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1

REVIEW: Chemically pumped oxygen---iodine laser  

Microsoft Academic Search

A review is given of the principles of operation of the oxygen---iodine laser. Various types of chemical generators of singlet oxygen, which are key components in oxygen---iodine lasers, are considered. Experimental investigations of cw and pulsed oxygen---iodine lasers are described. The state-of-the-art theoretical investigations and potential applications of oxygen---iodine lasers are discussed.

Nikolai N. Yuryshev

1996-01-01

2

Scalable chemical oxygen - iodine laser  

SciTech Connect

The problem of scaling chemical oxygen - iodine lasers (COILs) is discussed. The results of experimental study of a twisted-aerosol singlet oxygen generator meeting the COIL scalability requirements are presented. The energy characteristics of a supersonic COIL with singlet oxygen and iodine mixing in parallel flows are also experimentally studied. The output power of {approx}7.5 kW, corresponding to a specific power of 230 W cm{sup -2}, is achieved. The maximum chemical efficiency of the COIL is {approx}30%.

Adamenkov, A A; Bakshin, V V; Vyskubenko, B A; Efremov, V I; Il'in, S P; Ilyushin, Yurii N; Kolobyanin, Yu V; Kudryashov, E A; Troshkin, M V [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

2011-12-31

3

The chemically pumped oxygen-iodine laser  

Microsoft Academic Search

The present status of the chemical oxygen-iodine laser is discussed. The pertinent processes occurring in the chemical O2 generator, the O2(1Delta) transport region, and the nozzle are reviewed. The energy transfer kinetics, laser gain, and the performance and device efficiency are examined.

P. V. Avizonis; G. Hasen; K. A. Truesdell

1990-01-01

4

The standard chemical oxygen-iodine laser kinetics package  

Microsoft Academic Search

This report presents the Air Force Weapons Laboratory Standard Chemical Oxygen-Iodine Laser Kinetics Package. A complete reaction scheme including recommended rate coefficients for modeling the gas phase kinetics of chemical oxygen-iodine lasers (COIL) was established to provide a common basis for the research and development of COIL devices. A review of the experimental kinetic data base from which this model

Glen P. Perram; Gordon D. Hager

1988-01-01

5

Chemical oxygeniodine laser with mixing of supersonic jets  

Microsoft Academic Search

The results are reported of the first investigation of a chemical oxygeniodine laser with supersonic mixing of parallel jets of oxygen and of a mixture of nitrogen with iodine. It was found that, in principle, such a laser system is feasible. The maximum output power was 160 and 130 W with the chemical efficiency 13% and 14.3%, respectively.

V N Azyazov; M V Zagidullin; V D Nikolaev; V S Safonov

1997-01-01

6

OPTIMIZING HIGH PRESSURE CHEMICAL OXYGEN-IODINE LASERS  

Microsoft Academic Search

The Blaze II chemical laser model was baselined to existing oxygen-iodine research assessment and device improvement chemical laser (RADICL) gain data. Subsequent Fabry-Perot power calculations with Blaze II were an average of 33% higher than the corresponding stable resonator power data. With the Blaze II model baselined to RADICL gain data, a genetic algorithm (GA) was used to predict optimal

David L. Carroll

1996-01-01

7

Iodine dissociation in chemical oxygen-iodine lasers (COILs)  

Microsoft Academic Search

Iodine dissociation has been measured in the supersonic cavity of a chemical oxygen-iodine laser during lasing under a wide variety of flow conditions. By varying flow conditions, measured dissociations from 0 to 100 percent were observed. A simple model of the initial step in the dissociation process was developed that adequately rationalizes the measurements.

Charles A. Helms; J. Shaw; Gordon D. Hager; Keith A. Truesdell; David N. Plummer; J. Copland

1995-01-01

8

Chemical oxygen-iodine laser with cryosorption vacuum pump  

NASA Astrophysics Data System (ADS)

In a chemical oxygen-iodine laser (COIL), chemically prepared, gaseous gain medium at 3-10 Torr pressure is drawn through the laser cavity by vacuum suction. Multiple-stage vacuum pumps such as Roots blowers or steam ejectors are typically used to receive and compress the gas flowing from the laser and exhaust it to the atmosphere. The size and weight of such vacuum pumps present a significant challenge to engineering and packaging a transportable COIL system.

Vetrovec, John

2000-05-01

9

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

10

Mode locking of a cw supersonic chemical oxygen iodine laser  

Microsoft Academic Search

This paper presents the results of the first mode locking experiments on a supersonic chemical oxygen iodine laser (COIL). Mode locking has been achieved using an acousto-optic modulator (AOM) and lasing demonstrated on the TEM00 modes with a small intracavity aperture. A dc magnetic field was used to increase the number of axial modes and a peak power of 2.5

S. P. Phipps; Charles A. Helms; Richard J. Copland; Wolfgang G. Rudolph; Keith A. Truesdell; Gordon D. Hager

1997-01-01

11

Research on advanced chemical and discharge oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

Generation of singlet oxygen and atomic iodine for operation of the chemical or discharge oxygen-iodine laser (COIL/DOIL) is described, employing novel methods and device configurations proposed in our laboratory. A centrifugal spray generator of singlet oxygen was developed, based on the conventional reaction between chlorine and basic hydrogen peroxide. Recent results of theoretical and experimental investigation of the generator parameters are presented. A new conception of the discharge generator of singlet oxygen was initiated, based on a combined DC arc jet and RF discharge techniques. Principle of the generator currently developed and constructed is described. A new device configuration was designed for the alternative method of atomic iodine generation using a radiofrequency discharge decomposition of iodine compounds like CH3I or CF3I. Some recent experimental results of this research are also presented.

Kodymová, Jarmila; Jirásek, Vít; Schmiedberger, Josef; Spalek, Otomar; Censký, Miroslav

2009-02-01

12

High-power chemical oxygen-iodine laser welding  

NASA Astrophysics Data System (ADS)

The present paper describes the welding characteristics with a 10 kW class Chemical Oxygen-Iodine Laser (COIL), whose wavelength is 1.32 micrometer. Bead-on-plate welding tests of 304 stainless steel plates were carried out at laser power 8.5 kW and 11 kW. Three different shielding gases (N2, Ar and He) were used through a coaxial conical shape nozzle under the lens. In COIL welding, the interaction between the laser beam and the laser induced plasma is very small because the wavelength of COIL is shorter than that of CO2 laser, so that the laser beam reaches on the workpiece without absorption by the plasma. As the result of the welding tests, the welded bead shapes did not depend on a type of the shielding gas. Radiograph and longitudinal section tests of the welded beads were carried out. When He and Ar gases were used as the shielding gas, there were several porosities. On the other hand, the use of N2 gas made no porosity. The full penetration on 10 mm thick plate was achieved in the high aspect ratio without the welding defects under the condition of laser power 8.5 kW and welding speed 1.5 m/min.

Nakabayashi, Tokuhiro; Muro, Mikio

2000-02-01

13

Efficient chemical oxygen-iodine laser with longitudinal flow of the active medium  

SciTech Connect

A chemical oxygen-iodine laser with fast flow of the active medium along the optic axis was constructed. Lasing with an output power of 186 W and a chemical efficiency in excess of 20% were achieved. (lasers)

Zagidullin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

1999-02-28

14

Cutting Performance of a Chemical Oxygen-Iodine Laser William P. Latham, James A. Rothenflue, and Charles A. Helms  

E-print Network

Cutting Performance of a Chemical Oxygen-Iodine Laser William P. Latham, James A. Rothenflue. Green Street Urbana,IL 61801 . Abstract Chemical Oxygen-Iodine Laser (COIL) is a member of the class cutting and drilling. Chemical Oxygen- Iodine Laser (COIL) technology has received considerable interest

Carroll, David L.

15

Development of a chemical oxygen - iodine laser with production of atomic iodine in a chemical reaction  

SciTech Connect

The alternative method of atomic iodine generation for a chemical oxygen - iodine laser (COIL) in chemical reactions with gaseous reactants is investigated experimentally. The influence of the configuration of iodine atom injection into the laser cavity on the efficiency of the atomic iodine generation and small-signal gain is studied. (lasers)

Censky, M; Spalek, O; Jirasek, V; Kodymova, J [Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic); Jakubec, I [Institute of Inorganic Chemistry, Czech Academy of Sciences, Rez (Czech Republic)

2009-11-30

16

High-efficiency operation of chemical oxygen-iodine laser using nitrogen as buffer gas  

Microsoft Academic Search

High-efficiency operation of supersonic chemical oxygen-iodine laser (COIL) with an advanced jet-type singlet oxygen generator using nitrogen as buffer gas was demonstrated. Laser output was remarkably increased when buffer gas was cooled with liquid nitrogen. The effects of buffer gas temperature on the characteristics of the oxygen-iodine laser medium was discussed. A net chemical efficiency of 23.4% was obtained at

M. Endo; S. Nagatomo; S. Takeda; M. V. Zagidullin; V. D. Nikolaev; H. Fujii; F. Wani; D. Sugimoto; K. Sunako; K. Nanri; T. Fujioka

1998-01-01

17

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

18

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

Microsoft Academic Search

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

Otomar Špalek; V??t Jirásek; Miroslav ?enský; Jarmila Kodymová; Ivo Jakubec; Gordon D. Hager

2002-01-01

19

A 12-kW continuous-wave chemical oxygen-iodine laser  

SciTech Connect

A 12-kW continuous-wave chemical oxygen-iodine laser, provided with an original jet-type singlet oxygen generator, is developed and tested. The experimental and numerical techniques applied for the diagnostics and mathematical simulation of processes in the laser active medium are introduced. Some of the calculation and experimental results are presented. (lasers)

Boreysho, A S; Mal'kov, V M; Savin, Aleksandr V; Vasil'ev, D N; Evdokimov, I M; Trilis, A V; Strakhov, S Yu [Institute of Laser Instruments and Technologies, D F Ustinov 'VOENMEKh' Baltic State Technical University, St Petersburg (Russian Federation)

2003-04-30

20

Possibility of operation of a chemical oxygen–iodine laser without a cooled trap  

Microsoft Academic Search

A new proposal is made and discussed that it should be possible to operate a chemical oxygen–iodine laser not with the aid of a cooled trap for freezing out water vapor and hydrogen peroxide, but by deep cooling of a chemical generator. This may improve considerably the operating characteristics of such a laser.

M V Zagidullin; Valerii I Igoshin; V A Katulin; N L Kupriyanov

1983-01-01

21

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

22

Chemical oxygen-iodine laser with a new method of atomic iodine generation  

Microsoft Academic Search

A study of recently proposed chemical method of atomic iodine production in the Chemical Oxygen-Iodine Laser (COIL) was performed. The process using gaseous reactants is based on the fast reaction of hydrogen iodide with chemically produced atomic chlorine. In the absence of singlet oxygen, the high yield of atomic iodine was attained (80 to 100 %). In the flow of

Otomar Spalek; Miroslav Censky; Vít Jirásek; Jarmila Kodymová; Ivo Jakubec; Gordon D. Hager

2003-01-01

23

Efficient operation of a chemically pumped oxygen iodine laser utilizing dilute hydrogen peroxide  

Microsoft Academic Search

A chemically pumped oxygen iodine laser system has been operated employing 35 wt pct H2O2 rather than commonly used 90 wt pct H2O2. Laser power as high as 40 W has been extracted. The maximum overall efficiency of 20.7 percent, which is almost 25 percent higher than the previously reported best data, has been achieved.

S. Yoshida; H. Fujii; T. Sawano; M. Endo; T. Fujioka

1987-01-01

24

History of chemical oxygen-iodine laser (COIL) development in the USA  

Microsoft Academic Search

This is an overview of the development of Chemical Oxygen-Iodine Laser (COIL) technology in the United States. Key technical developments will be reviewed, beginning in 1960 and culminating in 1977 with the first COIL lasing demonstration at the Air Force Weapons Laboratory (now the Phillips Laboratory). The discussion will then turn to subsonic laser development, supersonic lasing demonstration and efficiency

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

1995-01-01

25

Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials William P. Latham, Kip R. Kendrick, James A. Rothenflue  

E-print Network

Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials William Lab, 104 5. Wright St., Urbana, Illinois 61801 ABSTRACT A chemical oxygen-iodine laser (COIL) was used:YAG lasers are used for such applications. More recently, the chemical oxygen-iodine laser (COIL) has

Carroll, David L.

26

Output Power Enhancement of a Chemical Oxygen-Iodine Laser by Predissociated Iodine Injection  

Microsoft Academic Search

Output power enhancement of a chemical oxygen-iodine laser (COIL) by an injection of predissociated iodine was studied. Iodine molecules were dissociated into atoms by the microwave discharge prior to injection. It was determined that predissociation caused a negative effect on the output power enhancement when this technique was applied to a conventional supersonic COIL@. Model calculations revealed that the existence

Masamori Endo; Daichi Sugimoto; Hideo Okamoto; Kenzo Nanri; Taro Uchiyama; Shuzaburo Takeda; Tomoo Fujioka

2000-01-01

27

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

Microsoft Academic Search

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

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

2011-01-01

28

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

Microsoft Academic Search

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

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

2011-01-01

29

Lasing performance of a chemical oxygen iodine laser (COIL) with advanced ejector nozzle banks  

Microsoft Academic Search

Experimental lasing results for the Chemical Oxygen Iodine Laser, (COIL), using four different ejector nozzle configurations are presented. These nozzle banks differed in the location of Iodine injection, the area of the oxygen nozzles, and the nozzle contour of the primary driver nitrogen. The aerodynamic choking of the oxygen jets caused by the under expanded primary driver nitrogen resulted in

Nickolay A. Khvatov; Valeri D. Nikolaev; Michael I. Svistun; Marsel V. Zagidullin; Gordon D. Hager

2002-01-01

30

Experiment and modeling of a small-scale, supersonic chemical oxygen-iodine laser  

Microsoft Academic Search

We report on detailed experiment and modeling of a small-scale, supersonic chemical oxygen-iodine laser. The laser has a 5 cm long active medium and utilizes a simple sparger-type O2(1?) chemical generator and a medium-size pumping system. A grid nozzle is used for iodine injection and supersonic expansion. 25 W of cw laser emission at 1.315 µm are obtained in the

A. Elior; B. D. Barmashenko; E. Lebiush; S. Rosenwaks

1995-01-01

31

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

32

Magnetic modulation of gain in a chemical oxygen-iodine laser  

Microsoft Academic Search

A magnetic modulation of gain in a continuous-wave (CW) chemical oxygen-iodine laser (COIL) is proposed for several regimes of laser generation. The principle of the method proposed is based on a direct magnetic modulation of gain in the active zone of a COIL utilizing the Zeeman effect on the laser transition 2P1\\/2 -2P3\\/2 of iodine atoms. The possible applications of

Josef Schmiedberger; Jarmila Kodymova; Jiri Kovar; Otomar Spalek; Pavel Trenda

1991-01-01

33

Efficient, small scale chemical oxygen-iodine laser  

SciTech Connect

More than 40% extractable power efficiency has been achieved in a transverse flow, small scale, chemically pumped iodine-atom laser. 5 W of cw laser emission at 1315 nm has been obtained via energy transfer from chemically generated O/sub 2/(/sup 1/..delta..) to I atoms in a 10 x 1 cm/sup 2/ rectangular flow duct. Simple construction materials, safely handled chemicals, and a medium size vacuum pump were used for fabricating and operating the laser. The importance of minimizing quenching of excited species by collision with water molecules or with the wall is demonstrated.

Bachar, J.; Rosenwaks, S.

1982-07-01

34

High-performance chemical oxygen-iodine laser using nitrogen diluent for commercial applications  

Microsoft Academic Search

A chemical oxygen-iodine laser (COIL), the VertiCOIL device, was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high-power VertiCOIL laser was measured with nitrogen diluent. New nozzle designs were investigated and implemented to optimize nitrogen performance. Nitrogen diluent chemical efficiencies of 23% were achieved; these

D. L. Carroll; D. M. King; L. Fockler; D. Stromberg; W. C. Solomon; L. H. Sentman; C. H. Fisher

2000-01-01

35

Performance of a high-efficiency 5-cm gain length supersonic chemical oxygen-iodine laser  

Microsoft Academic Search

The Air Force Phillips Laboratory has developed a small-scale supersonic chemical oxygen-iodine laser (COIL) test stand (VertiCOIL) to rapidly evaluate emerging potential technology improvements. VertiCOIL was designed to address issues relevant to military and commercial applications such as long run time, high-efficiency operation, and compact design. VertiCOIL demonstrated an overall chemical efficiency of nearly 27%, one of the highest chemical

Tilghman L. Rittenhouse; Stephen P. Phipps; Charles A. Helms

1999-01-01

36

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

Microsoft Academic Search

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

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

2005-01-01

37

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

SciTech Connect

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 for a twofold decrease in the specific energy yield for the lasing initiated by a longitudinal electric discharge compared to the photolytic initiation. (lasers)

Vagin, Nikolai P; Yuryshev, Nikolai N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2002-07-31

38

Chemical oxygen-iodine laser power generation with an off-axis hybrid resonator  

Microsoft Academic Search

A rectangular negative branch off-axis hybrid resonator was coupled to a 10 kW class chemical oxygen-iodine laser. Resonator setup and alignment turned out to be straightforward. The extracted power was 6.6 kW and reached approximately 70% of the power for an optimized stable resonator. The divergence of the emitted laser beam in the unstable direction was lower than two times

Jürgen Handke; Wolfgang O. Schall; Thomas Hall; Frank Duschek; Karin M. Grünewald

2006-01-01

39

Optical saturation and extraction from the chemical oxygen-iodine laser medium  

Microsoft Academic Search

A rate equation model for the loaded gain of a flowing chemical oxygen-iodine laser is described. It includes pumping of the upper laser level by O2(1?), deactivation by water and energy pooling with O2(1?), stimulated emission on the 3?4 transition, hyperfine relaxation (HFR) of the 2P1\\/2 and 2P3\\/2 iodine sublevels, and velocity cross-relaxation (VCR) of the iodine atoms. The solution

D. A. Copeland; A. H. Bauer

1993-01-01

40

Efficient operation of a chemically pumped oxygen iodine laser utilizing dilute hydrogen peroxide  

SciTech Connect

A chemically pumped oxygen iodine laser system has been operated employing 35 wt. % H/sub 2/O/sub 2/ rather than commonly used 90 wt. % H/sub 2/O/sub 2/. Laser power as high as 40 W has been extracted. The maimum overall efficiency of 20.7%, which is almost 25% higher than the previously reported best data, has been achieved.

Yoshida, S.; Fujii, H.; Sawano, T.; Endo, M.; Fujioka, T.

1987-11-09

41

Demonstration of a repetitively pulsed magnetically gain-switched chemical oxygen iodine laser  

Microsoft Academic Search

Recently, modulation of the output from a chemical oxygen iodine laser (COIL) has been demonstrated by applying a pulsed magnetic field directly to the laser cavity. A peak-to- average power enhancement of 3.2 was obtained. The rate of change of the magnetic field in these experiments, however, was relatively slow, 0.5 gauss\\/microsecond(s) . In this article, we report the demonstration

Gordon D. Hager; D. Kopf; David N. Plummer; T. Salsich; Peter G. Crowell

1993-01-01

42

GENETIC ALGORITHMS AND OPTIMIZING CHEMICAL OXYGEN-IODINE LASERS  

Microsoft Academic Search

This paper presents results from the first known application of the genetic algorithm (GA) technique for optimizing the performance of a laser system (chemical, solid-state, or gaseous). The effects of elitism, single point and uniform crossover, creep mutation, different random number seeds, population size, niching and the number of children per pair of parents on the performance of the GA

David L. Carroll

1996-01-01

43

Experimental results on chemical generation of atomic iodine via Cl atoms for chemical oxygen-iodine laser  

Microsoft Academic Search

An alternative chemical way of atomic iodine generation for the chemical oxygen-iodine laser (COIL) was studied. This development was aimed at the laser power increase and simplification of the laser operation control. The method is based on the fast reaction of hydrogen iodide with chemically produced chlorine atoms. Kinetics of the process was studied in two types of the small-scale

Otomar Spalek; Vít Jirásek; Miroslav Censky; Jarmila Kodymová; Ivo Jakubec; Gordon D. Hager

2003-01-01

44

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

Microsoft Academic Search

Efficient production of singlet delta oxygen in a bubble singlet oxygen generator (BSOG) under the influence of centrifugal acceleration, 136 g, has been obtained. An output power of 770 W 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

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

2005-01-01

45

Measurements of peak power enhancement and power conservation in magnetically gain-modulated chemical oxygen-iodine laser  

SciTech Connect

The chemical oxygen-iodine laser (COIL) operates in the near infrared region (1.315 [mu]m) on the magnetic dipole transition between the first electronic metastable state and the basic state of atomic iodine. A periodically pulsed regime of the magnetically gain-switched chemical oxygen iodine laser was investigated. The effects of different magnetic field intensity and pulse length on the laser power pulse enhancement and the mean power conservation were studied experimentally.

Schmiedberger, J.; Kodymova, J.; Kokes, A. (Czech Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics); Spalek, O. (Inst. of Inorganic Chemistry, Prague (Czechoslovakia))

1994-10-01

46

Experimental study of gain and output coupling characteristics of a CW chemical oxygen-iodine laser  

Microsoft Academic Search

Gain and output coupling characteristics of the CW chemical oxygen-iodine laser (COIL) are determined experimentally by means of varying the output coupling method. Under the conditions that the Cl2 flow rate is 11.8 mmol\\/s, the I2 molar flow rate is from 20 to 50 ?mol\\/s, and the duct pressure is 200 Pa, the following were obtained from the experimental data:

Josef Schmiedberger; Jarmila Kodymova; Otomar Spalek; Jiri Kovar

1991-01-01

47

Mode locking of a CW supersonic chemical oxygen-iodine laser  

Microsoft Academic Search

This paper presents the results of the first mode-locking experiments on a supersonic chemical oxygen-iodine laser (COIL). Mode locking has been achieved using an acoustooptic modulator (AOM) and lasing demonstrated on the TEM00 modes with a small intracavity aperture. A dc magnetic field was used to increase the number of axial modes and a peak power of 2.5 kW has

Stephen P. Phipps; Charles A. Helms; R. James Copland; Wolfgang Rudolph; Keith A. Truesdell; Gordon D. Hager

1996-01-01

48

A pared-down gas-phase kinetics for the chemical oxygen-iodine laser medium  

NASA Astrophysics Data System (ADS)

Kinetic data obtained in the last decade has resulted in revisions of some mechanisms of excitation and deactivation of excited states in the chemical oxygen-iodine laser (COIL) medium. This review considers new kinetic data and presents analyses of the mechanisms of pumping and quenching of electronically and vibrationally excited states in the oxygen-iodine laser media. An effective three-level model of I2 molecule excitation and relaxation has been developed. The calculated effective rate constants for deactivation of I2(X,11 ? ? ? 24) by O2, N2, He and CO2 are presented. A simplified kinetic package for the COIL active medium is recommended. This model consists of a 30-reaction set with 14 species. The results of calculations utilizing simplified model are in good agreement with the experimental data.

Pichugin, S. Yu.; Heaven, M. C.

2013-11-01

49

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser  

SciTech Connect

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of the exhaust gas to the atmosphere by using a diffuser and single-stage vacuum systems based on water circulating pumps. (lasers, active media)

Zagidullin, M V; Nikolaev, V D [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2001-06-30

50

Efficient generation in a chemical oxygen - iodine laser with a low buffer-gas flow rate  

SciTech Connect

The efficient generation in a chemical oxygen - iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M {<=} 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s{sup -1}, which corresponds to a chemical efficiency {eta}{sub ch} =23%. It is shown that the substitution of the buffer gas CO{sub 2} for N{sub 2} does not cause any significant variation in the dependence of the output power on the degree of dilution of the active medium. (lasers)

Azyazov, V N; Safonov, V S; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2002-09-30

51

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

52

LASERS: Highly efficient supersonic chemical oxygen --- iodine laser with a chlorine flow rate of 10 mmol s-1  

Microsoft Academic Search

An experimental parametric investigation was made of a compact supersonic chemical oxygen --- iodine laser. The output power of the laser was increased by displacing the point where iodine vapour was added to singlet oxygen from the subsonic to the transonic region of gas flow and by cooling of nitrogen. The output power was 200 W for a Mach number

M. V. Zagidullin; V. D. Nikolaev; M. I. Svistun; N. A. Khvatov; N. I. Ufimtsev

1997-01-01

53

Unstable resonators of high-power chemical oxygen-iodine lasers  

SciTech Connect

Configurations of unstable resonators are considered depending on the basic parameters of a high-power chemical oxygen-iodine laser and the design of an unstable resonator is proposed which provides the compensation of the inhomogeneity of the small-signal gain downstream of the active medium, a high energy efficiency, and stability to intracavity aberrations. The optical scheme of this resonator is presented and its properties are analysed by simulating numerically the kinetics of the active medium and resonator itself in the diffraction approximation. (laser beams and resonators)

Savin, A V; Strakhov, S Yu; Druzhinin, S L [Institute of Laser Instruments and Technologies, D F Ustinov 'VOENMEKh' Baltic State Technical University, St Petersburg (Russian Federation)

2006-09-30

54

Active-medium inhomogeneities and optical quality of radiation of supersonic chemical oxygen-iodine lasers  

SciTech Connect

Optical inhomogeneities of the active medium of a supersonic chemical oxygen-iodine laser (COIL) and their effect on the radiation parameters are studied in the case when an unstable resonator is used. Classification of optical inhomogeneities and the main factors affecting the quality of COIL radiation are considered. The results of numerical simulation of a three-dimensional gas-dynamic active medium and an unstable optical resonator in the diffraction approximation are presented. The constraints in the fabrication of large-scale COILs associated with a deterioration of the optical quality of radiation are determined. (lasers)

Boreysho, A S; Druzhinin, S L; Lobachev, V V; Savin, A V; Strakhov, S Yu; Trilis, A V [Institute of Laser Instruments and Technologies, D F Ustinov 'VOENMEKh' Baltic State Technical University, St Petersburg (Russian Federation)

2007-09-30

55

On a new method for chemical production of iodine atoms in a chemical oxygen-iodine laser  

SciTech Connect

A new method is proposed for generating iodine atoms in a chemical oxygen-iodine laser. The method is based on a branched chain reaction of dissociation of the alkyl iodide CH{sub 3}I in a medium of singlet oxygen and chlorine. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, A I; Sorokin, Vadim N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2004-11-30

56

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

57

Test bed for a high throughput supersonic chemical oxygeniodine laser  

NASA Astrophysics Data System (ADS)

The paper reports the development of a test bed for a chemical oxygeniodine 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 ~1.5 mole s-1 achieving a typical chemical efficiency of about 18%.

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.

2011-05-01

58

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

SciTech Connect

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. Pulses with a duration of 6.5 {mu}s were obtained, which corresponds to a concentration of iodine atoms of 1.8 x 10{sup 15} cm{sup -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{sup -1} and a specific power of 75 kW litre{sup -1} were obtained. The ways of increasing these parameters were indicated. It was found that SF{sub 6} is an efficient buffer gas favouring improvements in the energy pulse parameters. (lasers)

Vagin, Nikolai P; Yuryshev, Nikolai N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2001-02-28

59

Proceedings of the International Conference on Lasers `95, eds. V.J. Corcoran and T.A. Goldman, STS Press, McLean VA, 1996, pp. 225-231. OPTIMIZING HIGH PRESSURE CHEMICAL OXYGEN-IODINE LASERS  

E-print Network

Press, McLean VA, 1996, pp. 225-231. OPTIMIZING HIGH PRESSURE CHEMICAL OXYGEN-IODINE LASERS David L laser model was baselined to existing oxygen-iodine research assessment and device improvement chemical* by N2. I. Introduction The typical chemical oxygen-iodine laser (COIL) utilizes an energy transfer from

Carroll, David L.

60

High-performance chemical oxygen-iodine laser using nitrogen diluent for commercial applications  

SciTech Connect

A chemical oxygen-iodine laser (COIL), the VertiCOIL device, was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high-power VertiCOIL laser was measured with nitrogen diluent. New nozzle designs were investigated and implemented to optimize nitrogen performance. Nitrogen diluent chemical efficiencies of 23% were achieved; these are the highest reported chemical efficiencies with room-temperature nitrogen diluent. A long duration, high chemical efficiency test was demonstrated with nitrogen diluent; a chemical efficiency of 18.5% at 30 mmol/s of chlorine was maintained for 45 min. The highest performance was obtained with new iodine injector blocks and a larger throat height. The new iodine injector blocks moved the injectors closer to the throat by 0.7 cm and the throat height was increased from 0.897 to 1.151 cm (0.353 to 0.453 in). The performance enhancements were in qualitative agreement with the system design predictions of the Blaze II chemical laser model. Three-dimensional computational fluid dynamics calculations using the general aerodynamic simulation program code confirmed the principle design change of moving the iodine injectors closer to throat. Several researchers have suggested that COIL has a significant future as an industrial laser and have identified decommissioning and decontamination (D and D) of nuclear facilities as an important market for COIL.

Carroll, D.L.; King, D.M.; Fockler, L.; Stromberg, D.; Solomon, W.C.; Sentman, L.H.; Fisher, C.H.

2000-01-01

61

Parametric study of the gain in a small scale, grid nozzle, supersonic chemical oxygen-iodine laser  

Microsoft Academic Search

We report on experiments and model calculations of the small-signal gain and the gain profile in a grid nozzle supersonic chemical oxygen-iodine laser. The laser has a 5-cm long active medium and the gain is measured using a diode laser. The calculations are based on a simple one-dimensional semiempirical model previously developed in our laboratory. The gain is studied as

E. Lebiush; B. D. Barmashenko; A. Elior; S. Rosenwaks

1995-01-01

62

Enhancement of the efficiency and control of emission parameters of an unstable-resonator chemical oxygen-iodine laser  

SciTech Connect

The outlook is considered for the development of a high-power supersonic flowing chemical oxygen-iodine laser operating as an amplifier and controlled by radiation from a master oscillator by using an unstable resonator with a hole-coupled mirror. The influence of the seed radiation intensity, the coupling-hole diameter, the active-medium length, and the magnification factor on the parameters of laser radiation is analysed. It is shown that the use of such resonators is most advisable in medium-power oxygen-iodine lasers for which classical unstable resonators are inefficient because of their low magnification factors. The use of unstable resonators with a hole-coupled mirror and injection provides the control of radiation parameters and a considerable increase in the output power and brightness of laser radiation. (control of laser radiation parameters)

Boreisho, A S; Lobachev, V V; Savin, A V; Strakhov, S Yu; Trilis, A V [Institute of Laser Instruments and Technologies, D F Ustinov 'VOENMEKh' Baltic State Technical University, St Petersburg (Russian Federation)

2007-07-31

63

Power optimization of small-scale chemical oxygen-iodine laser with jet-type singlet oxygen generator  

Microsoft Academic Search

Studies of power optimization of a 5-cm gain length chemical oxygen-iodine laser (COIL) energized by a jet-type singlet oxygen generator (JSOG) are presented. For 10 mmol\\/s of Cl2 flow rate, output power of 132 W with chemical efficiency of 14.5% was obtained without a water vapor trap, 163 W and 18% were achieved when coholed (173 K). He was introduced

I. Blayvas; B. D. Barmashenko; D. Furman; S. Rosenwaks; M. V. Zagidullin

1996-01-01

64

A simplified analytic model for gain saturation and power extraction in the flowing chemical oxygen-iodine laser  

Microsoft Academic Search

This paper describes the development of a simplified saturation model (SSM) for predicting power extraction from a chemical oxygen-iodine laser (COIL). Using the Fabry-Perot gain saturation assumption, analytic expressions for COIL extraction efficiency are presented for both constant-density and variable-density cavity conditions. The model treats mirror scattering, nonsaturable distributed losses, and diffractive losses from the mode-limiting aperture and is shown

G. D. Hager; C. A. Helms; K. A. Truesdell; D. Plummer; J. Erkkila; P. Crowell

1996-01-01

65

Multiphase reacting flow modeling of singlet oxygen generators for chemical oxygen iodine lasers.  

