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Sample records for laser vaporization methods

  1. Novel methods of copper vapor laser excitation

    SciTech Connect

    McColl, W.B.; Ching, H.; Bosch, R.; Brake, M.; Gilgenbach, R.

    1990-12-31

    Microwave and intense electron beam excitation of copper vapor are being investigated to be used in copper vapor lasers for isotope separation. Both methods use copper chloride vapor by heating copper chloride. Helium was used as the buffer gas at 2 to 100 torr. In the microwave system, intense copperlines at 510 nm and 578 nm were observed. Initial electron beam results indicate that light emission follows the beam current.

  2. Detection of vapor phase mercury species by laser fluorescence methods

    NASA Astrophysics Data System (ADS)

    Tong, Xiaomei

    Several mercury species emissions have been identified in off-gases from industrial processes. At present, there is no commercial continuous emission monitoring (CEM) technique or instrumentation to reliably monitor volatile mercury species emissions from industrial stacks. Conventional measurement methods, such as cold vapor trap based techniques for elemental mercury, have difficulty in achieving both high sensitivity and the fast time resolution required for real-time monitoring. This doctoral research work gives a systematic study of potential methods for real-time trace detection of volatile elemental mercury and mercury compounds in industrial stack gases. It is based on laser-induced fluorescence techniques; photofragment fluorescence spectroscopy for detection of volatile mercury compounds, and resonance fluorescence for detection of elemental mercury. The capabilities and limitations of these detection techniques are investigated in this dissertation. Detection of mercury compounds is a challenge since they are non-fluorescent. With photofragment fluorescence spectroscopy, target compound concentrations are related to the fluorescence intensity from an excited fragment. In this doctoral research work, low concentrations of mercuric bromide vapor in an atmospheric pressure flow cell are irradiated by a focused laser beam at 222nm. Photofragment fluorescence is monitored at 253.7nm. Two detection schemes, Charge Coupled Device (CCD) and photomultiplier tube (PMT), are applied for the measurement of photofragment fluorescence. The performances of these two systems are compared in the dissertation. A supersonic jet is combined with resonance fluorescence for detection of elemental mercury vapor. With test gas expanded into a vacuum, fluorescence quenching and spectral broadening are reduced. In the experiment, the gas jet is crossed with a laser beam at 253.7nm to excite atomic fluorescence, which is distinguished from the elastic background by time gating

  3. Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

    DOEpatents

    Hagans, K.; Berzins, L.; Galkowski, J.; Seng, R.

    1996-08-27

    The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer`s law. 6 figs.

  4. Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

    DOEpatents

    Hagans, Karla; Berzins, Leon; Galkowski, Joseph; Seng, Rita

    1996-01-01

    The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer's law.

  5. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1986-01-01

    The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

  6. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P sub J) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus.

  7. Method and apparatus for convection control of metallic halide vapor density in a metallic halide laser

    NASA Technical Reports Server (NTRS)

    Pivirotto, T. J. (Inventor)

    1982-01-01

    An apparatus is disclosed in which a reservoir containing copper chloride is heated so that the copper chloride is maintained in a liquid form. The apparatus includes a means for flowing a buffer gas (which in the exemplary embodiment is neon) over the liquid copper chloride to provide a mixture of copper chloride vapor and neon above the liquid copper chloride. A conduit provides fluid communication between the reservoir containing the copper chloride vapor/neon mixture and the laser. The copper chloride vapor density in the laser is related to the liquid copper chloride temperature and the neon flow rate through the reservoir. In accordance with a further feature of the exemplary embodiment, neon is also provided directly to the laser in order to provide a further means of controlling the copper chloride vapor density in the laser.

  8. Efficient multiple time scale method for modeling compressible vapor plume dynamics inside transient keyhole during fiber laser welding

    NASA Astrophysics Data System (ADS)

    Pang, Shengyong; Chen, Xin; Li, Wen; Shao, Xinyu; Gong, Shuili

    2016-03-01

    Efficient coupling modeling of multiple time scale interactions between keyhole, weld pool and compressible vapor plume during laser welding has long been limited. To address this problem, we present a highly efficient multiple time scale method combining a novel dual-time stepping and Ghost Fluid interpolation strategy with incompressible and compressible fluid solvers, which allows us predicting the compressible plume dynamics inside transient keyhole in fiber laser welding for the first time. In our method, the compressible dynamic vapor inside the transient keyhole is solved with a Roe scheme based algorithm and the incompressible molten liquid of weld pool is calculated by a Projection method. A novel temperature dependent boundary condition of vapor plume is also proposed for the consideration of the dynamic evaporation phenomena on the transient keyhole wall. It is found that the time dependent distributions of vapor plume characteristics, including temperature, pressure, velocity, density and Mach number distributions inside the transient keyhole induced by laser welding can be reasonably predicted by comparing to experimental and literature data. It is also shown that the proposed multiple time scale method is around 60 times faster than the vapor plume modeling method using a single nanosecond scale time step. For the vapor plume in a typical fiber laser welding process, the results indicate that the peak pressure can be greater than 2.0 atmospheric pressures; the average density is around 0.15-0.3 kg/m3 which is much smaller than the air density; and the local Mach number can be greater than 0.8 or even 1.0 Mach which demonstrates the necessity to treat the vapor plume as a compressible fluid.

  9. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  10. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  11. Atomic vapor laser isotope separation process

    DOEpatents

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1990-08-21

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

  12. Vapor spill monitoring method

    DOEpatents

    Bianchini, Gregory M.; McRae, Thomas G.

    1985-01-01

    Method for continuous sampling of liquified natural gas effluent from a spill pipe, vaporizing the cold liquified natural gas, and feeding the vaporized gas into an infrared detector to measure the gas composition. The apparatus utilizes a probe having an inner channel for receiving samples of liquified natural gas and a surrounding water jacket through which warm water is flowed to flash vaporize the liquified natural gas.

  13. Alkali-vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.; Krupke, W. F.

    2010-02-01

    We report on the results from several of our alkali laser systems. We show highly efficient performance from an alexandrite-pumped rubidium laser. Using a laser diode stack as a pump source, we demonstrate up to 145 W of average power from a CW system. We present a design for a transversely pumped demonstration system that will show all of the required laser physics for a high power system.

  14. Laser using lead chloride vapor

    NASA Technical Reports Server (NTRS)

    Chen, C. J.

    1975-01-01

    By applying electric discharge, lead chloride vapor in tube is dissociated into lead and chlorine atoms. Population inversion of lead atoms is attained subsequently by second discharge, before chemical recombination of lead and chlorine has occurred. Optimum time interval between two discharges is required for maximum laser output.

  15. Wick for metal vapor laser

    DOEpatents

    Duncan, David B.

    1992-01-01

    An improved wick for a metal vapor laser is made of a refractory metal cylinder, preferably molybdenum or tungsten for a copper laser, which provides the wicking surface. Alternately, the inside surface of the ceramic laser tube can be metalized to form the wicking surface. Capillary action is enhanced by using wire screen, porous foam metal, or grooved surfaces. Graphite or carbon, in the form of chunks, strips, fibers or particles, is placed on the inside surface of the wick to reduce water, reduce metal oxides and form metal carbides.

  16. Copper vapor laser modular packaging assembly

    DOEpatents

    Alger, T.W.; Ault, E.R.; Moses, E.I.

    1992-12-01

    A modularized packaging arrangement for one or more copper vapor lasers and associated equipment is disclosed herein. This arrangement includes a single housing which contains the laser or lasers and all their associated equipment except power, water and neon, and means for bringing power, water, and neon which are necessary to the operation of the lasers into the container for use by the laser or lasers and their associated equipment. 2 figs.

  17. Copper vapor laser modular packaging assembly

    DOEpatents

    Alger, Terry W.; Ault, Earl R.; Moses, Edward I.

    1992-01-01

    A modularized packaging arrangement for one or more copper vapor lasers and associated equipment is disclosed herein. This arrangement includes a single housing which contains the laser or lasers and all their associated equipment except power, water and neon, and means for bringing power, water, and neon which are necessary to the operation of the lasers into the container for use by the laser or lasers and their associated equipment.

  18. Copper vapor laser acoustic thermometry system

    DOEpatents

    Galkowski, Joseph J.

    1987-01-01

    A copper vapor laser (CVL) acoustic thermometry system is disclosed. The invention couples an acoustic pulse a predetermined distance into a laser tube by means of a transducer and an alumina rod such that an echo pulse is returned along the alumina rod to the point of entry. The time differential between the point of entry of the acoustic pulse into the laser tube and the exit of the echo pulse is related to the temperature at the predetermined distance within the laser tube. This information is processed and can provide an accurate indication of the average temperature within the laser tube.

  19. Metal vapor lasers with increased reliability

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Sabotinov, N. V.; Polunin, Yu. P.; Shumeiko, A. S.; Kostadinov, I. K.; Vasilieva, A. V.; Reimer, I. V.

    2015-12-01

    Results of investigation and development of an excitation pulse generator with magnetic pulse compression by saturation chokes for pumping of active media of CuBr, Sr, and Ca vapor lasers are presented. A high-power IGBT transistor is used as a commutator. The generator can operate at excitation pulse repetition frequencies up to 20 kHz. The total average power for all laser lines of the CuBr laser pumped by this generator is ~6.0 W; it is ~1.3-1.7 W for the Sr and Ca lasers.

  20. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Koch, M. E.

    1980-01-01

    The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

  1. New Medical Applications Of Metal Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Anderson, Robert S.; McIntosh, Alexander I.

    1989-06-01

    The first medical application for metal vapor lasers has been granted marketing approval by the FDA. This represents a major milestone for this technology. Metalaser Technologies recently received this approval for its Vasculase unit in the treatment of vascular lesions such as port wine stains, facial telangiectasia and strawberry hemangiomas.

  2. Monitoring PVD metal vapors using laser absorption spectroscopy

    SciTech Connect

    Braun, D.G.; Anklam, T.M.; Berzins, L.V.; Hagans, K.G.

    1994-04-01

    Laser absorption spectroscopy (LAS) has been used by the Atomic Vapor Laser Isotope Separation (AVLIS) program for over 10 years to monitor the co-vaporization of uranium and iron in its separators. During that time, LAS has proven to be an accurate and reliable method to monitor both the density and composition of the vapor. It has distinct advantages over other rate monitors, in that it is completely non-obtrusive to the vaporization process and its accuracy is unaffected by the duration of the run. Additionally, the LAS diagnostic has been incorporated into a very successful process control system. LAS requires only a line of sight through the vacuum chamber, as all hardware is external to the vessel. The laser is swept in frequency through an absorption line of interest. In the process a baseline is established, and the line integrated density is determined from the absorption profile. The measurement requires no hardware calibration. Through a proper choice of the atomic transition, a wide range of elements and densities have been monitored (e.g. nickel, iron, cerium and gadolinium). A great deal of information about the vapor plume can be obtained from the measured absorption profiles. By monitoring different species at the same location, the composition of the vapor is measured in real time. By measuring the same density at different locations, the spatial profile of the vapor plume is determined. The shape of the absorption profile is used to obtain the flow speed of the vapor. Finally, all of the above information is used evaluate the total vaporization rate.

  3. A TUNABLE DIODE LASER STACK MONITOR FOR SULFURIC ACID VAPOR

    EPA Science Inventory

    A field prototype instrument for continuous in-situ monitoring of sulfuric acid vapor in industrial smoke stacks has been developed. The method of detection is dual wavelength differential absorption in the infrared. Two tunable diode lasers are locked to two specific frequencies...

  4. Precision micro drilling with copper vapor lasers

    SciTech Connect

    Chang, J.J.; Martinez, M.W.; Warner, B.E.; Dragon, E.P.; Huete, G.; Solarski, M.E.

    1994-09-02

    The authors have developed a copper vapor laser based micro machining system using advanced beam quality control and precision wavefront tilting technologies. Micro drilling has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratio up to 1:40 have been consistently drilled on a variety of metals with good quality. For precision trepanned holes, the hole-to-hole size variation is typically within 1% of its diameter. Hole entrance and exit are both well defined with dimension error less than a few microns. Materialography of sectioned holes shows little (sub-micron scale) recast layer and heat affected zone with surface roughness within 1--2 microns.

  5. Water vapor-nitrogen absorption at CO2 laser frequencies

    NASA Technical Reports Server (NTRS)

    Peterson, J. C.; Thomas, M. E.; Nordstrom, R. J.; Damon, E. K.; Long, R. K.

    1979-01-01

    The paper reports the results of a series of pressure-broadened water vapor absorption measurements at 27 CO2 laser frequencies between 935 and 1082 kaysers. Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized CW CO2 laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microns substantiate the existence of the large (greater than 200) self-broadening coefficients determined in an earlier study by McCoy. In this work, the case of water vapor in N2 at a total pressure of 1 atm has been treated.

  6. Copper vapor laser prospects in glaucoma treatment

    NASA Astrophysics Data System (ADS)

    Egorov, E. A.; Nesterov, Arcady P.; Novoderezhkin, Vladimir I.; Egorov, Alexey E.; Shaban, Naim; Ponomarev, Igor V.

    1996-05-01

    New advances of copper vapor laser (CVL-laser) have been studied. Two wavelength radiation of the laser (511 nm and 578 nm) gives deeper permeability into organic tissues. Besides, the short pulse prevents the warm relaxation of small vessels. The technical data of CVL-laser: operating regime -- pulse, pulse duration -- 20 ns, pulse frequency 15000 pulse/sec. The shutter works in intervals from 0.05 to 2.0 sec. The power varies in accordance with wavelength: 511 nm (green) -- 1.5 W, 578 nm (yellow) -- 1, 2 W. The diameter of coagulate may be different: 100, 150, 400, 1000 mkm. We chose CVL-laser 'Femta,' created by P. N. Lebedev Physical Institute of RAS, for ophthalmological use. Thirty eight eyes of 37 patients with different types and stages of glaucoma were studied and treated with CVL-laser. The operations of photomydriasis, gonioplasty and trabeculoplasty have been performed. CVL- laser demonstrated efficient application in treatment of interior eye segment of glaucoma patients. The advantages and disadvantages of the CVL-laser application in glaucoma surgery were discussed.

  7. Ambient Femtosecond Laser Vaporization and Nanosecond Laser Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Flanigan, Paul; Levis, Robert

    2014-06-01

    Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of <100 fs to enable matrix-free laser vaporization with little or no fragmentation. When coupled to electrospray ionization, femtosecond laser vaporization provides a universal, rapid mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 1013 W cm-2 desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.

  8. Injection locked oscillator system for pulsed metal vapor lasers

    DOEpatents

    Warner, Bruce E.; Ault, Earl R.

    1988-01-01

    An injection locked oscillator system for pulsed metal vapor lasers is disclosed. The invention includes the combination of a seeding oscillator with an injection locked oscillator (ILO) for improving the quality, particularly the intensity, of an output laser beam pulse. The present invention includes means for matching the first seeder laser pulses from the seeding oscillator to second laser pulses of a metal vapor laser to improve the quality, and particularly the intensity, of the output laser beam pulse.

  9. Metal vapor laser including hot electrodes and integral wick

    DOEpatents

    Ault, Earl R.; Alger, Terry W.

    1995-01-01

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube.

  10. Metal vapor laser including hot electrodes and integral wick

    DOEpatents

    Ault, E.R.; Alger, T.W.

    1995-03-07

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube. 5 figs.

  11. Controlling Metal-Halide Vapor Density in Lasers

    NASA Technical Reports Server (NTRS)

    Pivirotto, T. J.

    1984-01-01

    Streams of buffer gas convect and dilute metal-halide vapor. Technique uses flow of buffer gas through reservoir, which contains heated metal halide, to convect vapors into discharge tube. Second stream of buffer gas dilutes vapor. Final vapor density in laser tube controlled and changed by adjusting either one or both of buffer gas flow rates.

  12. ARTICLES: Thermal physics of transverse-discharge copper vapor lasers

    NASA Astrophysics Data System (ADS)

    Borovich, Boris L.; Grigoryan, R. A.; Kazeko, G. P.; Nikolaev, G. N.; Smirnov, V. M.

    1982-10-01

    One of the factors determining the ultimate characteristics of copper vapor lasers is the heating of the active medium by the pulse-periodic discharge providing the excitation. The gas temperature was measured on the axis of the discharge gap of a transversely excited copper vapor laser. Two methods were used: a spectroscopic method (based on the Doppler width of an emission line of the neon buffer gas) and an interferometric method (based on the fringe shift in a Mach-Zehnder interferometer at the instants when the discharge was switched abruptly on and off). Both methods yielded values close 2200 °K. The temperature distribution in the active zone with a rectangular cross section was computed numerically. The results of a theoretical calculation were used to estimate the efficiency of conversion of the discharge energy into heat, which was around 40%.

  13. Tunable lasers for water vapor measurements and other lidar applications

    NASA Technical Reports Server (NTRS)

    Gammon, R. W.; Mcilrath, T. J.; Wilkerson, T. D.

    1977-01-01

    A tunable dye laser suitable for differential absorption (DIAL) measurements of water vapor in the troposphere was constructed. A multi-pass absorption cell for calibration was also constructed for use in atmospheric DIAL measurements of water vapor.

