present study investigates the chemical, thermal, and thermomechanical effects produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and avalanche ionization to numerically simulate the temporal evolution of the free electron density during the laser pulse for a given irradiance, and to calculate the irradiance dependence of the free-electron density and volumetric energy density reached at the end of the laser pulse. The value of the energy density created by each laser pulse is then used to calculate the temperature distribution in the focal region after application of a single laser pulse and of series of pulses. The results of the temperature calculations yield, finally, the starting point for calculations of the thermoelastic stresses that are generated during the formation of the low-density plasmas. We found that, particularly for short wavelengths, a large 'tuning range' exists for the creation of spatially extremely confined chemical, thermal and mechanical effects via free electron generation through nonlinear absorption. Photochemical effects dominate at the lower end of this irradiance range, whereas at the upper end they are mixed with thermal effects and modified by thermoelastic stresses. Above the breakdown threshold, the spatial confinement is partly destroyed by cavitation bubble formation, and the laser-induced effects become more disruptive. Our simulations revealed that the highly localized ablation of intracellular structures and intranuclear chromosome dissection recently demonstrated by other researchers are probably mediated by free-electron- induced chemical bond breaking and not related to heating or thermoelastic stresses. We conclude that low density plasmas below the optical breakdown threshold can be a versatile tool for the manipulation of transparent biological media and other transparent materials. (enabling, e.g., the generation of optical waveguides in bulk glass). Low density plasmas may, however, also be a potential hazard in multiphoton microscopy and higher harmonic imaging.

Vogel, Alfred; Noack, Joachim; Huettmann, Gereon; Paltauf, Guenther

2002-04-01

460

High-Jc YBa2Cu3O7-? superconducting film grown by laser-assisted chemical vapor deposition using a single liquid source and its microstructure  

NASA Astrophysics Data System (ADS)

A YBa2Cu3O7-? (YBCO) film was prepared on a multilayer-coated Hastelloy C276 substrate by laser-assisted metalorganic chemical vapor deposition using a single liquid source precursor. A c-axis-oriented YBCO film was grown epitaxially on a (100) CeO2 layer at a deposition rate of 11 ?m h-1. A screw dislocation and stacking faults were observed in the cross-section of the YBCO film. The critical current density of the YBCO film reached 2.7 MA cm-2.

Zhao, Pei; Ito, Akihiko; Kato, Takeharu; Yokoe, Daisaku; Hirayama, Tsukasa; Goto, Takashi

2013-09-01

461

Passively Q-switched mode-locking Nd:GdVO4 laser with a chemically reduced graphene oxide saturable absorber  

NASA Astrophysics Data System (ADS)

A diode-pumped passively Q-switched mode-locking Nd:GdVO4 laser using a chemically reduced graphene oxide saturable absorber was demonstrated. The repetition rate and pulse width of the Q-switching envelopes were 5.7 MHz and 100 ns, respectively, while those of the mode-locking pulses that were modulated in the Q-switching envelopes were 139 MHz and 10 ps. At the maximum pump power of 7 W, the average output power was 1.38 W, corresponding to a slope efficiency of 25%.

Pan, Shu-Di; Cui, Liang; Liu, Jing-Quan; Teng, Bing; Liu, Jian-Hua; Ge, Xiao-Hui

2014-12-01

462

Mechanical and Electro-Chemical Properties of Laser Surface Alloyed AISI 304 Stainless Steel with WC+Ni+NiCr  

NASA Astrophysics Data System (ADS)

In the present study, a detailed evaluation of wear and corrosion resistance properties of laser surface alloyed of AISI 304 stainless steel with WC+Ni+NiCr (in the ratio of 70:15:15) has been undertaken. Laser processing has been carried out using a 5 kW continuous wave (CW) Nd:YAG laser (at a beam diameter of 3 mm) by surface melting and simultaneous deposition of precursor powder mixture in the melt zone (at a flow rate of 10 mg/s) and using Ar shroud at a gas flow rate of 5 l/min. Followed by laser processing, a detailed evaluation of fretting wear behavior has been conducted against WC surface. Finally, the corrosion property is measured using a potentiodynamic polarization testing unit in a 3.56 wt.% NaCl solution. The wear resistance property is significantly improved due to laser surface alloying which is attributed to the improvement in surface microhardness to 1350 VHN as compared to 220 VHN of as-received ?-stainless steel substrate. The mechanism of wear is established. The pitting corrosion resistance property is also improved due to the presence of Ni and Cr in solution and homogenization of microstructure due to laser processing.

Majumdar, J. D.

463

Advanced Diagnostics for COIL and DOIL  

NASA Astrophysics Data System (ADS)

In this paper we discuss the application of sensitive, non-intrusive diagnostic techniques to characterize species in the flow that are critical for chemical oxygen iodine laser (COIL) devices and the electric discharge oxygen iodine laser (DOIL) concept. The key diagnostics include chemiluminescence to detect O2(a,b) and I(2P1/2) and tunable diode laser absorption measurements of I* and temperature. We have characterized variations in O and O2(a) yields with discharge power and oxygen mole fraction. We observe O2(a) yields to increase dramatically with decreasing oxygen mole fraction. We also discuss the application of a novel imaging diagnostic to obtain 2-D images of species concentrations and temperature.