SciTech Connect

Singlet oxygen generators are multiphase flow chemical reactors used to generate energetic oxygen to be used as a fuel for chemical oxygen iodine lasers. In this paper, a theoretical model of the generator is presented along with its solutions over ranges of parameter space and oxygen maximizing optimizations. The singlet oxygen generator (SOG) is a low-pressure, multiphase flow chemical reactor that is used to produce molecular oxygen in an electronically excited state, i.e. singlet delta oxygen. The primary product of the reactor, the energetic oxygen, is used in a stage immediately succeeding the SOG to dissociate and energize iodine. The gas mixture including the iodine is accelerated to a supersonic speed and lased. Thus the SOG is the fuel generator for the chemical oxygen iodine laser (COIL). The COIL has important application for both military purposes--it was developed by the US Air Force in the 1970s--and, as the infrared beam is readily absorbed by metals, industrial cutting and drilling. The SOG appears in various configurations, but the one in focus here is a crossflow droplet generator SOG. A gas consisting of molecular chlorine and a diluent, usually helium, is pumped through a roughly rectangular channel. An aqueous solution of hydrogen peroxide and potassium hydroxide is pumped through small holes into the channel and perpendicular to the direction of the gas flow. So doing causes the solution to become aerosolized. Dissociation of the potassium hydroxide draws a proton from the hydrogen peroxide generating an HO{sub 2} radical in the liquid. Chlorine diffuses into the liquid and reacts with the HO{sub 2} ion producing the singlet delta oxygen; some of the oxygen diffuses back into the gas phase. The focus of this work is to generate a predictive multiphase flow model of the SOG in order to optimize its design. The equations solved are the so-called Eulerian-Eulerian form of the multiphase flow Navier-Stokes equations wherein one set of the equations represents the gas phase and another equation set of size m represents the liquid phase. In this case, m is representative of the division of the liquid phase into distinct representations of the various droplet sizes distributed in the reactor. A stabilized Galerkin formulation is used to solve the equation set on a computer. The set of equations is large. There are five equations representing the gas phase: continuity, vector momentum, heat. There are 5m representing the liquid phase: number density, vector momentum, heat. Four mass transfer equations represent the gas phase constituents and there are m advection diffusion equations representing the HO{sub 2} ion concentration in the liquid phase. Thus we are taking advantage of and developing algorithms to harness the power of large parallel computing architectures to solve the steady-state form of these equations numerous times so as to explore the large parameter space of the equations via continuation methods and to maximize the generation of singlet delta oxygen via optimization methods. Presented here will be the set of equations that are solved and the methods we are using to solve them. Solutions of the equations will be presented along with solution paths representing varying aerosol loading-the ratio of liquid to gas mass flow rates-and simple optimizations centered around maximizing the oxygen production and minimizing the amount of entrained liquid in the gas exit stream. Gas-entrained liquid is important to minimize as it can destroy the lenses and mirrors present in the lasing cavity.

Salinger, Andrew Gerhard; Pawlowski, Roger Patrick; Hewett, Kevin B. (Air Force Research Laboratory, Albuquerque, NM); Madden, Timothy J. (Air Force Research Laboratory, Albuquerque, NM); Musson, Lawrence Cale

2008-08-01

66

The I2 dissociation mechanisms in the chemical oxygen-iodine laser revisited.  

PubMed

The recently suggested mechanism of I(2) dissociation in the chemical oxygen-iodine laser (COIL) [K. Waichman, B. D. Barmashenko, and S. Rosenwaks, J. Appl. Phys. 106, 063108 (2009); and J. Chem. Phys. 133, 084301 (2010)] was largely based on the suggestion of V. N. Azyazov, S. Yu. Pichugin, and M. C. Heaven [J. Chem. Phys. 130, 104306 (2009)] that the vibrational population of O(2)(a) produced in the chemical generator is high enough to play an essential role in the dissociation. The results of model calculations based on this mechanism agreed very well with measurements of the small signal gain g, I(2) dissociation fraction F, and temperature T in the COIL. This mechanism is here revisited, following the recent experiments of M. V. Zagidullin [Quantum Electron. 40, 794 (2010)] where the observed low population of O(2)(b, v = 1) led to the conclusion that the vibrational population of O(2)(a) at the outlet of the generator is close to thermal equilibrium value. This value corresponds to a very small probability, ?0.05, of O(2)(a) energy pooling to the states O(2)(X,a,b, v > 0). We show that the dissociation mechanism can reproduce the experimentally observed values of g, F, and T in the COIL only if most of the energy released in the processes of O(2)(a) energy pooling and O(2)(b) quenching by H(2)O ends up as vibrational energy of the products, O(2)(X,a,b), where the vibrational states v = 2 and 3 are significantly populated. We discuss possible reasons for the differences in the suggested vibrational population and explain how these differences can be reconciled. PMID:22755574

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

2012-06-28

67

Proceedings of the International Conference on Lasers '98, ed. V.J. Corcoran, STS Press, McLean VA, 1999, in press. PERFORMANCE OF A HIGH POWER CHEMICAL OXYGEN-IODINE LASER  

E-print Network

, 1999, in press. PERFORMANCE OF A HIGH POWER CHEMICAL OXYGEN-IODINE LASER USING NITROGEN DILUENT D of moving the iodine injectors closer to throat. 1. Introduction Lasers made their debut for materials, HF/DF and the chemical oxygen-iodine laser (COIL) [2,3]. Of these other laser technologies, COIL

Carroll, David L.

68

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

69

Pulsed chemical oxygen-iodine laser with volume generation of iodine as a model of a high-power supersonic cw laser  

SciTech Connect

In view of the identity of the kinetic processes and of the active-medium parameters of cw and pulsed chemical oxygen-iodine lasers, a repetitively pulsed laser with volume generation of iodine atoms and with a low average output power can be used as a simulator of a high-power cw laser. A comparison is made of experimental results with the parameters of a cw laser predicted by a numerical model. (lasers and amplifiers)

Yuryshev, Nikolai N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1998-05-31

70

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

71

Diode-laser-based absorption spectroscopy diagnostics of a jet-type O2(1?) generator for chemical oxygen-iodine lasers  

Microsoft Academic Search

Using diode-laser-based diagnostics, O2(1?) yield and water vapor fraction were measured at the exit of a jet-type singlet oxygen generator (JSOG) for a chemical oxygen-iodine laser (COIL). Chlorine utilization and gas temperature at the generator exit were also measured, simultaneously. For conditions corresponding to the maximum chemical efficiency of the supersonic COIL energized by the JSOG, the O2(1?) yield, water

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

1999-01-01

72

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

E-print Network

of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region temperature. Keywords: chemical oxygen-iodine laser, COIL, ElectriCOIL, RF excitation of oxygen, singlet-delta oxygen, DOIL 1.0 INTRODUCTION The classic chemical oxygen-iodine laser (COIL) system1 operates on the I(2

Carroll, David L.

73

Performance of a Multistream Injection Chemical OxygenIodine Laser with Starlet Ejectors  

E-print Network

A variant of an ejector-mixing nozzle for a chemical oxygen­iodine laser was experimentally tested that the starlets provide faster mixing. Hot-flow testing demonstrated that the starlet design improved laser performance by 20­30% above the basic cylindrical ejector design. Furthermore, a conical ejector design

Carroll, David L.

74

Experimental study of cutting thick aluminum and steel with a chemical oxygen-iodine laser using an N2 or O2 gas assist  

Microsoft Academic Search

A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel. Cut depths of 20 mm were obtained in aluminum and 41 mm in carbon steel using an N2 gas assist and 5-6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an

David L. Carroll; James A. Rothenflue

1997-01-01

75

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

76

Lasing operation of chemical oxygen-iodine laser without water-vapor trap  

SciTech Connect

cw laser action from chemically pumped iodine atoms was achieved without a cold trap to freeze water vapor. An alkaline solution of H/sub 2/O/sub 2/ was circulated in a porous pipe generator, which made it possible to cool the solution externally. A lasing operation time of about 100 s with a constant output power of 5 W was obtained.

Takehisa, K.; Kikuchi, T.; Uchiyama, T.

1988-03-01

77

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

SciTech Connect

A volume self-sustained discharge (VSD) in iodides (C{sub 3}H{sub 7}I, C{sub 4}H{sub 9}I) and in their mixtures with SF{sub 6}, N{sub 2}, and O{sub 2} 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 SF{sub 6} or N{sub 2} to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O{sub 2} 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 C{sub 4}H{sub 9}I:O{sub 2}:SF{sub 6}=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{sup -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 oxygen - iodine laser. (lasers)

Belevtsev, A A [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Kazantsev, S Yu; Saifulin, A V; Firsov, K N [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2003-06-30

78

Detection of vibrationally excited O{sub 2} in the active medium of a chemical oxygen - iodine laser  

SciTech Connect

The presence of vibrationally excited oxygen in the active medium of a chemical oxygen - iodine laser is discovered using the emission technique. Using the analysis of the luminescence spectra of oxygen molecules on O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}, v=i){yields}O{sub 2}(X{sup 3{Sigma}}{sub g}{sup -}, v'=i) (i=0, 1, 2) electronic vibrational - rotational transitions, it is shown that {approx}22 % of O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}) molecules are at the first vibrational level and {approx}10 % are at the second one. Moreover, due to the fast EE energy exchange, a mean number of vibrational quanta per one molecule in each of the O{sub 2}(X{sup 3{Sigma}}{sub g}{sup -}), O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}) components is approximately the same and amounts to 30 % - 40 %. (active media. lasers)

Azyazov, V N; Antonov, I O; Pichugin, S Yu; Safonov, V S; Svistun, M I; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2003-09-30

79

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

E-print Network

a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser kinetics. 1. Introduction The classical chemical oxygen-iodine laser first reported by McDermott et al.1Oxygen Discharge and Post-Discharge Kinetics Experiments and Modeling for the Electric Oxygen-Iodine

Carroll, David L.

80

Mechanism of dark decomposition of iodine donor in the active medium of a pulsed chemical oxygen - iodine laser  

SciTech Connect

A scheme is proposed that describes the dark decomposition of iodide - the donor of iodine - and the relaxation of singlet oxygen in the chlorine-containing active medium of a pulsed chemical oxygen - iodine laser (COIL). For typical compositions of the active media of pulsed COILs utilising CH{sub 3}I molecules as iodine donors, a branching chain reaction of the CH{sub 3}I decomposition accompanied by the efficient dissipation of singlet oxygen is shown to develop even at the stage of filling the active volume. In the active media with CF{sub 3}I as the donor, a similar chain reaction is retarded due to the decay of CF{sub 3} radicals upon recombination with oxygen. The validity of this mechanism is confirmed by a rather good agreement between the results of calculations and the available experimental data. The chain decomposition of alkyliodides accompanied by an avalanche production of iodine atoms represents a new way of efficient chemical production of iodine for a COIL. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, A I; Sorokin, Vadim N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2002-06-30

81

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

82

Optically (solar) pumped oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

We present the results of theoretical and experimental studies demonstrating the possibility of developing an oxygen-iodine laser (OIL) with direct optical pumping of molecular oxygen involving inter-molecular interaction with charge transfer from donor molecule (buffer gas) to acceptor molecule (oxygen). This interaction lifts degeneracy of the lower energy states of molecular oxygen and increases its absorption cross section in the visible spectral region and the UV Herzberg band, where high quantum yield of singlet oxygen is achieved (QY ˜ 1 and QY ˜ 2, respectively) at the same time. A pulse-periodic optical pump sources with pulse energy of ˜50 kJ, pulse duration of ˜25 ?s, and repetition rate of ˜10 Hz, which are synchronized with the mechanism of singlet oxygen generation, are developed. This allows implementation of a pulse-periodic oxygen-iodine laser with an efficiency of ˜25%, optical efficiency of ˜40%, and parameter L/ T ˜ 1/1.5, where T is the thermal energy released in the laser active medium upon generation of energy L. It is demonstrated that, under direct solar pumping of molecular oxygen, the efficiency parameter of the OIL can reach L/ T ˜ 1/0.8 in a wide range of scaling factors.

Danilov, O. B.; Zhevlakov, A. P.; Yur'ev, M. S.

2014-07-01

83

Kinetic-fluid dynamics modeling of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers  

SciTech Connect

The mechanism of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers (COILs) is studied applying kinetic-fluid dynamics modeling, where pathways involving the excited species I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},10<=v<25), I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},25<=v<=47), I{sub 2}(A{sup '} {sup 3}PI{sub 2u}), I{sub 2}(A {sup 3}PI{sub 1u}), O{sub 2}(X {sup 3}SIGMA{sub g}{sup -},v), O{sub 2}(a {sup 1}DELTA{sub g},v), O{sub 2}(b {sup 1}SIGMA{sub g}{sup +},v), and I({sup 2}P{sub 1/2}) as intermediate reactants are included. The gist of the model is adding the first reactant and reducing the contribution of the second as compared to previous models. These changes, recently suggested by Azyazov, et al. [J. Chem. Phys. 130, 104306 (2009)], significantly improve the agreement with the measurements of the gain in a low pressure supersonic COIL for all I{sub 2} flow rates that have been tested in the experiments. In particular, the lack of agreement for high I{sub 2} flow rates, which was encountered in previous models, has been eliminated in the present model. It is suggested that future modeling of the COIL operation should take into account the proposed contribution of the above mentioned reactants.

Waichman, K. [Department of Physics, NRCN, P.O. Box 9001, Beer Sheva 89140 (Israel); Barmashenko, B. D.; Rosenwaks, S. [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel)

2009-09-15

84

Extraction efficiency of a 5-cm gain length supersonic chemical oxygen-iodine laser  

Microsoft Academic Search

Gain saturation and diffractive loss data have been collected on the Phillips Laboratory's VertiCOIL laser. These data have been applied to the COIL simplified saturation model to estimate the optical extraction efficiency of VertiCOIL. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting

Charles A. Helms; Tilghman L. Rittenhouse; S. P. Phipps; Keith A. Truesdell; Gordon D. Hager

1997-01-01

85

Deactivation rate of I{sub 2} molecules (X, v {>=} 30) in the medium of a chemical oxygen-iodine laser  

SciTech Connect

The effective deactivation rate constants are calculated for I{sub 2}(X) molecules at vibrational levels with v {>=} 30 colliding with N{sub 2} and O{sub 2} molecules in the medium of a chemical oxygen-iodine laser. The calculated constants (4x10{sup -12} cm{sup 3} s{sup -1} and 3x10{sup -12} cm{sup 3} s{sup -1}) are less by half plus than the corresponding constants found earlier in the paper of Lawrence et al., where the dissociation of I{sub 2} was neglected in calculations. (lasers, active media)

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

2008-08-31

86

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

87

g... production in flowing ArO2 surface-wave microwave discharges: Possible use for oxygen-iodine laser excitation  

E-print Network

be effectively used for the oxygen-iodine laser excitation. It is demonstrated that at pressures higher than 10 chemical oxygen-iodine laser operates on the electronic transition of the iodine atom at 1315 nm, where.e., the electric discharge oxygen-iodine laser DOIL as demonstrated by Carroll et al.1 Carroll et al. sug- gest

Guerra, Vasco

88

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  

Microsoft Academic Search

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

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

2009-01-01

89

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

E-print Network

Oxygen­Iodine Laser Using Nitrogen Diluent for Commercial Applications D. L. Carroll, D. M. King, L the principle design change of moving the iodine injectors closer to throat. Index Terms--Chemical lasers, gas lasers, iodine, laser appli- cations, laser materials-processing applications, lasers, nitrogen, oxygen

Carroll, David L.

90

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: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides  

Microsoft Academic Search

The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen---iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations

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

2009-01-01

91

Analytic study of the chain dark decomposition reaction of iodides — atomic iodine donors — in the active medium of a pulsed chemical oxygen—iodine laser: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides  

Microsoft Academic Search

The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen—iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations

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

2009-01-01

92

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

E-print Network

Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments; accepted 16 May 2006; published online 26 July 2006 In an electric discharge oxygen-iodine laser, laser.1063/1.2215355 I. INTRODUCTION Oxygen-iodine laser systems1 operate on the I 2 P1/2 I 2 P3/2 hereafter denoted I

Carroll, David L.

93

Systematic development of the electric discharge oxygen-iodine laser David L. Carrolla  

E-print Network

1 Systematic development of the electric discharge oxygen-iodine laser David L. Carrolla , Gabriel have led to continued improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system. Keywords: hybrid electric discharge oxygen-iodine laser, ElectricOIL, EOIL, DOIL, singlet oxygen 1

Carroll, David L.

94

Spatial and recovery measurements of gain in an electric oxygen-iodine laser  

E-print Network

Spatial and recovery measurements of gain in an electric oxygen- iodine laser G. F. Benavidesa ABSTRACT Recent investigations of an Electric Oxygen-Iodine Laser system have shown that computational oxygen-iodine laser kinetics rates. Understanding of this kinetic process should enable us to accommodate

Carroll, David L.

95

Super-linear Enhancement of the Electric Oxygen-Iodine Laser David L. Carrolla  

E-print Network

Super-linear Enhancement of the Electric Oxygen-Iodine Laser David L. Carrolla , Brian S. Woodardb., Urbana, Illinois, 61801, United States ABSTRACT Continuing experiments with Electric Oxygen-Iodine Laser: electric discharge oxygen-iodine laser, ElectricOIL, EOIL, DOIL, singlet delta oxygen 1. INTRODUCTION

Carroll, David L.

96

Gain recovery in an electric oxygen-iodine laser J. W. Zimmerman,1,a  

E-print Network

Gain recovery in an electric oxygen-iodine laser J. W. Zimmerman,1,a G. F. Benavides,2 A. D. Palla online 14 January 2009 Recent investigations of an electric oxygen-iodine laser system have shown American Institute of Physics. DOI: 10.1063/1.3064163 The electrically driven oxygen-iodine laser Electri

Carroll, David L.

97

The chemical oxygen iodine laser in the presence of a magnetic field. I. Gain measurements and polarization effects  

Microsoft Academic Search

For pt.II, see ibid., vol.29, no.3, p.944-53 (1993). The results from a combined experimental\\/theoretical investigation of the influence of a magnetic field on the gain and polarization in a supersonic chemical oxygen laser are described. Theoretical calculations are presented for the normalized gain as a function of magnetic field strength and are shown to be in good agreement with the

G. D. Hager; D. Kopf; B. S. Hunt; B. Anderson; C. Woolhiser; P. Crowell

1993-01-01

98

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

99

Excited states in the active media of oxygen - iodine lasers  

SciTech Connect

A review of investigations of kinetic processes in active media oxygen - iodine lasers (OILs) performed in the last decade is presented. The mechanisms of pumping and quenching of electronically and vibrationally excited O{sub 2} and I{sub 2} molecules are considered, and dissociation mechanisms of I{sub 2} in the active medium of the OIL are analysed. The values of kinetic constants of processes proceeding in the active media of OILs are recommended. (review)

Azyazov, V N [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation)

2009-11-30

100

Gain recovery in an electric oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Recent investigations of an electric oxygen-iodine laser system have shown that computational modeling overpredicts the experimentally measured power output for similar gain conditions. This discrepancy is potentially due to an unknown reaction that competes with the forward pumping of I(P21/2) by O2(a ?1). Measurements of gain recovery downstream of an operating laser cavity were performed. Modeling of this experiment shows that reducing the forward pumping rate by an effective factor of approximately 4 to simulate a competing mechanism results in the computational modeling matching the experimental gain recovery measurements, and in improved agreement between the measured and modeled laser power extraction.

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

2009-01-01

101

Electric oxygen-iodine laser discharge scaling and laser performance  

NASA Astrophysics Data System (ADS)

In 2004, a research partnership between the University of Illinois and CU Aerospace demonstrated the first electric discharge pumped oxygen-iodine laser referred to as ElectricOIL. This exciting improvement over the standard oxygen-iodine laser utilizes a gas discharge to produce the necessary electronically-excited molecular oxygen, O2(a 1Delta), that serves as the energy reservoir in the laser system. Pumped by a near-resonant energy transfer, the atomic iodine lases on the I(2P1/2) ? I(2P3/2) transition at 1315 nm. Molecular oxygen diluted with helium and a small fraction of nitric oxide flows through a radiofrequency discharge where O2(a 1Delta) and many other excited species are created. Careful investigations to understand the benefits and problems associated with these other states in the laser system allowed this team to succeed where other research groups had failed, and after the initial demonstration, the ElectricOIL research focus shifted to increasing the efficiencies along with the output laser energy. Among other factors, the laser power scales with the flow rate of oxygen in the desired excited state. Therefore, high yields of O2(a 1Delta) are desired along with high input oxygen flow rates. In the early ElectricOIL experiments, the pressure in the discharge was approximately 10 Torr, but increased flow rates forced the pressure to between 50 and 60 Torr requiring a number of new discharge designs in order to produce similar yields of O2(a1Delta) efficiently. Experiments were conducted with only the electric discharge portion of the laser system using emission diagnostics to study the effects of changing the discharge geometry, flow residence time, and diluent. The power carried by O2(a 1Delta) is the maximum power that could be extracted from the laser, and the results from these studies showed approximately 2500 W stored in the O2(a1Delta) state. Transferring this energy into the atomic iodine has been another challenge in ElectricOIL as experiments have shown that the iodine is pumped into the excited state slower than is predicted by the known kinetics, resulting in reduced output power. An elementary model is presented that may partially explain this problem. Larger laser resonator volumes are employed to improve power extraction by providing more flow time for iodine pumping. The results presented in this work in conjunction with the efforts of others led to ElectricOIL scaling from 200 mW in the initial demonstration to nearly 500 W.

Woodard, Brian S.

102

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

SciTech Connect

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 CH{sub 3}I is used as the donor of atomic iodine. The fraction of iodine extracted from CH{sub 3}I in the generator is {approx}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 {approx}3%. (elements of laser setups)

Azyazov, V N; Vorob'ev, M V; Voronov, A I; Kupryaev, Nikolai V; Mikheev, P A; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2009-01-31

103

Gain and continuous-wave laser power enhancement with a multiple discharge electric oxygen-iodine laser  

E-print Network

Gain and continuous-wave laser power enhancement with a multiple discharge electric oxygen-iodine in an electric oxygen-iodine laser. O2 a 1 is produced by two parallel radio-frequency-excited electric.1063/1.2948860 The electrically driven oxygen-iodine laser Electri- cOIL that was first demonstrated by Carroll et al.1,2 operates

Carroll, David L.

104

Enhanced performance of an electric oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Experiments and modeling have led to continued enhancements in 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. A 95% enhancement in cw laser power was achieved via a 50% increase in gain length, flow rates, and discharge power. A further 87% increase in extracted laser power was obtained using a larger mode volume resonator. The gain has improved by more than 100-fold from the initial demonstration of 0.002% cm-1 to 0.26% cm-1, and similarly the outcoupled laser power has improved more than 500-fold from 0.16 W to 102 W.

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

2010-02-01

105

Enhancement of electric oxygen-iodine laser performance using larger mode volume resonators  

E-print Network

Enhancement of electric oxygen-iodine laser performance using larger mode volume resonators Brian S.4130, 140.4780, 230.5750. The electrically driven oxygen-iodine laser (Electric- OIL) that was first report on the demonstration of an 87% enhancement in cw laser power on the 1315 nm transition of atomic

Carroll, David L.

106

Evolution of the electric discharge oxygen-iodine laser David L. Carrolla  

E-print Network

Evolution of the electric discharge oxygen-iodine laser David L. Carrolla , Gabriel F. Benavidesa 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

Carroll, David L.

107

Recent Electric Oxygen-Iodine Laser Experiments and Modeling David L. Carrolla  

E-print Network

Recent Electric Oxygen-Iodine Laser Experiments and Modeling David L. Carrolla , Gabriel F and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. A new with BLAZE-V shows that an iodine pre-dissociator can have a dramatic impact upon gain and laser performance

Carroll, David L.

108

Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L  

E-print Network

Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L G. F the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition

Carroll, David L.

109

Development of the electric discharge oxygen-iodine laser David L. Carrolla  

E-print Network

Development of the electric discharge oxygen-iodine laser David L. Carrolla , Joseph T. Verdeyena ABSTRACT In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O2(a1. As the development of this type of iodine laser continues, the roles of oxygen atoms and NO/NO2 are found to be very

Carroll, David L.

110

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

E-print Network

Enhancement of electric oxygen-iodine laser performance using a rectangular discharge and longer of Physics. doi:10.1063/1.3269811 The electrically driven oxygen-iodine laser Electri- cOIL that was first on the demonstration of a 95% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine via

Carroll, David L.

111

Enhanced performance of an electric oxygen-iodine laser D. L. Carrolla  

E-print Network

Enhanced performance of an electric oxygen-iodine laser D. L. Carrolla , G. F. Benavidesa,b , J. W and modeling have led to continued enhancements in 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

Carroll, David L.

112

Electric Oxygen-Iodine Laser Performance Enhancement using Larger Discharge and Resonator Mode Volumes  

E-print Network

Electric Oxygen-Iodine Laser Performance Enhancement using Larger Discharge and Resonator Mode that significantly higher power was available in the electric oxygen-iodine laser gas flow which could be extracted length of the laser cavity, plus the addition of an iodine pre-dissociator discharge are expected

Carroll, David L.

113

Test bench for studying the outlook for industrial applications of an oxygen-iodine laser  

SciTech Connect

We report the development and tests of a chemical oxygen-iodine laser test bench based on a twisted-aerosol-flow singlet-oxygen generator and a supersonic laser model for studying the outlook for industrial applications of this laser. The maximal output power of the laser is {approx}65 kW (the average power is {approx}50 kW), corresponding to a specific output power of {approx}110 W cm{sup -2}. The maximal chemical efficiency is {approx}34%. (letters)

Adamenkov, A A; Bakshin, V V; Bogachev, A V; Buryak, E V; Vdovkin, L A; Velikanov, S D; Vyskubenko, B A; Garanin, Sergey G; Gorbacheva, E V; Grigorovich, Sergei V; Il'in, S P; Il'kaev, R I; Ilyushin, Yurii N; Kalashnik, A M; Kolobyanin, Yu V; Leonov, M L; Svischev, V V; Troshkin, M V [Russian Federal Nuclear Center 'All-Russian Scientific Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod Region (Russian Federation)

2007-07-31

114

Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides  

SciTech Connect

The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen-iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations of singlet oxygen and iodide at that moment. The limiting parameters, calculated by using these expressions for a typical composition of the active medium of a pulsed COIL, well coincide with the results of numerical calculations. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2009-08-31

115

Evolution of the electric discharge oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

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, size scaling is presently showing a super-linear growth in performance; a 95% enhancement in cw laser power was achieved via a 50% increase in gain length, flow rates, and discharge power. New gain recovery measurements and modeling downstream of an operating laser cavity are presented in this work for a wider range of flow conditions to help identify previously unidentified kinetic processes. Larger volume resonators that extend further downstream in the flow direction were able to extract more of the excess energy being carried by the O2(a) from the ElectricOIL gain medium; a further 87% increase in extracted laser power was obtained. As understanding of the ElectricOIL system continues to improve, the design of the laser systematically evolves. The gain has improved by more than 100-fold from the initial demonstration of 0.002% cm-1 to 0.26% cm-1, and similarly the outcoupled laser power has increased more than 600-fold from 0.16 W to 109 W.

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

2010-11-01

116

Oxygen-iodine ejector laser with a centrifugal bubbling singlet-oxygen generator  

SciTech Connect

It is shown that if a supersonic oxygen-iodine ejector laser is fed by singlet oxygen from a centrifugal bubbling generator operating at a centrifugal acceleration of {approx}400g, the laser output power achieves a value 1264 W at a chemical efficiency of 24.6% for an alkaline hydrogen peroxide flow rate of 208 cm{sup 3}s{sup -1} and a specific chlorine load of 1.34 mmol s{sup -1} per square centimetre of the bubble layer. (lasers)

Zagidullin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2005-10-31

117

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  

Microsoft Academic Search

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

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

2009-01-01

118

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  

SciTech Connect

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. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2009-02-28

119

Efficient operation of a Co : MgF{sub 2} crystal laser pumped by radiation from a pulsed oxygen - iodine laser  

SciTech Connect

Radiation from a chemical oxygen - iodine laser was used for the first time to pump a Co : MgF{sub 2} crystal laser. The attained differential (slope) efficiency of 40%, corresponding to a quantum efficiency of 62%, demonstrated that a Co : MgF{sub 2} crystal can be used for efficient conversion and summation of iodine laser beams. (lasers)

Vagin, Nikolai P; Podmar'kov, Yu P; Frolov, M P; Yuryshev, Nikolai N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Kryukov, P G [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

1998-04-30

120

Spatial and recovery measurements of gain in an electric oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Recent investigations of an Electric Oxygen-Iodine Laser system have shown that computational modeling over-predicts the laser power output measured in experiments for similar gain conditions. To help resolve this discrepancy, detailed 2-axis mapping of gain and gain recovery measurements downstream of an operating laser cavity were performed. Modeling and analyses of the gain recovery experiments indicate that when the pumping rate of I(2P1/2) by O2(a1?) is reduced by an effective factor of approximately 4 as a result of an unknown competing reaction, the calculations are well matched to the experimental gain recovery measurements. The agreement between the measured and modeled laser power extraction also significantly improves when the reduced effective pumping rate is used. The results suggest that there may be a competing reaction that effectively reduces the forward pumping rate as compared to the classical chemical oxygen-iodine laser kinetics rates. Understanding of this kinetic process should enable us to accommodate or eliminate its impact on ElectricOIL performance.

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

2009-02-01

121

LASERS: Compact oxygen-iodine laser with a thermally insulated jet singlet---oxygen generator  

Microsoft Academic Search

A compact oxygen-iodine laser without a water vapour trap and with an uncooled jet singlet---oxygen generator was constructed. A laser output power of 150 W was reached when the oxygen preassure at the exit from the jet generator was 25 Torr. The specific power averaged over the oxygen-generator cross section was 10 W cm-2.

M. V. Zagidullin; V. D. Nikolaev; M. I. Svistun

1994-01-01

122

Conversion of solar energy to laser beam by fullerene-oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The concept of a solar energy conversion into laser radiation on a basis of fullerene-oxygen-iodine laser (FOIL) is considered. A basis of FOIL construction is the photoexcitation of fullerene molecules into their triplet state by the sunlight, interaction of the photoexcited fullerene molecules with molecular oxygen with a singlet oxygen formation and subsequent transmission of the singlet oxygen energy to iodine atoms. Efficiency of the given process makes 30 % approximately. It is shown that for solar energy transformation to the laser radiation the singlet oxygen generator is under construction on the basis of solid-state porous fullerene-containing membranes. Results of working out and research of solid-state generators of singlet oxygen are presented. Constructive design of fullerene-oxygen-iodine laser of the continuous operating mode with the solar pumping for transformation of the sunlight to the laser beam for the decision of power problems are presented.

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Mak, A. A.

2011-03-01

123

Conversion of solar energy to laser beam by fullerene-oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The concept of a solar energy conversion into laser radiation on a basis of fullerene-oxygen-iodine laser (FOIL) is considered. A basis of FOIL construction is the photoexcitation of fullerene molecules into their triplet state by the sunlight, interaction of the photoexcited fullerene molecules with molecular oxygen with a singlet oxygen formation and subsequent transmission of the singlet oxygen energy to iodine atoms. Efficiency of the given process makes 30 % approximately. It is shown that for solar energy transformation to the laser radiation the singlet oxygen generator is under construction on the basis of solid-state porous fullerene-containing membranes. Results of working out and research of solid-state generators of singlet oxygen are presented. Constructive design of fullerene-oxygen-iodine laser of the continuous operating mode with the solar pumping for transformation of the sunlight to the laser beam for the decision of power problems are presented.

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Mak, A. A.

2010-07-01

124

Determination of singlet-oxygen generator efficiency on a 10kW class supersonic chemical oxygen-iodine laser (RADICL)  

Microsoft Academic Search

With the advent of the Air Force Airborne Laser program, the emphasis of chemical oxggen-iodine laser (COIL) research has shifted toward improving the overall efficiency. A key component of the COIL is the singlet-oxygen generator (SOG). To assess the efficiency of the SOG, an accurate method of determining the yield of O2(a1 ?g), [O2(a1?g )]\\/[O2(total)] where [O2(total)]=[O2 (a1?g)]+[O2(X3 ?g-)], has

Kip R. Kendrick; Charles A. Helms; Brian G. Quillen

1999-01-01

125

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

126

Advanced chemical lasers  

Microsoft Academic Search

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.