  14. Vapor generation methods for explosives detection research

    SciTech Connect

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  15. Method and apparatus for vapor detection

    NASA Technical Reports Server (NTRS)

    Lerner, Melvin (Inventor); Hood, Lyal V. (Inventor); Rommel, Marjorie A. (Inventor); Pettitt, Bruce C. (Inventor); Erikson, Charles M. (Inventor)

    1980-01-01

    The method disclosed herein may be practiced by passing the vapors to be sampled along a path with halogen vapor, preferably chlorine vapor, heating the mixed vapors to halogenate those of the sampled vapors subject to halogenation, removing unreacted halogen vapor, and then sensing the vapors for organic halogenated compounds. The apparatus disclosed herein comprises means for flowing the vapors, both sample and halogen vapors, into a common path, means for heating the mixed vapors to effect the halogenation reaction, means for removing unreacted halogen vapor, and a sensing device for sensing halogenated compounds. By such a method and means, the vapors of low molecular weight hydrocarbons, ketones and alcohols, when present, such as methane, ethane, acetone, ethanol, and the like are converted, at least in part, to halogenated compounds, then the excess halogen removed or trapped, and the resultant vapors of the halogenated compounds sensed or detected. The system is highly sensitive. For example, acetone in a concentration of 30 parts per billion (volume) is readily detected.

  16. Application of laser Doppler velocimeter to chemical vapor laser system

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  17. Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

    NASA Astrophysics Data System (ADS)

    Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

    Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

  18. PRR performance of Cu- and CuBr-vapor lasers

    NASA Astrophysics Data System (ADS)

    Fedorov, V. F.; Evtushenko, Gennadiy S.; Klimkin, Vladimir M.; Polunin, Yu. P.; Soldatov, Anatoly N.; Sukhanov, Viktor B.

    1998-06-01

    Results obtained from comparative analysis of the pulse repetition rate performance of Cu- and CuBr-vapor lasers operated at high pump pulse repetitions (approximately 100 kHz) are reported. For a CuBr laser with a 8 mm diameter discharge tube the laser pulse repetition rate as high as 270 kHz was realized.

  19. Laser Prostatectomy: Holmium Laser Enucleation and Photoselective Laser Vaporization of the Prostate

    PubMed Central

    Bostanci, Yakup; Kazzazi, Amir; Djavan, Bob

    2013-01-01

    Historically, transurethral resection of the prostate has been the gold standard for the treatment of benign prostatic hyperplasia (BPH). Laser technology has been used to treat BPH for > 15 years. Over the past decade, it has gained wide acceptance by experienced urologists. This review provides an evidence-based update on laser surgery for BPH with a focus on photoselective laser vaporization and holmium laser enucleation of the prostate surgeries and assesses the safety, efficacy, and durability of these techniques. PMID:23671400

  20. Ex vivo efficacy evaluation of laser vaporization for treatment of benign prostatic hyperplasia using a 300-W high-power laser diode with a wavelength of 980 nm

    PubMed Central

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao

    2014-01-01

    Background and Objective: Laser vaporization of the prostate is considered to be a promising treatment for benign prostatic hyperplasia (BPH), and efficiency of vaporization and hemostasis are both important parameters for such treatment. In this study, we used a high-power laser diode with a wavelength of 980 nm to obtain high vaporization efficiency with good hemostasis. The objective of this study is to evaluate the efficacy of laser vaporization for treatment of BPH in ex vivo experiments using a 300-W high-power laser diode with a wavelength of 980 nm quantitatively. Materials and Methods: An ex vivo experimental setup simulating clinical treatment situation was constructed. Bovine prostate tissue was used as a sample. The power setting was 100, 150, 200, 250, or 300 W, and the irradiation time was 0.5, 1, or 2 s. After laser irradiation, vaporized and coagulated depths were measured. Results: The vaporized depth increased with the laser power and irradiation time, and the results confirmed that the high-power laser diode could efficiently vaporize the prostate tissue. Coagulated depth increased as the laser power became higher. Conclusions: Laser vaporization of prostate tissue using a high-power laser diode with a wavelength of 980 nm represents a promising treatment for BPH; this method exhibits high vaporization efficiency and good hemostasis. However, operators must be aware of the risk of postoperative perforation of the prostatic capsule caused by coagulation of deep regions that cannot be visualized by endoscopic observation. PMID:25368442

  1. Analysis of organic vapors with laser induced breakdown spectroscopy

    SciTech Connect

    Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh

    2015-09-15

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  2. Analysis of organic vapors with laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Nozari, Hadi; Rezaei, Fatemeh; Tavassoli, Seyed Hassan

    2015-09-01

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  3. Water vapor isotopes measurements at Mauna Loa, Hawaii: Comparison of laser spectroscopy and remote sensing with traditional methods, and the need for ongoing monitoring

    NASA Astrophysics Data System (ADS)

    Galewsky, J.; Noone, D.; Sharp, Z.; Worden, J.

    2009-04-01

    The isotopic composition of water vapor (2H/1H and 18O/16 ratios) provides unique information on the transport pathways that link water sources to regional sinks, and thus proves useful in understanding large scale atmospheric humidity budgets. Recent advances in measurement technology allow the monitoring of water vapor isotope composition in ways which has can revolutionize investigations of atmospheric hydrology. Traditional measurement of isotopic composition requires trapping of samples with either large volume vacuum flasks or by trapping liquid samples with cryogens for later analyses using mass spectrometry, and are laborious and seldom span more than just short dedicated observational periods. On the other hand, laser absorption spectroscopy can provide almost continuous and autonomous in situ measurements of isotope abundances with precision almost that of traditional mass spectrometry, and observations from spacecraft can make almost daily maps of the global isotope distributions. In October of 2008 three laser based spectrometers were deployed at the Mauna Loa Laboratory in Hawaii to make continuous measurement of the 2H and 18O abundance of free tropospheric water vapor. These results are compared with traditional measurements and with measurements from two satellite platforms. While providing field validation of the new methodologies, the data show variability which captures the transport processes in the region. The data are used to characterize the role of large scale mixing of dry air, the influence of the boundary layer and the importance of moist convection in controlling the low humidity of subtropical air near Hawaii. Although the record is short, it demonstrates the usefulness of using robust isotope measurements to understand the budgets of the most important greenhouse gas. This work motivates establishing a continuous record of isotopes measurement at baseline sites, like Mauna Loa, such that the changes in water cycle can be understood and

  4. Water vapor isotopes measurements at Mauna Loa, Hawaii: Comparison of laser spectroscopy and remote sensing with traditional methods, and the need for ongoing monitoring

    NASA Astrophysics Data System (ADS)

    Noone, D.; Galewsky, J.; Sharp, Z.; Worden, J.

    2008-12-01

    The isotopic composition of water vapor (2H/1H and 18O/16 ratios) provides unique information on the transport pathways that link the water sources to regional sinks, and thus proves useful in understanding the large scale humidity budgets. Recent advances in measurement technology allow the monitoring of water vapor isotope composition in ways which has can revolutionize investigations of atmospheric hydrology. Traditional measurement of isotopic composition requires trapping of samples with either large volume vacuum flasks or by trapping liquid samples with cryogens for later analyses using mass spectrometry, and are laborious and seldom span more than just short dedicated observational periods. On the other hand, laser absorption spectroscopy can provide almost continuous and autonomous in situ measurements of isotope abundances with precision almost that of traditional mass spectrometry, and observations from spacecraft can make almost daily maps of the global isotope distributions. In October of 2008 three laser based spectrometers were deployed at the Mauna Loa Laboratory in Hawaii to make continuous measurement of the 2H and 18O abundance of free tropospheric water vapor. These results are compared with traditional measurements and with measurements from two satellite platforms. While providing field validation of the new methodologies, the data show variability which captures the transport processes in the region. The data are used to characterize the role of large scale mixing of dry air, the influence of the boundary layer and the importance of moist convection in controlling the low humidity of subtropical air near Hawaii. Although the record is short, it demonstrates the usefulness of using robust isotope measurements to understand the budgets of the most important greenhouse gas. This work motivates establishing a continuous record of isotopes measurement at baseline sites, like Mauna Loa, such that the changes in water cycle can be understood and

  5. Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapor equilibration laser spectroscopy method

    NASA Astrophysics Data System (ADS)

    Hendry, M. J.; Schmeling, E.; Wassenaar, L. I.; Barbour, S. L.; Pratt, D.

    2015-06-01

    A method to measure the δ2H and δ18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapor equilibration and laser spectroscopy (DVE-LS) was first described in 2008, and has since been widely adopted by others. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE-LS over several years. Generally, good comparative agreement and accuracy is obtained between core pore water isotopic data obtained using DVE-LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE-LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g., water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE-LS analyses yield accurate formational isotopic data for fine-textured core (e.g., clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g., sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE-LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE-LS results can be obtained on core samples with gravimetric water contents < 5 % by increasing the sample size tested. Inexpensive Ziploc™ gas sampling bags were determined to be as good as, if not better, than other, more expensive bags. Sample storage in gas tight sample bags provides acceptable results for up to 10 days of storage; however, measureable water loss and evaporitic isotopic enrichment occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE-LS approach for obtaining high resolution pore water

  6. Computer simulated rate processes in copper vapor lasers

    NASA Technical Reports Server (NTRS)

    Harstad, K. C.

    1980-01-01

    A computer model for metal vapor lasers has been developed which places emphasis on the change of excited state populations of the lasant through inelastic collisions and radiative interaction. Also included are an energy equation for the pumping electrons and rate equations for laser photon densities. Presented are results of calculations for copper vapor with a neon buffer over a range of conditions. General agreement with experiments was obtained.

  7. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

    PubMed

    McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude. PMID:17902946

  8. Alexandrite laser transmitter development for airborne water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Chyba, Thomas H.; Ponsardin, Patrick; Higdon, Noah S.; DeYoung, Russell J.; Browell, Edward V.

    1995-01-01

    In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned 'on' and 'off' a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy greater than or equal to 100 mJ, high-resolution tuning capability (uncertainty less than 0.25 pm), good spectral stability (jitter less than 0.5 pm about the mean), and high spectral purity (greater than 99 percent). The off-line laser is generally detuned less than 100 pm away from the water vapor line. Its spectral requirements are much less stringent. In our past research, we developed and demonstrated the airborne DIAL technique for water vapor measurements in the 720-nm spectral region using a system based on an alexandrite laser as the transmitter for the on-line wavelength and a Nd:YAG laser-pumped dye laser for the off-line wavelength. This off-line laser has been replaced by a second alexandrite laser. Diode lasers are used to injection seed both lasers for frequency and linewidth control. This eliminates the need for the two intracavity etalons utilized in our previous alexandrite laser and thereby greatly reduces the risk of optical damage. Consequently, the transmitted pulse energy can be substantially increased, resulting in greater measurement range, higher data density, and increased measurement precision. In this paper, we describe the diode injection seed source, the two alexandrite lasers, and the device used to line lock the on-line seed source to the water vapor absorption feature.

  9. Industrial applications of high-power copper vapor lasers

    SciTech Connect

    Warner, B.E.; Boley, C.D.; Chang, J.J.; Dragon, E.P.; Havstad, M.A.; Martinez, M.; McLean, W. II

    1995-08-01

    A growing appreciation has developed in the last several years for the copper vapor laser because of its utility in ablating difficult materials at high rates. Laser ablation at high rates shows promise for numerous industrial applications such as thin film deposition, precision hole drilling, and machining of ceramics and other refractories.

  10. Vapor-melt Ratio in Laser Fine Cutting of Slot Arrays

    SciTech Connect

    Wang Xuyue; Meng Qingxuan; Kang Renke; Xu Wenji; Guo Dongming; Wang Lianji

    2011-05-04

    In order to improve cut quality for slot arrays, a new method of laser fine cutting under the consideration of the ratio of vapor to melt is presented. Laser cutting of 6063 aluminum alloy sheet, 0.5 mm in thickness, was carried out on a JK701H Nd:YAG pulse laser cutting system. The effects of vapor-melt ratio on kerf width, surface roughness and recast layer were studied which relate cutting qualities. Observation on the cut samples with different vapor-melt ratios (0.687, 1.574, 3.601 varied with laser power increasing, and 1.535, 3.601, 7.661 with decreasing of beam cutting speed) shows that high vapor-melt ratio improves laser cut quality clearly. Kerf width 0.2 mm of smooth area on kerf top area and thickness 2.03 {mu}m of recast layer are obtained. No dross was found on the kerf bottom and the percentage of the smooth area is up to 40% out of whole kerf side. The research on vapor-melt ratio provides a deeper understanding of laser cutting and improves laser cut quality effectively.

  11. Diode pumped alkali vapor lasers for high power applications

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.; Komashko, A.

    2008-02-01

    General Atomics has been engaged in the development of diode pumped alkali vapor lasers. We have been examining the design space looking for designs that are both efficient and easily scalable to high powers. Computationally, we have looked at the effect of pump bandwidth on laser performance. We have also looked at different lasing species. We have used an alexandrite laser to study the relative merits of different designs. We report on the results of our experimental and computational studies.

  12. Selective laser vaporization of polypropylene sutures and mesh

    NASA Astrophysics Data System (ADS)

    Burks, David; Rosenbury, Sarah B.; Kennelly, Michael J.; Fried, Nathaniel M.

    2012-02-01

    Complications from polypropylene mesh after surgery for female stress urinary incontinence (SUI) may require tedious surgical revision and removal of mesh materials with risk of damage to healthy adjacent tissue. This study explores selective laser vaporization of polypropylene suture/mesh materials commonly used in SUI. A compact, 7 Watt, 647-nm, red diode laser was operated with a radiant exposure of 81 J/cm2, pulse duration of 100 ms, and 1.0-mm-diameter laser spot. The 647-nm wavelength was selected because its absorption by water, hemoglobin, and other major tissue chromophores is low, while polypropylene absorption is high. Laser vaporization of ~200-μm-diameter polypropylene suture/mesh strands, in contact with fresh urinary tissue samples, ex vivo, was performed. Non-contact temperature mapping of the suture/mesh samples with a thermal camera was also conducted. Photoselective vaporization of polypropylene suture and mesh using a single laser pulse was achieved with peak temperatures of 180 and 232 °C, respectively. In control (safety) studies, direct laser irradiation of tissue alone resulted in only a 1 °C temperature increase. Selective laser vaporization of polypropylene suture/mesh materials is feasible without significant thermal damage to tissue. This technique may be useful for SUI procedures requiring surgical revision.

  13. Solar-powered alkali metal vapor lasers

    NASA Technical Reports Server (NTRS)

    Blount, Charles E.

    1989-01-01

    The emission spectrum of the A(1 Sigma u +) - X(1 Sigma g +) band of Na2 has been recorded following excitation by monochromatic radiation in the region of X-A and X-B absorption. The spectral profile has been investigated as a function of excitation wavelength, sodium vapor temperature and buffer gas pressure. Additionally, gain measurements were made for the satellite of the A-X band as a function of the sodium vapor temperature and buffer gas pressure.

  14. [Vaporization of urethral stenosis using the KTP 532 laser].

    PubMed

    Schmidlin, F; Oswald, M; Iselin, C; Rohner, S; Jichlinski, P; Delacrétaz, G; Leisinger, H J; Graber, P

    1997-01-01

    The authors treated 16 patients presenting with a total of 20 anterior urethral strictures using the KTP 16 Laser. The aetiology was iatrogenic in 50% of cases, infectious in 20% of cases, traumatic in 20% of cases and unknown in 10% of cases. The stricture was situated in the bulbous urethra (80%), membranous urethra (10%) or penil urethra (10%). Laser vaporization of the urethral stricture was performed over the entire circumference of the urethra when necessary, followed by bladder drainage by urethral catheter for 24 hours. All patients were prospectively reviewed at 3 weeks, 3 months and 6 months (clinical symptoms, uroflowmetry, cystourethrography). A complete symptom and urodynamic success was obtained in 13 patients (81%) at 3 and 6 months. The stricture recurred in 4 patients, but only three of them (19%) required treatment (reoperation of repeat dilatations). The mean maximum flow rate increased from 6 mL/s to 20 mL/s at 3 months and was maintained at 19 mL/s at 6 months. No intraoperative or postoperative complications were observed. In conclusion, our results confirm that KTP 532 laser urethral strictures is a reliable and effective method in the medium term. These good results also suggest an advantage in terms of the recurrence rate in comparison with internal urethrotomy. However, our series needs to be evaluated with a longer follow-up and prospective, randomized trials comparing the two methods need to be conducted. PMID:9157820

  15. Microprocessing with the assistance of copper vapor laser system

    NASA Astrophysics Data System (ADS)

    Azizbekian, G. A.; Grigorian, G. V.; Kazaryan, M. A.; Lyabin, N. A.; Morozova, E. A.; Pogosyan, L. A.; Tamanyan, A. G.