Davis, Steven J.; Rawlins, W. T.; Lee, Seonkyung; Silva, Michelle L.; Kessler, William J.; Mulhall, Phillip A.

2004-09-01

464

A two-stage ceramic tile grout sealing process using a high power diode laser—II. Mechanical, chemical and physical properties  

NASA Astrophysics Data System (ADS)

Ceramic tiles sealed using a portable 60 Wcw high power diode laser (HPDL) and a specially developed grout material having an impermeable enamel surface glaze have been tested in order to determine the mechanical, chemical and physical characteristics of the seals. The work showed that the generation of the enamel surface glaze resulted in a seal with improved mechanical and chemical properties over conventional epoxy tile grouts. Both epoxy tile grout and laser generated enamel seals were tested for compressive strength, surface roughness, wear, water permeability and acid/alkali resistance. The enamel seal showed clear improvements in strength, roughness and wear, whilst being impermeable to water, and resistant (up to 80% concentration) to nitric acid, sodium hydroxide and detergent acids. The bond strength and the rupture strength of the enamel seal were also investigated, revealing that the enamel adhered to the new grout and the ceramic tiles with an average bond strength of 45-60 MPa, whilst the rupture strength was comparable with the ceramic tiles themselves. The average surface roughness of the seals and the tiles was 0.36 and 0.06 ?m, respectively, whilst for the conventional epoxy grout the average surface roughness when polished was 3.83 ?m and in excess of 30 ?m without polishing. Life assessment testing revealed that the enamel seals had an increase in actual wear life of 2.9 to 30.4 times over conventional epoxy tile grout, depending upon the corrosive environment.

Lawrence, J.; Li, L.; Spencer, J. T.

1998-04-01

465

Pulsed laser photolysis and quantum chemical-statistical rate study of the reaction of the ethynyl radical with water vapor  

NASA Astrophysics Data System (ADS)

The rate coefficient of the gas-phase reaction C2H+H2O?products has been experimentally determined over the temperature range 500-825K using a pulsed laser photolysis-chemiluminescence (PLP-CL) technique. Ethynyl radicals (C2H) were generated by pulsed 193nm photolysis of C2H2 in the presence of H2O vapor and buffer gas N2 at 15Torr. The relative concentration of C2H radicals was monitored as a function of time using a CH * chemiluminescence method. The rate constant determinations for C2H+H2O were k1(550K)=(2.3±1.3)×10-13cm3s-1, k1(770cm3s-1, and k1(825cm3s-1. The error in the only other measurement of this rate constant is also discussed. We have also characterized the reaction theoretically using quantum chemical computations. The relevant portion of the potential energy surface of C2H3O in its doublet electronic ground state has been investigated using density functional theory B3LYP /6-311++G(3df,2p) and molecular orbital computations at the unrestricted coupled-cluster level of theory that incorporates all single and double excitations plus perturbative corrections for the triple excitations, along with the 6-311++G(3df,2p) basis set [(U)CCSD(T)/6-311++G(3df,2p)] and using UCCSD(T )/6-31G(d,p) optimized geometries. Five isomers, six dissociation products, and sixteen transition structures were characterized. The results confirm that the hydrogen abstraction producing C2H2+OH is the most facile reaction channel. For this channel, refined computations using (U)CCSD(T)/6-311++G(3df,2p)//(U)CCSD(T)/6-311++G(d,p) and complete-active-space second-order perturbation theory/complete-active-space self-consistent-field theory (CASPT2/CASSCF) [B. O. Roos, Adv. Chem. Phys. 69, 399 (1987)] using the contracted atomic natural orbitals basis set (ANO-L) [J. Almlöf and P. R. Taylor, J. Chem. Phys.86, 4070 (1987)] were performed, yielding zero-point energy-corrected potential energy barriers of 17kJmol-1 and 15kJmol-1, respectively. Transition-state theory rate constant calculations, based on the UCCSD(T) and CASPT2/CASSCF computations that also include H-atom tunneling and a hindered internal rotation, are in perfect agreement with the experimental values. Considering both our experimental and theoretical determinations, the rate constant can best be expressed, in modified Arrhenius form as k1(T)=(2.2±0.1)×10-21T3.05exp[-(376±100)/T]cm3s-1 for the range 300-2000K. Thus, at temperatures above 1500K, reaction of C2H with H2O is predicted to be one of the dominant C2H reactions in hydrocarbon combustion.

Carl, Shaun A.; Minh Thi Nguyen, Hue; Elsamra, Rehab M. I.; Tho Nguyen, Minh; Peeters, Jozef

2005-03-01

466

Laser Research  

NASA Technical Reports Server (NTRS)

Eastman Kodak Company, Rochester, New York is a broad-based firm which produces photographic apparatus and supplies, fibers, chemicals and vitamin concentrates. Much of the company's research and development effort is devoted to photographic science and imaging technology, including laser technology. Eastman Kodak is using a COSMIC computer program called LACOMA in the analysis of laser optical systems and camera design studies. The company reports that use of the program has provided development time savings and reduced computer service fees.