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

2004-01-01

127

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

128

Influence of an iodine donor on the output energy of a pulsed oxygen-iodine laser  

Microsoft Academic Search

The influence of atomic iodine donors (CH3I and CF3I) on the output energy of a pulsed oxygen-iodine laser was investigated. Their influence on the time dependence of the luminescence intensity of I (2P1\\/2) iodine atoms formed by laser photolysis of an RI–O2–M mixture (R = CH3, CF3, M is the buffer gas) was also studied. An analysis of the experimental

Nikolai P Vagin; V A Zolotarev; P G Kryukov; V S Pazyuk; Yu P Podmarkov; M P Frolov; Nikolai N Yuryshev

1991-01-01

129

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

130

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

131

Kinetics of saturation of the active medium of an oxygen-iodine laser  

Microsoft Academic Search

The influence of the incident-field intensity and the rate constants of the active-medium processes in an oxygen-iodine laser on the gain for the 2P(1\\/2)-2P(3\\/2) transition of the iodine atom is investigated theoretically, taking the electron energy exchange between I atoms and O2 molecules, the translational relaxation of I atoms, van der Waals mixing of the 2P(3\\/2) sublevels, and mixing of

M. V. Zagidullin; Valerii I. Igoshin; N. L. Kupriianov

1984-01-01

132

REVIEW: Excited states in the active media of oxygeniodine lasers  

NASA Astrophysics Data System (ADS)

A review of investigations of kinetic processes in active media oxygeniodine lasers (OILs) performed in the last decade is presented. The mechanisms of pumping and quenching of electronically and vibrationally excited O2 and I2 molecules are considered, and dissociation mechanisms of I2 in the active medium of the OIL are analysed. The values of kinetic constants of processes proceeding in the active media of OILs are recommended.

Azyazov, V. N.

2009-11-01

133

Chemical oxygen-iodine laser (COIL) beam quality predictions using 3D Navier-Stokes (MINT) and wave optics (OCELOT) codes  

NASA Astrophysics Data System (ADS)

This paper describes a series of analyses using the 3-d MINT Navier-Stokes and OCELOT wave optics codes to calculate beam quality in a COIL laser cavity. To make this analysis tractable, the problem was broken into two contributions to the medium quality; that associated with microscale disturbances primarily from the transverse iodine injectors, and that associated with the macroscale including boundary layers and shock-like effects. Results for both microscale and macroscale medium quality are presented for the baseline layer operating point in terms of single pass wavefront error. These results show that the microscale optical path difference effects are 1D in nature and of low spatial order. The COIL medium quality is shown to be dominated by macroscale effects; primarily pressure waves generated from flow/boundary layer interactions on the cavity shrouds.

Lampson, Alan I.; Plummer, David N.; Erkkila, John H.; Crowell, Peter G.; Helms, Charles A.

1998-05-01

134

Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L.  

PubMed

The authors report the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition was achieved with a factor of 3 increase in gain length. I(2P1/2) is pumped using energy transferred from O2(a1?) produced by flowing a gas mixture of O2-He-NO through three coaxial geometry radio-frequency discharges. Continuous wave (CW) average total laser power of 481 W was extracted with g0L=0.042. PMID:22555687

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

2012-05-01

135

Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser  

NASA Astrophysics Data System (ADS)

The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio ?. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at ?d <= 7. Efficient energy extraction from the OIL active medium is achieved in the case of ?d = 5 - 7, ? = 4 - 8.

Mezhenin, A. V.; Azyazov, V. N.

2012-12-01

136

Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.

Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Gerasimov, A. Yu; Gostev, I. V.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

2014-01-01

137

Small-signal gain and saturation parameter of a transverse-flow CW oxygen-iodine laser  

Microsoft Academic Search

The small-signal gain and saturation parameter of a transverse-flow CW oxygen-iodine laser have been experimentally obtained for the first time from output power measurements made as a function of the cavity losses without using a CW probe laser. These measurements typically yield a small-signal gain of 0.045 per m and a saturation parameter of 0.44 kW\\/sq cm for a Cl2

K. Watanabe; S. Kashiwabara; K. Sawai; S. Toshima; R. Fujimoto

1983-01-01

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

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

study of cutting thick aluminum and steel with a chemical oxygen-iodine laser using an N2 or O2 gas-5776 ABSTRACT A chemical oxygen-iodine laser (COIL) was used for cutting aluminum and carbon steel. Cut depths processing, thick-section cutting, chemical oxygen-iodine laser, COIL 1. INTRODUCTION Lasers made their debut

Carroll, David L.

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

Discharge singlet oxygen generator for oxygen iodine laser: I. Experiments with rf discharges at 13.56 and 81 MHz  

Microsoft Academic Search

The scaling on pressure for a discharge singlet oxygen generator based on the rf discharge excitation of O2 flow is studied in the context of the problem of oxygen-iodine laser pumping. With this aim, the evolution of O2(a 1 Deltag) and O_2\\\\,(b\\\\,^{1}\\\\!\\\\Sigma _g^{ + }) molecules as well as O(3P) atoms in 13.56 and 81 MHz discharges at pressures up

O. V. Braginsky; A. S. Kovalev; D. V. Lopaev; Yu A. Mankelevich; O. V. Proshina; T. V. Rakhimova; A. T. Rakhimov; A. N. Vasilieva

2006-01-01

142

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

143

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

Microsoft Academic Search

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(1Delta). In electrically pumped systems (eCOILs), electron impact excitation of O2 produces the O2(1Delta) and also produces O atoms through dissociative excitation. The O atoms, through reactions with I2, I(2P1\\/2) and I(2P3\\/2), lead to

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

2007-01-01

144

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

Microsoft Academic Search

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

Ramesh A Arakoni; Natalia Y Babaeva; Mark J Kushner

2007-01-01

145

Gain and continuous-wave laser power enhancement with a multiple discharge electric oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

Herein the authors report on the demonstration of a 70% enhancement in gain and 98% enhancement in continuous-wave laser power on the 1315nm transition of atomic iodine via an increase in flow rates and pressure using multiple discharges in an electric oxygen-iodine laser. O2(a?1) is produced by two parallel radio-frequency-excited electric discharges sustained in an O2-He-NO gas mixture, a secondary discharge predissociated the molecular iodine, and I(P1/22) is then pumped using energy transferred from O2(a?1). A gain of 0.17%cm-1 was obtained and the total laser output power was 12.3W.

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

2008-06-01

146

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

147

Studies of oxygen-helium discharges for use in electric oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

In recent work, the performance of the Electric Oxygen-Iodine Laser (ElectricOIL), developed in partnership by researchers at the University of Illinois and CU Aerospace, has been greatly improved through systematic study of various components of this new laser technology. One major contribution to the advancement of ElectricOIL technology has been the development of electric discharges capable of producing significant flow rates of the precursor electronically-excited molecular oxygen, O2(a1Delta). O2(a 1Delta) serves as an energy reservoir in the laser system, pumping atomic iodine by near-resonant energy transfer producing gain and laser on the I(2P1/2) ? I(2P3/2 ) transition at 1315 nm. Initial experimental work with radio-frequency discharges showed the importance of controlling O-atom flow rates to reduce quenching losses of energy stored in O2(a1Delta), and determined proper selection of the helium diluent ratio and specific power deposition (power per O2 flow rate). Further experimental investigations with transverse capacitive radio-frequency discharges in O2/He/NO mixtures in the pressure range of 1-100 Torr and power range of 0.1-1.2 kW have indicated that O2(a1Delta) production is a strong function of geometry (transverse gap), excitation frequency, and pressure. These parameters along with gas flow mixture dictate the current density at which the discharge operates, and its modal characteristics (normal vs. abnormal, homogeneous vs. inhomogeneous). A key result is that to encourage efficient O2(a1Delta) production these parameters should be selected in order to promote a homogeneous (low current density) discharge. The discharge behavior is characterized using terminal current-voltage-characteristics, microwave interferometer measurements, and plasma emission intensity measurements. Numerous spectroscopic measurements of O2(a1Delta), oxygen atoms, and discharge excited states are made in order to describe the discharge performance dependent on various parameters. The influence of NO on O-atom flow rates and O2(a1Delta) production is investigated. Progress of laser power extraction since initial reports in 2005 is overviewed.

Zimmerman, Joseph William

148

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-driven oxygen-iodine laser system (also often referred to as EOIL or DOIL in the literature), there have been

Carroll, David L.

149

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

150

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

151

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

152

Gas flow and chemical lasers  

SciTech Connect

This book contains current research developments and applications related to high power lasers, including an entire spectrum of activities: basic physics, aerothermodynamics, new laser media, laser design, diagnostic techniques, laser propagation, interaction pehnomena, and applications. Invited lectures include: chemically pumped electronic transition lasers, optical resonance transfer lasers for mode control, optical phase conjugation in laser resonators, laser material processing, and oxygen-iodine chemical lasers. Studies on high energy optics and adaptive optics are also included.

Onorato, M.

1984-01-01

153

Effect of iodine dissociation in an auxiliary discharge on gain in a pulser-sustainer discharge excited oxygen-iodine laser  

Microsoft Academic Search

The paper presents the results of iodine vapour dissociation measurements in a high voltage, nanosecond pulse duration, repetitively pulsed discharge, used as an auxiliary ('side') discharge in an electric discharge excited oxygen-iodine laser. The side discharge, sustained in a high-pressure iodine vapour\\/helium mixture remained stable in the entire range of experimental conditions. Iodine dissociation fraction generated in the side discharge

A. Hicks; J. R. Bruzzese; I. V. Adamovich

2010-01-01

154

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

SciTech Connect

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 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 (CH{sub 3}I, n-C{sub 3}H{sub 7}I, C{sub 2}H{sub 5}I) with oxygen and nitrogen at the specific energy depositions of {approx}5 J L{sup -1}, pressures of 10 - 25 Torr, and mixture volume of 2.5 L. (lasers)

Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-08-03

155

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

SciTech Connect

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 and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found.

Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2011-03-15

156

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 system Ruiping Huang `, Rong Zhang ' and Richard N. Zare Deparfmenfof in the chemical oxygen iodine laser (COIL) system. The O2(`4) isproduced by bubbling Cl, through an alkaline-energy chemical laser is the chem- ical oxygen iodine laser (COIL), operating at 1.315 pm on the zP,,2+2P,,2

Zare, Richard N.

157

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

NASA Astrophysics Data System (ADS)

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 sustainer discharge, which allows stable operation at significantly higher discharge powers. Gain on the 1315nm iodine atom transition and laser power in the M =3 transverse laser cavity are 0.049%/cm and 1.24W, at a flow temperature of T =100K.

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

2007-08-01

158

Enhancement of electric oxygen-iodine laser performance using larger mode volume resonators.  

PubMed

Herein the authors report on the demonstration of an 87% enhancement in cw laser power on the 1315 nm transition of atomic iodine via a 100% increase in the resonator mode volume. O(2)(a1Delta) is produced by a single rf-excited electric discharge sustained in an O(2)-He-NO gas mixture flowing through a rectangular geometry, and I(P2(1/2)) is then pumped using energy transferred from O(2)(a1Delta). A total laser output power of 102.5 W was obtained using a Z-pass resonator configuration. PMID:20479825

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

2010-05-15

159

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

160

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

161

Production of iodine atoms for an oxygen-iodine laser from iodine-containing molecules with the help of atomic oxygen  

SciTech Connect

A new technique is proposed for the production of atomic iodine for a cw oxygen-iodine laser with the use of reactions between iodine donor molecules and oxygen atoms. The CH{sub 3}I, CF{sub 3}I, or I{sub 2} molecules can be used as donors. Oxygen atoms are injected into the reaction region by admixing the flow of partially dissociated oxygen produced in an electric discharge. The use of atomic iodine instead of molecular iodine excludes the consumption of singlet oxygen O{sub 2}({sup 1{Delta}}) for the dissociation of I{sub 2} and quenching of I* by the I{sub 2} molecules. The latter will supposedly allow raising the optimal density of I and accordingly the gain coefficient. Estimates were made of the required degree of dissociation of oxygen employed to obtain iodine atoms at which the above advantages can be realised. (lasers)

Shepelenko, A A; Mikheev, P A [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2003-03-31

162

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 Oxygen Iodine Laser (ElectriCOIL) [Carroll, 2000]. ElectriCOIL operates on gaseous oxygen and iodine

Carroll, David L.

163

Effect of the solution temperature in a singlet-oxygen generator on the formation of active medium in an ejector oxygen - iodine laser  

SciTech Connect

The influence of the solution temperature in a singlet-oxygen generator on the formation of the active medium in the ejector oxygen - iodine laser is investigated. The following parameters of the active medium at the solution temperature -20{sup 0}C are obtained: the gain is 7.2 x 10{sup -3} cm{sup -1}, the Mach number is M=2, the temperature is 205 K, and the static pressure is 9.3 mmHg. As the solution temperature is increased to -4{sup 0}C, the gain decreases to 5 x 10{sup 3} cm{sup -1}, the Mach number decreases to 1.78, while the temperature and the static pressure increase to 241 K and 10.7 mmHg, respectively. As the solution temperature increases from -20 to -4{sup 0}C, the losses in O{sub 2}({sup 1}{Delta}) increase by less than 20%, while the dissociation efficiency of molecular iodine decreases by less than 21%. (lasers, active media)

Zagidullin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation); Palina, N Yu [Samara State University, Samara (Russian Federation)

2002-02-28

164

Proceedings of the Gas and Chemical Lasers and Intense Beam Applications III Conference, San Jose, California 22-24 January 2002, The Int. Soc. for Opt. Eng. Vol. 4631, P.O. Box 10, Bellingham, WA 98227-0010, pp. 154-160.  

E-print Network

. Keywords: chemical oxygen-iodine laser, COIL, ElectriCOIL, RF excitation of oxygen, singlet-delta oxygen 1 oxygen-iodine laser (COIL) [McDermott, 1978] operates on the electronic transition of the iodine atom into a practical laser system. Atomic iodine injection rather than molecular iodine injection will give added

Carroll, David L.

165

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

166

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

Microsoft Academic Search

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(a 1 ¢) concentration resulting from the presence of NO in

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

2007-01-01

167

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

E-print Network

In an electric discharge Oxygen-Iodine laser (ElectricOIL), laser action at 1315 nm on the I(2 P1/2) I(2 P3. Introduction HE classic chemical oxygen-iodine laser (COIL) system1 operates on the I(2 P1/2) I(2 P3 of a continuous flow hybrid electrically powered oxygen-iodine laser with electric discharges to produce the O2(a

Carroll, David L.

168

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

169

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

E-print Network

to improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased system parameters. I. Introduction The classical chemical oxygen iodine laser (COIL) system1 employs/2) state of the iodine atom following the molecule's dissociation. This laser has been heavily studied

Carroll, David L.

170

Development of a mist singlet oxygen generator for a chemical oxygen-iodine laser  

Microsoft Academic Search

Mist singlet oxygen generator (Mist-SOG) has been developed in order to increase the BHP utilization. On the other hand, Mist-SOG generates much more water vapor than conventional SOG because the heat capacity of the BHP is small. It is well known that the water vapor deactivates the excited iodine. In order to remove the water vapor, we developed a jet-cold

Shigeki Muto; Masamori Endo; Kenzo Nanri; Tomoo Fujioka

2003-01-01

171

Progress toward realization of a KW-class EOIL laser  

Microsoft Academic Search

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

Alan E. Hill

2008-01-01

172

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

E-print Network

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

Carroll, David L.

173

Effect of vibrationally excited I{sub 2}(a{sup 1{Delta}}{sub g}) molecules on the parameters of the active medium of an oxygen - iodine laser  

SciTech Connect

A comparison of the experimental and theoretical results shows that quenching of one singlet oxygen molecule leads to the formation of 4.5 vibrational quanta of the I{sub 2} molecule on the average in the active medium of an oxygen-iodine laser. The dependence of threshold yield of singlet oxygen and of the gain on the relative concentration of vibrationally excited I{sub 2}(a{sup 1{Delta}}{sub g}) molecules are studied. The threshold yield of singlet oxygen increases with the relative concentration of vibrationally excited I{sub 2} molecules and may be several percent higher than the value assumed earlier. The gain depends weakly on the relative concentration of vibrationally excited oxygen molecules. (active media)

Azyazov, V N; Antonov, I O; Pichugin, S Yu; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2004-12-31

174

An experimental research on the mixing process of supersonic oxygen-iodine parallel streams  

NASA Astrophysics Data System (ADS)

The O2(1?)/I2 mixing process is one of the most important steps in chemical oxygen-iodine laser (COIL). Based on the chemical fluorescence method (CFM), a diagnostic system was set up to image electronically excited fluorescent I2(B3?0) by means of a high speed camera. An optimized data analysis approach was proposed to analyze the mixing process of supersonic oxygen-iodine parallel streams, employing a set of qualitative and quantitative parameters and a proper percentage boundary threshold of the fluorescence zone. A slit nozzle bank with supersonic parallel streams and a trip tab set for enhancing the mixing process were designed and fabricated. With the diagnostic system and the data analysis approach, the performance of the trip tab set was examined and is demonstrated in this work. With the mixing enhancement, the fluorescence zone area was enlarged 3.75 times. We have studied the mixing process under different flow conditions and demonstrated the mixing properties with different iodine buffer gases, including N2, Ar, He and CO2. It was found that, among the four tested gases, Ar had the best penetration ability, whilst He showed the best free diffusion ability, and both of them could be well used as the buffer gas in our experiments. These experimental results can be useful for designing and optimizing COIL systems.

Wang, Zengqiang; Sang, Fengting; Zhang, Yuelong; Hui, Xiaokang; Xu, Mingxiu; Zhang, Peng; Zhao, Weili; Fang, Benjie; Duo, Liping; Jin, Yuqi

2014-12-01

175

Dissociation of I{sub 2} and the vibrational kinetics in the oxygen-iodine medium  

SciTech Connect

The comparative analysis of the processes responsible for dissociation of molecular iodine in the oxygen-iodine medium is made. The rate of relaxation of vibrationally excited oxygen in the O{sub 2}-I{sub 2}-H{sub 2}O medium is shown to be limited by the VV energy exchange between oxygen and water molecules, and the fraction of vibrationally excited O{sub 2} ({nu}=1) in the active medium of the oxygen-iodine laser can reach several tens of percent. It is noted that the VV exchange in O{sub 2}({sup 1{Delta}},{nu}=1)+I({sup 2}P{sub 3/2}){r_reversible}O{sub 2}({sup 3{Sigma}},{nu}=1)+I({sup 2}P{sub 1/2}) reaction may be of considerable importance in the kinetics of formation of the active medium in the oxygen-iodine laser. (active media)

Azyazov, V N; Safonov, V S; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2000-08-31

176

Recent Experiments and Post-Discharge Modeling of the ElectricOIL Laser System  

E-print Network

of a continuous wave laser at 1315 nm on the I(2 P1/2) I(2 P3/2) transition of atomic iodine where the O2(a1 and the quantitative comparisons to data are reasonable. Keywords: electric oxygen-iodine laser, ElectricOIL, RF excitation of oxygen, singlet-delta oxygen, DOIL I. INTRODUCTION The classic chemical oxygen-iodine laser

Carroll, David L.

177

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

178

Chemical lasers  

NASA Astrophysics Data System (ADS)

The application and the advances of quantum electronics, specifically, of optical quantum generators lasers is reviewed. Materials are cut, their surfaces are machined, chemical transformations of substances are carried out, surgical operations are performed, data are transmitted, three dimensional images are produced and the content of microimpurities, in the atmosphere, are analyzed by use of a beam. Laser technology is used in conducting investigations in the most diverse fields of the natural and technical sciences from controlled thermonuclear fusion to genetics. Many demands are placed on lasers as sources of light energy. The importance of low weight, compactness of the optical generator and the efficiency of energy conversion processes is emphasized.

Khariton, Y.

1984-08-01

179

New iodine laser achieves positive gain  

Microsoft Academic Search

The chemical oxygen-iodine laser (COIL) is a continuous-wave, near-infrared chemical laser. It offers excellent properties for ap- plications that require high-power laser output from a mobile platform. The best-known example of a COIL system may be the 'Airborne Laser' ballistic missile defense weapon system,1 which uses a multi-megawatt laser with good beam quality. For very-high-power applications, chemical lasers retain the

Masamori Endo

2008-01-01

180

Iodine lasers. (Latest citations from the INSPEC: Information Services for the Physics and Engineering Communities data base). Published Search  

SciTech Connect

The bibliography contains citations concerning the design, development, and analysis of iodine lasers for industrial and research applications. Topics include oxygen-iodine lasers, optical and chemical pumping, pulsed and continuous wave lasers, kinetic modelling, optical harmonic generation, and optical energy storage. (Contains a minimum of 165 citations and includes a subject term index and title list.)

Not Available

1992-10-01

181

International Symposium on Gas Flow and Chemical Lasers, 8th, Madrid, Spain, Sept. 10-14, 1990, Proceedings  

SciTech Connect

Papers are presented on current research developments and applications related to high-powered lasers. Recent advances in excimer laser technology, electron-beam-pumped excimer lasers, discharge technology for excimer lasers, and pulsed XeF lasers are examined. Consideration is given to short-wavelength lasers, chemical oxygen iodine lasers, and vibrational chemical lasers. Papers are presented on CO2, CO, N2O lasers, coupled CO2 lasers, laser induced perturbation in pulsed CO2 lasers, construction of sealed-off CO2 lasers, and computer modeling of discharge-excited CO gas flow. Topics discussed include gas-dynamic lasers, discharge and flow effects, matrix and laser optics and laser beam parameters. Laser-matter interactions, laser-induced surface plasma, plasma motion velocity along laser beams and thermocapillary effects are also discussed. Applications of laser technology are examined and high-speed laser welding, welding results, laser ablation, laser steel processing, and numerical modeling of laser-matter interaction in high-intensity laser applications are considered.

Orza, J.M.; Domingo, C.

1991-01-01

182

Chemically pumped iodine laser  

Microsoft Academic Search

McDermott et al. (1978) have developed a practical O2(1 Delta) generator based on bubbling Cl2 in alkaline H2O2. In the work described in the present paper, it proved possible to convert a transverse-flow mixing chemical laser, originally designed as a CO chemical laser, to a chemical iodine-atom laser by installing a version of the McDermott generator on the laser. The

R. J. Richardson; C. E. Wiswall

1979-01-01

183

Injection seeding of high-energy photolytically pumped I* laser  

Microsoft Academic Search

We report the operation of a short pulse photolytic iodine laser (PIL) using an unstable resonator under long-pulse and injection seeded operation. The laser is designed as a surrogate source to replicate the output from a q-switched chemical oxygen iodine laser (COIL). Under long pulse conditions the single shot laser produces up to 10 Joules in a 3 microsecond(s) pulse.

Andrew J. Brown; Marc Norsen; Charles H. Fisher; Matthias P. Leuchs; Ralph F. Tate; Melvin Harris; Gordon D. Hager

2000-01-01

184

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.

185

Chemically pumped iodine laser  

Microsoft Academic Search

A chemically pumped iodine-atom laser is described based on electronic energy transfer to atomic iodine from chemically generated O2(1?). The total extracted power (10 W) is approximately 3% of the power contained in the O2(1?) flow.

R. J. Richardson; C. E. Wiswall

1979-01-01

186

1150 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 39, NO. 9, SEPTEMBER 2003 Modeling of the ElectriCOIL System  

E-print Network

discharge oxygen-iodine laser (ElectriCOIL) system. Results of those studies along with more recent Terms--Chemical oxygen-iodine laser, chemical oxygen- iodine laser (COIL), discharge oxygen-iodine laser (DOIL) , elec- tric discharge oxygen-iodine laser (ElectriCOIL), radio frequency (RF) excitation

Carroll, David L.

187

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

E-print Network

of a continuous wave laser at 1315 nm on the I(2 P1/2) I(2 P3/2) transition of atomic iodine where the O2(a1 The classic chemical oxygen-iodine laser (COIL) system1 operates on the I(2 P1/2) I(2 P3/2) [hereafter attempts to implement electric discharges to generate O2(a) and transfer to iodine to make a laser

Carroll, David L.

188

Continuous-wave laser oscillation on the 1315 nm transition of atomic iodine pumped by O2,,a1  

E-print Network

Continuous-wave laser oscillation on the 1315 nm transition of atomic iodine pumped by O2,,a1 of atomic iodine in favor of the I 2 P1/2 state. The laser output power was 220 mW in a stable cavity.1063/1.1883317 The classic chemical oxygen-iodine laser COIL system1 operates on the I 2 P1/2 I 2 P3/2 electronic transi

Carroll, David L.

189

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

Microsoft Academic Search

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

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

2002-01-01

190

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

191

High energy chemical laser system  

Microsoft Academic Search

A high energy chemical laser system is described wherein explosive ; gaseous mixtures of a reducing agent providing hydrogen isotopes and interhalogen ; compounds are uniformly ignited by means of an electrical discharge, flash-; photolysis or an electron beam. The resulting chemical explosion pumps a lasing ; chemical species, hydrogen fluoride or deuterium fluoride which is formed in the ;

D. W. Gregg; R. K. Pearson

1975-01-01

192

High-power gas lasers; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990  

SciTech Connect

Various papers on high-power gas lasers are presented. Individual topics addressed include: review of high-power excimer lasers, long-pulse e-beam pumped XeF laser, mode-locking of long-pulse XeF and KrF lasers, development of an injection-controlled high-power XeF (C-A) excimer laser, design studies of a high-pulse excimer Eurolaser, highest-power excimer lasers, chemically produced XeF(B) electronic excited state, intense high repetition rate excimer lasers and applications, average-power scaling of the pulsed barium vapor laser, high-power gold vapor laser, high-power mid-IR gas lasers, irradiation distribution of a high-power laser near focal plane, copper vapor laser with self-filtering unstable resonator, high pressure pulsed chemical singlet oxygen generator, chemically pumped oxygen-iodine laser, 630-W average-power Q-switched chemical oxygen iodine laser, survey of the NF(b-X) visible laser candidate, production of Bi(2D) and BiF(A0+) in a supersonic flow, new fluid dynamical experimental techniques in chemical laser research, directed-energy overview, HF amplifiers.

Avizonis, P.V.; Freed, C.; Kim, J.J.; Tittel, F.K.

1990-01-01

193

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

194

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

E-print Network

molecular iodine in an electric oxygen-iodine laser G. F. Benavides,1 J. W. Zimmerman,2 B. S. Woodard,2 D. L and 38% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine through the addition of a secondary discharge to predissociate the molecular iodine in an electric oxygen-iodine laser

Carroll, David L.

195

Measurements of Improved ElectricOIL Performance, Gain, and Laser Power  

E-print Network

led to continued improvements in the Electric Oxygen-Iodine Laser (ElectricOIL) system demonstration of the electric oxygen-iodine laser (often referred to as ElectricOIL, EOIL, or DOIL) [Carroll1 Measurements of Improved ElectricOIL Performance, Gain, and Laser Power J. W. Zimmerman,1 G. F

Carroll, David L.

196

Continuous-wave laser oscillation in subsonic flow on the 1315 nm atomic iodine transition pumped by electric discharge produced O2,,a 1  

E-print Network

Continuous-wave laser oscillation in subsonic flow on the 1315 nm atomic iodine transition pumped.993% reflective mirrors. © 2006 American Institute of Physics. DOI: 10.1063/1.2346134 Oxygen-iodine laser systems1 into the possibility of a continu- ous flow hybrid electrically powered oxygen-iodine laser ElectricOIL with electric

Carroll, David L.

197

Quantum cascade lasers in chemical physics  

Microsoft Academic Search

In the short space of 15years since their first demonstration, quantum cascade lasers have become the most useful sources of tunable mid-infrared laser radiation. This Letter describes these developments in laser technology and the burgeoning applications of quantum cascade lasers to infrared spectroscopy. We foresee the potential application of quantum cascade lasers in other areas of chemical physics such as

Robert F. Curl; Federico Capasso; Claire Gmachl; Anatoliy A. Kosterev; Barry McManus; Rafal Lewicki; Michael Pusharsky; Gerard Wysocki; Frank K. Tittel

2010-01-01

198

Chemically-Assisted Pulsed Laser-Ramjet  

NASA Astrophysics Data System (ADS)

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

2010-10-01

199

Some laser techniques for chemical detection  

SciTech Connect

Spectroscopy provides a fast sensitive method for chemical analysis. Lasers are high intensity narrow bandwidth, collimated light sources in the infrared, visible, and ultraviolet spectral regions. Wavelength tunable lasers can be used for spectroscopic chemical identification by means of techniques such as opto-acoustic spectroscopy, thermal lensing, and fluorescence excitation. These methods all share the useful characteristic that their detection sensitivity to small quantities of chemicals improves with higher laser intensity. We have developed apparatuses to use these techniques for trace chemical identification and detection. In addition, a useful improvement to thermal lensing, which we designate thermal deflection spectroscopy, has been developed.

Sander, R.K.; Buchwald, M.I.

1980-01-01

200

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

201

Laser Induced Chemical Liquid Phase Deposition (LCLD)  

SciTech Connect

Laser induced chemical deposition (LCLD) of metals onto different substrates attracts growing attention during the last decade. Deposition of metals onto the surface of dielectrics and semiconductors with help of laser beam allows the creation of conducting metal of very complex architecture even in 3D. In the processes examined the deposition occurs from solutions containing metal ions and reducing agents. The deposition happens in the region of surface irradiated by laser beam (micro reactors). Physics -chemical reactions driven by laser beam will be discussed for different metal-substrate systems. The electrical, optical, mechanical properties of created interfaces will be demonstrated also including some practical-industrial applications.

Nanai, Laszlo; Balint, Agneta M. [University of Szeged, JGYPK, Department of General and Environmental Physics H-6725 Szeged, Boldogasszony sgt. 6 (Hungary); West University of Timisoara, Faculty of Physics, Department of Physics, Bulv. V. Parvan 4, Timisoara 300223 (Romania)

2012-08-17

202

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

NASA Astrophysics Data System (ADS)

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 O II-He flows at pressures of up to 120 torr and discharge powers of up to 2.2 kW. The reduced electric field in the DC sustainer discharge ranges from 6 to 12 Td. SDO yield in the discharge is up to 5.0-5.7% at the discharge temperatures of 400-420 K. The results suggest that SDO yield exceeds the gain threshold yield at the M=3 cavity temperature by up to a factor of three, which is confirmed by gain measurements. The highest gain measured in the supersonic cavity is 0.01%/cm.

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

2007-05-01

203

invited Paper CommercialApplications for COIL  

E-print Network

The chemical oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number applications are CO, excimer, HFIDF and the chemical oxygen-iodine laser (COIL) [2,3]. Of these other laser oxygen-iodine laser (COIL), the University of Illinois at Urbana-Champaign (UIUC)/STI Optronics team

Carroll, David L.

204

AIAA-98-2992 American Institute of Aeronautics and Astronautics  

E-print Network

oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number/DF and the chemical oxygen-iodine laser (COIL) [2,3]. Of these other laser technologies, COIL is of particular Transfer (STTR) program to commercialize the chemical oxygen-iodine laser (COIL), the University

Carroll, David L.

205

J. Phys. III Fiance 4 (1994) 2013-2029 OCTOBER 1994, PAGE 2013 Classification  

E-print Network

.55 42.55K 34.50 The subsonic chemical oxygen-iodine laser : comparison of a theoretical model extraction de la puissance laser. Abstract. The performances of a small scale subsonic chemical oxygen-iodine extraction. 1. Introduction. Since the first demonstration of the Chemical Oxygen-Iodine Laser (C.O.I.L.) ii

Paris-Sud XI, Université de

206

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

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. INTRODUCTION The classical chemical oxygen-iodine laser1 (COIL) operates on the electronic transition

Carroll, David L.