    2006-05-01

    Laser processing of materials always was the important field for laser applications. Copper vapor laser (CVL) system are widely used in micromechanical engineering where optical system may provide high image quality. That allows us to concentrate the energy on a small surface and to produce very tiny holes and very thin cutting edges. The possibility to use "generator-amplifier" laser system (copper vapor elements LT-5Cu and LT-30Cu) for processing material without mechanical movements was investigated. As the pumping generator was used the scheme with the current pulse duration about 80 - 100 ns and the laser pulse duration may vary up to 25 ns. In the unstable resonator scheme the special plane mirror with reflecting coating was used. With the help of this system a number of materials were processed, namely: copper, stainless steel, gold, aluminum and nonmetals: sapphire, ceramics, various rocks, plastics etc.

  16. Modelling of Laser-Enhanced Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1985-01-01

    Research is directed at development of a detailed model of mass and heat transfer and chemical reaction in the pyrolysis of silane for the growth of thin amorphous silicon substrates incorporating laser heating of the gas phase above the film. The model will be the basis for evaluation of the relative importances of the decomposition of SiH4 in the vapor phase, mass transfer of the intermediate species, e.g., SiH2, and the evolution of hydrogen gas. Plans are also underway for developing a model for homogeneous nucleation of Si in the vapor phase to model the rate limitations observed at high gas-phase temperatures and high partial pressures of silane. Work was concentrated on an almost one-dimensional model for the coupling of the CO2 laser beam for heat transfer of the vapor phase with simple kinetic models for SiH4 decomposition and subsequent absorption of Si vapor on the substrate. Mass transfer in the vapor phase is assumed to be solely by diffusion. The role of convection in the vapor phase caused by the large changes in density in and around the center of the laser beam will be analyzed to evaluate the potential of microgravity experiments for increasing the uniformity of the film and the deposition rate.

  17. High power diode pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.

    2008-05-01

    Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

  18. Laser-induced contained-vaporization in tissue

    SciTech Connect

    Dingus, R.S.

    1992-03-01

    When a transparent liquid or solid medium is present in front of an opaque target being irradiated by an intense laser beam, then the expansion of hot vapors generated (at the interface between the medium and the target) by the irradiant heating of the target is restrained by the medium. The tamping effect of the overlying liquid or solid can cause a much larger fraction of the deposited energy to go into kinetic energy, which leads to enhanced tissue disruption, compared to when a gas or vacuum is in front of the target. Condensable vapors and high thermal conductivity in the surrounding material facilitate rapid energy transport out of the vapor, which can cause a major reduction in the tamping enhancements. This contained-vaporization process is likely important in laser-medical applications such as, for example, laser angioplasty and laser lithotripsy. The work enhancement by the process is probably advantageous for lithotripsy in providing the necessary energy to break urinary stones; however, for angioplasty, the enhancement may provide little aid in removing plaque but may cause significant damage to arterial walls. If gas could be introduced into the artery proceeding irradiation of the plaque, then the enhancements could be avoided. In summary, careful management of the tamping conditions during tissue irradiations in the clinical applications of lasers should lead to significant improvements in the overall desired outcome.

  19. Localized planarization of optical damage using laser-based chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Matthews, Manyalibo J.; Elhadj, Selim; Guss, Gabe M.; Sridharan, Arun; Nielsen, Norman D.; Yoo, Jae-Hyuck; Lee, Daeho; Grigoropoulos, Costas

    2013-11-01

    We present a method to repair damaged optics using laser-based chemical vapor deposition (L-CVD). A CO2 laser is used to heat damaged silica regions and polymerize a gas precursor to form SiO2. Measured deposition rates and morphologies agree well with finite element modeling of a two-phase reaction. Along with optimizing deposition rates and morphology, we also show that the deposited silica is structurally identical to high-grade silica substrate and possesses high UV laser damage thresholds. Successful application of such a method could reduce processing costs, extend optic lifetime, and lead to more damage resistant laser optics used in high power applications.

  20. Method for laser machining explosives and ordnance

    DOEpatents

    Muenchausen, Ross E.; Rivera, Thomas; Sanchez, John A.

    2003-05-06

    Method for laser machining explosives and related articles. A laser beam is directed at a surface portion of a mass of high explosive to melt and/or vaporize the surface portion while directing a flow of gas at the melted and/or vaporized surface portion. The gas flow sends the melted and/or vaporized explosive away from the charge of explosive that remains. The method also involves splitting the casing of a munition having an encased explosive. The method includes rotating a munition while directing a laser beam to a surface portion of the casing of an article of ordnance. While the beam melts and/or vaporizes the surface portion, a flow of gas directed at the melted and/or vaporized surface portion sends it away from the remaining portion of ordnance. After cutting through the casing, the beam then melts and/or vaporizes portions of the encased explosive and the gas stream sends the melted/vaporized explosive away from the ordnance. The beam is continued until it splits the article, after which the encased explosive, now accessible, can be removed safely for recycle or disposal.

  1. Multimode-diode-pumped gas (alkali-vapor) laser

    SciTech Connect

    Page, R H; Beach, R J; Kanz, V K

    2005-08-22

    We report the first demonstration of a multimode-diode-pumped gas laser--Rb vapor operating on the 795 nm resonance transition. Peak output of {approx}1 Watt was obtained using a volume-Bragg-grating stabilized pump diode array. The laser's output radiance exceeded the pump radiance by a factor greater than 2000. Power scaling (by pumping with larger diode arrays) is therefore possible.

  2. Erbium:YAG-laser induced vapor bubbles as a function of the quartz fiber tip geometry

    NASA Astrophysics Data System (ADS)

    Mrochen, Michael; Riedel, Peter; Donitzky, Christof; Seiler, Theo

    2001-07-01

    Background. The use of modern erbium: yttrium-aluminum- garnet (YAG) laser systems in ophthalmic microsurgery requires a precise knowledge of the size and dynamics of the laser induced vapor bubbles. The aim of this work was to clarify the possibilities of controlling the vapor bubble shape and size by using an optimized fiber tip geometry for various ophthalmic applications with the erbium:YAG laser. Methods. The mid-infrared radiation of free-running erbium:YAG laser was coupled optically into means of different low OH- quartz fiber tips to investigate the vapor bubble formation in water by high-speed photography. The core diameter of four fiber tips ranged from 200 up to 940 micrometers . Fourteen fiber tips were polished at an angle graduated from 10 degree(s) to 70 degree(s) over the full core diameter (seven fiber tips) and over the half core diameter (seven fiber tips). Three fiber tips were produced to have a curvature at the distal end with curvature radii of 160, 230, and 420 micrometers . Results. The shape as well as the size of erbium:YAG laser induced vapor bubbles can be controlled systematically by using adequate fiber tip geometries. In detail, the used different angles and curvatures demonstrate that the propagation direction of the vapor bubbles can be estimated by optical modeling considering Snell's law and the Fresnel laws at a quartz-air boundary. Beside this, the size of a vapor bubble can be predetermined by choosing ideal fiber tip geometries to reduce or increase the radiant exposure at the distal end of the quartz fiber tip. Conclusions. The good possibility of controlling the shape and size of vapor bubbles offers a wider range of new applications, especially in ophthalmic microsurgery such as erbium YAG laser vitrectomy.

  3. Laser vaporization in treatment of superficial endometriosis of the uterine cervix

    NASA Astrophysics Data System (ADS)

    Wozniak, Jakub; Wilczak, Maciej; Opala, Tomasz; Pisarska-Krawczyk, Magdalena; Cwojdzinski, Marek; Pisarski, Tadeusz

    1996-03-01

    The study shows the treatment of superficial endometriosis of the uterine cervix in 79 patients. After first vaporization 74 patients were cured successfully. In two cases the laser procedure should be repeated and in 3 women the operation should be performed for the third time. All patients are still under control in our department and there is no recurrence observed. Carbon- dioxide laser vaporization under colposcopic control is an efficient method of treatment of superficial endometriosis of the uterine cervix that requires no anaesthesia. The healing process after laser procedures is fast and without complications. The number of recurrences is low. Use of carbon-dioxide laser under colposcopic control because of precise destruction of lesions, fast healing and a low number of recurrences seems to be the method of choice.

  4. Application of G criterion in metal vapor ion laser

    NASA Astrophysics Data System (ADS)

    Gang, Chen; Bailiang, Pan; Yi, Jin; Kun, Chen; Zhixin, Yao

    2003-09-01

    Application of G criterion to efficient operation of pulsed discharge-excited R-M transition metal vapor laser was successfully extended to univalent ionic lasing medium from neutral atomic lasing medium on the basis of analyzing the simulation results of 1.09 μm Sr + lasing process. All of the known 17 R-M transition laser lines of univalent ions follow the G criterion except one, to which an interpretation is given. Furthermore, we suggest that only 69 lines among 212 possible R-M transition laser lines predicted by S.V. Markova, which satisfy the G criterion, should be explored first.

  5. Ion formation in laser-irradiated cesium vapor

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. A.; Gamal, Y. E. E.; Abd El-Rahman, H. A.

    2006-11-01

    We study theoretically the formation of Cs and Cs2+ during cw laser radiation resonant with 6s-7p transition of Cs atomic vapor. This is done by numerically solving rate equations for the evolution of atomic state and electron populations. The results of calculations for the atomic and molecular ions density at different values of laser power clarified that the associative ionization and Penning ionization process play an important role for producing the Cs2+ and Cs, respectively, during the plasma formation. Also, the results showed that laser power of the order of 150 mW and 40 50 ns irradiation time are optimal in producing a fully ionized plasma.

  6. Isotope separation using metallic vapor lasers

    NASA Technical Reports Server (NTRS)

    Russell, G. R.; Chen, C. J.; Harstad, K. G. (Inventor)

    1977-01-01

    The isotope U235 is separated from a gasified isotope mixture of U235 and U238 by selectively exciting the former from the ground state utilizing resonant absorption of radiation from precisely tuned lasers. The excited isotope is then selectively ionized by electron bombardment. It then is separated from the remaining isotope mixture by electromagnetic separation.

  7. Growth of Carbon Nanostructure Materials Using Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeky, S.

    2000-01-01

    Since the potential applications of carbon nanotubes (CNT) was discovered in many fields, such as non-structure electronics, lightweight composite structure, and drug delivery, CNT has been grown by many techniques in which high yield single wall CNT has been produced by physical processes including arc vaporization and laser vaporization. In this presentation, the growth mechanism of the carbon nanostructure materials by laser vaporization is to be discussed. Carbon nanoparticles and nanotubes have been synthesized using pulsed laser vaporization on Si substrates in various temperatures and pressures. Two kinds of targets were used to grow the nanostructure materials. One was a pure graphite target and the other one contained Ni and Co catalysts. The growth temperatures were 600-1000 C and the pressures varied from several torr to 500 torr. Carbon nanoparticles were observed when a graphite target was used, although catalysts were deposited on substrates before growing carbon films. When the target contains catalysts, carbon nanotubes (CNT) are obtained. The CNT were characterized by scanning electron microscopy, x-ray diffraction, optical absorption and transmission, and Raman spectroscopy. The temperature-and pressure-dependencies of carbon nanotubes' growth rate and size were investigated.

  8. Vaporization behavior of non-stoichiometric refractory carbide materials and direct observations of the vapor phase using laser diagnostics

    SciTech Connect

    Butt, D.P.; Wantuck, P.J.; Rehse, S.J.; Wallace, T.C. Sr.

    1993-09-01

    Transition metal and actinide carbides, such as ZrC or NbC and UC or ThC, exhibit a wide range of stoichiometry, and therefore vaporize incongruently. At long times, steady state vaporization can be achieved where relative concentrations of atomic species on solid surface equals that in the gas phase. The surface composition under these steady state conditions is termed the congruently vaporizing composition, (CVC). Modeling the vaporization or corrosion behavior of this dynamic process is complex and requires an understanding of how the surface composition changes with time and a knowledge of CVC, which is both temperature and atmosphere dependent. This paper describes vaporization and corrosion behavior of non-stoichiometric refractory carbide materials and, as an example, describes a thermokinetic model that characterizes the vaporization behavior of the complex carbide U{sub x}Zr{sub 1-x}C{sub y} in hydrogen at 2500 to 3200 K. This model demonstrates that steady state corrosion of U{sub x}Zr{sub l-x}C{sub y} is rate limited by gaseous transport of Zr where partial pressure of Zr is determined by CVC. This paper also briefly describes efforts to image and characterize the vapor phase above the surface of ZrC in static and flowing gas environments using planar laser induced fluorescence. We have developed the method for monitoring and controlling the corrosion behavior of nuclear fuels in nuclear thermal rockets. However, the techniques described can be used, to image boundary layers, and could be used verifying corrosion models.

  9. Laser device and method

    SciTech Connect

    Myers, J. D.

    1985-06-25

    A simplified, relatively inexpensive laser device, wherein the laser elements are fixed in a body exoskeleton of electrical insulating material having a low coefficient of thermal expansion. The preferred embodiment includes a shotgun type laser filter having parallel bores which receive the laser flashlamp and laser rod in fixed relation in a body chamber. The reflector surrounds the laser filter and retains the filter within the body chamber. In the preferred method of this invention, several controlled lasing pulses are generated with each illumination pulse of the flashlamp, substantially increasing the efficiency of the laser device. The number of pulses is generally controlled by increasing the voltage to the flashlamp. The rapid multiple lasing pulses generate an elongated plasma in a fluid medium, such as the vitreous fluid body of an eye which makes the laser device extemely efficient for treating glaucoma and other medical treatments.

  10. Laser amplifier and method

    DOEpatents

    Backus, S.; Kapteyn, H.C.; Murnane, M.M.

    1997-07-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethrough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate. 7 figs.

  11. Laser amplifier and method

    DOEpatents

    Backus, Sterling; Kapteyn, Henry C.; Murnane, Margaret M.

    1997-01-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate.

  12. Apparatus and method to control atmospheric water vapor composition and concentration during dynamic cooling of biological tissues in conjunction with laser irradiations

    DOEpatents

    Nelson, J. Stuart; Anvari, Bahman; Tanenbaum, B. Samuel; Milner, Thomas E.

    1999-01-01

    Cryogen spray cooling of skin surface with millisecond cryogen spurts is an effective method for establishing a controlled temperature distribution in tissue and protecting the epidermis from nonspecific thermal injury during laser mediated dermatological procedures. Control of humidity level, spraying distance and cryogen boiling point is material to the resulting surface temperature. Decreasing the ambient humidity level results in less ice formation on the skin surface without altering the surface temperature during the cryogen spurt. For a particular delivery nozzle, increasing the spraying distance to 85 millimeters lowers the surface temperature. The methodology comprises establishing a controlled humidity level in the theater of operation of the irradiation site of the biological tissues before and/or during the cryogenic spray cooling of the biological tissue. At cold temperatures calibration was achieved by mounting a thermistor on a thermoelectric cooler. The thermal electric cooler was cooled from from 20.degree. C. to about -20.degree. C. while measuring its infrared emission.

  13. Diode laser based water vapor DIAL using modulated pulse technique

    NASA Astrophysics Data System (ADS)

    Pham, Phong Le Hoai; Abo, Makoto

    2014-11-01

    In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

  14. Raman-shifted dye laser for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

    1987-01-01

    For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

  15. High average power magnetic modulator for metal vapor lasers

    DOEpatents

    Ball, Don G.; Birx, Daniel L.; Cook, Edward G.; Miller, John L.

    1994-01-01

    A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

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

    PubMed

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

    2007-12-01

    One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of beta-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO(2) laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO(3) and SrTiO(3) can be formed from corresponding mixtures of beta-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation. PMID:18163736

  18. Scaling of strontium-vapor laser active volume

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Polunin, Yu. P.

    2008-01-01

    Variations in the energy performance of a self-terminating Sr-vapor laser (SrVL) are examined. The active laser volume is varied between 20 and 650 cm 3. A linear relation is revealed between the average power delivered by the SrVL and its active volume. The SrVL efficiency is found to increase with active volume and to be comparable with that of a copper-vapor laser for an active volume V = 650 cm 3 (0.45 %). As the volume is increased, the total lasing pulse duration increases from 30 to 120 ns. The beam divergence problems associated with the use of a Fabry-Perot cavity or an unstable resonator of the telescopic type are discussed. A total average power of 13.5 W is obtained from V = 650 cm 3 at a lasing PRR F = 19 kHz. The output power generated at different laser wavelengths is as follows: 10.4 W at λ = 6.456 μm, 2.6 W at λ = 3 μm, and 0.5 W at λ = 1 μm. The wavelength dependence of the lasing pulse duration is considered.

  19. Method and Apparatus for Concentrating Vapors for Analysis

    DOEpatents

    Grate, Jay W.; Baldwin, David L.; Anheier, Jr., Norman C.

    2008-10-07

    An apparatus and method are disclosed for pre-concentrating gaseous vapors for analysis. The invention finds application in conjunction with, e.g., analytical instruments where low detection limits for gaseous vapors are desirable. Vapors sorbed and concentrated within the bed of the apparatus can be thermally desorbed achieving at least partial separation of vapor mixtures. The apparatus is suitable, e.g., for preconcentration and sample injection, and provides greater resolution of peaks for vapors within vapor mixtures, yielding detection levels that are 10-10,000 times better than for direct sampling and analysis systems. Features are particularly useful for continuous unattended monitoring applications.