207

Production of O2,,1 ... in flowing plasmas using spiker-sustainer excitation  

E-print Network

December 2005; accepted 2 March 2006; published online 9 June 2006 In chemical oxygen iodine lasers COILs of Physics. DOI: 10.1063/1.2199387 I. INTRODUCTION Chemical oxygen iodine lasers are being investigated be, and favorable material interaction properties.1­6 Operation of the chemical oxygen iodine laser COIL is based

Kushner, Mark

208

Laser-initiated chemical chain reactions  

Microsoft Academic Search

A detailed kinetic and experimental analysis is presented for chemical chain reaction processes initiated by well-controlled, low power laser pulses. Realtime evolution of the chain reaction is followed by direct detection of infrared chemiluminescence from vibrationally excited HCl product molecules produced by one of the propagation reactions in the chain. By appropriate choice of conditions, the chain reactions may be

David J. Nesbitt; Stephen R. Leone

1980-01-01

209

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

permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system, possibly in conjunctionCOIL, COIL, chemical oxygen iodine laser, electric discharge modeling 1. INTRODUCTION The classic chemical oxygen-iodine laser (COIL) [McDermott, 1978] operates on the electronic transition of the iodine atom

Carroll, David L.

210

Alpha high-power chemical laser program  

NASA Astrophysics Data System (ADS)

Alpha is a megawatt-class hydrogen fluoride, continuous wave, space based chemical laser brassboard which demonstrates and validates technology for space-based applications. It consists of a cylindrical gain generator that exhausts radially outward through circumferential nozzles forming an annular lasing media and an annular ring resonator, which extracts the laser energy. Technical innovations first demonstrated on Alpha include: (1) use of extruded aluminum components, (2) diamond turned, annular optics made of molybdenum, (3) uncooled silicon mirrors, (4) light weight optical benches, and (5) active alignment. Alpha first lased in 1989, and has repeatably demonstrated megawatt-class power and excellent beam quality. Using Alpha, TRW has demonstrated the use of low weight uncooled mirrors in very high power lasers to reduce system jitter. They have performed flawlessly and beam jitter levels were significantly reduced.

Ackerman, Richard A.; Callahan, David; Cordi, Anthony J.; Lurie, Henry; Thomson, Matthew

1995-03-01

211

Laser Velocimetry of Chemical Vapor Deposition Flows  

NASA Technical Reports Server (NTRS)

Laser velocimetry (LV) is being used to measure the gas flows in chemical vapor deposition (CVD) reactors. These gas flow measurements can be used to improve industrial processes in semiconductor and optical layer deposition and to validate numerical models. Visible in the center of the picture is the graphite susceptor glowing orange-hot at 600 degrees C. It is inductively heated via the copper cool surrounding the glass reactor.

1993-01-01

212

Intense laser beams; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992  

NASA Technical Reports Server (NTRS)

Various papers on intense laser beams are presented. Individual topics addressed include: novel methods of copper vapor laser excitation, UCLA IR FEL, lasing characteristics of a large-bore copper vapor laser (CVL), copper density measurement of a large-bore CVL, high-power XeCl excimer laser, solid state direct-drive circuit for pumping gas lasers, united energy model for FELs, intensity and frequency instabilities in double-mode CO2 lasers, comparison of output power stabilities of CO and CO2 lasers, increasing efficiency of sealed-off CO lasers, thermal effects in singlet delta oxygen generation, optical extraction from the chemical oxygen-iodine laser medium, generation and laser diagnostic analysis of bismuth fluoride. Also discussed are: high-Q resonator design for an HF overtone chemical lasers, improved coatings for HF overtone lasers, scaled atmospheric blooming experiment, simulation on producing conjugate field using deformable mirrors, paraxial theory of amplitude correction, potential capabilities of adaptive optical systems in the atmosphere, power beaming research at NASA, system evaluations of laser power beaming options, performance projections for laser beam power to space, independent assessment of laser power beaming options, removal of atmospheric CFCs by lasers, efficiency of vaporization cutting by CVL.

Wade, Richard C. (editor); Ulrich, Peter B. (editor)

1992-01-01

213

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 discharge-driven oxygen-iodine laser system (called EOIL or DOIL in the literature), there have been

Carroll, David L.

214

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

E-print Network

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). Since this first reporting of a viable electric discharge-driven oxygen-iodine laser system (called EOIL

Carroll, David L.

215

Long pulse chemical laser. Final technical report  

SciTech Connect

This report covers the technical effort through February, 1989. This effort was directed towards the technology associated with the development of a large scale, long pulse DF-CO{sub 2} chemical laser. Optics damage studies performed under Task 1 assessed damage thresholds for diamond-turned salt windows. Task 2 is a multi-faceted task involving the use of PHOCL-50 for laser gain measurements, LTI experiments, and detector testing by LANL personnel. To support these latter tests, PHOCL-50 was upgraded with Boeing funding to incorporate a full aperture outcoupler that increased its energy output by over a factor of 3, to a full kilojoule. The PHOCL-50 carbon block calorimeter was also recalibrated and compared with the LANL Scientech meter. Cloud clearing studies under Task 3 initially concentrated on delivering a Boeing built Cloud Simulation Facility to LANL, and currently involves design of a Cold Cloud Simulation Facility. A Boeing IRAD funded theoretical study on cold cloud clearing revealed that ice clouds may be easier to clear then warm clouds. Task 4 involves the theoretical and experimental study of flow system design as related to laser beam quality. Present efforts on this task are concentrating on temperature gradients induced by the gas filling process. General support for the LPCL field effort is listed under Task 5, with heavy emphasis on assuring reliable operation of the Boeing built Large Slide Valve and other device related tests. The modification of the PHOCL-50 system for testing long pulse DF (4{mu}m only) chemical laser operation is being done under Task 6.

Bardon, R.L.; Breidenthal, R.E.; Buonadonna, V.R. [and others] [Boeing Aerospace Co., Seattle, WA (United States)

1989-02-01

216

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

217

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

218

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

219

Laser induced foaming and chemical modifications of gelatine films  

Microsoft Academic Search

This paper reports on the investigation of the microfoaming and chemical modifications following single-pulse laser irradiation conducted at 248nm (KrF excimer laser, 20ns fwhm) and at 266 and 355nm (Nd:YAG laser 4th and 3rd harmonic, 6ns fwhm) of gelatine films. Fluorescence emissions of the films were studied by laser induced fluorescence and spectrofluorimetry and the emission lifetimes were measured by

S. Gaspard; M. Oujja; C. Abrusci; F. Catalina; S. Lazare; J. P. Desvergne; M. Castillejo

2008-01-01

220

Chemical imaging sensor and laser beacon  

NASA Astrophysics Data System (ADS)

Design and functional aspects of PANSPEC, a panoramic-imaging chemical vapor sensor (PANSPEC is an abbreviation for infrared panoramic-viewing spectroradiometer), were advanced and its optical system reoptimized accordingly. The PANSPEC model unites camera and fused solid-state interferometer and photopolarimeter subsystems. The camera is an eye of the open atmosphere that collects, collimates, and images ambient infrared radiance from a panoramic field of view (FOV). The passive interferometer rapidly measures an infrared-absorbing (or infrared-emitting) chemical cloud traversing the FOV by means of molecular vibrational spectroscopy. The active photopolarimeter system provides a laser beam beacon. This beam carries identification (feature spectra measured by the interferometer) and heading (detector pixels disclosing these feature spectra) information on the hazardous cloud through a binary encryption of Mueller matrix elements. Interferometer and photopolarimeter share a common configuration of photoelastic modulation optics. PANSPEC was optimized for minimum aberrations and maximum resolution of image. The optimized design was evaluated for tolerances in the shaping and mounting of the optical system, stray light, and ghost images at the focal plane given a modulation transfer function metric.

Carrieri, Arthur H.

2003-05-01

221

Measurements of spectrum on HF chemical lasers with MOPA configuration  

NASA Astrophysics Data System (ADS)

HF chemical laser with master oscillator power amplifier (MOPA) configuration is a good solution to achieve high output power with high reliability and good beam quality. Researches of spectrum on HF chemical lasers with MOPA configuration are important for both enhancing atmospheric transmission and ensuring high power extraction efficiency on multiple vibrational transitions. A HF chemical laser operated in the line-selected mode which makes the output frequencies located in the atmospheric transparency windows will allow low atmospheric absorption, which will reduce thermal blooming effects and increase the intensity on the target. This will make the CW HF chemical lasers a possible development for long-distance transmission within the atmosphere. In this paper, a HF chemical laser with MOPA configuration using two identical discharge-driven CW HF laser modules as the laser oscillator and amplifier is presented. A multiple-selected-line, confocal, unstable resonator is also introduced. Measurements of spectrum on the laser have been taken by varying the flow parameters of the discharge-driven HF laser. It is concluded from our experiments that, the spectrum keeps stable with fixed flow parameters, even though the relative power of different lines varies slightly, and the maximum power is on the direct cascade of P2(7) and P1(8) lines. It is also believed that control of the flow parameters may allow high J direct cascade levels transitions, which may ensure high power extraction efficiency from multiple vibrational transitions.

Chen, Yu-bin; Chen, Xing; Liu, Wenguang

2012-10-01

222

Laser-based instrumentation for the detection of chemical agents  

SciTech Connect

Several laser-based techniques are being evaluated for the remote, point, and surface detection of chemical agents. Among the methods under investigation are optoacoustic spectroscopy, laser-induced breakdown spectroscopy (LIBS), and synchronous detection of laser-induced fluorescence (SDLIF). Optoacoustic detection has already been shown to be capable of extremely sensitive point detection. Its application to remote sensing of chemical agents is currently being evaluated. Atomic emission from the region of a laser-generated plasma has been used to identify the characteristic elements contained in nerve (P and F) and blister (S and Cl) agents. Employing this LIBS approach, detection of chemical agent simulants dispersed in air and adsorbed on a variety of surfaces has been achieved. Synchronous detection of laser-induced fluorescence provides an attractive alternative to conventional LIF, in that an artificial narrowing of the fluorescence emission is obtained. The application of this technique to chemical agent simulants has been successfully demonstrated. 19 figures.

Hartford, A. Jr.; Sander, R.K.; Quigley, G.P.; Radziemski, L.J.; Cremers, D.A.

1982-01-01

223

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

224

The fullerene-oxygen-iodine laser: problem of scaling of the singlet oxygen generator with optically pumped fullerene  

NASA Astrophysics Data System (ADS)

The paper presents the results of experimental study of the singlet oxygen (1?O II) lifetime in the solution, saturated by fullerene and oxygen in CCl 4 and irradiated by optical pump with various level of power and with various spectral content. It was shown that in the case of absence of the UV component in this optical pump, i.e. in the case using of only visible spectral range, the lifetime of 1?O II reaches ~ 50 ms for optical pump energy density of ~ 0/5 J/cm2. Pulse duration was ~ 0.5-1 ms. Such criterion makes it possible to develop the outlook of the realistic singlet oxygen generator with optical pumping of fullerenes for pulse-repetitive and CW regimes of FOIL operation.

Danilov, O. B.; Bagrov, I. V.; Belousova, I. M.; Grenishin, A. S.; Kiselev, V. M.; Murav'eva, T. D.; Sosnov, E. N.

2007-05-01

225

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

226

Demonstration of an iodine laser pumped by an air-helium electric discharge  

E-print Network

Demonstration of an iodine laser pumped by an air-helium electric discharge B. S. Woodard, J. W and a continuous-wave laser on the 1315 nm transition of atomic iodine using the energy transferred to I(2 P1W in a supersonic flow cavity. Keywords: electric oxygen iodine laser, electric discharge, singlet oxygen, active

Carroll, David L.

227

Measurements of Improved Hybrid ElectricOIL Discharge Performance, Gain, and Laser Power  

E-print Network

- Iodine Laser (ElectricOIL) system that significantly increased the discharge performance, supersonic. Introduction The first demonstration of the electric oxygen-iodine laser (often referred to as Electric1 Measurements of Improved Hybrid ElectricOIL Discharge Performance, Gain, and Laser Power D. L

Carroll, David L.

228

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

229

Chemical-free cleaning using excimer lasers  

NASA Astrophysics Data System (ADS)

A critical requirement in many industrial processes is the cleaning of oils and grease, oxides, solvent residues, particles, thin films and other contaminants from surfaces. There is a particularly acute need in the electronics industry for cleaning semiconductor wafers and computer chips and in the metals industry for removing oxides and other contaminants. Cleaning traditionally is done by various wet chemical processes, almost all consuming large amounts of water and producing large amounts of hazardous wastes. To further complicate this, some of these cleaning agents and vast water consumption are undergoing stringent restrictions. The Radiance ProcessSM is a novel, patented Excimer Laser approach to dry surface cleaning. The process has removed particles from 80 microns to submicron sizes, paints, inks, oxides, fingerprints, hazes, parts of molecules and metallic ions in fingerprints. The process does not ablate, melt or damage the underlying surface. Micro-roughening on some Silicon and Gallium Arsenide is on the order of 1A or less. This paper will discuss the various applications with this process and the latest results from a beta wafer cleaning prototype test bed system that is being built under an EPA grant and joint partnership between Radiance Services Company, Neuman Micro Technologies, Inc. and the Microelectronics Research Laboratory.

Lizotte, Todd E.; O'Keeffe, Terence R.

1996-04-01

230

Laser cutting with chemical reaction assist  

DOEpatents

A method 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.

Gettemy, Donald J. (Los Alamos, NM)

1992-01-01

231

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

232

Laser cutting with chemical reaction assist  

SciTech Connect

This invention is comprised of a method 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.

Gettemy, D.J.

1991-04-08

233

Chemically pumped iodine laser as a fusion driver  

SciTech Connect

The recently demonstrated chemically pumped iodine laser is evaluated for fusion requirements. Efficiencies greater than 8% and long energy storage times are predicted, with high repetition rates and elimination of pulsed power supplies.

Busch, G.E.

1980-01-01

234

Chemical and Laser Sciences Division annual report 1989  

SciTech Connect

The Chemical and Laser Sciences Division Annual Report includes articles describing representative research and development activities within the Division, as well as major programs to which the Division makes significant contributions.

Haines, N. (ed.)

1990-06-01

235

Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser  

SciTech Connect

The problems involved in designing autonomous mobile laser systems based on high-power cw chemical DF lasers, whose mass and size parameters would make it possible to install them on various vehicles, are discussed. The need for mobility of such lasers necessitates special attention to be paid to the quest for ways and means of reducing the mass and size of the main laser systems. The optimisation of the parameters of such lasers is studied for various methods of scaling their systems. A complex approach to analysis of the optical scheme of the laser system is developed. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Aleksandrov, B P; Bashkin, A S; Beznozdrev, V N; Parfen'ev, M V; Pirogov, N A; Semenov, S N [Open Joint-Stock Company, V.P. Glushko Energomash Research and Production Assocation, Khimki-1, Moscow region (Russian Federation)

2003-01-31

236

JOURNAL DE PHYSIQUEIV Colloque C4, suppltment au Journal de Physique 111, Volume 4, avril1994  

E-print Network

Chemical oxygen iodine laser: technical overview and future potential W.L.BOHN DLR Institutefor TechnicalPhysics, Stuttgart, Germany As the only true electronic transition chemical laser the Oxygen Iodine Chemical Laser processes that characterize the physico-chemical properties of the laser. In particular, the crucial

Paris-Sud XI, Université de

237

Application of laser Doppler velocimeter to chemical vapor laser system  

NASA Technical Reports Server (NTRS)

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

238

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

239

Continuous wave chemically pumped atomic iodine laser  

SciTech Connect

Cw laser action achieved on the 2p178-2p3/2 transition of the iodine atom by energy transfer from the 1 delta metastable state of O2 is discussed. The effluent from a conventional oxygen generator was mixed with molecular iodine at the entrance of a longitudinal flow laser cavity where the I2 was dissociated by a small amount of O2 (1 sigma ) that was present in the flow due to energy pooling processes. The measured output power was greater than 4MW

Benard, D.J.; Bousek, R.R.; Mcdermott, W.E.; Pchelkin, N.R.

1981-05-12

240

Calcium fluoride windows for high-energy chemical lasers  

Microsoft Academic Search

The development of high-energy lasers requires optical windows capable of handling megajoule beam energies without compromising the system’s performance. Calcium fluoride (CaF2) has been identified as a prime candidate for windows operating at chemical laser wavelengths due to very low bulk absorption and exceptionally small thermal lensing coefficients; it is, however, vulnerable to structural failure owing to poor mechanical strength

Claude A. Klein

2006-01-01

241

Calcium fluoride windows for high-energy chemical lasers  

Microsoft Academic Search

The development of high-energy lasers requires optical windows capable of handling megajoule beam energies without compromising the system's performance. Calcium fluoride (CaF2) has been identified as a prime candidate for windows operating at chemical laser wavelengths due to very low bulk absorption and exceptionally small thermal lensing coefficients; it is, however, vulnerable to structural failure owing to poor mechanical strength

Claude A. Klein

2006-01-01

242

Laser-based sensors for chemical detection  

Microsoft Academic Search

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),

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

2010-01-01

243

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

244

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

245

Investigation of performance and mechanism for chemical laser propulsion  

NASA Astrophysics Data System (ADS)

Chemical laser propulsion (CLP) is accompanied by the release of chemical energy in the process of laser propulsion, which can improve laser propulsion performance. In this article the propulsion performance of POM propellant under the constraint of a cylindrical tube-type thruster in atmospheric and nitrogen environments, respectively, has been conducted experimentally. The results indicate that the ablation masses of a single pulse under two gas environments are close, but the momentum coupling coefficient Cm and specific impulse Isp in atmospheric environment are higher than that in nitrogen environment, which demonstrates an exothermic reaction occurred between the ablation product and the environment oxygen. To learn the mechanism of CLP the molecular spectra for ablation products of POM propellant in atmospheric and vacuum environments are measured and analyzed, respectively, and it reveals that the final product in a vacuum is CH2O, while the final products are CO2 and H2O in the atmosphere. Then the chemical reaction, composition and chemical energy release have been confirmed in the atmospheric environment. By using Arrhenius finite rate chemical reaction model with the code Fluent the flow field evolution of ablation product was simulated numerically. The results show the intensity of chemical energy release is related to the contact and mixing degree of the ablation product and the oxygen in the atmosphere, mixing more fully, the chemical energy released more intensively.

Tang, Zhiping; Li, Long

2013-05-01

246

RESEARCH ARTICLE Mixing enhancement in a multi-stream injection nozzle  

E-print Network

in a chemical oxygen-iodine laser. To visualize mixing, image sequences were acquired with planar laser by stretching the mixing interface. 1 Introduction The chemical oxygen iodine laser (COIL) was originally efficient COIL lasers with supersonic mixing of iodine and oxygen have

Carroll, David L.

247

ElectriCOIL: An Advanced Chemical Iodine Laser Concept  

Microsoft Academic Search

Advanced chemical iodine laser technology will logically include novel all gas phase generation techniques for an iodine energy donor and the injection of atomic rather than molecular iodine. Candidate methods are discussed for the creation of an all gas phase energy donor as well as for injecting atomic iodine. This research will lead directly to designs that will be fabricated

David L. Carroll; Wayne C. Solomon

2000-01-01

248

The chemically pumped iodine laser as a fusion driver  

Microsoft Academic Search

A chemically pumped iodine laser is evaluated for fusion requirements. Efficiencies greater than 8 percent and long energy storage times are predicted, with high repetition rates and elimination of pulsed power supplies. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in text query field) Abstract Text Return: Query Results

G. E. Busch

1980-01-01

249

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

250

American Institute of Aeronautics and Astronautics Low Pressure Schlieren Imaging of a Multi-Stream Injection  

E-print Network

pressures between 6.6 and 17.5 torr. Nomenclature COIL = chemical oxygen iodine laser mmol/s = millimoles on well-mixed flows. Two of these areas are combustion, and chemical oxygen-iodine lasers (COILs flows. From previous planar laser induced fluorescence images it was concluded that small starletted

Carroll, David L.

251

JOURNALDE PHYSIQUEIV ColloqueC7, suppl6ment au Journal de Physique 111,Vol. 1, dhmbre 1991  

E-print Network

are being conducted on a high power chemical oxygen iodine laser. Optical diagnostics were developed t o power o f at least one kilowatt i s expected. 1 - Introduction The chemical oxygen iodine laser (COIL, 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

252

Superpowerful lasers on chain chemical reactions for studying dense relativistic plasma and laser fusion  

NASA Astrophysics Data System (ADS)

The expected energetic performances are presented for amplification of short pulses (approximately 10-12 s) either directly in chain pulsed chemical laser (PCL) active medium, or in active media created by optical pumping of resonantly absorbing molecules by radiation of PCL. The calculations were based on the data for PCL energetic and amplifying performances and also on the data for pumping of N2O molecules by HF laser radiation, both being obtained by us earlier. For amplifying a short pulse in DF-CO2 PCL active medium, the energy output of 6J/l is achievable, while 8 - 10 J/l is attainable for regenerative amplification in HF(DF) laser (50 J/l(DOT)atm - under free oscillation conditions for both). For regime of optical pumping, the energy of N2O short-pulse radiation can make 10% of pump (PCL output) energy. A series of other promising three- and four-atomic molecules is considered. The comparison of various variants of embodying of superpowerful laser systems based of chain chemical lasers is carried out. The conception of construction of short- pulsed laser systems with radiation energy of up to 104 J is submitted with the expectation of their using for creation of dense relativistic plasma, as new perspective object of researches, and for realization of laser fusion.

Bravy, Boris G.; Vasiliev, German K.; Makarov, E. F.; Chernyshev, Yu. A.

2002-03-01

253

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

254

Important kinetic effects in the hybrid ElectricOIL system Joseph W. Zimmermana,b  

E-print Network

into the system to benefit O2(a1 ) production is investigated. Keywords: oxygen-iodine laser, ElectricOIL, DOIL The classical chemical oxygen-iodine laser first reported by McDermott1 operates on the electronic transition Sciences Inc., Andover, MA 01810 d Emory University, Atlanta, GA 30322 ABSTRACT Laser action at 1315 nm

Carroll, David L.

255

Physical and Chemical Changes of Polystyrene Nanospheres Irradiated with Laser  

SciTech Connect

It has been reported that polymer resist such as PMMA (Poly(methyl methacrylate) which is a well known and commonly used polymer resist for fabrication of electronic devices can show zwitter characteristic due to over exposure to electron beam radiation. Overexposed PMMA tend to changes their molecular structure to either become negative or positive resist corresponded to electron beam irradiation doses. These characteristic was due to crosslinking and scissors of the PMMA molecular structures, but till now the understanding of crosslinking and scissors of the polymer resist molecular structure due to electron beam exposure were still unknown to researchers. Previously we have over exposed polystyrene nanospheres to various radiation sources, such as electron beam, solar radiation and laser, which is another compound that can act as polymer resist. We investigated the physical and chemical structures of the irradiated polystyrene nanospheres with FTIR analysis. It is found that the physical and chemical changes of the irradiated polystyrene were found to be corresponded with the radiation dosages. Later, combining Laser irradiation and Reactive Ion Etching manipulation, created a facile technique that we called as LARIEA NSL (Laser and Reactive Ion Etching Assisted Nanosphere Lithography) which can be a facile technique to fabricate controllable carbonaceous nanoparticles for applications such as lithographic mask, catalysts and heavy metal absorbers.

Mustafa, Mohd Ubaidillah; Juremi, Nor Rashidah Md.; Mohamad, Farizan; Wibawa, Pratama Jujur [Microelectronic and Nanotechnology-Shamsudin Research Centre, Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia (Malaysia); Agam, Mohd Arif; Ali, Ahmad Hadi [Faculty of Science, Art and Heritage, University Tun Hussein Onn Malaysia (Malaysia)

2011-05-25

256

Nuclear pumped laser for next step ICF driver  

SciTech Connect

A conceptual design for an alternative laser driver for the Laboratory Microfusion Facility (LMF) is presented. A pulsed fission reactor is used to excite an oxygen-iodine laser in this study based on preliminary data on nuclear pumping of O/sub 2/(/sup 1/..delta..). Although a working NPL of this specific type has not yet been assembled, the authors believe this concept holds great potential both as a test facility driver and as a future power reactor.

Balog, S.; Chung, H.; Doczy, M.; Duraski, R.; Hutcheson, M.; Eglezopoulos, L.R.; Russ, D.

1989-03-01

257

JOURNAL DE PHYSIQUE IV Colloque C7,slipplBmentau Journal de Physique111,Vol. 1,dbembre 1991  

E-print Network

. Introduction A Chemical Oxygen-Iodine Laser (COIL) can generate kilowatt output powers in the CW regime of a COIL utilizing the Zeeman effect on the laser transition P~/~-*P,, of iodine atoms. An increase, Czechoslovakia Abstract - A periodically-pulsed regime of generation in an originally CW chemical oxygen-iodine

Paris-Sud XI, Université de

258

Modeling of a Multi-Stream Injection COIL with Enhanced Mixing Ejectors  

E-print Network

-pressure chemical oxygen- iodine laser (COIL) have been experimentally tested. To obtain a better understanding The chemical oxygen-iodine laser (COIL) was first demonstrated in 1978 [McDermott, 1978]. Since that initial good iodine mixing, cavity kinetics, and generator pressure can have a dramatic impact on the overall

Carroll, David L.

259

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 measurements of gain/absorption using the PSI Iodine Scan diagnostic coupled with a data reduction technique

Carroll, David L.

260

JOURNAL DE PHYSIQUE Colloque C7, supplhment au n012, Tome 48, dhcembre 1987  

E-print Network

. It is of fundamental importance for the comprehensioi of the mechanism of the chemical oxygen-Iodine laser (R. Bacis OXYGEN-IODINE REACTION : POPULATION OF ROVIBRATIONAL LEVELS OF THE IODINE GROUND STATE THROUGH INVERSION OF LASER EXCITED SPECTRA P. CROZET, R. BACIS, A. BOUVIER, A.J. BOUVIER, S. CHURASSY and J.P. PIQUE

Paris-Sud XI, Université de

261

Achievement of 30% conversion from O2 to O2(a1Delta) at 50 torr using an integrally cooled, controlled avalanche ionized electric O2(a1Delta) generator  

Microsoft Academic Search

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

Alan E. Hill

2007-01-01

262

Gain generator optimization for hydrogen fluoride overtone and fundamental chemical lasers  

Microsoft Academic Search

The hydrogen fluoride (HF) chemical laser is the baseline concept for SDIO space based laser (SBL) weapons systems. Ground based tests at power levels appropriate for this application have been demonstrated. Because the brightness of a laser beam projected to the far field is inversely proportional to the square of the wavelength, shorter wavelengths are desirable to enhance brightness on

William A. Duncan; Stanley P. Patterson; Bruce R. Graves; Jeffrey L. Sollee; Gordon N. Yonehara; John P. Dering

1993-01-01

263

Laser-based instrumentation for detection of chemical-warfare agents  

SciTech Connect

Several laser-based techniques are being developed for remote, point, and surface contamination detection of chemical warfare agents. These techniques include optoacoustic spectroscopy, laser-induced breakdown spectroscopy, and synchronous detection of laser-induced fluorescence. Detection limits in the part-per-million to part-per-billion regime have been demonstrated.

Quigley, G.P.; Radziemski, L.J.; Sander, R.K.; Hartford, A. Jr.

1981-01-01

264

Thermal effect of chemical reactions in interactions of laser pulse with solids  

Microsoft Academic Search

The heat energy released by chemical reactions was measured in the interaction of 50-ns Nd- laser pulse with titanium, germanium, coke, and sulphur samples placed in different gas media. The samples were exposed to focused laser radiation in the intensity range of 1 - 800 MW\\/cm2. It was found that the maximum value of the ratio of released chemical energy

Anatoly Y. Vorobyov

1994-01-01

265

... production in flowing He/O2 plasmas. I. Axial transport and pulsed power formats  

E-print Network

to multikilowatt powers. Recent research has focused on pumping the iodine with O2 1 produced by electric infrared light available from chemical oxygen-iodine lasers COILs couples efficiently with most metals 50011 Received 18 May 2005; accepted 23 August 2005; published online 12 October 2005 Chemical oxygen-iodine

Kushner, Mark

266

Numerical analysis of the lasing regimes of the DF-CO2 chemical laser  

Microsoft Academic Search

The energy characteristics of a pulsed DF-CO2 chemical laser were calculated for laser mixtures with a large margin of chemical energy (2 kJ\\/liter atm). The effects of the following parameters on laser characteristics were studied: intensity and duration of initiation, the initial temperature of the medium, the relative content of CO2 and He, the degree of mixture dilution by the

V. I. Igoshin; V. Iu. Nikitin; A. N. Oraevskii

1980-01-01

267

Laser enhanced chemical reaction studies. Technical progress report  

SciTech Connect

A powerful infrared diode laser probe was used to determine final states of small (2-5 atom) molecules produced by collisions, photofragmentation, or chemical reactions with spectral resolution 0.0003 cm{sup {minus}1} and time resolution 10{sup {minus}7}s. Besides picturing the vibrational rotational quantum states of product molecules, this also provides a picture of the translational motion of recoiling fragments through the infrared Doppler line width profile. This method was used to probe collisions between cool bath molecules and vibrationally hot molecules, in order to understand the quenching mechanism for unimolecular chemical reactions. Long-range collisions appear to dominate production of bath molecules which become vibrationally excited during this quenching process. Glimpses are being provided of the separate behavior of translational and rotational degrees of freedom of recoiling bath molecules during relaxation of highly vibrationally excited donors. A study was completed of collisions between hot H atoms and CO{sub 2}, by measuring probability for excitation of the antisymmetric vibrational overtone level CO{sub 2}(00{sup 0}2). Comparison with a 00{sup 0}1 fundamental level study suggests that translational and rotational energy distributions in this collision can be described by classical mechanics, but that vibrational excitation probabilities require full quantum treatment. Relaxation of hot pyrazine by CO{sub 2} was studied. Multiphoton ionization studies have been begun.

Flynn, G.

1993-12-31

268

Discharge singlet oxygen generator for oxygen iodine laser: II. Two-dimensional modelling of flow oxygen rf plasma at 13.56 and 81 MHz power frequency  

Microsoft Academic Search

A 2D self-consistent simulation of an rf discharge in a gas flow in pure oxygen over a wide range of discharge parameters was carried out. The simulation was made at the experimental conditions of Part I of this paper for the discharge tube with an HgO coating where the most effective production of O2(a 1Deltag) was experimentally observed. The simulation

O. V. Proshina; T. V. Rakhimova; O. V. Braginsky; A. S. Kovalev; D. V. Lopaev; Yu A. Mankelevich; A. T. Rakhimov; A. N. Vasilieva

2006-01-01

269

On the possibility of O2(a 1Dgrg) production by a non-self-sustained discharge for oxygen iodine laser pumping  

Microsoft Academic Search

O2(a 1Dgrg) production in a non-self-sustained discharge (ND) in pure oxygen and oxygen mixtures with inert gases (Ar and He) has been studied. A self-consistent model of ND in pure oxygen is developed, allowing us to simulate all the obtained experimental data. Agreement between the experimental and simulated results for pure oxygen over a wide range of reduced electric fields

A. N. Vasiljeva; K. S. Klopovskiy; A. S. Kovalev; D. V. Lopaev; Y. A. Mankelevich; N. A. Popov; A. T. Rakhimov; T. V. Rakhimova

2004-01-01

270

Chemical hydrogen fluoride lasers - The extent to which we understand their possibilities  

NASA Astrophysics Data System (ADS)

A review of experimental data is used to assess the possibilities of chemical hydrogen fluoride lasers. It is shown that the possibilities of such lasers are well understood when the direct chain is used for the pumping (i.e., when there is complete suppression of the branching mechanism). Theory agrees well with experimental results for the D2-F2-CO2-laser, but good agreement for the H2-F2 laser is lacking. The use of hydrogen fluoride lasers in laser fusion due to their high efficiency remains an interesting possibility. Finally, attention is given to the search for effective mechanisms of active-center multiplication in such lasers without the use of external initiation sources; the excitation of a hydrogen fluoride laser by radiation from another hydrogen fluoride laser is discussed.

Bashkin, A. S.; Nikitin, V. Iu.; Oraevskii, A. N.; Porodinkov, O. E.; Tomashov, V. N.; Frolov, M. P.; Iuryshev, N. N.

1982-08-01

271

Comparison of tin oxide chemical sensors prepared by PLD and laser-assisted CVD methods  

NASA Astrophysics Data System (ADS)

Tin oxide active layers were deposited by Pulsed Laser Deposition (PLD) and Laser assisted Chemical Vapor Deposition (LCVD) methods. The films were grown on the same substrate chips for the thin layer conductive sensor. Their chemical and morphological properties were studied in connection with gas sensor applications. The influence of the Pd catalyst was tested. The chemical composition was investigated by XPS analysis. A sensitivity to 1000 ppm of hydrogen of about 1090 for PLD and 5 for LCVD was achieved.

Lancok, Jan; Jelinek, Miroslav; Vyslouzil, Filip; Vrnata, Martin; Myslik, Vladimir; Santoni, Antonino; Menucucci, Ivano

2001-06-01

272

Metal film deposition by laser breakdown chemical vapor deposition  

NASA Astrophysics Data System (ADS)

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 CO2 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

273

Laser ablation of maskant used in chemical milling process for aerospace applications  

NASA Astrophysics Data System (ADS)

Chemical etching is a non-traditional machining process where a chemical solution is used to remove unwanted material by dissolution. To shape the etched area, before the process, a chemical inert paint (maskant) is applied on the surface. Then the maskant is trimmed away and the uncovered area is subject to the etching. The maskant cut could be obtained mechanically or by laser ablation. In this work, the effect of process parameters, cutting speed and beam power, on interaction phenomena and defect formation in laser cutting of polymeric maskant is studied, using a 30W CO2 laser source.

Leone, C.; Lopresto, V.; Memola Capece Minutolo, F.; de Iorio, I.; Rinaldi, N.

2010-09-01

274

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

275

Calcium fluoride windows for high-energy chemical lasers  

NASA Astrophysics Data System (ADS)

The development of high-energy lasers requires optical windows capable of handling megajoule beam energies without compromising the system's performance. Calcium fluoride (CaF2) has been identified as a prime candidate for windows operating at chemical laser wavelengths due to very low bulk absorption and exceptionally small thermal lensing coefficients; it is, however, vulnerable to structural failure owing to poor mechanical strength characteristics and a large thermal stress factor. It is, therefore, essential to properly assess the ultimate potential of this material, which we attempt to do here in the following manner: (a) We assemble reliable numbers for all pertinent properties of (111)-oriented CaF2 single crystals and polycrystalline isotropic aggregates (PIAs), such as fusion-cast CaF2, which requires addressing issues relating to the elastic properties, the stress-optic coefficients, and the flexural strength. (b) We provide correct analytical expressions for evaluating the impact of pressure- and beam-induced effects on wave-front phase distortions and mechanical failure modes, taking advantage of a previous investigation [J. Appl. Phys. 98, 043103 (2005)]. (c) We perform detailed calculations on "model" windows made of either (111)CaF2 or (PIA )CaF2 that transmit optimally truncated Gaussian beams at wavelengths of 1.15 and 3.39?m, for run times such that lateral heat conduction and surface cooling can be ignored. Our main conlusions are as follows: (a) With CaF2 windows thermal lensing, as measured in terms of the Strehl ratio and on assuming coating absorptances of no more than 3×10-5, is of no consequence in the sense that catastrophic failure may occur at fluence levels way below the threshold for optical distortion. (b) Evidence of a poor Weibull shape factor (m ?3.5) degrades the design safety margins, which requires operating at peak intensities of no more than 100kW/cm2 to achieve optimum on-target fluences. (c) Regarding the issue of (111)CaF2 vs (PIA)CaF2, we note that fusion-cast material outperforms single crystals based on the figure of merit for distortion, as well as fracture and yield strengths, but contrary to (111)-oriented material, it exhibits birefringence that may rule out its use if depolarization is of concern.

Klein, Claude A.

2006-10-01

276

Electrically initiated pulsed chemical DF-CO2 and DF lasers  

Microsoft Academic Search

The time-resolved spectral output of pulsed DF and DF-CO2 chemical lasers initiated by fast electrical pulses has been investigated. Short-pulse electrical initiation of the D2+F2 mixture in the high-pressure DF-CO2 laser results in prompt laser emission from both DF and CO2 molecules in addition to the usual more energetic, but delayed, CO2 emission. Studies of the time correlation of the

R. Turner; T. O. Poehler

1976-01-01

277

Kinetic analyses of energy storage in a chemically pumped iodine laser  

Microsoft Academic Search

A set of 16 kinetic rate equations is numerically integrated to yield energy storage lifetimes in a chemically pumped iodine laser (CPIL) for various experimental parameters. Storage times greater than 3 ms are possible at room temperature, making the CPIL an interesting candidate for a high efficiency pulsed fusion laser. At low temperatures, storage times may even exceed 1 s.

G. E. Busch

1981-01-01

278

Theoretical study of a large-scale chemically pumped pulsed iodine laser amplifier  

Microsoft Academic Search

The feasibility of a 100 kJ class chemically pumped iodine laser amplifier is studied by numerical calculations of the Maxwell-Bloch equations. The idea is based on a chemical iodine pulse laser utilizing a porous-pipe, high-pressure singlet oxygen generator. It is shown that at the high singlet oxygen pressure conditions, the energy transfer reaction from singlet oxygen to ground state iodine

Masamori Endo; K. Kodama; Y. Handa; Taro Uchiyama

1993-01-01

279

Ultrafast laser induced breakdown spectroscopy for high spatial resolution chemical analysis  

NASA Astrophysics Data System (ADS)

Femtosecond laser induced breakdown spectroscopy (LIBS) was used to identify the spatial resolution limitations and assess the minimal detectable mass restrictions in laser-ablation based chemical analysis. The atomic emission of sodium (Na) and potassium (K) dopants in transparent dielectric Mica matrices was studied, to find that both these elements could be detected from 450 nm diameter ablation craters, full-width-at-half-maximum (FWHM). Under optimal conditions, mass as low as 220 ag was measured, demonstrating the feasibility of using laser-ablation based chemical analysis to achieve high spatial resolution elemental analysis in real-time and at atmospheric pressure conditions.

Zorba, Vassilia; Mao, Xianglei; Russo, Richard E.

2011-02-01

280

... 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 Chemical laser operation on the 2 P1/22 P3/2 transition in atomic iodine has been investigated due to its high effi- ciency and potential for multikilowatt cw power.1­6 The chemical oxygen-iodine laser COIL

Kushner, Mark

281

Studies of visible chemical lasers---II. Modeling of an IF chemical laser within the F--NH sub 3 --IF system  

SciTech Connect

The laser emission mechanism of an IF chemical laser pumped by chemical reactions within the F--NH{sub 3}--IF system is described by 14 kinetic processes. The population densities of IF ({ital B}) and the other excited states, the gain coefficient of the transition IF ({ital B}, {nu}{prime}=0, {ital J}{prime}=21){r arrow}IF({ital X}, {nu}{double prime}=5, {ital J}{double prime}=20), and their dependences on the cavity characteristics, are computed using Gear's automatic integration method. The results show that when the pressure in the cavity is higher than 6 Torr, the gain coefficient becomes positive, and laser action begins when the pressure is above 10 Torr. The energy transfer channels generating IF({ital B}) molecules are also discussed.

Zhuang Qi; Wang Chengdong; Feng Hao; Zhang Cunhao (Dalian Institute of Chemical Physics, Academia Sinica, Dalian (CN))

1989-10-01

282

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

283

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

284

N2O pure chemical cw flame laser  

Microsoft Academic Search

We report the first observation of laser amplification and oscillation in a continuously operating flame with N2O as the optically active species. Outputs have been observed at five wavelengths in the 001–100 vibrational-rotational band of N2O when excited by the Na-catalyzed combustion of N2O with CO in a coaxial flow laser cavity. At the equivalent wavelengths in CO2 neither significant

D. J. Benard; R. C. Benson; R. E. Walker

1973-01-01

285

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

286

Advanced nozzle characterization for hydrogen fluoride overtone chemical lasers  

Microsoft Academic Search

The parametric characterization and optimization of the hypersonic, low-temperature (HYLTE) nozzle concept for the hydrogen fluoride (HF) overtone and HF fundamental performance are reviewed. The HF fundamental space-based laser for weapons systems is considered to be more mature, nearer term potential application than the overtone. Emphasis is placed on the Task 3 advanced gain generator technology configurations (AGGTC) aimed at

William A. Duncan; Stanley P. Patterson; Bruce R. Graves; Jeffrey L. Sollee; Gordon N. Yonehara; John P. Dering

1992-01-01

287

About possibilities of clearing near-Earth space from dangerous debris by a spaceborne laser system with an autonomous cw chemical HF laser  

SciTech Connect

The possibility of clearing hazardous near-Earth space debris using a spaceborne laser station with a large autonomous cw chemical HF laser is substantiated and the requirements to its characteristics (i.e., power and divergence of laser radiation, pulse duration in the repetitively pulsed regime, repetition rate and total time of laser action on space debris, necessary to remove them from the orbits of the protected spacecrafts) are determined. The possibility of launching the proposed spaceborne laser station to the orbit with the help of a 'Proton-M' carrier rocket is considered. (laser applications)

Avdeev, A V; Bashkin, A S; Katorgin, Boris I; Parfen'ev, M V

2011-07-31

288

Improvements on the electrical resistivity of chemical bath deposited CdS films by laser annealing  

NASA Astrophysics Data System (ADS)

The dark resistivity of cw Ar+ ion laser annealed chemical bath deposited CdS films has been measured. A two-decade decrement of the electrical resistivity, as compared to the unannealed samples, is reported. A threshold laser power density for reproducible annealing has been found to be ?50 W/cm2. Log ? vs 1/T plots were used to calculate the mobility ratio b = ?n/?p. This ratio shows a slight increment on laser annealed but it is not sufficient to explain the resistivity changes.

Martínez, G.; Martínez, J. L.; Zehe, A.

1982-06-01

289

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

290

Synchronization: from pendulum clocks to chaotic lasers and chemical oscillators  

Microsoft Academic Search

Many natural and human-made nonlinear oscillators exhibit the ability to adjust their rhythms due to weak interaction: two lasers, being coupled, start to generate with a common frequency; cardiac pacemaker cells fire simultaneously; violinists in an orchestra play in unison. Such coordination of rhythms is a manifestation of a fundamental nonlinear phenomenon--synchronization. Discovered in the 17th century by Christiaan Huygens,

Michael Rosenblum; Arkady Pikovsky

2003-01-01

291

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.

292

Volume 197, number 4,5 CHEMICAL PHYSICS LETTERS 18 September 1992 Laser-induced molecular stabilization and trapping  

E-print Network

Volume 197, number 4,5 CHEMICAL PHYSICS LETTERS 18 September 1992 Laser-induced molecular-lying vibrational states) can be dis- sociated much more efficiently at higher laser intensities. In this Letter, we Publishers B.V. All rights reserved. 413 #12;Volume 197, number 4,s CHEMICAL PHYSICS LETTERS 18September 1992

Chu, Shih-I

293

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 CHEMICAL PHYSICS LETTERS 15 December 1989 occur predominantly in the far infrared. Direct mea- surement radicals and clusters contain- ing free radicals. Excimer laser photolysis of a suitable precursor

Cohen, Ronald C.

294

Laser photoacoustic spectroscopy helps fight terrorism: High sensitivity detection of chemical Warfare Agent and explosives  

Microsoft Academic Search

Tunable laser photoacoustic spectroscopy is maturing rapidly in its applications to real world problems. One of the burning problems of the current turbulent times is the threat of terrorist acts against civilian population. This threat appears in two distinct forms. The first is the potential release of chemical warfare agents (CWA), such as the nerve agents, in a crowded environment.

C. K. N. Patel

2008-01-01

295

Implications of applying a global energy balance to laser-supported and chemical detonation waves  

Microsoft Academic Search

A closer examination of the conditions needed to propagate a steady-state shock wave is made and generalized to include energy added in the vicinity of the wave via both laser deposition and chemical rections. This analysis yields slightly different results than standard detonation theory, and these differences are explored. A case is made for the correctness of the present method

E. J. Jumper

1984-01-01

296

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

297

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

E-print Network

. Blending PLA with another biodegradable polymer, poly(glycolic acid), to adjust the degradation rate: Biodegradable polymer Poly(L-lactic acid) Laser irradiation Chemical modification Crystallinity Radical mobility a b s t r a c t The biodegradable polymer such as poly(L-lactic acid) (PLLA) is promising in drug

Yao, Y. Lawrence

298

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

E-print Network

small quantities. The majority of high quality carbon nano- tubes have been prepared using either is best visualized as a planar sheet of carbon atoms (graphene) wrapped into a tube, fallsLaser assisted chemical vapor deposition synthesis of carbon nanotubes and their characterization S

Wang, Zhong L.

299

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

SciTech Connect

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 R/sub 2/ and I/sub 2/. Laser- and rf-discharge-based methods for regenerating starting materials from by-products are evaluated experimentally. For economical operation of large iodine laser systems, CF/sub 3/I 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 CF/sub 3/I molecule using pulsed rf-discharge techniques is 5.8 eV.

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

1980-01-01

300

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

301

Kinetics and reaction mechanisms of laser-assisted chemical vapor deposition of polycrystalline silicon dots from silane  

Microsoft Academic Search

Polycrystalline silicon dots have been deposited on silicon-coated SiO2 substrates from silane irradiated with a continuous wave (cw) argon ion laser and a cw CO2 laser. Various experimental configurations were adopted for laser-assisted chemical vapor deposition of Si dots. The cw argon ion laser was focused either directly on the surface of absorbent polycrystalline Si films acting as substrates (front

Y. Pauleau; D. Tonneau

2002-01-01

302

Solid state chemical ionization for characterization of organic compounds by laser mass spectrometry.  

PubMed

A new technique involving the addition of a compound to the analyte to serve as a source of "reagent" ions has been developed for negative-ion laser mass spectrometry. This "solid state chemical ionization" leads to ions characteristic of the analyte, owing to ion-molecule reactions between the "reagent" ion and the neutral analyte in the laser-generated plume. Polycyclic aromatic hydrocarbons show formation of an ion corresponding to (M + O - H)(-) in their negative-ion laser mass spectra when mixed with compounds such as sym-trinitrobenzene, sodium nitrate and sodium peroxide. NO(-)(2), O(-), and O(-)(2) serve as "reagent" ions in these compounds. Formation of (M + Cl)(-) is seen in the laser mass spectra of glycosides mixed with hexachlorobenzene. Chloride serves as the "reagent" ion in this case. PMID:18964680

Balasanmugam, K; Viswanadham, S K; Hercules, D M

1989-01-01

303

JOURNAL DE PHYSIQUE CoZZoque C9, suppZ6ment au noll, Tome 41, novembre 1980, page ~ 9 -1 DEUTERIUM FLUORIDE CW CHEMICAL LASERS  

E-print Network

FLUORIDE CW CHEMICAL LASERS Leroy E. Wilson Air Force Weapons Laboratory, KirtZand Air Force Base, New fluoride (DF) cw chemical lasers. The fundamental principles of the laser are explained. The advantages deuterium fluoride (DF) laser has been extensively developed for atmospheric pressure recovery

Paris-Sud XI, Université de

304

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

305

Change in the surface morphology and chemical composition of some oxide crystals under UV laser irradiation  

SciTech Connect

The effect of the 248-nm KrF and 355-nm YAG:Nd{sup 3+} laser radiation on the surface morphology and chemical composition of SrTiO{sub 3}, Sr{sub 2}RuO{sub 4}, PbMoO{sub 4}, LiNbO{sub 3}, Y{sub 3}Al{sub 5}O{sub 12}, and Al{sub 2}O{sub 3} crystals has been studied. A relationship between the laser energy density on the sample surface and the surface roughness caused by the irradiation is determined. A technique for determining exactly the geometric surface characteristics is proposed. The effect of the surface roughness on the results of energy-dispersive X-ray (EDX) microanalysis has been investigated. A method for correcting the EDX data for samples with a rough surface has been developed. It is shown that the small variation in the composition of PbMoO{sub 4}, LiNbO{sub 3}, Y{sub 3}Al{sub 5}O{sub 12}, and Al{sub 2}O{sub 3} samples after laser irradiation can be explained by the measurement error, related to the change in the surface roughness. At the same time, the irradiation of SrTiO{sub 3} and Sr{sub 2}RuO{sub 4} crystals by a YAG:Nd laser changes the chemical composition of their surface layers. (interaction of laser radiation with matter)

Kuzanyan, A S; Badalyan, G R; Kuzanyan, V S; Nikogosyan, V R; Pilosyan, S Kh; Nesterov, V M

2011-07-31

306

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

PubMed

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 mm(3)) consisting of SiC, Ni/NiO(x), 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 H(2) gas ambient due to the higher thermal conductivity, temperatures up to 1000 °C were achieved even in 200 Torr H(2). 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. PMID:23020398

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

2012-09-01

307

Chemical Etch Effects on Laser-Induced Surface Damage Growth in Fused Silica  

SciTech Connect

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 351nm laser light. The results show that damage sites that have been etched to depths greater than about 9 {micro}m have about a 40% chance for zero growth with 1000 shots at fluences of 6.8-9.4 J/cm{sup 2}. 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, L W; Norton, M A; Molander, W A; Wegner, P J; Staggs, M; Demos, S G; Britten, J A; Summers, L J; Lindsey, E F; Kozlowski, M R

2000-12-22

308

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

309

A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics.  

PubMed

A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic approximately 4-10 keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments. PMID:18052502

Fullagar, Wilfred; Harbst, Michael; Canton, Sophie; Uhlig, Jens; Walczak, Monika; Wahlström, Claes-Göran; Sundström, Villy

2007-11-01

310

A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics  

NASA Astrophysics Data System (ADS)

A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic ˜4-10keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments.

Fullagar, Wilfred; Harbst, Michael; Canton, Sophie; Uhlig, Jens; Walczak, Monika; Wahlström, Claes-Göran; Sundström, Villy

2007-11-01

311

ZnO-coated SMS structure interrogated by a fiber ring laser for chemical sensing  

NASA Astrophysics Data System (ADS)

A zinc oxide (ZnO)-coated single mode–multimode–single mode fiber (SMS) structure interrogated by a fiber ring laser has been developed as a chemical sensor. Response to relative humidity (RH) and ethanol volatilization was evaluated by tracking the wavelength shifts of the output laser line in different moisture environments and ethanol solutions, respectively. For humidity sensing a linear response with a measurement range of 4–96% RH, and a sensitivity of 0.06?nm per %RH were obtained. As for ethanol volatilization sensing obvious wavelength blue shift was observed for the sensor immersed in 50% and 62% ethanol solution, while no variation could be detected in pure ethanol solution (purity larger than 97%). With the advantages of low cost, ease of fabrication and sensitive response, ZnO-coated SMS interrogated with a fiber ring laser was demonstrated to be an effective sensor for humidity and ethanol volatilization sensing.

Wen, X. Y.; Huang, J.; Xiao, H.; Yang, M. H.

2014-11-01

312

Direct Laser Ablation and Ionization of Solids for Chemical Analysis by Mass Spectrometry  

SciTech Connect

A laser ablation/ionization mass spectrometer system is described for the direct chemical analysis of solids. An Nd:YAG laser is used for ablation and ionization of the sample in a quadrupole ion trap operated in an ion-storage (IS) mode that is coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). Single pulse experiments have demonstrated simultaneous detection of up to 14 elements present in glasses in the ppm range. However, detection of the components has produced non-stoichiometric results due to difference in ionization potentials and fractionation effects. Time-of-flight secondary ionization mass spectrometry (TOF-SIMS) was used to spatially map elemental species on the surface and provide further evidence of fractionation effects. Resolution (m/Dm) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

Holt, J K; Nelson, E J; Klunder, G L

2005-09-02

313

Possibility of a high-efficiency pulsed vibrational overtone HF chemical laser  

NASA Astrophysics Data System (ADS)

The possibility of high-efficiency frequency conversion using first vibrational overtone transitions in a discharge-initiated nonchain (H2/SF6)HF chemical laser is theoretically analyzed. By totally suppressing fundamental transitions, vibrational overtone HF laser energy can be obtained, in pulsed operation, with a conversion efficiency of 67 percent of the fundamental output energy. A multiline oscillation of 1.3-1.5 microns is expected in the first vibrational overtone transitions. An overtone laser energy density of 0.87 mJ per cubic cm is found to be achievable from a discharge-initiated He-diluted gas mixture of SF6/H2/He = 84/12/404-664 Torr.

Ashidate, Shu-Ichi; Obara, Minoru

1989-03-01

314

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

315

Potential for ultrafast dynamic chemical imaging with few-cycle infrared lasers  

E-print Network

We studied the photoelectron spectra generated by an intense few-cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity, and wavelength, these extracted elastic scattering cross sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle infrared lasers as powerful table-top tools for imaging chemical and biological transformations, with the desired unprecedented temporal and spatial resolutions.

Morishita, T; Chen, Z; Lin, C D

2007-01-01

316

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

317

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

318

Lasers.  

ERIC Educational Resources Information Center

Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

Schewe, Phillip F.

1981-01-01

319

Laser photoacoustic spectroscopy helps fight terrorism: High sensitivity detection of chemical Warfare Agent and explosives  

Microsoft Academic Search

.  \\u000a Tunable laser photoacoustic spectroscopy is maturing \\u000a rapidly in its applications to real world problems. One of the burning \\u000a problems of the current turbulent times is the threat of terrorist acts \\u000a against civilian population. This threat appears in two distinct forms. The \\u000a first is the potential release of chemical warfare agents (CWA), such as the \\u000a nerve agents, in a crowded

C. K. N. Patel

2008-01-01

320

Theoretical study of a new energy extraction scheme of a chemically pumped pulsed iodine laser amplifier  

Microsoft Academic Search

A new energy extraction scheme of a chemically pumped pulsed large-scale iodine laser based on a high-pressure pulsed singlet oxygen generator is proposed. In previous investigations only low-pressure oxygen generators have been considered. Since they require a high iodine density for an efficient amplifier operation, the lifetime of the stored energy is correspondingly small and thus only small-sized iodine amplifiers

M. Endo; K. Kodama; Y. Handa; T. Uchiyama

1993-01-01

321

Implications of applying a global energy balance to laser-supported and chemical detonation waves  

NASA Astrophysics Data System (ADS)

A closer examination of the conditions needed to propagate a steady-state shock wave is made and generalized to include energy added in the vicinity of the wave via both laser deposition and chemical rections. This analysis yields slightly different results than standard detonation theory, and these differences are explored. A case is made for the correctness of the present method by citing the results of other researchers.

Jumper, E. J.

1984-09-01

322

Chemical bonding and nanomechanical studies of carbon nitride films synthesised by reactive pulsed laser deposition  

Microsoft Academic Search

Carbon nitride films were grown on Al2O3–TiC substrates by reactive pulsed KrF excimer laser ablation of graphite targets. Nitrogen contents up to 19 at.% were obtained by increasing the nitrogen partial pressure, PN2 to 75 mtorr. The effects of PN2 on the chemical bond structure and nanomechanical properties of CNx films were investigated by Raman, Fourier transform infra-red, X-ray photoelectron

P Papakonstantinou; D. A Zeze; A Klini; J McLaughlin

2001-01-01

323

Laser-based standoff detection of surface-bound explosive chemicals  

NASA Astrophysics Data System (ADS)

Avoiding or minimizing potential damage from improvised explosive devices (IEDs) such as suicide, roadside, or vehicle bombs requires that the explosive device be detected and neutralized outside its effective blast radius. Only a few seconds may be available to both identify the device as hazardous and implement a response. As discussed in a study by the National Research Council, current technology is still far from capable of meeting these objectives. Conventional nitrocarbon explosive chemicals have very low vapor pressures, and any vapors are easily dispersed in air. Many pointdetection approaches rely on collecting trace solid residues from dust particles or surfaces. Practical approaches for standoff detection are yet to be developed. For the past 5 years, SRI International has been working toward development of a novel scheme for standoff detection of explosive chemicals that uses infrared (IR) laser evaporation of surfacebound explosive followed by ultraviolet (UV) laser photofragmentation of the explosive chemical vapor, and then UV laser-induced fluorescence (LIF) of nitric oxide. This method offers the potential of long standoff range (up to 100 m or more), high sensitivity (vaporized solid), simplicity (no spectrometer or library of reference spectra), and selectivity (only nitrocompounds).

Huestis, David L.; Smith, Gregory P.; Oser, Harald

2010-04-01

324

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

325

Ambient diode laser desorption dielectric barrier discharge ionization mass spectrometry of nonvolatile chemicals.  

PubMed

In this work, the combined use of desorption by a continuous wave near-infrared diode laser and ionization by a dielectric barrier discharge-based probe (laser desorption dielectric barrier discharge ionization mass spectrometry (LD-DBDI-MS)) is presented as an ambient ionization method for the mass spectrometric detection of nonvolatile chemicals on surfaces. A separation of desorption and ionization processes could be verified. The use of the diode laser is motivated by its low cost, ease of use, and small size. To achieve an efficient desorption, the glass substrates are coated at the back side with a black point (target point, where the sample is deposited) in order to absorb the energy offered by the diode laser radiation. Subsequent ionization is accomplished by a helium plasmajet generated in the dielectric barrier discharge source. Examples on the application of this approach are shown in both positive and negative ionization modes. A wide variety of multiclass species with low vapor pressure were tested including pesticides, pharmaceuticals and explosives (reserpine, roxithromycin, propazine, prochloraz, spinosad, ampicillin, dicloxacillin, enrofloxacin, tetracycline, oxytetracycline, erythromycin, spinosad, cyclo-1,3,5,7-tetramethylene tetranitrate (HMX), and cyclo-1,3,5-trimethylene trinitramine (RDX)). A comparative evaluation revealed that the use of the laser is advantageous, compared to just heating the substrate surface. PMID:23419061

Gilbert-López, Bienvenida; Schilling, Michael; Ahlmann, Norman; Michels, Antje; Hayen, Heiko; Molina-Díaz, Antonio; García-Reyes, Juan F; Franzke, Joachim

2013-03-19

326

COMPONENTS OF LASER SYSTEMS: Transport of high-pressure O2(1?)  

NASA Astrophysics Data System (ADS)

Calculations and experimental studies were made of the influence of heat evolution on the transport of high-pressure singlet oxygen used in a supersonic oxygen—iodine laser. The heat release as a result of relaxation of O2(1?) slowed down the motion of the gas in the singlet-oxygen generator and also in the duct along which the oxygen was transported. Moreover, the heat reduced the mass flow rate of the gas and the efficiency of the singlet-oxygen generator in the supersonic laser.

Azyazov, V. N.; Zagidullin, M. V.; Nikolaev, V. D.; Svistun, M. I.; Khvatov, N. A.

1994-03-01

327

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

328

Volume 217, number 3 CHEMICAL PHYSICS LETTERS 14January 1994 Laser-induced fluorescence studies of C3 formation and  

E-print Network

Volume 217, number 3 CHEMICAL PHYSICS LETTERS 14January 1994 Laser-induced fluorescence studies PHYSICS LETTERS 14January 1994 highly vibrationally excited molecules with excita- tion energies. Introduction In the previous work on the 193 nm laser photol- ysis of allene, Jackson et al. used angle

Song, Xueyu

329

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

330

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

331

Photothermal temperature control of a chemical reaction on a microchip using an infrared diode laser.  

PubMed

We have demonstrated that a miniaturized device with IR laser heating of the solvent, based on a photothermal effect, is capable of fast and localized control of an enzymatic reaction on a microchip under flow conditions. Using noncontact spectroscopic temperature-sensing techniques, we measured temperature dynamics and spatial distribution and compared the measurements with results of numerical simulation analysis. The device was operated at ultrafast heating and cooling rates of 67 and 53 degrees C/s, respectively, which is 30 times faster than conventional systems and 3-6 times faster than electrothermal miniaturized thermocyclers. The IR laser-mediated heater is characterized by a significantly reduced heated volume of only 5 nL, compared to existing chip-based systems with electrothermal heating. Direct heating of a sample with extremely small heat capacity led us to a fast heating rate, and efficient heat removal through heat transfer to the glass substrate resulted in a fast cooling rate. Reproducible temperature levels with dwell times shorter than 0.5 s were achieved. The enzyme reaction on a chip was successfully controlled with 0.6-s time resolution, using periodic photothermal heating by IR laser. The IR diode laser is compact and thus suits well the miniaturized system design. Our work gives the basis for integration in a chip format of a variety of chemical processes that require fast temperature control. PMID:11534733

Slyadnev, M N; Tanaka, Y; Tokeshi, M; Kitamori, T

2001-08-15

332

Volume 136, number 6 CHEMICAL PHYSICS LETTERS 22 May 1987 MECHANISM FOR BOND-SELECTIVE PROCESSES IN LASER DESORPTION  

E-print Network

Volume 136, number 6 CHEMICAL PHYSICS LETTERS 22 May 1987 MECHANISM FOR BOND-SELECTIVE PROCESSES, number 6 CHEMICAL PHYSICS LETTERS 22 May 1987 ecule can therefore be slow and a relatively cold mol IN LASER DESORPTION R.N. ZARE Department of Chemistry, Stanford University, Stanford, CA 94305, USA and R

Zare, Richard N.

333

Supersonic jet/multiphoton ionization spectrometry of chemical species resulting from thermal decomposition and laser ablation of polymers  

SciTech Connect

The chemical species resulting from thermal decomposition and laser ablation of polymers are measured by excitation/fluorescence and multiphoton ionization/mass spectrometries after supersonic jet expansion for rotational cooling to simply the optical spectrum. The signal of minor chemical species occurred is strongly enhanced by resonant excitation and multiphoton ionization, and even the isomer can be clearly differentiated. For example, p-cresol occurred by thermal decomposition of polycarbonate is detected selectively by mass-selected resonant multiphoton ionization spectrometry. Various chemical species occurred by laser ablation of even a polystyrene foam are also measured by this technique.

Hozumi, Masami; Murata, Yoshiaki; Cheng-Huang Lin; Imasaka, Totaro [Department of Chemical Science and Technology, Faculty of Engineering, Hakozaki, Higashi-Ku, Fukuoka 812 (Japan)

1995-04-01

334

Chemical reactions of excited nitrogen atoms for short wavelength chemical lasers. Final technical report  

SciTech Connect

Accomplishments of this program include the following: (1) Scalable, chemical generation of oxygen atoms by reaction of fluorine atoms and water vapor. (2) Production of nitrogen atom densities of 1 {times} 10{sup 1}5 cm{sup {minus}3} with 5% electrical efficiency by injecting trace amounts of fluorine into microwave discharged nitrogen. (3) Production of cyanide radicals by reaction of high densities of N atoms with cyanogen. (4) Production of carbon atoms by reaction of nitrogen atoms with cyanogen or with fluorine atoms and hydrogen cyanide. (5) Confirmation that the reaction of carbon atoms and carbonyl sulfide produces CS(a{sup 3} {Pi}{sub r}), as predicted by conservation of electron spin and orbital angular momenta and as proposed by others under another SWCL program. (6) Production of cyanide radicals by injection of cyanogen halides into active nitrogen and use as spectroscopic calibration source. (7) Demonstration that sodium atoms react with cyanogen chloride, bromide and iodide and with cyanuric trifluoride to produce cyanide radicals. (8) Demonstration of the potential utility of the fluorine atom plus ammonia reaction system in the production of NF(b{sup l}{Sigma}{sup +}) via N({sup 2}D) + F{sub 2}.

Not Available

1989-12-15

335

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

E-print Network

, applications and effects. His pioneering efforts on advancing atomic iodine laser technology, both Photolytic 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

336

JOURNAL DE PHYSIQUE Colloque C7, supplkment au n012, Tome 48, dbcembre 1987  

E-print Network

Aerospatiales, BP 72, F-92322 Chdtillon Cedex, France The Chemical Oxygen Iodine Laser (COIL) is a recently LASER (COIL) PROSPECTS OF INDUSTRIAL USE D. PIGACHE Office National dSEtudeset de Recherches developed high power cw laser. It is the first electronic transition chemical laser and its wavelength 1315

Paris-Sud XI, Université de

337

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

E-print Network

, applications and effects. His pioneering efforts on advancing atomic iodine laser technology, both Photolytic 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

338

Control of Chemical Dynamics Using Arbitrary Shaped Optical Pulses and Laser-Enhanced NMR Spectroscopy.  