  20. Tm:germanate Fiber Laser for Planetary Water Vapor Atmospheric Profiling

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; De Young, Russell

    2009-01-01

    The atmospheric profiling of water vapor is necessary for finding life on Mars and weather on Earth. The design and performance of a water vapor lidar based on a Tm:germanate fiber laser is presented.

  1. Means and method for vapor generation

    DOEpatents

    Carlson, Larry W.

    1984-01-01

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid--starting as "feedwater" heating where no vapors are present, progressing to "nucleate" heating where vaporization begins and some vapors are present, and concluding with "film" heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10-30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  2. Means and method for vapor generation

    DOEpatents

    Carlson, L.W.

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid - starting as feedwater heating where no vapors are present, progressing to nucleate heating where vaporization begins and some vapors are present, and concluding with film heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10 to 30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  3. From a metal vapor laser projection microscope to a laser monitor (by the 50 year-anniversary of metal vapor lasers)

    NASA Astrophysics Data System (ADS)

    Evtushenko, G. S.

    2015-12-01

    The paper presents the history of active optical systems development from a laser projection microscope to a laser monitor. The examples of object visualization and diagnostics of high speed processes hidden by the intense background radiation are discussed. These are the processes of laser-surface interaction, self-propagating high-temperature synthesis (SHS), the corona discharge in the air, the nanoparticle production process using a high-power fiber laser, and etc. The results obtained by different research groups suggest that high-speed metal vapor brightness amplifiers and active optical systems based on them need further research, development and novel applications.

  4. Atomic vapor laser isotope separation using resonance ionization

    SciTech Connect

    Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J.; Paisner, J.; Solarz, R.; Worden, E.

    1986-09-01

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.

  5. Analysis of temporal jitter in a copper vapor laser system.

    PubMed

    Durga Praveen Kumar, D; Gantayet, L M; Singh, Sunita; Rawat, A S; Rana, Paramjit; Rajasree, V; Agarwalla, Sandeep K; Chakravarthy, D P

    2012-02-01

    Temporal jitter in a magnetic pulse compression based copper vapor laser (CVL) system is analyzed by considering ripple present in the input dc power supply and ripple present in the magnetic core resetting power supply. It is shown that the jitter is a function of the ratio of operating voltage to the designed voltage, percentage ripple, and the total propagation delay of the magnetic pulse compression circuit. Experimental results from a CVL system operating at a repetition rate of 9 kHz are presented. PMID:22380123

  6. Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

    PubMed

    Atutov, S N; Baldini, W; Biancalana, V; Calabrese, R; Guidi, V; Mai, B; Mariotti, E; Mazzocca, G; Moi, L; Pod'yachev, S P; Tomassetti, L

    2001-11-19

    Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process. PMID:11736344

  7. Improved performance of the pulsed copper-vapor-laser CuCl-vapor-laser with a compact device by applying an ac continuous-glow-discharge

    NASA Astrophysics Data System (ADS)

    Saito, H.; Taniguchi, H.; Ohgami, K.

    1985-10-01

    An additional continuous-glow-discharge was applied to the aperiodic pulsed CuCl-vapor laser. The experimental results exhibited an increase of up to 60 percent the laser-output average power at the maximum point, an increase of 1.5 times the peak power and pulse repetition frequency, and twice the pulse width in the laser oscillation against the laser without the continuous-glow discharge. Further, the additional technique led the CuCl-vapor-laser to operate in the higher operating-temperature region.

  8. Femtosecond laser fluorescence and propagation in very dense potassium vapor.

    PubMed

    Makdisi, Y; Kokaj, J; Afrousheh, K; Nair, R; Mathew, J; Pichler, G

    2013-12-16

    Femtosecond (fs) laser propagation and fluorescence of dense potassium vapor was studied, and the spectral region around the first and the second doublets of the principal series lines of potassium atoms was investigated. In our search we did not observe the conical emission in the far field, although it was previously observed in the case of rubidium. We discuss the possible reason of this unexpected result. The fluorescence spectrum revealed Rb impurity resonance lines in emission due to the collisional redistribution from the K(4p) levels into the Rb(5p) levels. In the forward propagation of 400 nm femtosecond light we observed the molecular band red shifted from potassium second doublet. However, no molecular spectrum was observed when the mode-locked fs laser light was discretely tuned within the wings of the first resonance lines, at 770 nm. PMID:24514609

  9. An application of oil vaporization evaluation methods

    SciTech Connect

    Fleckenstein, W.W.; Bouck, L.S.; Hudgens, D.; Querin, M.; Williams, L.

    1992-02-01

    This paper describes and quantifies the benefits of residual oil vaporization in an enhanced recovery gas injection project. Vaporized oil is recovered as natural gas liquid (NGL) when the injected gas is produced. In the reservoir application studied, 20% of the liquid hydrocarbons produced were being recovered as NGL. (VC)

  10. Application of pulsed-uv laser Raman spectroscopy to chemical vapor deposition

    SciTech Connect

    Hargis, P.J. Jr.

    1981-01-01

    Raman detection limits obtained with a KrF laser excitation source were comparable to those obtained by laser-induced fluorescence and photofragment emission spectroscopy under chemical vapor deposition conditions.

  11. Single frequency and wavelength stabilized near infrared laser source for water vapor DIAL remote sensing application

    NASA Astrophysics Data System (ADS)

    Chuang, Ti; Walters, Brooke; Shuman, Tim; Losee, Andrew; Schum, Tom; Puffenberger, Kent; Burnham, Ralph

    2015-02-01

    Fibertek has demonstrated a single frequency, wavelength stabilized near infrared laser transmitter for NASA airborne water vapor DIAL application. The application required a single-frequency laser transmitter operating at 935 nm near infrared (NIR) region of the water vapor absorption spectrum, capable of being wavelength seeded and locked to a reference laser source and being tuned at least 100 pm across the water absorption spectrum for DIAL on/off measurements. Fibertek is building a laser transmitter system based on the demonstrated results. The laser system will be deployed in a high altitude aircraft (ER-2 or UAV) to autonomously perform remote, long duration and high altitude water vapor measurements.

  12. High intensity vacuum ultraviolet and extreme ultraviolet production by noncollinear mixing in laser vaporized media

    NASA Astrophysics Data System (ADS)

    Todt, Michael A.; Albert, Daniel R.; Davis, H. Floyd

    2016-06-01

    A method is described for generating intense pulsed vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) laser radiation by resonance enhanced four-wave mixing of commercial pulsed nanosecond lasers in laser vaporized mercury under windowless conditions. By employing noncollinear mixing of the input beams, the need of dispersive elements such as gratings for separating the VUV/XUV from the residual UV and visible beams is eliminated. A number of schemes are described, facilitating access to the 9.9-14.6 eV range. A simple and convenient scheme for generating wavelengths of 125 nm, 112 nm, and 104 nm (10 eV, 11 eV, and 12 eV) using two dye lasers without the need for dye changes is described.

  13. Industrial aspects of precision machining with copper vapor lasers

    NASA Astrophysics Data System (ADS)

    Hartmann, Martin; Koch, Juergen; Lang, Adolf; Schutte, Karsten; Bergmann, Hans W.

    1997-08-01

    The applications of conventional infrared lasers running cw or quasi-sw for drilling, cutting and shaping are limited in the precision achievable due to the long interaction time which leads to heat affected zones. The necessity to use a gas jet to blow the molten material out of the cut kerf will damage fragile workpieces like thin foils. Short laser pulses of sufficient intensity remove the material directly by evaporation and minimize the amount of heat transferred into the solid. Classical infrared laser sources generate a shielding air plasma within some ns at power densities above some 107W/cm2. The optical breakdown threshold value in air can be shifted to higher intensities by using visible light as well as reducing the focal diameter. An alternative way is to shorten the pulse duration to less than 10 ps that a plasma is generated only after the pulse. Thus, the material removal process begins after the deposition of the pulse energy into the material. But such short pulses will generate a pressure wave due to the sudden thermal expansion and can damage or destroy microscopic components. For industrial production the productivity is a further aspect. Hence, a certain mean power is required in order to obtain the desired production rate. Considering the above aspects, copper vapor lasers (CVLs) with ns pulse duration are well suited for precision machining of metals and ceramics. Processing with CVLs is an advantage in that its wavelength is highly absorbed by metallic targets and the probability for the optical breakdown in air is low. CVLs in an oscillator-amplifier-setup incorporate diffraction limited beam quality and high average power. The present paper outlines the potential of the CVL for the industrial use regarding high processing speed and precision. Under these aspects the limiting mechanisms on the material removal process and the necessary processing strategies for scaling up the productivity are shown. The relevant laser parameters for

  14. Alexandrite laser characterization and airborne lidar developments for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, P.; Higdon, N. S.; Grossmann, B. E.; Browell, E. V.

    1991-01-01

    The spectral characteristics of an Alexandrite laser used for making water vapor DIAL measurements have been evaluated. The optical servo-system used to lock the laser wavelength on a water vapor absorption line is described. A brief description of the DIAL system is given and the data obtained with this lidar during flight tests in March 1990 are also presented.

  15. Numerical and experimental analysis of middle-bore copper-vapor laser discharge

    NASA Astrophysics Data System (ADS)

    Yu, Deli; Tao, Yongxiang; Yin, Xianhua; Chen, Lin; Yang, Yan; Li, Hailan; Wang, Runwen

    1998-08-01

    A single simulation model describing the discharge circuitry is introduced. First the differential equations are presented. In order to calculate the laser head discharge current, the thyratron resistance with a switching time coefficient (tau) s is investigated. The plasma conductivity used in these models is estimated using the available data on plasma parameters. Here 0.6 eV of the average electron temperature and 80 nH of thyratron inductance are assumed according to our previous model. The laser head discharge current of the differential equations is calculated with the method of Runge- Kutta. The discharge current profiles of the simulation are found to be in close agreement with the experimental data which come from 4.8-cm-diameter and 6.5-cm-diameter middle- bore Copper-Vapor Laser. In this way, the factors which effect the short rise time to increase lasing ability in the CVL (Copper-Vapor Laser) are studied on the bases of studying the storage capacitor's and the peaking capacitor's effect. As a calculation result, the inductance of the laser head takes an inferior effect to the thyratron circuit inductance on the discharge current rise time. Very good agreement exists between the calculated and measured results. This is a successful single discharge model.

  16. Stabilization and spectral characterization of an alexandrite laser for water vapor lidar measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Higdon, Noah S.; Grossman, Benoist E.; Browell, Edward V.

    1991-01-01

    A description of an optical system used to lock the alexandrite laser frequency on a water vapor absorption line is presented. The laser spectral characteristics, which include the spectral purity, the effect of the laser linewidth on the absorption, and the laser wavelength stability, are evaluated.

  17. High-repetition-rate tunable dye lasers pumped by copper vapor laser

    SciTech Connect

    Zherikin, A.N.; Letokhov, V.S.; Mishin, V.I.; Belyaev, V.P.; Evtyunin, A.N.; Lesnoi, M.A.

    1981-06-01

    A study was made of stimulated emission and amplification of light in lasers with active media consisting of alcohol solutions of rhodamines 110, 6G, and B, and of oxazine 17. The pulse repetition frequency was 10 kHz and pumping was provided by a mass-produced copper vapor laser of the ILGI-101 type. The dye lasers emitted in the range 530--720 nm. The efficiency of the oxazine 17 laser was 20% and the efficiency of the rhodamine 6G amplifier was 30% when the width of the laser emission spectrum was 0.8 cm/sup -1/. A Fabry--Perot interferometer was used to reduce the width of the spectrum to 0.04 cm/sup -1/, but this reduced the efficiency to 7%. The maximum output power was 0.6 W. The radiation was transformed to the second harmonic in the 265--360 nm range with an efficiency of 5%.

  18. BRIEF COMMUNICATIONS: High-repetition-rate tunable dye lasers pumped by copper vapor laser

    NASA Astrophysics Data System (ADS)

    Zherikin, A. N.; Letokhov, V. S.; Mishin, V. I.; Belyaev, V. P.; Evtyunin, A. N.; Lesnoĭ, M. A.

    1981-06-01

    A study was made of stimulated emission and amplification of light in lasers with active media consisting of alcohol solutions of rhodamines 110, 6G, and B, and of oxazine 17. The pulse repetition frequency was 10 kHz and pumping was provided by a mass-produced copper vapor laser of the ILGI-101 type. The dye lasers emitted in the range 530-720 nm. The efficiency of the oxazine 17 laser was 20% and the efficiency of the rhodamine 6G amplifier was 30% when the width of the laser emission spectrum was 0.8 cm-1. A Fabry-Perot interferometer was used to reduce the width of the spectrum to 0.04 cm-1, but this reduced the efficiency to 7%. The maximum output power was 0.6 W. The radiation was transformed to the second harmonic in the 265-360 nm range with an efficiency of 5%.

  19. Laser pulse stacking method

    DOEpatents

    Moses, Edward I.

    1992-01-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter.

  20. Laser pulse stacking method

    DOEpatents

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  1. Method for controlling corrosion in thermal vapor injection gases

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.

    1981-01-01

    An improvement in the method for producing high pressure thermal vapor streams from combustion gases for injection into subterranean oil producing formations to stimulate the production of viscous minerals is described. The improvement involves controlling corrosion in such thermal vapor gases by injecting water near the flame in the combustion zone and injecting ammonia into a vapor producing vessel to contact the combustion gases exiting the combustion chamber.

  2. Endoscopic photodynamic therapy of tumors using gold vapor laser

    NASA Astrophysics Data System (ADS)

    Kuvshinov, Yury P.; Poddubny, Boris K.; Mironov, Andrei F.; Ponomarev, Igor V.; Shental, V. V.; Vaganov, Yu. E.; Kondratjeva, T. T.; Trofimova, E. V.

    1996-01-01

    Compact sealed-off gold vapor laser (GVL) with 2 W average power and 628 nm wavelength was used for endoscopic photodynamic therapy in 20 patients with different tumors in respiratory system and upper gastrointestinal tract. Russian-made hematoporphyrin derivative (Hpd) `Photohem' was used as a photosensitizer. It was given intravenously at a dose of 2 - 2.5 mg/kg body weight 48 hours prior to tumor illumination with 628 nm light from GVL. Intermittent irradiation with GVL was done through flexible endoscope always under local anaesthesia at a power of 200 - 400 mW/sm2 and a dose of 150 - 400 J/sm2. 80% patients showed complete or partial response depending on stage of tumor. In cases of early gastric cancer all patients had complete remission with repeated negative biopsies. No major complication occurred.

  3. Thermal electric vapor trap arrangement and method

    DOEpatents

    Alger, Terry

    1988-01-01

    A technique for trapping vapor within a section of a tube is disclosed herein. This technique utilizes a conventional, readily providable thermal electric device having a hot side and a cold side and means for powering the device to accomplish this. The cold side of this device is positioned sufficiently close to a predetermined section of the tube and is made sufficiently cold so that any condensable vapor passing through the predetermined tube section is condensed and trapped, preferably within the predetermined tube section itself.

  4. Thermal electric vapor trap arrangement and method

    DOEpatents

    Alger, T.

    1988-03-15

    A technique for trapping vapor within a section of a tube is disclosed herein. This technique utilizes a conventional, readily providable thermal electric device having a hot side and a cold side and means for powering the device to accomplish this. The cold side of this device is positioned sufficiently close to a predetermined section of the tube and is made sufficiently cold so that any condensable vapor passing through the predetermined tube section is condensed and trapped, preferably within the predetermined tube section itself. 4 figs.

  5. Method and apparatus for concentrating vapors for analysis

    DOEpatents

    Grate, Jay W.; Baldwin, David L.; Anheier, Jr., Norman C.

    2012-06-05

    A pre-concentration device and a method are disclosed for concentrating gaseous vapors for analysis. Vapors sorbed and concentrated within the bed of the pre-concentration device are thermally desorbed, achieving at least partial separation of the vapor mixtures. The pre-concentration device is suitable, e.g., for pre-concentration and sample injection, and provides greater resolution of peaks for vapors within vapor mixtures, yielding detection levels that are 10-10,000 times better than direct sampling and analysis systems. Features are particularly useful for continuous unattended monitoring applications. The invention finds application in conjunction with, e.g., analytical instruments where low detection limits for gaseous vapors are desirable.

  6. A new method for measuring vapor emissions

    SciTech Connect

    Knaebel, K.S.; Yeoman, L.D.

    1996-12-31

    A new approach for measuring point-source emissions of volatile organic compounds, acidic vapors, and other species is presented. The basic principle is that the amount emitted is determined directly, by mass, and is cumulative rather than intermittent. As a result, wide fluctuations of concentration and erratic flow behavior are accommodated without affecting the accuracy of the measured emission rate. The vapors are retained by a sorbent, such as activated carbon, ion exchange resin, or zeolite, or a combination of those. Validation tests have been conducted in which a known quantity of vapor in a carrier gas was admitted to the test unit, and that was compared with the amount measured. The vapor comprised a single VOC, a mixture of VOCs, or a mixture of a VOC with water. Conditions studied were: the compound or mixture of compounds, concentration, carrier gas, flow rate, and adsorbent. In some tests the VOC was admitted intermittently. The VOCs included: hexane, acetone, toluene, vinyl acetate, and 1,1,1 trichloroethane. The average absolute error of the delivered and measured VOC emission rates was 6.8% and the standard deviation was 3.4%. 6 refs., 6 figs., 3 tabs.