NASA Astrophysics Data System (ADS)

A key feature of this thesis is the application of novel laser techniques to various fields of spectroscopy. The overall effort has been towards achieving either chemical control or enhanced spectroscopic resolution. The issue of chemical control forms the major bulk. Over the past decade, theoretical and technological developments have made it possible for a modern day chemist to be a more active participant in nature's chemical processes. Consequently, although the idea of manipulating chemical reactions has been a long term dream, it is only now that realization of such dreams has become realistic. One of the major contributions that is leading towards this realization is the development of pulse shaping techniques. Here, we concentrate on the important developments in this area that has come by recently, particularly emphasizing new results from our laboratory. We discuss in detail the current state-of-the-art, and present some experimental and theoretical demonstrations of chemical control by using arbitrarily shaped pulses. The major strength of our approach to pulse shaping has been in considering "robustness in the laboratory" as a primary constraint. Most of the shapes, addressed here, work under adiabatic conditions where the exact shape of the pulse is not critical as long as the basic criteria dictated by the adiabatic theorem are satisfied. A novel approach of "molecular pulse shaping"--using the molecule itself to generate its own pulse shape--is presented as an example of the ultimate form of robustness. Finally, we get into the issue of resolution enhancement by coupling laser radiation into a Nuclear Magnetic Resonance (NMR) spectrometer. Spectroscopic resolution enhancement is an everlasting effort in the field of NMR--even more for biological NMR. We present some of the recent experimental findings in our laboratory that show selective dispersion in the NMR spectrum when it is acquired under a non-resonant laser irradiation of the sample. Albeit promising, the observed effects are weak and the theoretical understanding of these experiments is not profound enough for implementing any immediate applications.

Goswami, Debabrata

339

Nonequilibrium population of the first vibrational level of O{sub 2}({sup 1{Sigma}}) molecules in O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O gas flow at the output of chemical singlet-oxygen generator  

SciTech Connect

The concentrations of electron-excited particles have been determined by measuring the absolute spectral irradiance in the range of 600 - 800 nm of O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O gas mixture at the output of a chemical singlet-oxygen generator (SOG). A nonequilibrium population of the first vibrational level of O{sub 2}({sup 1{Sigma}}) molecules has been clearly observed and found to depend on the water vapour content. In correspondence with the results of these measurements and according to the analysis of kinetics processes in the O{sub 2} - O{sub 2}({sup 1{Delta}}) - H{sub 2}O mixture, the maximum number of vibrational quanta generated in the O{sub 2}({sup 1{Delta}}) + O{sub 2}({sup 1{Delta}}) {yields} O{sub 2}({sup 1{Sigma}}) + O{sub 2}({sup 3{Sigma}}) reaction is 0.05 {+-} 0.03. It is concluded that the vibrational population of O{sub 2}({sup 1{Delta}}) at the output of the SOG used in a chemical oxygen-iodine laser is close to thermal equilibrium value. (active media)

Zagidullin, M V [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation)

2010-11-13

340

Research on excimer laser-induced chemical vapor deposition of diamond films  

NASA Astrophysics Data System (ADS)

In our work, the result about the research on excimer-laser- induced chemical vapor deposition (CVD) of diamond films is reported. The XeCl excimer laser was employed as active energy source for photodissociation of carbon source gas. The wavelength of the laser beam is 308 nm with pulse-width of 25 ns, output energy of 180 mJ and power density on the local region up to 300 MW/cm2. The gas mixture was consisted of aromatics (C6 H6 or C7 H8) and H2. The substrate was p-type silicane. The ratio between aromatics and buffer gas (H2) is from 1:1 to 1:4. The temperature of the substrate was controlled at 300 degrees Celsius. A swan band of C2 radical (516 nm) can be observed from the emission spectrum of gas mixture. After two hours deposition, the films were analyzed by Raman spectroscopy. It is shown that there is a wide peak at 1552 cm-1, which is characteristic spectrum of diamond- like films. The diamond-like films were obtained.

Ren, Deming; Hu, Xiaoyong; Liu, Fengmei M.; Zhao, Jingshan

1996-10-01

341

Wang S. Zhou W. and Cui S. Simultaneous Determination Catecholamines Micellar Electrokinetic Chromatography Laser-Induced Fluorescence Detection International Conference Chemistry Chemical Engineering  

EPA Pesticide Factsheets

Search instead for Wang S. Zhou W. and Cui S. Simultaneous Determination Catecholamines Micellar Electrokinetic Chromatography Laser-Induced Fluorescence Detection International Conference Chemistry Chemical Engineering ?

342

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

343

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

344

Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments.  

PubMed

Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and hatching pattern, were investigated using a Ti powder of less than 45 ?m particle size. The results show that a fully dense plate thinner than 1.8 mm was obtained when the laser power to scanning speed ratio was greater than 0.5 and the hatch spacing was less than the laser diameter, with a 30 ?m thick powder layer. Porous Ti metals with structures analogous to human cancellous bone were fabricated and the compressive strength measured. The compressive strength was in the range 35-120 MPa when the porosity was in the range 75-55%. Porous Ti metals fabricated by SLM were heat-treated at 1300 °C for 1h in an argon gas atmosphere to smooth the surface. Such prepared specimens were subjected to NaOH, HCl, and heat treatment to provide bioactivity. Field emission scanning electron micrographs showed that fine networks of titanium oxide were formed over the whole surface of the porous body. These treated porous bodies formed bone-like apatite on their surfaces in a simulated body fluid within 3 days. In vivo studies showed that new bone penetrated into the pores and directly bonded to the walls within 12 weeks after implantation into the femur of Japanese white rabbits. The percentage bone affinity indices of the chemical- and heat-treated porous bodies were significantly higher than that of untreated implants. PMID:20883832

Pattanayak, Deepak K; Fukuda, A; Matsushita, T; Takemoto, M; Fujibayashi, S; Sasaki, K; Nishida, N; Nakamura, T; Kokubo, T

2011-03-01

345

Fabrication of high-aspect ratio, micro-fluidic channels and tunnels using femtosecond laser pulses and chemical etching  

Microsoft Academic Search

We present novel results obtained in the fabrication of high-aspect ratio micro-fluidic microstructures chemically etched from fused silica substrates locally exposed to femtosecond laser radiation. A volume sampling method to generate three-dimensional patterns is proposed and a systematic SEM-based analysis of the microstructure is presented. The results obtained gives new insights toward a better understanding of the femtosecond laser interaction

Yves Bellouard; Ali Said; Mark Dugan; Philippe Bado

2004-01-01

346

Chemical studies of intraocular lenses after experimental generation of lesions by a short-pulsed Nd-YAG laser  

Microsoft Academic Search

It is theoretically possible that lesions generated by a Q-switched Nd-YAG laser could lead to chemical changes in polymethylmethacrylate (PMMA) intraocular lenses. These changes could be of clinical relevance. Therefore, we measured the residual monomer content of intraocular lenses before and after generation of lesions by means of a short-pulsed Nd-YAG laser. Despite the explosive destruction of the lens surface

O. F. Scheiffarth; K. Ludwig; R. Birngruber; V.-P. Gabel; L. Meyer

1984-01-01

347

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

348

AIAA JOURNAL Vol. 34, No. 2, February 1996  

E-print Network

manner. Blaze II was baselined to existing chemical oxygen-iodine laser data taken with the research for the research assessment and device improvement chemical laser nozzle indicate that higher iodine flow rates iodine laser transition of interest. A number of papers have investigated issues associated

Carroll, David L.

349

JOURNALDE PHYSIQUE IV ColloqueC7,supplt5ment au Journalde Physique111,Vol, 1,dkembre 1991  

E-print Network

-ku, Yokohama223,Japan ABSTRACT : A pulsed iodine laser driven by a chemical oxygen generator was developed is same as the conventional Chemically pumped Oxygen-Iodine Lasers (COIL), it is unique in that the pulsed was estimated to be 7.7J/1. 1:Introduction The iodine photodissociation laser is one of the most high

Boyer, Edmond

350

Advanced COIL based on atomic iodine generation using gaseous reactants  

Microsoft Academic Search

Development of a Chemical Oxygen-Iodine Laser (COIL) with alternative ways of atomic iodine generation is aimed at power increase and simplified laser operation. Advantages of chemical generation of atomic iodine using gaseous reactants directly in the laser medium are confronted with disadvantages of using molecular iodine as a source of atomic iodine in conventional COIL devices. Some recent results on

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

2004-01-01

351

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 1988 Optically pumped laser action has been achieved over the XeF (B-X) and (C+A) transitions that the laser should be tunable over the broad C+A band of =80 nm. 1. Introduction We report the first

Apkarian, V. Ara

352

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-infrared laser. A least-squares analysis has been performed to determine the centrifugal distortion constants der Waals molecules. Mid-infrared laser spectroscopy of van der Waals clusters generated in a pulsed

Cohen, Ronald C.

353

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 limitation in the range of 600 watts.The influence of the excessive water vapour content on laser output. Introduction A high power kilowatt class COIL has been developed at ONERA /l/. During laser tests, the laser

Paris-Sud XI, Université de

354

Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds  

Microsoft Academic Search

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended\\u000a for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic\\u000a Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser\\u000a detection. Standoff distances for pulsed measurements were 35 m

William Ortiz-Rivera; Leonardo C. Pacheco-Londoño; Samuel P. Hernández-Rivera

2010-01-01

355

Measurement of pH field of chemically reacting flow in microfluidic devices by laser-induced fluorescence  

Microsoft Academic Search

The interaction between chemical reactions and the flow field in microfluidic devices is investigated by a laser-induced fluorescence technique refined for use at microscopic spatial resolution. The pH distribution of chemically reacting flow at a Y-junction in a neutralization reaction in a microfluidic device is successfully visualized at a spatial resolution of 0.89 µm × 0.89 µm.

Kyosuke Shinohara; Yasuhiko Sugii; Koji Okamoto; Haruki Madarame; Akihide Hibara; Manabu Tokeshi; Takehiko Kitamori

2004-01-01

356

Metastable phase formation in thin films formed by laser breakdown chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Thin films produced by laser breakdown chemical vapor deposition (LBCVD) from Ni and Fe carbonyls were examined and their structure characterized, with emphasis on identifying the phases present. A brightfield micrograph observed in the Ni samples and the corresponding selected area diffraction (SAD) pattern are shown along with two darkfield micrographs of Ni-C film obtained from two positions on the same diffraction ring. It is seen that the decomposition of both carbonyls results in the formation of a supersaturated fcc phase and the carbide phase. The study shows that even a severe quench from the gas phase fails to completely stop the system from approaching its equilibrium structure. This indicates that the carbides Ni3C and Fe3C are associated with a very high thermodynamic driving force for their formation even though both of these phases are metastable.

Menon, S. K.; Jervis, T. R.

1986-11-01

357

Volume 155,number 4,5 CHEMICAL PHYSICS LETTERS IOMarch 1989 LASER-INDUCED THERMAL DESORPTION OF CO ON Ni(ll1)  

E-print Network

Volume 155,number 4,5 CHEMICAL PHYSICS LETTERS IOMarch 1989 LASER-INDUCED THERMAL DESORPTION OF CO different from those induced by slow heating In this Letter, we show that pulsed laser heating to induce Division ) #12;Volume 155,number 4,5 CHEMICAL PHYSICS LETTERS 10March 1989 uration coverage), can

Zhu, Xiangdong

358

Focused laser spike (FLaSk) annealing of photoactivated chemically amplified resists for rapid hierarchical patterning.  

PubMed

Lithographic alternatives to conventional layer-by-layer processes for the design of 3D structures such as photonic or phononic crystals often present a dichotomy: patterning control versus patterning area. We demonstrate a combined technique of large area interference lithography and local area direct write focused laser spike (FLaSk) annealing that can enable the microscale patterning of hierarchical structures defined in their morphology by the interference and defined in placement and shape by the direct write. This is accomplished by doping a commercial chemically amplified photoresist (SU-8) with an absorbing dye to provide thermal activation at a wavelength shifted from that causing UV crosslinking. In this way, the necessary post-exposure bake to complete the crosslinking of the resist is locally performed by the FLaSk laser, rather than globally on a hot plate. By utilizing the same experimental setup as used by a 3D direct write system, it is possible to integrate another level of patterning by enabling fully dense, arbitrarily written features on multiple length scales. Both experimental and simulated results of this novel processing method are shown. PMID:21503354

Singer, Jonathan P; Kooi, Steven E; Thomas, Edwin L

2011-07-01

359

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

360

Thermal diffusion and chemical kinetics in laminar biomaterial due to heating by a free-electron laser  

Microsoft Academic Search

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 mm where water is the main absorber and

M. Shane Hutson; Susanne A. Hauger; Glenn Edwards

2002-01-01

361

Chemical studies of intraocular lenses after experimental generation of lesions by a short-pulsed Nd-YAG laser.  

PubMed

It is theoretically possible that lesions generated by a Q-switched Nd-YAG laser could lead to chemical changes in polymethylmethacrylate (PMMA) intraocular lenses. These changes could be of clinical relevance. Therefore, we measured the residual monomer content of intraocular lenses before and after generation of lesions by means of a short-pulsed Nd-YAG laser. Despite the explosive destruction of the lens surface caused by this type of laser, there is no measurable release of monomer in the sense of a depolymerization of the PMMA material, even when over 100 lesions are generated. The lesions generated on intraocular PMMA lenses with the Nd-YAG laser are predominantly of a mechanical nature and include the chipping away of small particles from the intraocular lens. PMID:6510725

Scheiffarth, O F; Ludwig, K; Birngruber, R; Gabel, V P; von Meyer, L

1984-01-01

362

IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Efficiency of an H2—SF6 laser with electron-beam initiation of chemical reactions  

NASA Astrophysics Data System (ADS)

The spectral and amplitude—time characteristics of HF lasers pumped by a nonchain chemical reaction and initiated by radially convergent and planar electron beams were investigated. The principal channels leading to the formation of vibrationally excited HF molecules were analysed. It was confirmed that high efficiencies (~10%) of a nonchain HF laser may be attained only as a result of the simultaneous formation of atomic and molecular fluorine when the active mixture is acted upon by an electron beam and of the participation of molecular fluorine in population inversion. It was shown that a laser pulse has a complex spectral—temporal profile caused by the successive generation of P-lines and the overlap during the radiation pulse of both the rotational lines of the same vibrational band and of individual vibrational bands.

Erofeev, M. V.; Orlovskii, Viktor M.; Skakun, V. S.; Sosnin, E. A.; Tarasenko, Viktor F.

2000-06-01

363

Portable open-path chemical sensor using a quantum cascade laser  

NASA Astrophysics Data System (ADS)

Remote sensing of enemy installations or their movements by trace gas detection is a critical but challenging military objective. Open path measurements over ranges of a few meters to many kilometers with sensitivity in the parts per million or billion regime are crucial in anticipating the presence of a threat. Previous approaches to detect ground level chemical plumes, explosive constituents, or combustion have relied on low-resolution, short range Fourier transform infrared spectrometer (FTIR), or low-sensitivity near-infrared differential optical absorption spectroscopy (DOAS). As mid-infrared quantum cascade laser (QCL) sources have improved in cost and performance, systems based on QCL's that can be tailored to monitor multiple chemical species in real time are becoming a viable alternative. We present the design of a portable, high-resolution, multi-kilometer open path trace gas sensor based on QCL technology. Using a tunable (1045-1047cm-1) QCL, a modeled atmosphere and link-budget analysis with commercial component specifications, we show that with this approach, accuracy in parts per billion ozone or ammonia can be obtained in seconds at path lengths up to 10 km. We have assembled an open-path QCL sensor based on this theoretical approach at City College of New York, and we present preliminary results demonstrating the potential of QCLs in open-path sensing applications.

Corrigan, Paul; Lwin, Maung; Huntley, Reuven; Chhabra, Amandeep; Moshary, Fred; Gross, Barry; Ahmed, Samir

2009-05-01

364

Laser applications to chemical dynamics; Proceedings of the Meeting, Los Angeles, CA, Jan. 13, 14, 1987  

Microsoft Academic Search

The use of lasers in the experimental investigation of dynamic processes in chemistry is discussed in reviews and reports of recent investigations. Consideration is given to studies of state-to-state molecular dynamics, nonlinear and ultrafast laser techniques applied to atoms and molecules, laser linear and nonlinear photochemistry, and lasers and cluster dynamics. Topics examined include collisional quenching and energy transfer in

Mustafa A. El-Sayed

1987-01-01

365

Physico-chemical properties of Pd nanoparticles produced by Pulsed Laser Ablation in different organic solvents  

NASA Astrophysics Data System (ADS)

Palladium nanoparticles are arousing an increasing interest because of their strong activity in heterogeneous catalysis in a wide range of reactions. Driven by the interest of producing Pd nanoparticles to be deposited for catalysis over hydrophobic supports, we investigated their synthesis via Pulsed Laser Ablation in Liquid in several organic solvents, as acetone, ethanol, 2-propanol, toluene, n-hexane. The colloids were produced by using a Nd:YAG ns laser and without the addition of surfactant agents. The morphology, composition, stability and oxidation state of the obtained nanoparticles were investigated by TEM-EDS analysis, UV-vis spectroscopy, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy. The results evidence that the nature of the solvent influences both the yield and the physico-chemical properties of the produced nanoparticles. While in acetone and alcohols spheroidal, non aggregated and stable particles are obtained, in case of toluene and n-hexane few unstable particles surrounded by a gel-like material are produced. Raman/XPS measurements suggest the presence of amorphous or graphitic carbon onto crystalline Pd nanoparticles, which could have hindered their growth and determined the observed smaller sizes if compared to nanoparticles produced in water. The stability of Pd colloids obtained in acetone and alcohols was attributed to adsorbed anions like enolates or alcoholates; non polar solvents like toluene and n-hexane, unable to give rise to adsorbed anionic species, cannot provide any stabilization to the palladium nanoparticles. XPS analyses also evidenced a partial oxidation of particles surface, with a ratio Pd 2+:Pd 0 of 1:2.5 and 1:4 in acetone and ethanol, respectively.

Cristoforetti, Gabriele; Pitzalis, Emanuela; Spiniello, Roberto; Ishak, Randa; Giammanco, Francesco; Muniz-Miranda, Maurizio; Caporali, Stefano

2012-01-01

366

Chemical pumping of potential visible laser transistions in bismuth monofluoride by thermal dissociation of fluorine azide  

NASA Astrophysics Data System (ADS)

A visible chemical laser on the BiF(A-X) transistions at 430-470 nm can potentially be generated by the interaction of Bi-atoms with metastable species such as NF(a1?). Experiments were performed in which these constituents were obtained in situ by fast pulsed CO2 laser pyrolysis of FN3 and Bi(CH3)3, respectively. Time-resolved optical diagnostics were used to follow the concentrations of FN3, NF(a1?), Bi(CH3)x, Bi(2D) and BiF(A). The optimal concentrations of FN3 and Bi(CH3)3 were limited by NF(a1?) self-annihilation and Bi(2D) quenching reactions, respectively. The Bi(CH3)3 was found to be only 20 % dissociated at the peak of the NF(a1?) time profile and the yield of Bi-atoms from dissociated Bi(CH3)3 was determined to be approximately 5%; however, significant recycling of the active Bi/BiF species was observed at a limiting rate of 4 - 5 x 10-11 cm3/s, driven by NA(a1?). On the basis of these results, a peak BiF(A) concentration of 1013/cm3 was predicted by kinetic modeling and subsequently observed. The model also predicts an absolute population inversion of the BiF(A-X) transistion at high NF(a1?) concentration with unsaturated gains of approximately 10-3/cm. Intracavity experiments have verified that the BiF(X) ground state concentration is low enough relative to the excited state to generate at least a partial inversion, and initial evidence for an absolute population inversion has been obtained.

Winker, Bruce K.; Benard, David J.; Seder, Tom A.

1990-06-01

367

Laser photoacoustic spectroscopy helps fight terrorism: High sensitivity detection of chemical Warfare Agent and explosives  

NASA Astrophysics Data System (ADS)

Tunable laser photoacoustic spectroscopy is maturing rapidly in its applications to real world problems. One of the burning problems of the current turbulent times is the threat of terrorist acts against civilian population. This threat appears in two distinct forms. The first is the potential release of chemical warfare agents (CWA), such as the nerve agents, in a crowded environment. An example of this is the release of Sarin by Aum Shinrikyo sect in a crowded Tokyo subway in 1995. An example of the second terrorist threat is the ever-present possible suicide bomber in crowded environment such as airports, markets and large buildings. Minimizing the impact of both of these threats requires early detection of the presence of the CWAs and explosives. Photoacoustic spectroscopy is an exquisitely sensitive technique for the detection of trace gaseous species, a property that Pranalytica has extensively exploited in its CO2 laser based commercial instrumentation for the sub-ppb level detection of a number of industrially important gases including ammonia, ethylene, acrolein, sulfur hexafluoride, phosphine, arsine, boron trichloride and boron trifluoride. In this presentation, I will focus, however, on our recent use of broadly tunable single frequency high power room temperature quantum cascade lasers (QCL) for the detection of the CWAs and explosives. Using external grating cavity geometry, we have developed room temperature QCLs that produce continuously tunable single frequency CW power output in excess of 300 mW at wavelengths covering 5 ?m to 12 ?m. I will present data that show a CWA detection capability at ppb levels with false alarm rates below 1:108. I will also show the capability of detecting a variety of explosives at a ppb level, again with very low false alarm rates. Among the explosives, we have demonstrated the capability of detecting homemade explosives such as triacetone triperoxide and its liquid precursor, acetone which is a common household liquid. This capability, deployed at airports and other public places, will go a long way towards increasing public safety and minimizing inconveniences faced in airline travel.

Patel, C. K. N.

2008-01-01

368

JOURNALDE PHYSIQUE IV ColloqueC7,supplCment au Journalde Physique 111,Vol. 1,dCcembre 1991  

E-print Network

Iodine Laser (COIL) cannot occur a single collision. A two-step model where the excited intermediate - Introduction The dissociation of I, by 0,(lag) in a Chemical Oxygen Iodine Laser (COIL) cannot occur~eriInental The laser excites the iodine molecules from the vibrational levels with 5 s V ,

Paris-Sud XI, Université de

369

J. Phys. Chem. 1083, 87, 2153-2161 2153 Electronic-to-Vibrational Energy Transfer from I * (5 2P1,2)to 12( 25< Y <43)  

E-print Network

implicationsfor the mechanism of I2 dissociation in the chemical oxygen/iodine laser. A chain- branchingmechanism oxy- gen/iodine laser. Previous investigationsof this system2-10 had resulted in the following dissociation of I,, while reactions 5 and 6 invert the iodine atom population, allowing laser emission at 1

Houston, Paul L.

370

JOURNALDE PHYSIQUEIV ColloqueC4,supplbmentau JournaldePhysique111,Volume4, avril1994  

E-print Network

stateare alsopresented. Introduction. At present, the Chemical Oxygen Iodine Laser (COIL) is the only) are of relevance to the chemical oxygen iodinelaser. We have investigated relaxation of 12(vM>20)by pulsed laser techniques. Individualro-vibrationallevels were populated by stimulatedemission pumping. Collisionally

Paris-Sud XI, Université de

371

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

) technique for optimizing the performance of a laser system (chemical, solid-state, or gaseous). The effects, pp. 411-424. GENETIC ALGORITHMS AND OPTIMIZING CHEMICAL OXYGEN-IODINE LASERS David L. Carroll1 of elitism, single point and uniform crossover, creep mutation, different random number seeds, population

Carroll, David L.

372

0/sub 2/(/sup 1/. delta. ) generation mechanisms in the chemically pumped iodine laser  

SciTech Connect

The reactivity of Cl/sub 2/ with aqueous H/sub 2/O/sub 2/, both with and without added base, was investigated in a static bulb. The rate data for Cl/sub 2/ absorption in these solutions are explained in terms of a diffusion-reaction model, and the results are consistent with the assumption that the reaction responsible for O/sub 2/(/sup 1/..delta..) production in the O/sub 2/(/sup 1/..delta..) generator utilized in the chemically pumped iodine laser is a direct reaction between Cl/sub 2/ and HO/sup -//sub 2/ at the generator gas-liquid interface. The data indicate that the probability of loss of a Cl/sub 2/ molecule that strikes the alkaline H/sub 2/O/sub 2/ gas-liquid interface is approx.10/sup -2/. The solubility of Cl/sub 2/ in H/sub 2/O/sub 2/-H/sub 2/O mixtures as well as implications of the experiment for practical O/sub 2/(/sup 1/..delta..) generators are discussed.

Richardson, R.J.; Kelley, J.D.; Wiswall, C.E.

1981-02-01

373

Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a commercial 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. From the four APCI reagent systems tested, neat carbon disulfide provided the best results. 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 but minor amount of fragmentation was observed for these two 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 predominantly form stable molecular ions.

Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

2011-03-01

374

Examination of quantum cascade laser source for a MEMS-scale photoacoustic chemical sensor  

NASA Astrophysics Data System (ADS)

Photoacoustic spectroscopy is a useful monitoring technique that is well suited for trace gas detection. The technique also possesses favorable detection characteristics when the system dimensions are scaled to a micro-system design. The objective of present work is to incorporate two strengths of the Army Research Laboratory (ARL), Quantum Cascade Laser (QCL) source development and chemical and biological sensing into a monolithic micro-electromechanical systems (MEMS) photoacoutic trace gas sensor. Past examination of a one quarter scale photoacoustic (PA) macro-cell has indicated a pathway to incorporate a photoacoustic resonance structure in a micro-mechanical platform. Initial studies involve the incorporation of a QCL source operating @ ~3.45 ?m into the PA macro-cell system as a means to discern proper operational characteristics in relation to the photoacoustic cell design. Results will be presented describing beam conditioning, modulation control and wavelength selection associated with the QCL source. Some preliminary information regarding MEMS-scale designs based off of hybrid concept, involving commercially available microphone and fully fabricated MEMS photoacoustic resonator will be described.

Heaps, David A.; Pellegrino, Paul M.

2006-05-01

375

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

376

Chemically assisted femtosecond laser machining for applications in LiNbO3 and LiTaO3  

NASA Astrophysics Data System (ADS)

We introduce and optimize a fabrication procedure that employs both femtosecond laser machining and hydrofluoric acid etching for cutting holes or voids in slabs of lithium niobate and lithium tantalate. The fabricated structures have 3 ?m lateral resolution, a lateral extent of at least several millimeters, and cut depths of up to 100 ?m. Excellent surface quality is achieved by initially protecting the optical surface with a sacrificial silicon dioxide layer that is later removed during chemical etching. To optimize cut quality and machining speed, we explored various laser-machining parameters, including laser polarization, repetition rate, pulse duration, pulse energy, exposure time, and focusing, as well as scanning, protective coating, and etching procedures. The resulting structures significantly broaden the capabilities of terahertz polaritonics, in which lithium niobate and lithium tantalate are used for terahertz wave generation, imaging, and control. The approach should be applicable to a wide range of materials that are difficult to process by conventional methods.

Sivarajah, Prasahnt; Werley, Christopher A.; Ofori-Okai, Benjamin K.; Nelson, Keith A.

2013-09-01

377

A refractometer based on a micro-slot in a fiber Bragg grating formed by chemically assisted femtosecond laser processing.  

PubMed

A liquid core waveguide as a refractometer is proposed. Microtunnels were created in standard optical fiber using tightly focused femtoscond laser inscription and chemical etching. A 1.2(h)x125(d) x500(l) mum micro-slot engraved along a fiber Bragg grating (FBG) was used to construct liquid core waveguide by filling the slot with index matching oils. The device was used to measure refractive index and sensitivity up to 10- 6/pm was obtained. PMID:19550870

Zhou, Kaiming; Lai, Yicheng; Chen, Xianfeng; Sugden, Kate; Zhang, Lin; Bennion, Ian

2007-11-26

378

Rh2O3\\/Ti electrode preparation using laser anneal and its application to the determination of chemical oxygen demand  

Microsoft Academic Search

The method of preparation of a Rh2O3\\/Ti electrode by using laser calcination and the characterization by x-ray diffractometer were proposed. The electrode, which could develop organic electrocatalytical oxidation, was employed as an amperometric sensor, together with a flow injection analysis, to measure chemical oxygen demand (COD) of waste water in a speedy way. The measuring principle was based on the

Jiaqing Li; Luoping Li; Lei Zheng; Yuezhong Xian; Litong Jin

2006-01-01

379

Fabrications of Si Thin-Film Solar Cells by Hot-Wire Chemical Vapor Deposition and Laser Doping Techniques  

Microsoft Academic Search

In this paper, we report a novel low-temperature process for fabricating a Si thin-film solar cell on a glass substrate. The cell structure was composed of glass\\/Al\\/p-i-n Si\\/Ag (grid), where the Si intrinsic layer was deposited by hot-wire chemical vapor deposition. All the doped Si layers were produced using a postgrowth laser-doping process. The hot-wire-deposited amorphous, microcrystalline and polycrystalline Si

Shui-Yang Lien; Dong-Sing Wuu; Hsin-Yuan Mao; Bing-Rui Wu; Yen-Chia Lin; In-Cha Hseih; Ray-Hua Horng

2006-01-01

380

Chemically reduced and laser-ablated gold nanoparticles immobilized to silanized glass plates: Preparation, characterization and SERS spectral testing  

Microsoft Academic Search

SERS-active surfaces based on gold colloidal nanoparticles attached to silanized glass plates were prepared and characterized by surface plasmon extinction (SPE) and atomic force microscopy (AFM). Aminopropyltrimethoxysilane (APTMS) was found to be more efficient in the silanization process than mercaptopropyltrimethoxysilane (MPTMS). Gold colloidal nanoparticles prepared by three different procedures, i.e. laser-ablation and chemical reduction of HAuCl4 by sodium borohydride or

Natália Hajduková; Marek Procházka; Josef Št?pánek; Milena Špírková

2007-01-01

381

Characterization of tungsten, tungsten oxide, and platinum cluster films fabricated by laser-assisted chemical vapor deposition  

Microsoft Academic Search

Optically transparent tungsten, tungsten oxide, and platinum thin films have been fabricated by laser-assisted chemical vapor deposition (LCVD) through multiphoton and\\/or single photon dissociation of organometallic precursors. The films were characterized by FTIR, Raman and UV-visible spectroscopies, refractive index measurements, transmission electron microscopy (TEM), and electron diffraction to elucidate the gas phase processes which govern deposition. These methods provide evidence

1992-01-01

382

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

10, Bellingham, WA 98227-0010, pp. 40-44. ElectriCOIL: An Advanced Chemical Iodine Laser Concept at Urbana-Champaign, Urbana, IL 61801 ABSTRACT Advanced chemical iodine laser technology will logicallyCOIL will reduce weight and simplify both military and commercial chemical iodine laser systems. Potential cost

Carroll, David L.

383

Standoff detection of explosives and chemical agents using broadly tuned external-cavity quantum cascade lasers (EC-QCLs)  

NASA Astrophysics Data System (ADS)

Civilian soft targets such as transportation systems are being targeted by terrorists using IEDs and suicide bombers. Having the capability to remotely detect explosives, precursors and other chemicals would enable these assets to be protected with minimal interruption of the flow of commerce. Mid-IR laser technology offers the potential to detect explosives and other chemicals in real-time and from a safe standoff distance. While many of these agents possess "fingerprint" signatures in the mid-IR (i.e. in the 3-20 micron regime), their effective interrogation by a practical, field-deployable system has been limited by size, complexity, reliability and cost constraints of the base laser technology. Daylight Solutions has addressed these shortcomings by developing compact, portable, broadly tunable mid-IR laser sources based upon external-cavity quantum cascade technology. This technology is now being applied by Daylight in system level architectures for standoff and remote detection of explosives, precursors and chemical agents. Several of these architectures and predicted levels of performance will be presented.

Takeuchi, Eric B.; Rayner, Timothy; Weida, Miles; Crivello, Salvatore; Day, Timothy

2007-10-01

384

Laser-stimulated chemical reaction I/sub 2/ + C/sub 2/H/sub 2/  

SciTech Connect

The laser-initiated chemical reaction of I/sub 2/ + C/sub 2/H/sub 2/ has been studied by exciting the B-X system of the I/sub 2/ molecule at 4880, 5145, and 6040 A, using the output from an Ar/sup +/ laser and a CW dye laser pumped by an Ar/sup +/ laser. At 5145 and 4880 A, the reaction products were mostly C/sub 2/H/sub 2/I/sub 2/ and a trace amount of C/sub 2/H/sub 2/I/sub 4/, which was greater at 4880 A than at 5145 A and satisfactorily correlated with the excited iodine atoms produced at these wavelengths; C/sub 2/H/sub 2/I/sub 2/ was the only product at 6040 A. A mechanism for the reaction of the laser-excited I/sub 2/ with the C/sub 2/H/sub 2/ has been proposed and, on the basis of thermal experiments, has been indicated to be nonthermal. 17 references, 2 figures.

Kushawaha, V.S.

1980-01-02

385

Laser-induced breakdown spectroscopy – An emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications  

Microsoft Academic Search

Laser induced breakdown spectroscopy (LIBS) is a simple spark spectrochemical sensor technology in which a laser beam is directed at a sample surface to create a high-temperature microplasma and a detector used to collect the spectrum of light emission and record its intensity at specific wavelengths. LIBS is an emerging chemical sensor technology undergoing rapid advancement in instrumentation capability and

Russell S. Harmon; Frank C. DeLucia; Catherine E. McManus; Nancy J. McMillan; Thomas F. Jenkins; Marianne E. Walsh; Andrzej Miziolek

2006-01-01

386

Volume 101, number 4.5 CHEMICAL PHYSICS LETTERS 28 October 1983 ENERGY DEPOSITION IN SO, VIA INTENSE INFRARED LASER MULTIPHOTON EXCITATION  

E-print Network

Volume 101, number 4.5 CHEMICAL PHYSICS LETTERS 28 October 1983 ENERGY DEPOSITION IN SO, VIA INTENSE INFRARED LASER MULTIPHOTON EXCITATION James V. TIETZ and Shill-1 CHU * Departnwnr of Ckmisr using the MPPA indicates thnt col- lisionless MPD xxill not be achieved at laser field strengths under

Chu, Shih-I

387

Investigation of the Production of O2(a1 ) in Rectangular  

E-print Network

Oxygen- Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm-section and multi-circular tube discharges. I. Introduction The electrically driven oxygen-iodine laser (Electric as O2(a)]. Since the first reporting of a viable electric discharge-driven oxygen-iodine laser system

Carroll, David L.

388

ElectricOIL Performance Enhancement via Increases in g0L David L. Carrolla  

E-print Network

Oxygen-Iodine Laser (ElectricOIL) technology have significantly increased laser power output was observed giving a peak outcoupled power of 538 W. Keywords: electric discharge oxygen-iodine laser, ElectricOIL, EOIL, DOIL, singlet delta oxygen 1. INTRODUCTION The electrically driven oxygen-iodine laser

Carroll, David L.

389

Bioactive Ti metal analogous to human cancellous bone: Fabrication by selective laser melting and chemical treatments  

Microsoft Academic Search

Selective laser melting (SLM) is a useful technique for preparing three-dimensional porous bodies with complicated internal structures directly from titanium (Ti) powders without any intermediate processing steps, with the products being expected to be useful as a bone substitute. In this study the necessary SLM processing conditions to obtain a dense product, such as the laser power, scanning speed, and

Deepak K. Pattanayak; A. Fukuda; T. Matsushita; M. Takemoto; S. Fujibayashi; K. Sasaki; N. Nishida; T. Nakamura; T. Kokubo

2011-01-01

390

Remote explosive and chemical agent detection using broadly tunable mid-infrared external cavity quantum cascade lasers  

NASA Astrophysics Data System (ADS)

Terrorists both with IEDs and suicide bombers are targeting civilian infrastructures such as transportation systems. Although explosive detection technologies exist and are used effectively in aviation, these technologies do not lend themselves well to protecting open architecture soft targets, as they are focused on a checkpoint form factor that limits throughput. However, remote detection of explosives and other chemicals would enable these kinds of targets to be protected without interrupting the flow of commerce. Tunable mid-IR laser technology offers the opportunity to detect explosives and other chemicals remotely and quickly. Most chemical compounds, including explosives, have their fundamental vibrational modes in the mid-infrared region (3 to 15?m). There are a variety of techniques that focus on examining interactions that have proven effective in the laboratory but could never work in the field due to complexity, size, reliability and cost. Daylight Solutions has solved these problems by integrating quantum cascade gain media into external tunable cavities. This has resulted in miniaturized, broadly tunable mid-IR laser sources. The laser sources have a capability to tune to +/- 5% of their center wavelength, which means they can sweep through an entire absorption spectrum to ensure very good detection and false alarm performance compared with fixed wavelength devices. These devices are also highly portable, operate at room temperature, and generate 10's to 100's of mW in optical power, in pulsed and continuous wave configurations. Daylight Solutions is in the process of developing a variety of standoff explosive and chemical weapon detection systems using this technology.

Rayner, Timothy; Weida, Miles; Pushkarsky, Michael; Day, Timothy

2007-04-01

391

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

392

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

393

Continuous-wave operation of AlGaInP/GaInP quantum-well lasers grown by metalorganic chemical vapor deposition using tertiarybutylphosphine  

NASA Astrophysics Data System (ADS)

Strained AlGaInP/GaInP multiple-quantum-well laser structures have been grown by metalorganic chemical vapor deposition using teriarybutylphosphine as the phosphorus precursor and ridge waveguide lasers of 4 ?m wide have been fabricated. Room temperature continuous-wave lasing has been obtained with an emission wavelength of about 670 nm. A single-facet output power of more than 18 mW has been achieved for an as-cleaved laser chip. It can be concluded that it is feasible to fabricate AlGaInP red lasers using less toxic metalorganic source tertiarybutylphosphine in parallel with conventionally used highly toxic PH3.

Dong, Jian-Rong; Teng, Jing-Hua; Chua, Soo-Jin; Foo, Boon-Chin; Wang, Yan-Jun; Zhang, Lian-Wen; Yuan, Hai-Rong; Yuan, Shu

2004-05-01

394

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

395

Detection of chemical changes in bone after irradiation with Er,Cr:YSGG laser  

NASA Astrophysics Data System (ADS)

The use of laser for bone cutting can be more advantageous than the use of drill. However, for a safe clinical application, it is necessary to know the effects of laser irradiation on bone tissues. In this study, the Fourier Transform Infrared spectroscopy (FTIR) was used to verify the molecular and compositional changes promoted by laser irradiation on bone tissue. Bone slabs were obtained from rabbit's tibia and analyzed using ATR-FTIR. After the initial analysis, the samples were irradiated using a pulsed Er,Cr:YSGG laser (2780nm), and analyzed one more time. In order to verify changes due to laser irradiation, the area under phosphate (1300-900cm-1), amides (1680-1200cm-1), water (3600-2400cm-1), and carbonate (around 870cm-1 and between 1600-1300cm-1) bands were calculated, and normalized by phosphate band area (1300-900cm-1). It was observed that Er,Cr:YSGG irradiation promoted a significant decrease in the content of water and amides I and III at irradiated bone, evidencing that laser procedure caused an evaporation of the organic content and changed the collagen structure, suggesting that these changes may interfere with the healing process. In this way, these changes should be considered in a clinical application of laser irradiation in surgeries.

Benetti, Carolina; Santos, Moises O.; Rabelo, Jose S.; Ana, Patrícia A.; Correa, Paulo R.; Zezell, Denise M.

2011-03-01

396

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers  

NASA Technical Reports Server (NTRS)

This work is directed toward the design and chemical synthesis of new media for solar-pumped I* lasers. In view of the desirability of preparing a perfluoroalkyl iodide absorbing strongly at 300 nm, the relationship betwen perfluoroalkyl iodide structure and the corresponding absorption wavelength was reexamined. Analysis of existing data suggests that, in this family of compounds, the absorption maximum shifts to longer wavelength, as desired, as the C-I bond in the lasant is progressively weakened. Weakening of the C-I bond correlates, in turn, with increasing stability of the perfluoroalkyl radical formed upon photodissociation of the iodide. The extremely promising absorption characteristics of perfluoro-tert-butyl iodide can be accounted for on this basis. A new technique of diode laser probing to obtain precise yields of I* atoms in photodissociation was also developed.

Shiner, C. S.

1985-01-01

397

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

398

Synthesis of single wall carbon nanotubes with invariant diameters using a modified laser assisted chemical vapour deposition route  

NASA Astrophysics Data System (ADS)

We have developed a fast and facile CO2 laser assisted chemical vapour deposition LA-CVD synthesis route for carbon nanotubes, which requires no supplementary hydrocarbon feedstock. The technique yields a broad range of carbon nanostructures due to the sharp thermal gradient afforded by the laser. This in turn provides useful information on the changes in nanostructure formation with temperature. A distinct and unusual aspect of this route is that, unlike other synthesis approaches, the obtained single wall carbon nanotube diameters show no dependence on the synthesis parameters and this is attributed to their nucleation via fullerenes and fullerene caps. The results suggest fullerene nucleation may also be active in other CVD synthesis routes.

Rümmeli, M. H.; Kramberger, C.; Löffler, M.; Kalbác, M.; Hübers, H.-W.; Grüneis, A.; Barreiro, A.; Grimm, D.; Ayala, P.; Gemming, T.; Schäffel, F.; Dunsch, L.; Büchner, B.; Pichler, T.

2006-11-01

399

A study of dynamics and chemical reactions in laser-ablated PbTiO3 plume by optical-wavelength-sensitive CCD photography  

Microsoft Academic Search

The plasma plume formed by pulsed laser ablation of PbTiO3 (PT) in ambients of oxygen, nitrogen, and argon was studied by using a CCD camera. Two optical filters with different transmittance bands were used to identify the excitation, dissociation, ionization, and, especially, the chemical reactions in the plume. The results show that the atomic processes and chemical reaction mechanisms in

X. Y. Chen; Z. C. Wu; Z. G. Liu; X. Y. Lei; Z. S. Sha

1998-01-01

400

Volume 70, number 1 CHEMICAL PHYSICS LETI'ERS 15 February 1980 SEMICLASSICAL THEORY OF WBRATIONAL COLLISIONS IN A LASER FtELD  

E-print Network

are respectively the dipole moment and 205 #12;Volume 70, number 1 CHEMICAL PHYSICS LETTERS 15 February 1980Volume 70, number 1 CHEMICAL PHYSICS LETI'ERS 15 February 1980 SEMICLASSICAL THEORY OF WBRATIONAL COLLISIONS IN A LASER FtELD shlh-I CHU Department of CJzemJstry. UnwersHy of Kansas. Lawrence. Kansas 6604

Chu, Shih-I

401

Atmospheric propagation for tactical directed-energy applications  

Microsoft Academic Search

As a corollary to the USAF strategic Airborne Laser program, Boeing has been analyzing the use of the Chemical Oxygen Iodine Laser for tactical scenarios. These include its use in an airborne platform operating against low flying cruise missiles and miscellaneous ground targets, as well as on a mobile ground platform providing support defense against shorter-range rocket attack. Practical design

Alan J. MacGovern; David A. Nahrstedt; Michael M. Johnson

2000-01-01

402

A method for comparison of computational fluid dynamic simulation and planar laser induced fluorescence images for a supersonic flowfield  

NASA Astrophysics Data System (ADS)

Non-intrusive diagnostics, such as planar laser induced fluorescence (PLIF) provide an excellent means to interrogate flowfields with minimal perturbation to the thermodynamic state of the gas. In the case of PLIF, the diagnostic can provide multidimensional information regarding the spread of a tracer, such as I II, providing an excellent means for quantifying mixing between multiple streams of gases. The images obtained using PLIF can in turn be used to compare directly to images generated by computational fluid dynamic (CFD) simulations for the experiment, providing an excellent mechanism to compare CFD to experiment. An issue that exists with interpreting PLIF images from compressible flows is that the local density and temperature of the I II varies throughout the field of imaging, leading to variations in the rate of fluorescence and the rate of quenching of the excited state of I II. These variations lead to local changes in the number of photons generated during the course of the laser pulse that excites the I II, beyond the variation due to the varying density of I II. Thus, when comparing PLIF images for compressible flows with CFD simulation data, some effort should be made to ensure that the CFD image reflects the local variations in photon production that occur in compressible flows. A method is presented here where a CFD simulation data for a compressible PLIF experiment is used to predict the local photon production during the course of interrogating laser pulse. The experiment consists of a chemical oxygen-iodine laser mixing nozzle utilizing Mach 3 injection of a He/I II mixture into a Mach 2.5 crossflow with a mixture of He and O II and has strong compressibility. The method utilizes numerical solutions for the ordinary differential equations describing the state-to-state processes within the I II fluorescence process where I II(X) is pumped to the I II(B), fluoresces and is quenched. These equations are solved locally within the flowfield predicted by the CFD simulation to predict the variations within the photon production, and compare directly with PLIF images from the experiment.

Madden, Timothy J.; Noren, Carrie A.; Emmert, Luke; Heaven, Michael C.

2008-02-01

403

SITE - EMERGING TECHNOLOGIES: LASER INDUCED PHOTO- CHEMICAL OXIDATIVE DESTRUCTION OF TOXIC ORGANICS IN LEACHATES AND GROUNDWATERS  

EPA Science Inventory

The technology described in this report has been developed under the Emerging Technology Program of the Superfund Innovative Technology Evaluation (SITE) Program to photochemically oxidize organic compounds in wastewater by applying ultraviolet radiation using an excimer laser. T...

404

Thermal-mechanical and physical-chemical properties of phosphate laser glasses  

SciTech Connect

A compositional study of the effects of various network formers on the physical properties of phosphate laser glasses used in fusion research lasers is reported. The network formers include P{sub 2}O{sub 5}, Al{sub 2}O{sub 3}, SiO{sub 2} and B{sub 2}O{sub 3} and most glass compositions are metaphosphates or near-ultraphosphates. We have chosen Schott's commercial LG-750 laser glass as a reference composition. The results show that laser glasses having improved physical properties compared to LG-750 can be prepared by decreasing the Al{sub 2}O{sub 3} and increasing the P{sub 2}O{sub 5} content. Figures-of-merit are used to characterize the relative improvements of the various glasses studied. 17 refs., 11 figs.

Elder, M.L.; Campbell, J.H.; Payne, S.A.; Wilke, G.D. (Lawrence Livermore National Lab., CA (United States)); Hayden, Y.T. (Schott Glass Technologies, Inc., Duryea, PA (United States))

1991-07-12

405

Experimental study and chemical application of GaAs semiconductor laser treating trigeminal neuralgia  

NASA Astrophysics Data System (ADS)

GaAs semiconductor laser was used to treat trigeminal neuralgia with an effective rate of 91.1%, and no side effects were found in 67 cases. Changes in and the recovery of the trigeminal nerve cell were studied with light and electromicroscope. Discussed in this article are the time length and quantity of laser treatment with low power. Experimental study and clinical application of the GaAs semiconductor laser have been carried out in our department since 1987. One-hundred-fifteen patients with various diseases in the maxillofacial region (including 67 cases of trigeminal neuralgia) have been treated with satisfactory effects and without any side-effects. The wavelength of the laser is 904 mu, the largest pulse length is 200 mu, and the average power is 2000 HZ.

Qiu, Ke-Qum; Cao, Shu-Chen; Wang, Hu-Zhong; Wang, Ke-Ning; Xiao, Ton-Ha; Shen, Ke-Wei

1993-03-01

406

Theoretical modeling of chemical generators producing O2(1Delta) at high pressure for chemically pumped iodine lasers  

Microsoft Academic Search

A theoretical model is developed for chemical generators producing O2(1Delta) at high pressure. The model treats different types of generators, e.g., bubble-column, film, aerosol, and jet generators. The main factor affecting the O2(1Delta) yield under high pressure is liquid-phase quenching enhanced by depletion of HO2(-) ions near the gas\\/liquid interface. Simple analytical expressions are derived for the O2(1Delta) yield at

B. D. Barmashenko; S. Rosenwaks

1993-01-01

407

A new energy transfer chemical laser at 1.315 ?m  

Microsoft Academic Search

CW laser action has been demonstrated on the electronic I?(2P1\\/2)?I(2P3\\/2) transition of atomic iodine at 1.315 ?m from the NCl (a1?)+I(2P 3\\/2) energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3, was injected into a flow of iodine and chlorine atoms. The measured laser output power was 180 mW.

Thomas L. Henshaw; Gerald C. Manke II; Timothy J. Madden; Michael R. Berman; Gordon D. Hager

2000-01-01

408

Preparation of superhard B x C y fibers by microvortex-flow hyperbaric laser chemical vapor deposition  

Microsoft Academic Search

A novel class of freestanding BxCy fibers was prepared by hyperbaric-pressure laser chemical vapor deposition. Utilizing mixtures of diborane and helium with hydrocarbons, such as methane, ethene, and pentane, BxCy-alloy fibers were prepared at axial rates of up to 12.2 ?m\\/s. Regions of kinetically-limited and transport-limited growth were identified, and the activation energy for deposition from B2H6+C5H20+He mixtures (at relative concentrations

James L. Maxwell; Craig A. Chavez; Robert W. Springer; Karlene R. Maskaly; Dan Goodin

2007-01-01

409

*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 oxygen-iodine laser, COIL, ElectriCOIL, RF excitation of oxygen, singlet-delta oxygen 1.0 INTRODUCTION

Carroll, David L.

410

Three-dimensional laser chemical vapor deposition of nickel-iron alloys  

SciTech Connect

A systematic study of the composition of Ni-Fe steel microstructures grown from iron pentacarbonyl and nickel tetracarbonyl by direct laser-induced pyrolysis is presented. The partial pressures of both precursors were varied from 2 to 40 mbar, resulting in needles of iron, nickel, and iron-nickel alloys. An Ar+ laser was employed at incident powers of 100 to 600 mW. Auger Spectroscopy and a microprobe were used to determine the composition of the needles vs. partial pressure and laser power. Composition was also measured along the length of the rods to determine temperature changes during needle growth. This latter effect is useful in modelling the heat flow mechanisms during 3-dimensional laser CVD, as the threshold decomposition temperatures of Fe(CO){sub 5} and Ni(CO){sub 4} differ and the composition of the rods affects their thermal conductivity. In some iron samples, periodic banded structures were observed along the length of the rods, indicative of periodic melting. Axial deposition rates were also measured relative to laser power density, and rates up to 40 {micro}m/s were achieved. Photolysis in the gas phase was observed for the iron-nickel carbonyl mixture, and was largely eliminated with a high-pass UV filter at 420 nm. Additional disassociation of the carbonyl groups produced carbon soot near the reaction zone, but only for high nickel carbonyl concentrations. Convective cooling of the needles during growth was determined to be the primary heat transfer mechanism.

Maxwell, J.L.; Pegna, J.; Deangelis, D.A.; Messia, D.V. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Integrated Electronics and Electronics Manufacturing

1996-12-31

411

Influence of laser power on the orientation and microstructure of CeO 2 films deposited on Hastelloy C276 tapes by laser chemical vapor deposition  

NASA Astrophysics Data System (ADS)

CeO 2 films were prepared on LaMnO 3/MgO/Gd 2Zr 2O 7 multi-coated Hastelloy C276 tapes by laser chemical vapor deposition at different laser power ( PL) from 46 to 101 W. Epitaxial (1 0 0) CeO 2 films were prepared at PL = 46-93 W (deposition temperature, Tdep = 705-792 K). Epitaxial CeO 2 films had rectangular-shaped grains at PL = 46-77 W ( Tdep = 705-754 K), while square-shaped grains were obtained at PL = 85-93 W ( Tdep = 769-792 K). CeO 2 films showed a columnar microstructure. Epitaxial (1 0 0) CeO 2 films with rectangular grains exhibited full width at half maximum of ?-scan on (2 0 0) reflection and ?-scan on (2 2 0) reflection of 3.4-3.2° and 6.0-7.2°, respectively. The deposition rate of the epitaxial (1 0 0) CeO 2 films had a maximum of 4.6 ?m h -1 at PL = 77 W ( Tdep = 754 K).

Zhao, Pei; Ito, Akihiko; Tu, Rong; Goto, Takashi

2010-08-01

412

Efficient GaAs solar cells formed by UV laser chemical doping  

NASA Astrophysics Data System (ADS)

GaAs p-n junctions have been formed by ArF and XeF excimer laser radiation, which releases S atoms by the dissociation of H2S gas while simultaneously heating the substrate to allow incorporation of the S dopant. In addition to fabricating solar cells having AM1 efficiencies of 10.8% from these junctions, the process can produce doped GaAs layers with sheet resistances as low as 30 Ohms/square unit. This efficiency compares favorably with the 12% value obtained for ion-implanted, CW Nd:YAG laser-annealed GaAs solar cells of smaller area.

Deutsch, T. F.; Fan, J. C. C.; Ehrlich, D. J.; Turner, G. W.; Chapman, R. L.; Gale, R. P.

1982-04-01

413

Fabrication of honeycomb texture on poly-Si by laser interference and chemical etching  

NASA Astrophysics Data System (ADS)

In this paper, we present a laser-interference method to fabricate honeycomb textures on poly-Si wafer for reflection reduction. When exposed to three interfering pulsed laser beams at 532 nm, the Si surface was periodically melted in accordance with the interference pattern. As a result, concave holes were generated on the surface because the melted material overflowed and condensed at the periphery. Subsequent acid etching revealed uniform and clean honeycomb textures. The texture depth could be controlled by varying the irradiation condition and a minimum reflectance of 10% was obtained. Transmission electron microscopy analysis showed that no irradiation-induced damage remained after etching. This approach can be a cost-effective alternative to lithographic processes for fabricating high-efficiency poly-Si solar cells.

Yang, Bogeum; Lee, Myeongkyu

2013-11-01

414

Measurement of fluorine atom concentrations and reaction rates in chemical laser systems  

Microsoft Academic Search

The line positions of all three components of the fluorine atom ground state fine structure transition have been measured by diode laser absorption spectroscopy, using a water vapor pure rotational line at 404.077\\/cm as a wavelength reference. These results imply a spin orbit splitting for fluorine of 404.142 + or - 0.005\\/cm. The results for the line positions are in

A. C. Stanton; J. C. Wormhoudt; J. W. Duff

1982-01-01

415

Laser-Shot-Induced Chemical Reactions inside Nanotubes: a TDDFT investigation  

NASA Astrophysics Data System (ADS)

We present the application of the time-dependent density functional theory (TDDFT) on ultrafast laser pulse which induces dynamics in molecules encapsulated by a nanotube. A strong laser pulse polarized perpendicular to the tube axis induces a giant bond-stretch of an HCl molecule inside both C and BN nanotubes. Depending on the initial orientation of the HCl molecule, the subsequent laser-induced dynamics is different [1]. We also observed a radial motion of the nanotube and vacancies appear on the tube wall when the HCl is perpendicular to tube axis. Furthermore, the disintegration of HCl molecules took place when their molecular axis tilted to tube axis. These simulations are important to analyze light-induced nanochemistry and manipulation of nanostructures encapsulated in organic and inorganic nanotubes. The computational scheme used in present work was a combination of the molecular dynamics and real-time propagation of electron wave functions under presence of strong optical field [2,3]. The energy conservation rule was checked to monitor the numerical stability. [1] Y. Miyamoto, H. Zhang, and A, Rubio, submitted., [2] O. Sugino and Y. Miyamoto, Phys. Rev. B59, 2579 (1999). [3] A. Castro, E. Rasanen, A. Rubio and E. K. U. Gross, Eur. Phys. Lett. 87, 53001 (2009).

Zhang, Hong; Miyamoto, Yoshiyuki; Rubio, Angel

2011-03-01

416

Volume 125, number2 CHEMICAL PHYSICS LETTERS 28 March 1986 VELOCITY ~O~U~~ON LASER ~PE~OSCOPY OF VIB~~~NALLY EXCITED CF +  

E-print Network

Volume 125, number2 CHEMICAL PHYSICS LETTERS 28 March 1986 VELOCITY ~O~U~~ON LASER ~PEIium/CsF, discharge by velocity moduiation laser spectroscopy. A total of 56 transitions has been fitted to Dunham laser spectroscopy, and the rotational spectrum has recently been studied by mummer and co-workers [5

Cohen, Ronald C.

417

Analysis of chemical degradation mechanism within sky blue phosphorescent organic light emitting diodes by laser-desorption\\/ionization time-of-flight mass spectrometry  

Microsoft Academic Search

We present an investigation of the intrinsic chemical degradation mechanisms of phosphorescent OLEDs based on the common sky blue emitter bis(2-(4,6-difluorophenyl)pyridyl-N,C2?)iridium(III)picolinate (FIrpic). The OLEDs are investigated using the laser-desorption\\/ionization time-of-flight mass spectrometry. The comparison between the collected spectra for electrically aged and unaged OLEDs allows the identification of different reaction products, like fragments which are mainly related to the chemical

Ines Rabelo de Moraes; Sebastian Scholz; Björn Lüssem; Karl Leo

2011-01-01

418

Fabrications of Si Thin-Film Solar Cells by Hot-Wire Chemical Vapor Deposition and Laser Doping Techniques  

NASA Astrophysics Data System (ADS)

In this paper, we report a novel low-temperature process for fabricating a Si thin-film solar cell on a glass substrate. The cell structure was composed of glass/Al/p-i-n Si/Ag (grid), where the Si intrinsic layer was deposited by hot-wire chemical vapor deposition. All the doped Si layers were produced using a postgrowth laser-doping process. The hot-wire-deposited amorphous, microcrystalline and polycrystalline Si films showed significant differences in band gap and structural properties as determined by Raman spectroscopy, spectral optical transmission measurements, and transmission electron microscopy. The corresponding crystalline volume fractions were 93, 73, and 12%, respectively. It was found that the best solar cells were fabricated with a Si intrinsic layer deposited at the transition from microcrystalline to polycrystalline regimes. A preliminary efficiency of 1.9% was obtained for an n-i-p structured solar cell on an untextured glass substrate.

Lien, Shui?Yang; Wuu, Dong?Sing; Mao, Hsin?Yuan; Wu, Bing?Rui; Lin, Yen?Chia; Hseih, In?Cha; Horng, Ray?Hua

2006-04-01

419

Comparison of the structural and chemical composition of two unique micro/nanostructures produced by femtosecond laser interactions on nickel  

SciTech Connect

The structural and chemical composition of two unique microstructures formed on nickel, with nanoscale features, produced using femtosecond laser surface processing (FLSP) techniques is reported in this paper. These two surface morphologies, termed mounds and nanoparticle-covered pyramids, are part of a larger class of self-organized micro/nanostructured surfaces formed using FLSP. Cross-sections of the structures produced using focused ion beam milling techniques were analyzed with a transmission electron microscope. Both morphologies have a solid core with a layer of nanoparticles on the surface. Energy dispersive X-ray spectroscopy by scanning transmission electron microscopy studies reveal that the nanoparticles are a nickel oxide, while the core material is pure nickel.

Zuhlke, Craig A.; Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)] [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

2013-09-16

420

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

421

Recovery of a chemical vapor deposited diamond detection system from strong pulses of laser produced x rays  

NASA Astrophysics Data System (ADS)

We are planning an experiment that will study the response of a chemical vapor deposited (CVD) diamond detector to a strong x-ray pulse followed by a second weaker pulse arriving 50-300ns later, with a contrast in amplitude of about 1000. These tests will be performed at the LLNL Jupiter laser facility and are intended to produce charge carrier densities similar to those expected during a DT implosion at the National Ignition Facility, where a large 14.1MeV neutron pulse is followed by a weak downscattered neutron signal produced by slower 6-10MeV neutrons. The areal density ?R is proportional to the number of downscattered neutrons. The challenge of measuring ?R resides consequently in the effects of the first strong pulse on the weaker later pulse, which may include the saturation of the diamond wafer, saturation of the oscilloscope, or saturation of the associated power and data acquisition electronics. We are presenting the preparation of a double pulse experiment that will use a system of three polycrystalline CVD diamond detectors irradiated by 8.6keV x rays produced by two laser beams incident on a zinc target.

Dauffy, L. S.; Koch, J. A.; Izumi, N.; Tommasini, R.

2006-10-01

422

CONTROL OF LASER RADIATION PARAMETERS: Two-coordinate control of the radiation pattern of a chemical non-chain electric-discharge DF laser by using space—time light modulators  

NASA Astrophysics Data System (ADS)

The results of studies of radiation parameters of a chemical non-chain DF laser (emitting in the range from 3.5 to 4.1 ?m) with an intracavity control of the radiation pattern with the help of spatiotemporal modulators based on PLZT electrooptic ceramics are presented.

Alekseev, V. N.; Kotylev, V. N.; Liber, V. I.

2008-07-01

423

Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems Delamination of Thin Films Using Laser  

E-print Network

#12;Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems Delamination of Thin pull, double cantilever, and nanoindentation tests.1 Though these tests are commonly employed, they all size of a few nanometers, new techniques to measure interface adhesion of such thin films are warranted

Sottos, Nancy R.

424

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

425

Possibilities of improving the performance of an autonomous cw chemical DF laser by replacing the slot nozzles by the ramp ones in the nozzle array  

SciTech Connect

The results of a comparative numerical study of the performance of an autonomous cw chemical DF laser are obtained by simulating the processes in the nozzles and laser cavity where several configurations of slot and ramp nozzle arrays are employed. Three-dimensional Navier-Stokes equations solved with the Ansys CFX software are used to describe the reacting multicomponent flow in the nozzles and laser cavity. To investigate lasing characteristics, a supplementary code is developed and is used to calculate the radiation intensity in the Fabry-Perot resonator, taking into account its nonuniform distribution along the aperture width and height. It is shown that the use of the nozzle array consisting of ramp nozzles, which, in contrast to the slot nozzles, provide enhanced mixing of the reactants makes it possible to improve the laser performance in the case of a high-pressure (more than 15 Torr) active medium. (control of radiation parameters)

Bashkin, A S; Gurov, L V; Kurdyukov, M V

2011-08-31

426

JOURNALDE PHYSIQUE IV ColloqueC7, supplkmentau Journalde PhysiqueIII, Vol. 1,dkembre 1991  

E-print Network

. The main processes which determine the gain in the active media of the Chemical Oxygen Iodine Laser (COIL model of the molecular iodine dissociation in the singlet oxygen(S0) media is considered. The mean number of SO molecules, which are spent to dissociate one iodine molecule, is evaluated, depending

Paris-Sud XI, Université de

427

High-gain high-pressure highly efficient COIL  

Microsoft Academic Search

The activity of development a COIL with high potential recovered pressure, high gain and efficiency is described. Two nozzle banks with conical supersonic nozzles for the driver nitrogen but with different nozzle arrangements have been developed for generation of the gain flow of chemical oxygen-iodine laser. The nozzle banks were supplied by oxygen flow from the cross-flow singlet oxygen generator

Marsel V. Zagidullin; Valery D. Nikolaev; Michael I. Svistun; Nikolai A. Khvatov; Gordon D. Hager

2004-01-01

428

Forced convection and transport effects during hyperbaric laser chemical vapor deposition  

SciTech Connect

This work explores mass transport processes during HP-LCYD, including the transverse forced-flow of precursor gases through a nozzle to enhance fiber growth rates. The use of laser trapping and suspension of nano-scale particles in the precursor flow is also described, providing insights into the nature of the gas flow, including jetting from the fiber tip and thermodiffusion processes near the reaction zone. The effects of differing molecular-weight buffer gases is also explored in conjunction with the Soret effect, and it is found that nucleation at the deposit surface (and homogeneous nucleation in the gas phase) can be enhanced/ retarded, depending on the buffer gas molecular weight. To demonstrate that extensive microstructures can be grown simultaneously, three-dimensional fiber arrays are also grown in-parallel using diffractive optics--without delatory effects from neighboring reaction sites.

Maxwell, James L [Los Alamos National Laboratory; Chavez, Craig A [Los Alamos National Laboratory; Espinoza, Miguel [Los Alamos National Laboratory; Black, Marcie [Los Alamos National Laboratory; Maskaly, Karlene [Los Alamos National Laboratory; Boman, Mats [UPPSALA UNIV

2009-01-01

429

02(1D) generation mechanisms in the chemically pumped iodine laser  

Microsoft Academic Search

The reactivity of Cl2 with aqueous H2O2, both with and without added base, was investigated in a static bulb. The rate data for Cl2 absorption in these solutions are explained in terms of a diffusion-reaction model, and the results are consistent with the assumption that the reaction responsible for O2(1D) production in the O2(1D) generator utilized in the chemically pumped

R. J. Richardson; J. D. Kelley; C. E. Wiswall

1981-01-01

430

JOURNAL DE PHYSIQUE CoZZoque C9, suppl6ment au nO1l, Tome 41, novembre 1980, page C9-51 MODELING OF CW HF CHEMICAL LASERS WITH R Q W I D N A L NDNEQULUBRLUM  

E-print Network

OF CW HF CHEMICAL LASERS WITH R Q W I D N A L NDNEQULUBRLUM Tien Tsai Yang RockweZZ ~nternutiona relaxation time constant model of Hough, for pulsed chemical lasers, has been extended to CW diffusion been demonstrated. I. INTRODUCTION Early modeling of CW diffusion chemical lasers treated

Paris-Sud XI, Université de

431

Chemical imaging of trichome specialized metabolites using contact printing and laser desorption/ionization mass spectrometry.  