  7. Method and apparatus for conducting variable thickness vapor deposition

    DOEpatents

    Nesslage, G.V.

    1984-08-03

    A method of vapor depositing metal on a substrate in variable thickness comprises conducting the deposition continuously without interruption to avoid formation of grain boundaries. To achieve reduced deposition in specific regions a thin wire or ribbon blocking body is placed between source and substrate to partially block vapors from depositing in the region immediately below.

  8. Fragmentation methods in laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Jiang, Zhi X.; Whitehurst, Colin; King, Terence A.

    1991-07-01

    Following a series of opto-acoustic-mechanical and spectroscopic studies into the basic mechanisms of laser lithotripsy, a plasma-mediated opto-mechanical energy transfer model is presented. Laser energy, first absorbed by the calculi material at the surface and couples into the initiated plasma following ionization of vaporized material, is finally transformed into destructive mechanical energy via a shock wave induced by the impulsive expansion of the resulting plasma. This leads to the fragmentation of the calculi. The laser-plasma energy coupling gives a new definition for the fluence threshold to laser induced breakdown, which agrees with shock wave detection and analysis. A laser pulse shape with initial low intensity and sufficient fluence to vaporize a required amount of target material (lasting a few microsecond(s) ) and terminating in a short, intense pulse of about 1microsecond(s) or less, to couple most of the laser energy into the dense young plasma and so create high pressures, is required to produce optimum effect for laser lithotripsy. An opto-mechanical coupler has been designed which transfers the maximum laser energy into mechanically destructive energy, and successfully fragments various types of urinary and biliary calculi even including those calculi with poor surface absorptance, like pure white cystine. A solid state laser, Ho:YAG (2.1 micrometers wavelength and 150 microsecond(s) pulse width), has also been tested as an alternative to the flashlamp-excited dye laser. The underwater shock wave induced by this laser has been measured and has successfully fragmented calculi with poor absorptance in the visible region.

  9. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers

    SciTech Connect

    Sell, J. F.; Gulyuz, K.; Sprouse, G. D.

    2009-12-15

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized {sup 208-210}Fr ion beams at beam energies of 5 keV and intensities of 10{sup 5} s{sup -1}. Efficient neutralization ({>=}80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

  10. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers

    NASA Astrophysics Data System (ADS)

    Sell, J. F.; Gulyuz, K.; Sprouse, G. D.

    2009-12-01

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized F208-210r ion beams at beam energies of 5 keV and intensities of 105 s-1. Efficient neutralization (≥80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

  11. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers.

    PubMed

    Sell, J F; Gulyuz, K; Sprouse, G D

    2009-12-01

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized (208-210)Fr ion beams at beam energies of 5 keV and intensities of 10(5) s(-1). Efficient neutralization (> or = 80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate. PMID:20059132

  12. Simulation studies of vapor bubble generation by short-pulse lasers

    SciTech Connect

    Amendt, P.; London, R.A.; Strauss, M.

    1997-10-26

    Formation of vapor bubbles is characteristic of many applications of short-pulse lasers in medicine. An understanding of the dynamics of vapor bubble generation is useful for developing and optimizing laser-based medical therapies. To this end, experiments in vapor bubble generation with laser light deposited in an aqueous dye solution near a fiber-optic tip have been performed. Numerical hydrodynamic simulations have been developed to understand and extrapolate results from these experiments. Comparison of two-dimensional simulations with the experiment shows excellent agreement in tracking the bubble evolution. Another regime of vapor bubble generation is short-pulse laser interactions with melanosomes. Strong shock generation and vapor bubble generation are common physical features of this interaction. A novel effect of discrete absorption by melanin granules within a melanosome is studied as a possible role in previously reported high Mach number shocks.

  13. A Three Level Analytic Model for Alkali Vapor Lasers

    SciTech Connect

    Hager, Gordon D.; Perram, Glen P.

    2010-10-08

    A three level analytic model for optically pumped alkali metal vapor lasers is developed considering the steady-state rate equations for the longitudinally averaged number densities of the ground {sup 2}S{sub 1/2} and first excited {sup 2}P{sub 1/2} and {sup 2}P{sub 3/2} states. The threshold pump intensity includes both the requirements to fully bleach the pump transition and exceed optical losses, typically about 200 W/cm{sup 2}. Slope efficiency depends critically on the fraction of incident photons absorbed and the overlap of pump and resonator modes, approaching the quantum efficiency of 0.95-0.98, depending on alkali atom. For efficient operation, the collisional relaxation between the two upper levels should be fast relative to stimulated emission. By assuming a statistical distribution between the upper levels, the limiting analytic solution for the quasi-two level system is achieved. Application of the model and comparisons to recent laser demonstrations is presented.

  14. Fabrication of highly ultramicroporous carbon nanofoams by SF6-catalyzed laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hattori, Yoshiyuki; Shuhara, Ai; Kondo, Atsushi; Utsumi, Shigenori; Tanaka, Hideki; Ohba, Tomonori; Kanoh, Hirofumi; Takahashi, Kunimitsu; Vallejos-Burgos, Fernando; Kaneko, Katsumi

    2016-05-01

    We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF6. This method would offer advantages for the production of aggregates of nanoscale foams (nanofoams) at high rates. Pyrolysis of the as-grown nanofoams induced the high surface area (1120 m2 g-1) and significantly enhanced the adsorption of supercritical H2 (16.6 mg g-1 at 77 K and 0.1 MPa). We also showed that the pyrolized nanofoams have highly ultramicroporous structures. The pyrolized nanofoams would be superior to highly microporous nanocarbons for the adsorption of supercritical gases.

  15. The threshold of vapor channel formation in water induced by pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Guo, Wenqing; Zhang, Xianzeng; Zhan, Zhenlin; Xie, Shusen

    2012-12-01

    Water plays an important role in laser ablation. There are two main interpretations of laser-water interaction: hydrokinetic effect and vapor phenomenon. The two explanations are reasonable in some way, but they can't explain the mechanism of laser-water interaction completely. In this study, the dynamic process of vapor channel formation induced by pulsed CO2 laser in static water layer was monitored by high-speed camera. The wavelength of pulsed CO2 laser is 10.64 um, and pulse repetition rate is 60 Hz. The laser power ranged from 1 to 7 W with a step of 0.5 W. The frame rate of high-speed camera used in the experiment was 80025 fps. Based on high-speed camera pictures, the dynamic process of vapor channel formation was examined, and the threshold of vapor channel formation, pulsation period, the volume, the maximum depth and corresponding width of vapor channel were determined. The results showed that the threshold of vapor channel formation was about 2.5 W. Moreover, pulsation period, the maximum depth and corresponding width of vapor channel increased with the increasing of the laser power.

  16. High-Efficiency 894-nm Laser Emission of Laser-Diode-Bar-Pumped Cesium-Vapor Laser

    NASA Astrophysics Data System (ADS)

    Zheng, Yujin; Niigaki, Minoru; Miyajima, Hirofumi; Hiruma, Teruo; Kan, Hirofumi

    2009-03-01

    We report a high-efficiency cesium-vapor laser with a high-gas-pressure (˜3-atm helium and 0.49-atm ethane) cell pumped by a high-power external-cavity laser-diode bar. Peak laser power of 12.1 W at 894 nm was obtained, when the absorbed peak pump power was 23.1 W. The achieved slope efficiencies with the incident pump power and the absorbed pump power were 33 and 81.7%, respectively.

  17. Carbon dioxide laser vaporization of the inferior turbinate for allergic rhinitis: short-term results.

    PubMed

    Imamura, Shun-ichi; Honda, Hideyuki

    2003-12-01

    Carbon dioxide laser vaporization of the turbinate has recently become accepted as a common treatment for allergic rhinitis. Usually, only a single procedure is applied to minimize trauma. However, repeated procedures on separate days are often required to achieve an adequate effect. Therefore, we attempted a new method of vaporization and evaluated the outcome, and also tried to determine which patients have good indications for laser treatment. To widely and deeply vaporize the inferior turbinate, we repeated the procedure 3 times in 1 session after removing the carbon coating from the previous vaporization under nasal endoscopic observation. After the procedure, most patients experienced complete nasal obstruction for 2 or 3 days, but there was no intraoperative or postoperative bleeding or severe pain. All patients obtained improvement of their chief complaints and were satisfied 2 months after the operation. In particular, 60% of the patients were completely relieved of refractory nasal obstruction. Most patients were more satisfied with the effects than are those treated by the usual methods. Completely successful cases (improvement in all symptoms and complete satisfaction obtained) were selected and were compared with other cases. Favorable prognostic factors are more severe complaints, longer symptomatic periods, stronger allergic reactions, and worse nasal resistance and its greater improvement with administration of decongestant nasal drops. This method may be especially accepted by patients with severe complaints, in particular nasal obstruction, who do not experience enough relief with conservative therapies or have enough time to make frequent visits to an outpatient clinic over a period of several weeks. PMID:14703108

  18. Internal Energy Deposition for Low Energy, Femtosecond Laser Vaporization and Nanospray Post-ionization Mass Spectrometry using Thermometer Ions

    NASA Astrophysics Data System (ADS)

    Flanigan, Paul M.; Shi, Fengjian; Archer, Jieutonne J.; Levis, Robert J.

    2015-05-01

    The internal energy of p-substituted benzylpyridinium ions after laser vaporization using low energy, femtosecond duration laser pulses of wavelengths 800 and 1042 nm was determined using the survival yield method. Laser vaporization of dried benzylpyridinium ions from metal slides into a buffered nanospray with 75 μJ, 800 nm laser pulses resulted in a higher extent of fragmentation than conventional nanospray due to the presence of a two-photon resonance fragmentation pathway. Using higher energy 800 nm laser pulses (280 and 505 μJ) led to decreased survival yields for the four different dried benzylpyridinium ions. Analyzing dried thermometer ions with 46.5 μJ, 1042 nm pulse-bursts resulted in little fragmentation and mean internal energy distributions equivalent to nanospray, which is attributable to the absence of a two-photon resonance that occurs with higher energy, 800 nm laser pulses. Vaporization of thermometer ions from solution with either 800 nm or 1042 nm laser pulses resulted in comparable internal energy distributions to nanospray ionization.

  19. Internal energy deposition for low energy, femtosecond laser vaporization and nanospray post-ionization mass spectrometry using thermometer ions.

    PubMed

    Flanigan, Paul M; Shi, Fengjian; Archer, Jieutonne J; Levis, Robert J

    2015-05-01

    The internal energy of p-substituted benzylpyridinium ions after laser vaporization using low energy, femtosecond duration laser pulses of wavelengths 800 and 1042 nm was determined using the survival yield method. Laser vaporization of dried benzylpyridinium ions from metal slides into a buffered nanospray with 75 μJ, 800 nm laser pulses resulted in a higher extent of fragmentation than conventional nanospray due to the presence of a two-photon resonance fragmentation pathway. Using higher energy 800 nm laser pulses (280 and 505 μJ) led to decreased survival yields for the four different dried benzylpyridinium ions. Analyzing dried thermometer ions with 46.5 μJ, 1042 nm pulse-bursts resulted in little fragmentation and mean internal energy distributions equivalent to nanospray, which is attributable to the absence of a two-photon resonance that occurs with higher energy, 800 nm laser pulses. Vaporization of thermometer ions from solution with either 800 nm or 1042 nm laser pulses resulted in comparable internal energy distributions to nanospray ionization. PMID:25724375

  20. Single titanium crystals encapsulated in carbon nanocages obtained by laser vaporization of sponge titanium in benzene vapor

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Huang, Rong-bin; Tang, Zi-chao; Zheng, Lan-sun; Zhou, Guang-wen; Zhang, Ze

    2000-07-01

    A technique, laser vaporization by ablating at a solid target in the vapor phase, is developed to produce encapsulated titanium nanocrystals. By vaporizing sponge titanium in benzene vapor, the single titanium crystals encapsulated in carbon nanocages have been synthesized in good yields. The sizes of the encapsulated crystals are around 5-15 nm and the numbers of the wrapped graphitic layers are on the order of 3-10 layers. Characteristic lattice spacings and angles observed by high-resolution transmission electron microscopy identify two phases of the nanocrystals inside the carbon onion cavities as α-Ti and β-Ti. The latter has never been stable below 850 °C until the experiment. The encapsulated titanium crystals adsorbed a large amount of hydrogen released in the synthesis.

  1. Laser chemical vapor deposition of Cu and Ni in integrated circuit repair

    NASA Astrophysics Data System (ADS)

    Leppaevuori, Seppo; Remes, Janne; Moilanen, Hannu

    1996-09-01

    Laser-assisted chemical vapor deposition (LCVD) of nickel from Ni(CO)4 and copper from Cu(hfac)tmvs was utilized in the restructuring of an integrated circuit (IC) interconnection. Nickel and copper lines were deposited on passivated ICs by using a focused Ar+ laser beam to achieve new local rewirings on the chip. Nickel line depositions were carried out over the pressure range of 0.2 to 2.2 mbar of Ni(CO)4 buffered in 200 - 800 mbar He. The typical laser beam scan speed was 24 micrometers per second for both metals. The Cu(hfac)tmvs precursor gas partial pressure was 0.3 mbar buffered in 10 mbar He or H2 and typical laser scan speed was 24 micrometers per second. The morphology and chemical contents of the deposited interconnection microstructures was examined by atomic force microscopy (AFM), optical microscopy and laser ionization mass analysis (LIMA). The LIMA analysis indicated that the deposited copper surface was contaminated but the contamination level decreased when the layer was depth profiled. The deposited Ni lines were found to be pure Ni with only traces of carbon contamination. The utilization of XeCl excimer laser in the cutting of Al and Mo conductor lines and passivation contact via opening for IC modification is also described. LCVD method was successful in numerous different IC failure inspection and circuit modification cases.

  2. Gas phase versus surface contributions to photolytic laser chemical vapor deposition rates

    NASA Astrophysics Data System (ADS)

    Braichotte, D.; van den Bergh, H.

    1988-04-01

    The rate of cw photolytic laser chemical vapor deposition (LCVD) of platinum is measured for λ≈350 nm as a function of the light intensity and the metalorganic vapor pressure. The growth of the metal films is studied in situ and in real time by monitoring their optical transmission. At low intensities the transmitted light decreases monotonically with time, and the LCVD process is photolytic with its rate limiting step in the surface adlayer. At higher intensities we observe two distinct time domains: Relatively slow initial photolytic deposition with its rate limiting step in the gas phase, which is followed by much faster pyrolytic LCVD. An improved method for distinguishing between adlayer and gas-phase limiting processes is demonstrated. These observations are confirmed by studying the photolytic deposition rates while varying the thickness of the adlayer.

  3. Characteristics of a dye laser amplifier transversely pumped by copper vapor lasers with a two-dimensional calculation model

    SciTech Connect

    Sugiyama, A.; Nakayama, T.; Kato, M.; Maruyama, Y.

    1997-08-01

    A two-dimensional rate equation model, taking into consideration the transverse absorption loss of pump laser power, is proposed to evaluate the characteristics of a dye laser amplifier with a large input laser beam diameter pumped by high average power copper vapor lasers. The calculations are in good agreement with the measurements taken with a Rhodamine 6G dye, and the model can be used for evaluation of the dye concentration at any wavelength. {copyright} 1997 Optical Society of America

  4. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    DOEpatents

    Yeung, Edward S.; Chang, Yu-chen

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent.

  5. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    DOEpatents

    Yeung, E.S.; Chang, Y.C.

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent. 8 figs.

  6. Note: A novel and robust circuit for jitter reduction in copper vapor laser system

    NASA Astrophysics Data System (ADS)

    Mishra, R. K.; Raju, D. V. S.; Nakhe, S. V.

    2015-11-01

    A novel circuit scheme is presented to improve timing jitter performance of high voltage pulse power supply utilizing semiconductor switches and magnetic pulse compressors, for pumping pulsed copper vapor lasers. The circuit effectively handles reflected energy from the laser load and achieves better jitter performance. The proposed circuit scheme had typical jitter value of ±2 ns whereas the standard circuit used earlier had jitter of more than ±10 ns under similar conditions. Performance of the circuit scheme is studied on a copper vapor laser operating at average laser power of 40 W.

  7. Note: A novel and robust circuit for jitter reduction in copper vapor laser system.

    PubMed

    Mishra, R K; Raju, D V S; Nakhe, S V

    2015-11-01

    A novel circuit scheme is presented to improve timing jitter performance of high voltage pulse power supply utilizing semiconductor switches and magnetic pulse compressors, for pumping pulsed copper vapor lasers. The circuit effectively handles reflected energy from the laser load and achieves better jitter performance. The proposed circuit scheme had typical jitter value of ±2 ns whereas the standard circuit used earlier had jitter of more than ±10 ns under similar conditions. Performance of the circuit scheme is studied on a copper vapor laser operating at average laser power of 40 W. PMID:26628188

  8. Systems and methods for generation of hydrogen peroxide vapor

    DOEpatents

    Love, Adam H; Eckels, Joel Del; Vu, Alexander K; Alcaraz, Armando; Reynolds, John G

    2014-12-02

    A system according to one embodiment includes a moisture trap for drying air; at least one of a first container and a second container; and a mechanism for at least one of: bubbling dried air from the moisture trap through a hydrogen peroxide solution in the first container for producing a hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above a hydrogen peroxide solution in the second container for producing a hydrogen peroxide vapor. A method according one embodiment includes at least one of bubbling dried air through a hydrogen peroxide solution in a container for producing a first hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above the hydrogen peroxide solution in a container for producing a second hydrogen peroxide vapor. Additional systems and methods are also presented.

  9. A simple method for vapor dosing of charcoal sorbent tubes.

    PubMed

    Thomas, M L; Cohen, B S

    1995-01-01

    A method for vapor-dosing of charcoal sorbent tubes (CST) that does not require the expense and effort of a test chamber was used to test the desorption efficiency (DE) of seven solvent vapors, representing six classes of solvents as follows: aromatic hydrocarbons (m-xylene); ether/alcohol (2-ethoxyethanol); vinyl monomers (styrene monomer, vinyl acetate); aliphatic hydrocarbons (n-hexane); aliphatic esters (n-butyl acetate); and aliphatic acrylic monomers (methyl methacrylate). The quantities of the solvents used in these experiments would represent eight-hour exposures to concentrations of approximately 0.2 to 10 ppm. The vapor-dosing experimental system consisted of a loaded filter cassette connected directly to a CST. Vapor was generated by injecting liquid solvent onto the glass fiber filter and drawing air through the system. The solvent was desorbed from the filter and charcoal for analysis. Vapor desorption efficiency was determined from the fraction of the injected solvent evaporated from the filter and the amount recovered from the charcoal. The measured DEs were similar to those reported for liquid dosed charcoal. Vapor dosing of sorbent tubes is more representative of samples collected for industrial hygiene exposure assessment. The system is simple to use and applicable for vapor dosing of any sorbent tube. PMID:7872204

  10. Comparison of the treatment of vascular lesions with the copper-vapor laser and flashlamp-pumped dye laser

    NASA Astrophysics Data System (ADS)

    Flock, Stephen T.; Waner, Milton; McGrew, Ben; Colvin, G. B.; Montague, Donna

    1992-08-01

    Vascular lesions such as port-wine stains and telangiectases are sometimes treated with carbon-dioxide lasers, argon lasers or argon-pumped dye lasers; however these lasers are non- specific in their thermal effect on tissues and as a result often cause significant scarring. Recently, evidence has accumulated that the flashlamp-pumped dye (585 nm) and copper- vapor (578 nm) lasers, which produce pulsed light that is efficiently absorbed by hemoglobin, are more selective in coagulating abnormal vascular tissue and as a result give a superior clinical result. It is not yet clear what the most important physical and biological mechanisms are during the light-tissue interaction mediated by these two lasers. The post-treatment sequence of events is different for tissue irradiated by each laser; most significantly, the flashlamp-pumped dye laser causes significant transient purpura, whereas the copper vapor laser causes blanching and eschar formation. The clinical outcome, that is regression of the lesion, is equally successful with either laser although some evidence has accumulated showing that the flashlamp-pumped dye laser is best suited to the treatment of small vessel disease while the copper-vapor laser is better for the treatment of large vessel disease. In this paper, we will discuss our observations of the treatment of vascular lesions on humans with the copper-vapor and flashlamp-pumped dye lasers using empirically derived efficacious treatment parameters. Mathematical models of light and heat propagation and in vivo experiments involving mice ears and rat skin flaps will be used to elucidate what we feel are the important underlying mechanisms of this vascular lesion laser therapy.

  11. Laser-assisted chemical vapor deposition of nickel and laser cutting in integrated circuit restructuring

    NASA Astrophysics Data System (ADS)

    Remes, J.; Moilanen, H.; Leppävuori, S.

    1997-01-01

    Laser-assisted chemical vapor deposition (LCVD) of nickel from Ni(CO)4 has been utilised for the restructuring of integrated circuit (IC) interconnections. Nickel lines were deposited on a SiO2 passivated IC to achieve new local interconnections between integrated circuit structures. Depositions were carried out over the pressure range of 0.2 to 2.2 mbar of pure Ni(CO)4 buffered in 0 to 800 mbar He. Argon ion laser wavelengths of 488 and 514.5 nm, laser power of 50-150 mW and a laser scan speed of 80 μm/s were utilised for the deposition. The morphology and chemical contents of the deposited interconnection microstructures was examined by AFM, optical microscopy and LIMA. The resistivity of the deposited lines was found to be close to the nickel bulk resistivity. The utilisation of Nd: YAG and XeCl excimer lasers in the cutting of Al and Mo conductor lines for integrated circuit modification is also described.

  12. Advances in Diode-Laser-Based Water Vapor Differential Absorption Lidar

    NASA Astrophysics Data System (ADS)

    Spuler, Scott; Repasky, Kevin; Morley, Bruce; Moen, Drew; Weckwerth, Tammy; Hayman, Matt; Nehrir, Amin

    2016-06-01

    An advanced diode-laser-based water vapor differential absorption lidar (WV-DIAL) has been developed. The next generation design was built on the success of previous diode-laser-based prototypes and enables accurate measurement of water vapor closer to the ground surface, in rapidly changing atmospheric conditions, and in daytime cloudy conditions up to cloud base. The lidar provides up to 1 min resolution, 150 m range resolved measurements of water vapor in a broad range of atmospheric conditions. A description of the instrument and results from its initial field test in 2014 are discussed.

  13. Preliminary results on diode-laser assisted vaporization of prostate tissue

    NASA Astrophysics Data System (ADS)

    Sroka, Ronald; Seitz, Michael; Reich, Oliver; Bachmann, Alexander; Steinbrecher, Verena; Ackermann, Alexander; Stief, Christian

    2007-07-01

    Introduction and objectives: The aim was to identify the capability and the laser parameter of under water tissue vaporisation by means of a diode laser (1470 nm). Afterwards the feasibility and postoperative clinical outcome of vaporization of the prostate was investigated. Method: After acquiring suitable laser parameters in in-vitro experiments using a perfused tissue model patients (n=10) suffering from bladder outlet obstruction due to benign prostatic hyperplasia (BPH) were treated by diode laser. Their clinical outcome, in terms of acceptance and post-operatively voiding were evaluated. The diode laser emitted light of the wavelength of 1470 nm at 50 W (Biolitec GmbH) and delivered to the tissue by means of a side-fire fibre introduced through a 24F continuous-flow cystoscope. Normal saline was used for irrigation with an additive of 1% ethanol. The prostatic lobes (volume range 35-80ml) were vaporized within the prostatic capsular using sweeping and push and pull technique. The mean time of laser application was 2400 sec (1220-4000 sec) resulting in applied energies of 121 kJ in the mean (range: 61-200kJ). Results: During laser treatment none of the 10 patients showed any significant blood loss or any fluid absorption (no ethanol uptake). Foley catheters were removed between 18 and 168 hours postoperatively (mean: 49.8h+/-46h). After removal of the catheter the mean peak urine flow rate increased from 8.9ml/s +/- 2.9ml/s pre-operatively in comparison to 15.7ml/s +/- 5 ml/s (p=0.049) post-operatively. 8/10 patients were satisfied with their voiding outcome. None of the patients showed appearance of urgency, dysuria, hematuria, or incontinence but two patients required re-catheterization. After a follow-up of 1month, 8/10 patients showed evidence of good results and are satisfied with the outcome. Two patients required consecutive TUR-P. After a follow-up of 6-month the 8 patients are still satisfied. Conclusions: This very early and limited experience using

  14. Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method

    NASA Technical Reports Server (NTRS)

    Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor)

    2014-01-01

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  15. Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method

    DOEpatents

    Smith, Michael W; Jordan, Kevin C

    2014-03-25

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  16. Recent progress in the development of electrically and optically pumped dye vapor lasers

    NASA Astrophysics Data System (ADS)

    Marowsky, G.

    1980-01-01

    This paper reviews new results in the field of organic dye vapor lasers. Gain studies of the scintillator dye POPOP in liquid solution and in the vapor phase show that a dye vapor exhibits optical gain nearly as high as in the solution case under excitation by a N2 laser. Superradiant emission has been observed from both optically excited POPOP vapor and electron-beam excited vapor. The optimum operating conditions of an electron-beam pumped dye vapor-buffer gas system with high purity argon as buffer are reported. Potential energy transfer processes from the rare-gas buffer to the dye vapor are discussed. The metastable ionic species Ar2(+) has been identified as the most likely POPOP excitation source after intense electron pumping of the dense Ar buffer gas at typically 4-5 atm. An estimate of the conversion efficiency from electronic energy deposited in the Ar buffer to stimulated emission of the dye yields 5 percent. These results suggest that an efficient tunable electron beam pumped dye vapor laser is feasible.

  17. New powerful metal vapor lasers oscillating in deep ultraviolet and middle infrared spectral ranges

    NASA Astrophysics Data System (ADS)

    Temelkov, K. A.; Vuchkov, N. K.; Sabotinov, N. V.

    2010-09-01

    Middle infrared and deep ultraviolet laser systems, which are based on high-power high-beam-quality stable-operating He-SrBr2 and Cu+ Ne-CuBr lasers excited in nanosecond pulsed longitudinal discharge, are developed, patented and studied. Optimal discharge conditions, such as active zone diameter, vapor pressure, buffer-gas pressure, electrical excitation scheme parameters, average input power, pulse repetition frequency, are found. The highest output laser parameters are obtained for the Sr atom and Cu+ lasers, respectively. These lasers equipped with optical systems for control of laser radiation parameters, such as laser beam divergence, laser intensity distribution, etc. are used in a large variety of applications, such as precise material microprocessing, including biological tissues, determination of linear optical properties of different materials newly developed, laser-induced modification of conductive polymers, laserinduced fluorescence in wide-gap semiconductors, instead of free electron and excimer lasers, respectively.

  18. Laser scattering diagnostics of an argon atmospheric-pressure plasma jet in contact with vaporized water

    NASA Astrophysics Data System (ADS)

    Seo, B. H.; Kim, J. H.; You, S. J.; Seong, D. J.

    2015-12-01

    The radial profiles of the electron density, electron temperature, and molecular rotational temperature are investigated in an argon atmospheric-pressure plasma jet in contact with vaporized water, which is driven by a 13.56 MHz radio frequency by means of the Thomson and Raman laser scattering methods. There is a distinct difference in the radial profiles of the plasma parameters between plasmas in contact with water and those without water contact. In the case of plasmas without vaporized water contact, all the parameters have a single-peak distribution with maximum values at the center of the discharge. In the case of plasmas in contact with vaporized water, all parameters have double-peak distributions; a neighboring peak appears beside the main peak. The new peak may have originated from the ripple of the water surface, which works as a cathode, and the peak of the ripple offers a sharp curvature point, playing the role of a pin. Our experimental results and the underlying physics are described in detail.

  19. Investigation of lasing in lead vapor by the double pulse method

    SciTech Connect

    Kazakov, V.V.; Markova, S.V.; Molchanova, L.V.; Petrash, G.G.

    1983-05-01

    The double pulse method was to study the 722.9 nm line emitted by a lead vapor laser. The parameters of the second excitation pulse were measured simultaneously with the lasing characteristics. It was found that the main factor determining a decrease in the laser output power in the second pulse was the residual population of the lower active level. Variations in the excitation pulse had a relatively weak influence on the form of this dependence and were essentially manifested when there was a relatively long delay between the excitation pulses.

  20. Histologic comparison of the pulsed dye laser and copper vapor laser effects on pig skin

    SciTech Connect

    Tan, O.T.; Stafford, T.J.; Murray, S.; Kurban, A.K. )

    1990-01-01

    Albino pig skin was exposed to the copper vapor (CVL) and flash-lamp pulsed dye (PDL) lasers at 578 nm with a 3 mm diameter spotsize over a range of fluences until purpura and whitening were first established. The total irradiation time was the parameter that was varied in order for the CVL to reach the desired fluence. The lowest fluence producing each clinical endpoint was designated the threshold fluence: 34 J/cm{sup 2} was required to produce purpura using the CVL compared to 7.5 J/cm{sup 2} with the PDL laser. Histologically, skin exposed to purpura fluences from the CVL revealed the presence of constricted, disrupted papillary dermal blood vessels with trapped RBC's within them which were unlike those exposed to PDL where the irradiated vessels were dilated and packed with masses of intravascular agglutinated RBC's. The whitening threshold fluences for the CVL and PDL lasers were 67 J/cm{sup 2} and 29 J/cm{sup 2}, respectively. Streaming of epidermal cells and dermal collagen denaturation were observed in CVL irradiated skin, compared to occasional dyskeratotic epidermal cells and focal dermal collagen denaturation following PDL exposure. The mechanisms responsible for the clinical and histologic changes produced by the two laser systems are discussed.

  1. Excimer-pumped alkali vapor lasers: a new class of photoassociation lasers

    NASA Astrophysics Data System (ADS)

    Readle, J. D.; Wagner, C. J.; Verdeyen, J. T.; Spinka, T. M.; Carroll, D. L.; Eden, J. G.

    2010-02-01

    Excimer-pumped alkali vapor lasers (XPALs) are a new class of photoassociation lasers which take advantage of the spectrally broad absorption profiles of alkali-rare gas collision pairs. In these systems, transient alkali-rare gas molecules are photopumped from the thermal continuum to a dissociative X2Σ+ 1/2 interaction potential, subsequently populating the n2P3/2 state of the alkali. The absorption profiles >=5 nm and quantum efficiencies >98% have been observed in oscillator experiments, indicating XPAL compatibility with conventional high power laser diode arrays. An alternative technique for populating the n2P3/2 state is direct photoexcitation on the n2P3/2<--n2S1/2 atomic transition. However, because the XPAL scheme employs an off-resonant optical pump, the strengths of resonantly-enhanced nonlinear processes are minimized. Additionally, the absorption coefficient may be adjusted by altering the number densities of the lasing species and/or perturbers, a valuable asset in the design of large volume, high power lasers. We present an overview of XPAL lasers and their operation, including the characteristics of recently demonstrated systems photopumped with a pulsed dye laser. Lasing has been observed in Cs at both 894 nm and 852 nm by pumping CsAr or CsKr pairs as well as in Rb at 795 nm by pumping RbKr. These results highlight the important role of the perturbing species in determining the strength and position of the excimer absorption profile. It is expected that similar results may be obtained in other gas mixtures as similar collision pair characteristics have historically been observed in a wide variety of transient diatomic species.

  2. Method and apparatus for precision laser micromachining

    DOEpatents

    Chang, Jim; Warner, Bruce E.; Dragon, Ernest P.

    2000-05-02

    A method and apparatus for micromachining and microdrilling which results in a machined part of superior surface quality is provided. The system uses a near diffraction limited, high repetition rate, short pulse length, visible wavelength laser. The laser is combined with a high speed precision tilting mirror and suitable beam shaping optics, thus allowing a large amount of energy to be accurately positioned and scanned on the workpiece. As a result of this system, complicated, high resolution machining patterns can be achieved. A cover plate may be temporarily attached to the workpiece. Then as the workpiece material is vaporized during the machining process, the vapors condense on the cover plate rather than the surface of the workpiece. In order to eliminate cutting rate variations as the cutting direction is varied, a randomly polarized laser beam is utilized. A rotating half-wave plate is used to achieve the random polarization. In order to correctly locate the focus at the desired location within the workpiece, the position of the focus is first determined by monitoring the speckle size while varying the distance between the workpiece and the focussing optics. When the speckle size reaches a maximum, the focus is located at the first surface of the workpiece. After the location of the focus has been determined, it is repositioned to the desired location within the workpiece, thus optimizing the quality of the machined area.