PubMed

Cell transfer by contact printing coupled with carbon-substrate-assisted laser desorption/ionization was used to directly profile and image secondary metabolites in trichomes on leaves of the wild tomato Solanum habrochaites. Major specialized metabolites, including acyl sugars, alkaloids, flavonoids, and terpenoid acids, were successfully detected in positive ion mode or negative ion mode, and in some cases in both modes. This simple solvent-free and matrix-free sample preparation for mass spectrometry imaging avoids tedious sample preparation steps, and high-spatial-resolution images were obtained. Metabolite profiles were generated for individual glandular trichomes from a single Solanum habrochaites leaf at a spatial resolution of around 50 ?m. Relative quantitative data from imaging experiments were validated by independent liquid chromatography-mass spectrometry analysis of subsamples from fresh plant material. The spatially resolved metabolite profiles of individual glands provided new information about the complexity of biosynthesis of specialized metabolites at the cellular-resolution scale. In addition, this technique offers a scheme capable of high-throughput profiling of metabolites in trichomes and irregularly shaped tissues and spatially discontinuous cells of a given cell type. PMID:24220760

Li, Chao; Wang, Zhenzhen; Jones, A Daniel

2014-01-01

432

Laser-induced damage to transparent polymers: chemical effect of short-pulsed (Q-switched) Nd:YAG laser radiation on ophthalmic acrylic biomaterials. I. A review.  

PubMed

The use of short-pulsed lasers in ophthalmic surgery inspired and called for research on the damage inflicted by the laser radiation upon the acrylic polymers from which artificial intraocular lenses are made. The possible release of toxic monomers by laser-induced depolymerization is of great concern but past investigations of this phenomenon have been very limited. The present knowledge of various types of laser-induced damage to transparent polymers is reviewed with particular emphasis on the acrylic materials and intraocular lenses. PMID:2205301

Chirila, T V; Constable, I J; van Saarloos, P P; Barrett, G D

1990-07-01

433

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

434

Chemical composition and antimicrobial activity of the extracts of Kefe cumin (Laser trilobum L.) fruits from different regions.  

PubMed

Structural properties (using gas chromatographic analyses: gas chromatography and gas chromatography-mass spectrometry) of some compounds (pure chemicals, essential oils, extracts, etc.) and systematic investigation of antimicrobial activities (with agar dilution and agar diffusion disc methods) were determined in the fruits of Kefe cumin (Laser trilobum L.) obtained from different regions (Germany, India, and Turkey). The main components were established as limonene (41.03-72.24%) and perillaldehyde (4.23-32.75%) in the essential oils determined by gas chromatography-mass spectrometry. Mineral contents in the fruits were determined by inductively coupled plasma atomic emission spectrometer. It was determined that the fruits were rich in potassium, calcium, phosphorus, magnesium, sodium, arsenic and aluminium minerals. The highest sodium content was found to be 9,261.28 mg/kg in the samples obtained from Turkey, but the potassium content of the samples from Germany and India was higher than that of Kefe cumin fruits obtained from Turkey. The fruit extracts had a significant antimicrobial effect on pathogen bacteria such as Staphylococcus aureus, Proteus vulgaris (FMC 1), Proteus mirabilis, Bacillus cereus (FMC 19), Aeromonas hydrophila (ATCC 7965), Enterococcus faecalis (ATCC 15753), Klebsiella pneumoniae (FMC 5), Salmonella typhimurium, Enterobacter aerogenes (CCM 2531) and Escherichia coli (ATCC 8739), whereas no significant antimicrobial effect of the essential oils was observed. PMID:19817640

Parlatan, Ahmet; Sariçoban, Cemalettin; Ozcan, Mehmet Musa

2009-11-01

435

A study of laser-induced blue emission with nanosecond decay of silicon nanoparticles synthesized by a chemical etching method  

NASA Astrophysics Data System (ADS)

Silicon nanoparticles (Si NPs), exhibiting a strong visible photoluminescence (PL), have found many applications in optoelectronics devices, biomedical tags and flash memories. Chemical etching is a well-known method for synthesizing orange-luminescent, hydride-capped silicon nanoparticles (H/Si NPs). However, a blueshift in emission wavelength occurs when reducing the particle size to exciton Bohr radius or less. In this paper, we attempted to synthesize and characterize H/Si NPs that emit lower wavelengths at room temperature. We proved that our method succeeded in synthesizing H/Si NPs with emission in the blue region. The wavelength-resolved and time-resolved studies of the PL were executed for H/Si NPs in methanol (MeOH), pyridine (py) and furan, using the 355 nm pulsed radiation from a Nd:YAG laser. In addition, excitation wavelength-dependent and PL studies were executed using the spectrofluorometer with a xenon (Xe) broad band light source. We noticed solvent-dependent PL spectra with sharp peaks near 420 nm and a short lifetime less than 100 ns. The morphology and particle size were investigated by high resolution transmission electron microscope (HRTEM). Particles as small as one nanometer were observed in MeOH and py suspensions while two-nanometer particles were observed in the furan suspension.

Bagabas, Abdulaziz A.; Gondal, Mohammed A.; Dastageer, Mohammed A.; Al-Muhanna, Abdulrahman A.; Alanazi, Thaar H.; Ababtain, Moath A.

2009-09-01

436

A study of laser-induced blue emission with nanosecond decay of silicon nanoparticles synthesized by a chemical etching method.  

PubMed

Silicon nanoparticles (Si NPs), exhibiting a strong visible photoluminescence (PL), have found many applications in optoelectronics devices, biomedical tags and flash memories. Chemical etching is a well-known method for synthesizing orange-luminescent, hydride-capped silicon nanoparticles (H/Si NPs). However, a blueshift in emission wavelength occurs when reducing the particle size to exciton Bohr radius or less. In this paper, we attempted to synthesize and characterize H/Si NPs that emit lower wavelengths at room temperature. We proved that our method succeeded in synthesizing H/Si NPs with emission in the blue region. The wavelength-resolved and time-resolved studies of the PL were executed for H/Si NPs in methanol (MeOH), pyridine (py) and furan, using the 355 nm pulsed radiation from a Nd:YAG laser. In addition, excitation wavelength-dependent and PL studies were executed using the spectrofluorometer with a xenon (Xe) broad band light source. We noticed solvent-dependent PL spectra with sharp peaks near 420 nm and a short lifetime less than 100 ns. The morphology and particle size were investigated by high resolution transmission electron microscope (HRTEM). Particles as small as one nanometer were observed in MeOH and py suspensions while two-nanometer particles were observed in the furan suspension. PMID:19671981

Bagabas, Abdulaziz A; Gondal, Mohammed A; Dastageer, Mohammed A; Al-Muhanna, Abdulrahman A; Alanazi, Thaar H; Ababtain, Moath A

2009-09-01

437

A hyphenated optical trap capillary electrophoresis laser induced native fluorescence system for single-cell chemical analysis  

PubMed Central

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.

2013-01-01

438

Direct monitoring of chemical transformations by combining thin layer chromatography with nanoparticle-assisted laser desorption/ionization mass spectrometry.  

PubMed

A nanomaterial-assisted method that combines thin layer chromatography (TLC) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was developed to directly monitor chemical transformations. A substrate-dependent extraction strategy was studied and successfully used to identify target molecules from the depths of a developed TLC plate. By using this strategy, a hydrophobic sample of interest was enriched on the surface of the TLC plate in the presence of acetonitrile, in contrast to using water and methanol to identify hydrophilic samples. The successful enrichment of samples by specific solvents provided stable desorption/ionization efficiencies of compounds of interest and led to very good sensitivity near the attomole scale. The method was then used to monitor 4-dimethylaminopyridine (DMAP)-catalyzed acylation in preparation of bifunctional sulfonamides. The labile DMAP-acyl intermediate and final sulfonamide product were clearly identified on TLC plates without external purification or sample preparation. Furthermore, in combination with collision-induced dissociation (CID) to provide structural information, the technique was successfully used in the natural product discovery of anti-inflammatory flavonoids from Helminthostachys zeylanica, a traditional Chinese herb. The newly proposed method provides a very low background from silica supports or organic matrices in the low molecular weight range (100-1000 Da). The technique may greatly accelerate studies of metabolomics, drug discovery, and organic synthesis. PMID:23330148

Chen, Chun-Chi; Yang, Yung-Lin; Ou, Chun-Lin; Chou, Chih-Hung; Liaw, Chih-Chuang; Lin, Po-Chiao

2013-03-01

439

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

440

626. 2-nm pulsed operation (300 K) of an AlGaInP double heterostructure laser grown by metalorganic chemical vapor deposition  

SciTech Connect

Room-temperature pulsed laser operation of (Al/sub 0.55/Ga/sub 0.45/)/sub 0.5/In/sub 0.5/P /(Al/sub 0.17/Ga/sub 0.83/)/sub 0.5/In/sub 0.5/P / (Al/sub 0.55/Ga/sub 0.45/)/sub 0.5/In/sub 0.5/P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved. The lasing wavelength is 626.2 nm, which is the shortest ever reported for an AlGaInP double heterostructure laser. Threshold current density is 50 kA/cm/sup 2/ for a diode with a 20-..mu..m-wide and 200-..mu..m-long stripe.

Kobayashi, K.; Hino, I.; Suzuki, T.

1985-01-01

441

Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992  

NASA Technical Reports Server (NTRS)

Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

Wang, Charles P. (editor)

1993-01-01

442

Spatially-resolved temperature diagnostic for supersonic flow using cross-beam Doppler-limited laser saturation spectroscopy  

NASA Astrophysics Data System (ADS)

Optical techniques for measuring the temperature in three-dimensional supersonic reactive flows have typically depended on lineshape measurements using single-beam laser absorption spectroscopy. However, absorption over extended path lengths in flows with symmetric, turbulent eddies can lead to systematically high extracted temperatures due to Doppler shifts resulting from flow along the absorption path. To eliminate these problems and provide full three-dimensional spatial resolution, two variants of laser saturation spectroscopy have been developed and demonstrated, for the first time, which utilize two crossed and nearly copropogating laser beams. Individual rotational lines in the visible I2 X 1Sigma 0+g ? B 3pi 0+u transition were used to develop the two diagnostic to support research on the Chemical Oxygen-Iodine Laser (COIL), the weapon aboard the USAF Airborne Laser. Cross-Beam Saturation Absorption Spectroscopy (CBSAS) and Cross-Beam Inter-Modulated Fluorescence (CBIMF) were demonstrated as viable methods for recording the spectral signal of an I2 ro-vibrational line in a small three-dimensional volume using a tunable CW dye laser. Temperature is extracted by fitting the recorded signal with a theoretical signal constructed from the Doppler-broadened hyperfine components of the ro-vibrational line. The CBIMF technique proved successful for extracting the temperature of an I2-seeded, Ar gas flow within a small, Mach 2, Laval nozzle where the overlap volume of the two 1 mm diameter laser beams was 2.4 mm 3. At a test point downstream of the nozzle throat, the average temperature of 146 K +/- 1.5 K extracted from measurements of the I2 P(46) 17-1 spectral line compared favorably with the 138 K temperature calculated from isentropic, one-dimensional flow theory. CBIMF provides sufficient accuracy for characterizing the temperature of the gas flow in a COIL device, and could be applied to other areas of flow-field characterization and nozzle design. In contrast, the CBSAS signal was not sufficiently strong for reliable temperature extraction from the 2.4 mm3 overlap volume required in the nozzle experiments. Otherwise, the CBSAS technique could have greater success for application in flow field test environments that allow the use of a larger overlap-volume. CBIMF and CBSAS measurements were also made in a static cell at 293 K. At 50 mTorr of I2, the standard error in temperature from CBIMF measurements of the I2 P(46) 17-1 line was approximately 0.5 K. For CBSAS, the standard error in temperature was approximately 3 K at 50 mTorr of I2. Accuracy improved with increasing I2 pressure. In addition, the spatial-resolution capability of CBIMF and CBSAS was demonstrated in a static cell with an applied temperature gradient ranging from 300 to 365 K. Extracted temperatures were compared to thermocouple measurements at multiple positions in the gradient. Agreement between extracted temperatures and thermocouple measurements was better at the lower temperatures. Doppler-free measurements of several I2 hyperfine spectra were also performed to support development of the theoretical model. Saturation Absorption Spectroscopy was used to obtain Ar pressure broadening rates of 8.29 +/- 0.30 MHz/Torr for the I2 P(70) 17-1 hyperfine spectrum, and 10.70 +/- 0.41 MHz/Torr for the I2 P(10) 17-1 hyperfine spectrum.

Phillips, Grady T.

443

Physical and chemical processes in the working mixture of I2 laser of the UV-range with optical pumping  

NASA Astrophysics Data System (ADS)

A creation of a laser with a wavelength in UV spectrum field, as an element of lidar systems, can be perspective for monitoring of the atmospheric impurities. A gas laser on electronic transition D'-->A' (342 nm) with optical pumping (I2- laser) is based on collisional transfer of electronic energy between terms 3?u +(D) and 3?2g(D') of iodine molecules. The dependence of intensity of luminescence D'-->A' on pressure of buffer gas for 25 substances was studied. Effective working mixtures of I2-laser with optical pumping on a basis of perfluoroalkanes were found.

Alexandrov, B. S.; Baboshin, V. N.; Fokanov, V. P.; Pavlov, A. B.

2008-10-01

444

Total microcystins analysis in water using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry.  

PubMed

A new approach for the analysis of the cyanobacterial microcystins (MCs) in environmental water matrices has been developed. It offers a cost efficient alternative method for the fast quantification of total MCs using mass spectrometry. This approach permits the quantification of total MCs concentrations without requiring any derivatization or the use of a suite of MCs standards. The oxidation product 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) was formed through a Lemieux oxidation and represented the total concentration of free and bound MCs in water samples. MMPB was analyzed using laser diode thermal desorption-atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). LDTD is a robust and reliable sample introduction method with ultra-fast analysis time (<15 s sample(-1)). Several oxidation and LDTD parameters were optimized to improve recoveries and signal intensity. MCs oxidation recovery yield was 103%, showing a complete reaction. Internal calibration with standard addition was achieved with the use of 4-phenylbutyric acid (4-PB) as internal standard and showed good linearity (R(2)>0.999). Limits of detection and quantification were 0.2 and 0.9 ?g L(-1), respectively. These values are comparable with the WHO (World Health Organization) guideline of 1 ?g L(-1) for total microcystin-LR congener in drinking water. Accuracy and interday/intraday variation coefficients were below 15%. Matrix effect was determined with a recovery of 91%, showing no significant signal suppression. This work demonstrates the use of the LDTD-APCI-MS/MS interface for the screening, detection and quantification of total MCs in complex environmental matrices. PMID:24745740

Roy-Lachapelle, Audrey; Fayad, Paul B; Sinotte, Marc; Deblois, Christian; Sauvé, Sébastien

2014-04-11

445

First steps towards probing chemical systems and dynamics with free-electron laser radiation--case studies at the FLASH facility  

NASA Astrophysics Data System (ADS)

It is expected that free-electron laser (FEL) radiation with its unique properties will allow real-time tracking of structural changes during chemical reactions. The methods suggested being applied range from x-ray spectroscopy to diffraction. In order to reach this goal, in this work we will present our studies utilizing soft x-ray FEL radiation generated at the FLASH facility. We will present case studies of ultrafast x-ray diffraction on nanocrystalline lamellar assemblies of chemical relevance and heat dissipation studies on polymer foils (upon FLASH excitation) as revealed by ultrafast optical reflectivity. The extension of these studies to characterize in vacuum water jets during their interaction with FEL radiation will be given at the end if this overview. In conclusion, it can be stated that FLASH-FEL radiation can be used for studying chemical processes as long as the pulse duration is smaller than the characteristic time scales of destruction (ionization) and heat dissipation processes.

Hallmann, J.; Grübel, S.; Rajkovic, I.; Quevedo, W.; Busse, G.; Scholz, M.; More, R.; Petri, M.; Techert, S.

2010-10-01

446

Femtosecond Laser Etching of GaN and InGaN Thin Films Grown by Metal Organic Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

In this work a possibility of selective GaN and InGaN layer etching via femtosecond laser ablation was investigated. The samples of different indium concentrations were grown by metal organic chemical vapor deposition (MOCVD) technique on sapphire substrates. Prior to the laser treatment all samples were characterized by the means of photoluminescence and X-ray diffraction techniques. Further the laser-induced damage thresholds (LIDT) were estimated in multiple pulse (S-on-1) and single pulse (1-on-1) regimes for 1030, 515, and 343 nm wavelengths covering NIR--UV spectral regions. Experimental results indicated a strong interrelation between LIDT, indium concentration and band-gap. An abrupt change in single pulse LIDT is observed when the multi-photon absorption experiences transition from three to two photon absorption. Furthermore an overview of typical laser induced damage morphologies is performed and discussed. A selective smooth etching of GaN and InGaN layers was obtained when exposing with multiple pulses in UV range.

Š?iuka, Mindaugas; Grinys, Tomas; Dmukauskas, Mantas; Plerpait?, Viktorija; Melninkaitis, Andrius

2013-08-01

447

Femtosecond Laser Etching of GaN and InGaN Thin Films Grown by Metal Organic Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

In this work a possibility of selective GaN and InGaN layer etching via femtosecond laser ablation was investigated. The samples of different indium concentrations were grown by metal organic chemical vapor deposition (MOCVD) technique on sapphire substrates. Prior to the laser treatment all samples were characterized by the means of photoluminescence and X-ray diffraction techniques. Further the laser-induced damage thresholds (LIDT) were estimated in multiple pulse (S-on-1) and single pulse (1-on-1) regimes for 1030, 515, and 343 nm wavelengths covering NIR-UV spectral regions. Experimental results indicated a strong interrelation between LIDT, indium concentration and band-gap. An abrupt change in single pulse LIDT is observed when the multi-photon absorption experiences transition from three to two photon absorption. Furthermore an overview of typical laser induced damage morphologies is performed and discussed. A selective smooth etching of GaN and InGaN layers was obtained when exposing with multiple pulses in UV range.

Š?iuka, Mindaugas; Grinys, Tomas; Dmukauskas, Mantas; Plerpait?, Viktorija; Melninkaitis, Andrius

2013-08-01

448

InP substrate temperature measurements in a horizontal, low-pressure metalorganic chemical vapor deposition reactor by infrared laser interferometric thermometry  

NASA Astrophysics Data System (ADS)

Infrared laser interferometric thermometry was used to measure InP substrate temperatures in a horizontal, low pressure metalorganic chemical vapor deposition (MOCVD) reactor. These measurements were made by using a 1.53 ?m distributed feedback laser, demonstrating the use of semiconductor lasers to diagnose an epitaxial crystal growth process. The laser beam was reflected off of 2 inch diameter (100) n-type InP substrates in a commercial low-pressure MOCVD reactor. Substrate temperature profiles were taken as a function of reactor pressure from 20-1000 mbar and as a function of substrate position on the susceptor. For a constant susceptor set-point temperature of 640°C, temperatures increase monotonically from 600 to 615°C at 20 mbar along the substrate in the gas flow direction, increasing to 621 to 655°C at 1000 mbar for a substrate positioned in the downstream location of a two-well susceptor used for normal epitaxial growth runs. The variation in temperature decreases when the substrate is placed in a center well susceptor. The data shows that improvements in temperature uniformity, and hence compositional uniformity can be achieved by judicious choice of substrate position and reactor pressure. In particular, uniform temperature profiles resulted in improved compositional uniformity obtained for 1.15 ?m InGaAsP layers grown on a 2 inch diameter substrate placed in the center well susceptor.

McCrary, V. R.; Donnelly, V. M.; Napholtz, S. G.; Hayes, T. R.; Davisson, P. S.; Bruno, D. C.

1992-11-01

449

Chemically pumped iodine laser  

Microsoft Academic Search

The production of O2(1 delta) by the reaction of chlorine fluorosulfate (CFS) vapor and chlorine gas with concentrated basic hydrogen peroxide solutions was studied under conditions of controlled contact area, contact time, and temperature. Variables were temperature, CFS and C1(-2) flowrates, liquid flowrates, and liquid concentrations. Effluent flow, O(-2) flow, and O2(1 delta)\\/O2 were measured. O2(1 delta) yields with the

S. Hurlock; H. Laeger; R. Wagner

1979-01-01

450

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers. Semiannual Progress Report, 1 January-30 June 1985  

SciTech Connect

This work is directed toward the design and chemical synthesis of new media for solar-pumped I* lasers. In view of the desirability of preparing a perfluoroalkyl iodide absorbing strongly at 300 nm, the relationship betwen perfluoroalkyl iodide structure and the corresponding absorption wavelength was reexamined. Analysis of existing data suggests that, in this family of compounds, the absorption maximum shifts to longer wavelength, as desired, as the C-I bond in the lasant is progressively weakened. Weakening of the C-I bond correlates, in turn, with increasing stability of the perfluoroalkyl radical formed upon photodissociation of the iodide. The extremely promising absorption characteristics of perfluoro-tert-butyl iodide can be accounted for on this basis. A new technique of diode laser probing to obtain precise yields of I* atoms in photodissociation was also developed.

Shiner, C.S.

1985-01-01

451

Temperature-dependent photoluminescence of GaInP/AlGaInP multiple quantum well laser structure grown by metalorganic chemical vapor deposition with tertiarybutylarsine and tertiarybutylphosphine  

NASA Astrophysics Data System (ADS)

A GaInP/AlGaInP multiple quantum well laser structure was grown by low-pressure metalorganic chemical vapor deposition with tertiarybutylarsine and tertiarybutylphosphine. Laser diodes fabricated from this structure lased at room temperature. Photoluminescence (PL) measurements were performed from 10 to 230 K. The PL energy increased with temperature from 10 to 70 K and decreased above 70 K. The former was attributed to thermal activation of trapped carriers due to localization in the quantum wells, while the latter was attributed to temperature-induced band-gap shrinkage. The PL intensity as a function of temperature was fitted by employing two nonradiative recombination mechanisms with good agreement, resulting in two activation energies that correspond to losses of photogenerated carriers to nonradiative centers.

Liu, C. Y.; Yuan, Shu; Dong, J. R.; Chua, S. J.; Chan, M. C. Y.; Wang, S. Z.

2003-09-01

452

The role of physical and chemical properties of Pd nanostructured materials immobilized on inorganic carriers on ion formation in atmospheric pressure laser desorption/ionization mass spectrometry.  

PubMed

Fundamental parameters influencing the ion-producing efficiency of palladium nanostructures (nanoparticles [Pd-NP], nanoflowers, nanofilms) during laser irradiation were studied in this paper. The nanostructures were immobilized on the surface of different solid inorganic carrier materials (porous and mono-crystalline silicon, anodic porous aluminum oxide, glass and polished steel) by using classical galvanic deposition, electroless local deposition and sputtering. It was the goal of this study to investigate the influence of both the nanoparticular layer as well as the carrier material on ion production for selected analyte molecules. Our experiments demonstrated that the dimensions of the synthesized nanostructures, the thickness of the active layers, surface disorders, thermal conductivity and physically or chemically adsorbed water influenced signal intensities of analyte ions during surface-assisted laser desorption/ionization (SALDI) while no effects such as plasmon resonance, photoelectric effect or catalytic activity were expected to occur. Excellent LDI abilities were seen for Pd-NPs immobilized on steel, while Pd nanoflowers on porous silicon exhibited several disadvantages; viz, strong memory effects, dependency of the analytical signal on amount of physically and chemically adsorbed water inside porous carrier, reduced SALDI activity from unstable connections between Pd and semiconductor material, decrease of the melting point of pure silicon after Pd immobilization and resulting strong laser ablation of metal/semiconductor complex, as well as significantly changed surface morphology after laser irradiation. The analytical performance of Pd-NP/steel was further improved by applying a hydrophobic coating to the steel surface before galvanic deposition. This procedure increased the distance between Pd-NPs, thus reducing thermal stress upon LDI; it simultaneously decreased spot sizes of deposited sample solutions. PMID:24913399

Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

2014-06-01

453

New chemically pumped I (2P 1\\/2-2P 3\\/2) laser at 1.315 um  

Microsoft Academic Search

CW laser action has been demonstrated on the electronic I* (2P1\\/2) yields I(2P3\\/2) transition of atomic iodine at 1.315 micrometer from the NCl (a1(Delta) ) + I(2P3\\/2) energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3 was injected into a flow of iodine and chlorine atoms. The measured laser output power

Gordon D. Hager; Thomas L. Henshaw; Gerald C. Manke; Timothy J. Madden; Michael R. Berman

2000-01-01

454

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

455

Effect of pulsed laser irradiation on the structure of GeTe films deposited by metal organic chemical vapor deposition: A Raman spectroscopy study  

SciTech Connect

Phase changes between amorphous and crystallized states were induced by laser irradiation with nanosecond pulses in Ge{sub x}Te{sub y} films grown by metal organic chemical vapor deposition. The different phases were obtained by adjusting the pulse energy and could be distinguished by their different optical reflectivities. The corresponding structural changes were studied by Raman spectroscopy, showing marked differences for the two phases. A clear correlation is found between optical reflectivity levels, crystallographic state and the evolution of Ge-Ge, Te-Te, and Ge-Te Raman bands.

Salicio, O.; Wiemer, C.; Fanciulli, M. [CNR-INFM MDM Laboratory, via C. Olivetti 2, 20041 Agrate Brianza (Italy); Gawelda, W.; Siegel, J.; Afonso, C. N. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, E-28006 Madrid (Spain); Plausinaitiene, V.; Abrutis, A. [Department of General and Inorganic Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-2006 VU (Lithuania)

2009-02-01

456

Atmospheric propagation for tactical directed-energy applications  

NASA Astrophysics Data System (ADS)

As a corollary to the USAF strategic Airborne Laser program, Boeing has been analyzing the use of the Chemical Oxygen Iodine Laser for tactical scenarios. These include its use in an airborne platform operating against low flying cruise missiles and miscellaneous ground targets, as well as on a mobile ground platform providing support defense against shorter-range rocket attack. Practical design concepts yielding high target lethality at significant ranges have been developed.

MacGovern, Alan J.; Nahrstedt, David A.; Johnson, Michael M.

2000-07-01

457

COIL performance modeling and recent advances in diagnostic measurements  

Microsoft Academic Search

This paper describes the analysis of power extraction from a chemical oxygen iodine laser (COIL) using a simplified saturation model (SSM). Previously our COIL modeling efforts have been limited by an inability to accurately measure O2(1(Delta) ) concentrations which in turn is a measure of the power available in the laser. Earlier application of the SSM to RotoCOIL data implied

Keith A. Truesdell; Charles A. Helms; S. Frerking; Gordon D. Hager; David N. Plummer; Richard J. Copland

1997-01-01

458

Direct Chemical Analysis of Solids by Laser Ablation in an Ion-Storage Time-of-Flight Mass Spectrometer  

SciTech Connect

A laser ablation/ionization mass spectrometer system is described for the direct analysis of solids, particles, and fibers. The system uses a quadrupole ion trap operated in an ion-storage (IS) mode, coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). The sample is inserted radially into the ring electrode and an imaging system allows direct viewing and selected analysis of the sample. Measurements identified trace contaminants of Ag, Sn, and Sb in a Pb target with single laser-shot experiments. Resolution (m/{micro}m) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

Klunder, G L; Grant, P M; Andresen, B D; Russo, R E

2003-09-29

459

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers  

NASA Technical Reports Server (NTRS)

Research is directed toward the design and synthesis of new media for solar-pumped I* lasers. Since the most effective existing lasants are perfluoroalkyl iodides, a strategy was proposed for the development of improved materials of this type with absorption maxima at 300 nm. Absorption spectra were synthesized and measured for prototypical species containing iodine bound to boron, iron, and cobalt.

Shiner, Christopher S.

1986-01-01

460

Characterization of Pad-Wafer Contact and Surface Topography in Chemical Mechanical Planarization Using Laser Confocal Microscopy  

Microsoft Academic Search

In this study, an optical method using laser confocal microscopy was developed to measure the surface contact area and topography of pads under a dry and static condition. A custom-made pad sample holder with a sapphire window and a miniature load cell was used to collect pad surface contact images at controlled loads. By extracting the black spots in the

Ting Sun; Yun Zhuang; Leonard Borucki; Ara Philipossian

2010-01-01

461

Chemical and Isotopic Analysis of Trace Organic Matter on Meteorites and Interstellar Dust Using a Laser Microprobe Instrument  

NASA Technical Reports Server (NTRS)

Polycyclic Aromatic Hydrocarbons (PAHs) are of considerable interest today because they are ubiquitous on Earth and in the interstellar medium (ISM). In fact, about 20% of cosmic carbon in the galaxy is estimated to be in the form of PAHs. Investigation of these species has obvious uses for determining the cosmochemistry of the solar system. Work in this laboratory has focused on four main areas: 1) Mapping the spatial distribution of PAHs in a variety of meteoritic samples and comparing this distribution with mineralogical features of the meteorite to determine whether a correlation exists between the two. 2) Developing a method for detection of fullerenes in extraterrestrial samples using microprobe Laser Desorption Ionization Mass Spectroscopy and utilizing this technique to investigate fullerene presence, while exploring the possibility of spatially mapping the fullerene distribution in these samples through in situ detection. 3) Investigating a possible formation pathway for meteoritic and ancient terrestrial kerogen involving the photochemical reactions of PAHs with alkanes under prebiotic and astrophysically relevant conditions. 4) Studying reaction pathways and identifying the photoproducts generated during the photochemical evolution of PAH-containing interstellar ice analogs as part of an ongoing collaboration with researchers at the Astrochemistry Lab at NASA Ames. All areas involve elucidation of the solar system formation and chemistry using microprobe Laser Desorption Laser Ionization Mass Spectrometry. A brief description of microprobe Laser Desorption Ionization Mass Spectroscopy, which allows selective investigation of subattomole levels of organic species on the surface of a sample at 10-40 micrometer spatial resolution, is given.

Zare, Richard N.; Boyce, Joseph M. (Technical Monitor)

2001-01-01

462

Quartz fiberguides for laser and medical applications, obtained by microwave plasma-chemical deposition from gas phase  

Microsoft Academic Search

Quartz-quartz lightguides with fluorine cladding and pure silica glass core for the transmission of high power UV (?=0.308 ?m) and IR (?=1.06 ?m) laser radiation were produced by a microwave plasmochemical deposition method at low pressure.

V. A. Babenko; V. V. Grigorjantz; L. Yu. Kochmarev; I. P. Shilov

2002-01-01

463

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.

1979-01-01

464

Atomic iodine generation via F atoms for COIL  

Microsoft Academic Search

Chemical generation of atomic iodine for a Chemical Oxygen-Iodine Laser (COIL) was investigated experimentally. This all-gas process includes atomic fluorine as an intermediate species. In the two-step reaction mechanism, F atoms are produced in reaction of molecular fluorine with NO and react further with hydrogen iodide to iodine atoms. The efficiency of this process was studied in dependence on mixing

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

2004-01-01

465

IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 48, NO. 6, JUNE 2012 741 Superlinear Enhancement of Discharge Driven  

E-print Network

of Discharge Driven Electric Oxygen-Iodine Laser by Increasing g0L Gabriel F. Benavides, Brian S. Woodard with electric oxygen-iodine laser (ElectricOIL) technology have significantly increased laser power output size) by a factor of 3, a 5-fold increase in laser output on the 1315-nm transition of atomic iodine

Carroll, David L.

466

Modeling of Recent ElectricOIL Gain Recovery Data Andrew D. Palla1  

E-print Network

- Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition. Introduction The electrically driven oxygen-iodine laser (ElectricOIL) that was first demonstrated by Carroll as O2(a)]. Since the first reporting of a viable electric discharge-driven oxygen-iodine laser system

Carroll, David L.