  3. Laser vaporization of cirrus-like ice particles with secondary ice multiplication

    PubMed Central

    Matthews, Mary; Pomel, François; Wender, Christiane; Kiselev, Alexei; Duft, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Leisner, Thomas

    2016-01-01

    We investigate the interaction of ultrashort laser filaments with individual 90-μm ice particles, representative of cirrus particles. The ice particles fragment under laser illumination. By monitoring the evolution of the corresponding ice/vapor system at up to 140,000 frames per second over 30 ms, we conclude that a shockwave vaporization supersaturates the neighboring region relative to ice, allowing the nucleation and growth of new ice particles, supported by laser-induced plasma photochemistry. This process constitutes the first direct observation of filament-induced secondary ice multiplication, a process that strongly modifies the particle size distribution and, thus, the albedo of typical cirrus clouds. PMID:27386537

  4. Laser vaporization of cirrus-like ice particles with secondary ice multiplication.

    PubMed

    Matthews, Mary; Pomel, François; Wender, Christiane; Kiselev, Alexei; Duft, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Leisner, Thomas

    2016-05-01

    We investigate the interaction of ultrashort laser filaments with individual 90-μm ice particles, representative of cirrus particles. The ice particles fragment under laser illumination. By monitoring the evolution of the corresponding ice/vapor system at up to 140,000 frames per second over 30 ms, we conclude that a shockwave vaporization supersaturates the neighboring region relative to ice, allowing the nucleation and growth of new ice particles, supported by laser-induced plasma photochemistry. This process constitutes the first direct observation of filament-induced secondary ice multiplication, a process that strongly modifies the particle size distribution and, thus, the albedo of typical cirrus clouds. PMID:27386537

  5. A Linearly-Polarized Cesium Vapor Laser with Fundamental Mode Output and Low Threshold

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Yong; Tan, Rong-Qing; Huang, Wei; Xu, Cheng

    2014-04-01

    We report a cesium vapor laser with fundamental mode output and a wavelength of 894 nm. The laser is pumped by a laser diode array with an external cavity of a holographic grating by using Littrow's structure. A slope efficiency of 22.4% is obtained by using a pumping source with a linewidth of 0.26 nm and 80 kPa methane as the buffer gas. The threshold pumping power is 1.56 W.

  6. Space Debris-de-Orbiting by Vaporization Impulse using Short Pulse Laser

    SciTech Connect

    Early, J; Bibeau, C; Claude, P

    2003-09-16

    Space debris constitutes a significant hazard to low earth orbit satellites and particularly to manned spacecraft. A quite small velocity decrease from vaporization impulses is enough to lower the perigee of the debris sufficiently for atmospheric drag to de-orbit the debris. A short pulse (picosecond) laser version of the Orion concept can accomplish this task in several years of operation. The ''Mercury'' short pulse Yb:S-FAP laser being developed at LLNL for laser fusion is appropriate for this task.

  7. Application of high-resolution laser spectroscopy to the monitoring of vapor-phase metals

    SciTech Connect

    Lipert, R.J.; Wang, Z.M.; Schuler, R.; Edelson, M.C.

    1992-10-01

    Research conducted in the Ames Laboratory Nuclear Safeguards and Security Program is reviewed. Progress in applying high-resolution laser spectroscopy to the monitoring of vapor-phase metals is described. The spectroscopic techniques employed include fluorescence excitation in an atomic beam, laser atomic absorption in a heat-pipe oven and atomic beam, Doppler-free saturated absorption in a heat-pipe oven, and Doppler-free polarization spectroscopy for the stabilization of the laser wavelength.

  8. Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Shumate, M. S.

    1976-01-01

    Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

  9. Dichroic atomic vapor laser lock with multi-gigahertz stabilization range.

    PubMed

    Pustelny, S; Schultze, V; Scholtes, T; Budker, D

    2016-06-01

    A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the (85)Rb ground state or as far as 16 GHz away from the closest optical transition. PMID:27370426

  10. Dichroic atomic vapor laser lock with multi-gigahertz stabilization range

    NASA Astrophysics Data System (ADS)

    Pustelny, S.; Schultze, V.; Scholtes, T.; Budker, D.

    2016-06-01

    A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the 85Rb ground state or as far as 16 GHz away from the closest optical transition.

  11. Computer modeling of the sensitivity of a laser water vapor sensor to variations in temperature and air speed

    NASA Technical Reports Server (NTRS)

    Tucker, George F.

    1994-01-01

    Currently, there is disagreement among existing methods of determining atmospheric water vapor concentration at dew-points below -40 C. A major source of error is wall effects which result from the necessity of bringing samples into the instruments. All of these instruments also have response times on the order of seconds. NASA Langley is developing a water vapor sensor which utilizes the absorption of the infrared radiation produced by a diode laser to estimate water vapor concentration. The laser beam is directed through an aircraft window to a retroreflector located on an engine. The reflected beam is detected by an infrared detector located near the laser. To maximize signal to noise, derivative signals are analyzed. By measuring the 2f/DC signal and correcting for ambient temperature, atmospheric pressure and air speed (which results in a Doppler shifting of the laser beam), the water vapor concentration can be retrieved. Since this is an in situ measurement there are no wall effects and measurements can be made at a rate of more than 20 per second. This allows small spatial variations of water vapor to be studied. In order to study the sensitivity of the instrument to variations in temperature and air speed, a computer program which generated the 2f, 3f, 4f, DC and 2f/DC signals of the instrument as a function of temperature, pressure and air speed was written. This model was used to determine the effect of errors in measurement of the temperature and air speed on the measured water vapor concentration. Future studies will quantify the effect of pressure measurement errors, which are expected to be very small. As a result of these studied, a retrieval algorithm has been formulated, and will be applied to data taken during the PEM-West atmospheric science field mission. Spectroscopic studies of the water vapor line used by the instrument will be used to refine this algorithm. To prepare for these studies, several lasers have been studied to determine their

  12. Probing temperature during laser spot welding from vapor composition and modeling

    NASA Astrophysics Data System (ADS)

    He, X.; DebRoy, T.; fürschbach, P. W.

    2003-11-01

    Measurement of weld pool temperature during laser spot welding is a difficult task because of the short pulse duration, often lasting only a few milliseconds, highly transient nature of the process, and the presence of a metal vapor plume near the weld pool. This article describes recent research to estimate weld pool temperatures experimentally and theoretically. Composition of the metal vapor from the weld pool was determined by condensing a portion of the vapor on the inner surface of an open ended quartz tube which was mounted perpendicular to the sample surface and coaxial with the laser beam. It was found that iron, chromium, and manganese were the main metallic species in the vapor phase. The concentrations of Fe and Cr in the vapor increased slightly while the concentration of Mn in the vapor decreased somewhat with the increase in power density. The vapor composition was used to determine an effective temperature of the weld pool. A transient, three-dimensional numerical heat transfer and fluid flow model based on the solution of the equations of conservation of mass, momentum and energy was used to calculate the temperature and velocity fields in the weld pool as a function of time. The experimentally determined geometry of the spot welds agreed well with that determined from the computed temperature field. The effective temperature determined from the vapor composition was found to be close to the numerically computed peak temperature at the weld pool surface. Because of the short process duration and other serious problems in the direct measurement of temperature during laser spot welding, estimating approximate values of peak temperature from metal vapor composition is particularly valuable.

  13. High-speed photography of energetic materials and components with a copper vapor laser

    SciTech Connect

    Dosser, L.R.; Reed, J.W.; Stark, M.A.

    1988-01-01

    The evaluation of the properties of energetic materials, such as burn rate and ignition energy, is of primary importance in understanding their reactions and the functioning of devices containing them. One method for recording such information is high-speed photography at rates of up to 20,000 images per second. When a copper vapor laser is synchronized with the camera, laser-illuminated images can be recorded that detail the performance of a material and/or component in a manner never before possible. The laser can also be used for ignition of the energetic material, thus eliminating the need for bridgewires or electric squibs that can interfere with photography. Details of such ignitions are readily observable, and the burn rate of a material can be determined directly from the film. There are indications that information useful for the modeling of pyrotechnic reactions will become available as well. Recent results from high-speed photography of several pyrotechnic materials and devices will be presented. 9 figs.

  14. Laser-induced fluorescence studies of polycyclic aromatic hydrocarbons (PAH) vapors at high temperatures.

    PubMed

    Chi, Z; Cullum, B M; Stokes, D L; Mobley, J; Miller, G H; Hajaligol, M R; Vo-Dinh, T

    2001-06-01

    In this work, we present the fluorescence spectra of anthracene and pyrene vapors at different elevated temperatures (from 150 to 650 degrees C) excited with the 337 nm line of a nitrogen laser. We describe the high temperature effects on the resulting spectral properties including spectral intensity, spectral bandwidth and spectral shift. We found that the PAH fluorescence spectral bandwidths become very broad as the temperature increases. The broadening is mainly due to thermal vibrational sequence congestion. We also have found that the fluorescence intensity of pyrene vapor increases with increasing temperature, which results from the increase of the pyrene vapor absorption cross section at 337 nm. PMID:11446693

  15. Development of Field-deployable Diode-laser-based Water Vapor Dial

    NASA Astrophysics Data System (ADS)

    Pham Le Hoai, Phong; Abo, Makoto; Sakai, Tetsu

    2016-06-01

    In this paper, a field-deployable diode-laser-based differential absorption lidar (DIAL) has been developed for lower-tropospheric water vapor observation in Tokyo, Japan. A photoacoustic cell is used for spectroscopy experiment around absorption peaks of 829.022 nm and 829.054 nm. The water vapor density extracted from the observational data agrees with the referenced radiosonde data. Furthermore, we applied modulated pulse technique for DIAL transmitter. It enables DIAL to measure water vapor profile for both low and high altitude regions.

  16. Production of dense vapor targets for laser-plasma interaction studies with intense, ultra-short pulses

    SciTech Connect

    Bolton, P.R.; Eder, D.C.; Guethlein, G.; Stewart, R.E.; Young, P.E.

    1993-03-19

    The technique of laser-induced ablation of thin films from glass slide substrates has been investigated as a candidate vapor target production method for studies of both tunneling-driven x-ray/xuv recombination lasers and relativistic propagation using intense, ultra-short laser pulses. It is shown by simultaneous two-wavelength interferometry that particle densities of order 10{sup 19}/cm{sup 3} are readily achieved and that some intrinsic ionization accompanies the plume formation. Absorption measurements with both 100 picosecond and 125 femtosecond pulses are consistent with observed edge velocities near 10{sup 6} cm/sec. The level of ionization driven by the intense 125 femtosecond laser pulse has been coarsely estimated. Averaged estimates from spectral blue shifting of spectra transmitted through the plume are consistently lower than those obtained from evaluation of saturation intensity thresholds based on the sequential nonresonant optical field ionization (OFI) process.

  17. Nano structured physical vapor deposited coatings by means of picosecond laser radiation.

    PubMed

    Bobzin, K; Bagcivan, N; Ewering, M; Gillner, A; Beckemper, S; Hartmann, C; Theiss, S

    2011-10-01

    Molding of nano structures by injection molding leads to special requirements for the tools e.g., wear resistance and as low as possible release forces of the molded components. On the other hand it is not allowed to affect the replication precision. Physical vapor deposition is one of the promising technologies for applying coatings with adapted properties like high hardness, low roughness, low Young's modulus and less adhesion to the plastics melt. Although physical vapor deposition technology allows the deposition of films on micro structures without changing the structure significantly, film deposition on nano structures and small micro structures leads to a relevant change in surface topography. For this reason direct structuring of physical vapor deposition coatings might be beneficial. In this paper structuring was done using a picoseconds ultraviolet laser, Lumera Laser "Rapid," with a master oscillator power amplifier system at 355 nm. Two different coatings were deposited by magnetron sputter ion plating physical vapor deposition technology for laser structuring tests ((Cr, Al)N, (Cr, Al,Si)N). After deposition, the coatings were analyzed by common techniques regarding hardness, Young's modulus and morphology. The structures were analyzed by scanning electron microscopy. The results show a high potential for laser structuring of coatings deposited via physical vapor deposition. Linear structures with sizes between 400 nm and 10microm were realized. PMID:22400258

  18. High-energy transversely pumped alkali vapor laser

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.

    2011-03-01

    We report on the results from our transversely pumped alkali laser. This system uses an Alexandrite laser to pump a stainless steel laser head. The system uses methane and helium as buffer gasses. Using rubidium, the system produced up to 40 mJ of output energy when pumped with 63 mJ. Slope efficiency was 75%. Using potassium as the lasing species the system produced 32 mJ and a 53% slope efficiency.

  19. Investigation of SRS conversion of XeCl laser emission in lead vapor, methane, and hydrogen

    SciTech Connect

    Mel'chenko, S.V.; Panchenko, A.N.; Tarasenko, V.F.; Evtushenko, G.S. )

    1994-01-01

    The rapid advances in the development of electric-discharge exciplex lasers and powerful effective sources of UV coherent radiation have uncovered far-reaching prospects for their practical use in various fields of sciences and engineering, such as microelectronics, medicine, ecology (remote detection of contamination in the atmosphere), photochemistry, plasma diagnostics, and others. The wavelength range in which high-power coherent radiation is possible can be greatly expanded by using stimulated Raman scattering (SRS) in metal vapor and compressed gases. This paper is devoted to an investigation of the optimal conditions of SRS-conversion of XeCl-laser emission in lead vapor, methane, and hydrogen.

  20. Containerless laser-induced flourescence study of vaporization and optical properties for sapphire and alumina

    NASA Technical Reports Server (NTRS)

    Nordine, Paul C.; Schiffman, Robert A.

    1988-01-01

    Evaporation of aluminum oxide was studied from 1800 to 2327 K by laser-induced flourescence (LIF) detection of Al atom vapor over sapphire and alumina spheres that were levitated in an argon gas jet and heated with a continuous wave CO2 laser. Optical properties were determined from apparent specimen temperatures measured with an optical pyrometer and true temperatures deduced from the LIF intensity versus temperature measurements using the known temperature dependence of the Al atom vapor concentration in equilibrium with Al2O3. The effects of impurities and dissolved oxygen on the high-temperature optical properties of aluminum oxide were discussed.

  1. Laser pulse propagation in a meter scale rubidium vapor/plasma cell in AWAKE experiment

    NASA Astrophysics Data System (ADS)

    Joulaei, A.; Moody, J.; Berti, N.; Kasparian, J.; Mirzanejhad, S.; Muggli, P.

    2016-09-01

    We present the results of numerical studies of laser pulse propagating in a 3.5 cm Rb vapor cell in the linear dispersion regime by using a 1D model and a 2D code that has been modified for our special case. The 2D simulation finally aimed at finding laser beam parameters suitable to make the Rb vapor fully ionized to obtain a uniform, 10 m-long, at least 1 mm in radius plasma in the next step for the AWAKE experiment.

  2. Ex vivo evaluation of safety and efficacy of vaporization of the prostate using a 300 W high-power laser diode with the wavelength of 980 nm

    NASA Astrophysics Data System (ADS)

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao; Awazu, Kunio

    2014-03-01

    Laser vaporization of the prostate is one of the promising technique for less-invasive treatment of benign prostatic hyperplasia. However, shorter operative duration and higher hemostatic ability are expected. The wavelength of 980 nm offers a high simultaneous absorption by water and hemoglobin, so that it combines the efficient vaporization with good hemostasis. Therefore, we have evaluated the safety and efficacy of vaporization of the prostate using a recently developed 300 W high-power laser diode with the wavelength of 980 nm. First, validity of bovine prostate tissue as the sample was confirmed by measuring the optical properties of bovine and human prostate tissue using a double integrating sphere optical system. Next, contact and non-contact ex vivo irradiations were performed for various irradiation powers and times, and vaporized and coagulated depths were measured. In the contact irradiation, the vaporized depth at the power of 300 W was significantly deeper than that at the power of 100 W, while the difference was relatively smaller for the coagulated depths at 300 and 100 W. In the non-contact irradiation, coagulation as thick as that in the contact irradiation was observed almost without vaporization. Therefore, it is suggested that the treatment in the contact irradiation using the high-power laser diode can vaporize the prostate more efficiently without increasing the risk of perforation. Hemostasis with the coagulation would be possible in both irradiation methods. To prevent the postoperative perforation, operators need to understand the relationship between the coagulated depth and the irradiation conditions.

  3. Instantaneous Measurement of Local Concentration and Vapor Fraction in Liquid-Gas Mixtures by Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kido, Akihiro; Hoshi, Kenji; Kusaka, Hiroto; Ogawa, Hideyuki; Miyamoto, Noboru

    Laser-induced breakdown spectroscopy (LIBS) with atomic emission excited with a focused high-energy ND: YAG laser was applied to quantify the concentration and the vapor fraction of liquid-gas mixtures. With LIBS it is possible to quantify local concentrations accurately even in liquid-gas mixtures as the ratio of the number of fuel-borne hydrogen atoms to nitrogen or oxygen atoms in the ambient gas. The ratio has a strong linear relation with the ratio of the peak emission intensities regardless of phase of the fuel. As the full width at half maximum (FWHM) of the emission peak from the fuel-borne hydrogen increases linearly with the liquid fraction due to the Doppler shift with micro-explosions, the FWHM yields the fuel vapor fraction. Simultaneous, high-resolution measurements of equivalence ratios and vapor fractions in an intermittent fuel spray in a pressurized atmosphere were obtained with this method. The results showed that the tip of the intermittent spray has a richer mixture with a lower vapor fraction.

  4. Anesthesia Methods in Laser Resurfacing

    PubMed Central

    Gaitan, Sergio; Markus, Ramsey

    2012-01-01

    Laser resurfacing technology offers the ability to treat skin changes that are the result of the aging process. One of the major drawbacks of laser resurfacing technologies is the pain associated with the procedure. The methods of anesthesia used in laser resurfacing to help minimize the pain include both noninvasive and invasive procedures. The noninvasive procedures can be divided into topical, cryoanesthesia, and a combination of both. The invasive methods of anesthesia include injected forms (infiltrative, nerve blocks, and tumescent anesthesia) and supervised anesthesia (monitored anesthesia care and general anesthesia). In this review, the authors summarize the types of anesthesia used in laser resurfacing to aid the provider in offering the most appropriate method for the patient to have as painless a procedure as possible. PMID:23904819

  5. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  6. Laser beam pulse formatting method

    DOEpatents

    Daly, T.P.; Moses, E.I.; Patterson, R.W.; Sawicki, R.H.

    1994-08-09

    A method for formatting a laser beam pulse using one or more delay loops is disclosed. The delay loops have a partially reflective beam splitter and a plurality of highly reflective mirrors arranged such that the laser beam pulse enters into the delay loop through the beam splitter and circulates therein along a delay loop length defined by the mirrors. As the laser beam pulse circulates within the delay loop a portion thereof is emitted upon each completed circuit when the laser beam pulse strikes the beam splitter. The laser beam pulse is thereby formatted into a plurality of sub-pulses. The delay loops are used in combination to produce complex waveforms by combining the sub-pulses using additive waveform synthesis. 8 figs.

  7. Radial distribution of radiation in a CuBr vapor brightness amplifier used in laser monitors

    NASA Astrophysics Data System (ADS)

    Gubarev, F. A.; Trigub, M. V.; Klenovskii, M. S.; Li, Lin; Evtushenko, G. S.

    2016-01-01

    The paper presents a study of the effect of excitation conditions in a CuBr vapor brightness amplifier in a monostatic laser monitor on the radial non-uniformity of the radiation bearing the information about the object being visualized. A significant dependence of radial signal distribution on the concentrations of CuBr, HBr and pumping power has been demonstrated. In particular, an increase in CuBr vapor concentration causes the gain profile of the active medium to constrict and the axial gain to increase. The conditions for the most uniform radial distribution of the laser monitor signal are substantially different from those for the maximum radiated power. The paper demonstrates HBr doping to be usable as a tool to correct the non-uniformity of the radial distribution of laser monitor radiation. An addition of ~0.15 Torr HBr broadens and flattens the radiation profile, improving an important aspect of laser monitor image quality.

  8. Chemical speciation in laser-desorption and impact-induced vapor in minerals

    NASA Astrophysics Data System (ADS)

    Shen, A. H.; Dundas, C. M.; Ahrens, T. J.; Beauchamp, J. L.

    2002-12-01

    Knowledge of the chemical species in vapors produced by hypervelocity impact on spacecraft impact detectors as well as planetary surfaces have applications ranging from determination of the composition of cosmic dust to the effects on atmospheres and climates of large impactors. Direct study of resulting atomic, molecular and ionic species is best accomplished via mass spectrometry. Pulsed laser desorption can be used to approximate small impacts on solid surfaces. We conducted pulsed laser desorption-ionization experiments using two different instruments: (1) a Caltech-built Time-of-Flight Mass Spectrometer (TOFMS) similar to that on board the Cassini spacecraft and (2) a commercial Matrix Assisted Laser Desorption Ionization TOFMS made by Applied Biosystems (Model, Voyager-DE Pro). Minerals included in this study were calcite, dolomite, gypsum, anhydrite, olivine, kamacite, brucite, serpentine, and pyrrhotite. We collected only positive ions. A nitrogen laser (337 nm wavelength, 4 μsec pulse width, and 300 mJ) with power density ranging from 1.0x107 to 1.3x109 W/cm2 induced vaporization and ionization. The results can be summarized as: (1) from kamacite and pyrrhotite, only 54Fe+, 56Fe+, 57Fe+ (both kamacite and pyrrhotite) and 58Ni+, 60Ni+ (kamacite only) as well as contamination ions such as 23Na+ and 39K+, 41K+were observed; (2) Ca-containing minerals (calcite, dolomite, gypsum and anhydrite) produced vapors containing 40Ca+ ions, and, at higher laser power, both 40Ca+ as well as CaO+ ions; (3) Mg-containing minerals (dolomite, olivine, brucite and serpentine) produced vapors containing MgO+ ion; (4) for all hydrous minerals, neither H+ nor H3O+ were observed in the vapor; (5) in the vapors of silicate minerals (olivine and serpentine), SiO+ was observed only from serpentine but not from olivine.

  9. Buffer gas effects on output power of a copper vapor laser

    NASA Astrophysics Data System (ADS)

    Behrouzinia, S.; Khorasani, K.; Farahmandjou, M.

    2016-05-01

    A copper vapor laser with an active medium length of 60 cm and bore of 16 mm was operated and optimized using different buffer gases to investigate the effect of pressure and gas flow rates on the laser output power. It was shown that a special interval of operational pressure and an optimum gas flow rate associated with the type of buffer gas were obtained.

  10. Copper vapor laser machining of polyimide and polymethylmethacrylate in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Ventzek, P. L. G.; Gilgenbach, R. M.; Ching, C. H.; Lindley, R. A.; McColl, W. B.

    1992-10-01

    A repetitively pulsed copper vapor laser (510 and 578 nm) is used to machine an opaque polymer (polyimide-Vespel) and a transparent polymer (polymethylmethacrylate-Lucite). Lucite is machinable by coating the surface with an ink which is semi-opaque to the green and yellow laser light. The repetition rate of the laser was 10 kHz with approximately 0.35 mJ/pulse and 3.5 W average power at the copper vapor laser wavelengths for a pulse width of 40 ns. The copper vapor laser thermally loads the target, generating thermal waves and sound waves in the gas which are investigated using HeNe laser beam deflection. The gas adjacent to the target is heated to steady state on the order of 100-400 s. Above the etching threshold, at approximately 10 mJ/cm2/pulse, the target is rapidly machined: 2-mm-diam, 2-mm-deep holes are drilled in 300 s in Vespel. At higher fluences of 100-150 mJ/cm2/pulse in 760 Torr of air it takes 180 s to bore through a 2-mm-thick disk of Vespel. The machined surfaces of the two polymers are very different. Machined Vespel samples are charred and cratered, whereas the Lucite samples show evidence of melting with little charring. The machining of polymers by visible-light copper vapor lasers is being compared to UV photoablation by KrF excimer laser light in order to study thermal versus nonthermal etching mechanisms.

  11. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  12. Method for producing laser targets

    DOEpatents

    Jarboe, Thomas R.; Baker, William R.

    1977-01-01

    An apparatus and method for producing deuterium targets or pellets of 25.mu. to 75.mu. diameter. The pellets are sliced from a continuously spun solid deuterium thread at a rate of up to 10 pellets/second. The pellets after being sliced from the continuous thread of deuterium are collimated and directed to a point of use, such as a laser activated combustion or explosion chamber wherein the pellets are imploded by laser energy or laser produced target plasmas for neutral beam injection.

  13. Probing laser induced metal vaporization by gas dynamics and liquid pool transport phenomena

    SciTech Connect

    DebRoy, T.; Basu, S.; Mundra, K. )

    1991-08-01

    During laser beam welding of many important engineering alloys, an appreciable amount of alloying element vaporization takes place from the weld pool surface. As a consequence, the composition of the solidified weld pool is often significantly different from that of the alloy being welded. Currently there is no comprehensive theoretical model to predict, from first principles, laser induced metal vaporization rates and the resulting weld pool composition changes. The weld pool heat transfer and fluid flow phenomena have been coupled with the velocity distribution functions of the gas molecules at various locations above the weld pool to determine the rates of the laser induced element vaporization for pure metals. The procedure allows for calculations of the condensation flux based on the equations of conservation of mass, momentum and energy in both the vapor and the liquid phases. Computed values of the rates of vaporization of pure metals were found to be in good agreement with the corresponding experimentally determined values. The synthesis of the principles of gas dynamics and weld pool transport phenomena can serve as a basis for weld metal composition control.

  14. Ablation of biological tissues by radiation of strontium vapor laser

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Vasilieva, A. V.

    2015-11-01

    A two-stage laser system consisting of a master oscillator and a power amplifier based on sources of self- contained transitions in pairs SrI and SrII has been developed. The radiation spectrum contains 8 laser lines generating in the range of 1 - 6.45 μm, with a generation pulse length of 50 - 150 ns, and pulse energy of ˜ 2.5 mJ. The divergence of the output beam was close to the diffraction and did not exceed 0.5 mrad. The control range of the laser pulse repetition rate varied from 10 to 15 000 Hz. The given laser system has allowed to perform ablation of bone tissue samples without visible thermal damage.

  15. Micro-ablation with high power pulsed copper vapor lasers.

    PubMed

    Knowles, M

    2000-07-17

    Visible and UV lasers with nanosecond pulse durations, diffraction-limited beam quality and high pulse repetition rates have demonstrated micro-ablation in a wide variety of materials with sub-micron precision and sub-micron-sized heat-affected zones. The copper vapour laser (CVL) is one of the important industrial lasers for micro-ablation applications. Manufacturing applications for the CVL include orifice drilling in fuel injection components and inkjet printers, micro-milling of micromoulds, via hole drilling in printed circuit boards and silicon machining. Recent advances in higher power (100W visible, 5W UV), diffraction-limited, compact CVLs are opening new possibilities for manufacturing with this class of nanosecond laser. PMID:19404369

  16. Ablation of biological tissues by radiation of strontium vapor laser

    SciTech Connect

    Soldatov, A. N. Vasilieva, A. V.

    2015-11-17

    A two-stage laser system consisting of a master oscillator and a power amplifier based on sources of self- contained transitions in pairs SrI and SrII has been developed. The radiation spectrum contains 8 laser lines generating in the range of 1 – 6.45 μm, with a generation pulse length of 50 – 150 ns, and pulse energy of ∼ 2.5 mJ. The divergence of the output beam was close to the diffraction and did not exceed 0.5 mrad. The control range of the laser pulse repetition rate varied from 10 to 15 000 Hz. The given laser system has allowed to perform ablation of bone tissue samples without visible thermal damage.

  17. Laser Desorption of Explosives Traces with Low Vapors Pressure

    NASA Astrophysics Data System (ADS)

    Akmalov, A. E.; Chistyakov, A. A.; Kotkovskii, G. E.

    In this work comparison of the desorption effectiveness of picosecond and nanosecond laser sources (λ = 266, 532 nm) were carried out to investigate the possibility of creating a non-contact sampling device for detectors of explosives on the principles of ion mobility spectrometry (IMS) and field asymmetric ion mobility spectrometry (FAIMS). The results of mass spectrometric studies of TNT (2,4,6-Trinitrotoluene), HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), RDX (1,3,5-Trinitro-1,3,5-triazacyclohexane) laser desorption from a quartz substrate are presented. It is shown that the most effective laser source is a Nd:YAG3+ laser (λ = 266 nm; E = 1 mJ; τ = 5-10 ns; q = 108 W/cm2). The typical desorbed mass is 2 ng for RDX, 4-6 ng for TNT and 0.02 ng HMX per single laser pulse. The results obtained make it possible to create a non-contact portable laser sampling device operating in frequency mode with high efficiency.

  18. Multi-wavelength metal vapor laser systems for solving applied problems of atmospheric spectroscopy

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Mirza, S. Y.; Polunin, Yu. P.; Shumeiko, A. S.; Kostadinov, I. K.

    2015-11-01

    Results of a cycle of experimental investigations of a multi-wavelength metal vapor laser system based on original configuration of a multi-medium metal vapor laser source are presented. Novelty of our approach consists in that two gas-discharge active elements (on copper bromide and strontium vapors) are arranged in a common cavity, and each of them is pumped by an independent power supply unit, which allows them to be optimized independently for excitation conditions and thereby the output set of lasing wavelengths and their relative power distribution to be regulated. This makes the above-described system promising for a number of scientific and technological applications. The total output power of 11 spectral components lying in the range 0.43-6.45 μm reached ~17 W.

  19. Single Frequency, Pulsed Laser Diode Transmitter for Dial Water Vapor Measurements at 935nm

    NASA Technical Reports Server (NTRS)

    Switzer, Gregg W.; Cornwell, Donald M., Jr.; Krainak, Michael A.; Abshire, James B.; Rall, Johnathan A. R.

    1998-01-01

    We report a tunable, single frequency, narrow linewidth, pulsed laser diode transmitter at 935.68nm for remote sensing of atmospheric water vapor. The transmitter consists of a CW, tunable, external cavity diode laser whose output is amplified 2OdB using a tapered diode amplifier. The output is pulsed for range resolved DIAL lidar by pulsing the drive current to the diode amplifier at 4kHz with a .5% duty cycle. The output from the transmitter is 36OnJ/pulse and is single spatial mode. It maintains a linewidth of less than 25MHz as its wavelength is tuned across the water vapor absorption line at 935.68nm. The transmitter design and its use in a water vapor measurement will be discussed.

  20. Modeling CO{sub 2} laser ablation impulse of polymers in vapor and plasma regimes

    SciTech Connect

    Sinko, John E.; Phipps, Claude R.

    2009-09-28

    An improved model for CO{sub 2} laser ablation impulse in polyoxymethylene and similar polymers is presented that describes the transition effects from the onset of vaporization to the plasma regime in a continuous fashion. Several predictions are made for ablation behavior.

  1. Preparation of γ-Al2O3 films by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

    γ- and α-Al2O3 films were prepared by chemical vapor deposition using CO2, Nd:YAG, and InGaAs lasers to investigate the effects of varying the laser wavelength and deposition conditions on the phase composition and microstructure. The CO2 laser was found to mostly produce α-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced γ-Al2O3 films when used at a high total pressure. γ-Al2O3 films had a cauliflower-like structure, while the α-Al2O3 films had a dense and columnar structure. Of the three lasers, it was the Nd:YAG laser that interacted most with intermediate gas species. This promoted γ-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

  2. High-power high-repetition-rate copper-vapor-pumped dye laser

    SciTech Connect

    Singh, S.; Dasgupta, K.; Kumar, S.; Manohar, K.G.; Nair, L.G.; Chatterjee, U.K. . Laser and Plasma Technology Div.)

    1994-06-01

    The design and development of an efficient high average power dye laser oscillator-amplifier system developed at the Laser and Plasma Technology Division, Bhabha Atomic Research Centre, is reported. The dye laser is pumped by a 6.5-kHz repetition rate copper vapor laser. The signal beam to the dye amplifier is obtained from an efficient narrow-band grazing incidence grating (GIG) dye laser oscillator incorporating a multiple prism beam expander. Amplifier extraction efficiency up to 40% was obtained in a single amplifier stage, using rhodamine 6G (Rh6G) in ethanol. The authors have also demonstrated simultaneous amplification of two laser beams at different wavelengths in the same dye amplifier cell.

  3. Piston pump and method of reducing vapor lock

    DOEpatents

    Phillips, Benjamin A.; Harvey, Michael N.

    2000-02-15

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  4. Piston pump and method of reducing vapor lock

    SciTech Connect

    Phillips, Benjamin A.; Harvey, Michael N.

    2001-01-30

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  5. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, Mark W.; Biblarz, Oscar

    1991-01-01

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.

  6. A tunable MWIR laser remote sensor for chemical vapor detection

    NASA Astrophysics Data System (ADS)

    Bunn, Thomas L.; Noblett, Patricia M.; Otting, William D.

    1998-01-01

    The Air Force vision for Global Virtual Presence suggests a need for active remote sensing systems that provide both global coverage and the ability to detect multiple gaseous chemical species at low concentration from a significant standoff distance. The system will need to have acceptable weight, volume, and power characteristics, as well as a long operating lifetime for integration with various surveillance platforms. Laser based remote sensing systems utilizing the differential absorption lidar (DIAL) technique are promising for long range chemical sensing applications. Recent advancements in pulsed, diode pumped solid state laser (DPSSL) technology and in tunable optical parametric oscillators (OPO) make broadly tunable laser transmitters possible for the DIAL system. Also the characteristic narrow spectral bandwidth of these laser devices provides high measurement sensitivity and spectral selectivity with the potential to avoid interfering species. Rocketdyne has built and tested a tunable, midwave infrared (MWIR) DIAL system using DPSSL/OPO technology. The key to the system is a novel tuning and line narrowing technology developed for the OPO. The tuning system can quickly adjust to the desired wavelength and precisely locate a narrow spectral feature of interest. Once the spectral feature is located, a rapid dither tuning technique is employed. The laser pulses are tuned ``on'' and ``off'' the spectral resonance of a molecule with precise and repeatable performance as required to make the DIAL measurement. To date, the breadboard system has been tested by measuring methane, ethane, and sulfur dioxide in a calibrated gas cell at a range of 60 meters.

  7. Spherical silicon-shell photonic band gap structures fabricated by laser-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wang, H.; Yang, Z. Y.; Lu, Y. F.

    2007-02-01

    Laser-assisted chemical vapor deposition was applied in fabricating three-dimensional (3D) spherical-shell photonic band gap (PBG) structures by depositing silicon shells covering silica particles, which had been self-assembled into 3D colloidal crystals. The colloidal crystals of self-assembled silica particles were formed on silicon substrates using the isothermal heating evaporation approach. A continuous wave Nd:YAG laser (1064nm wavelength) was used to deposit silicon shells by thermally decomposing disilane gas. Periodic silicon-shell/silica-particle PBG structures were obtained. By removing the silica particles enclosed in the silicon shells using hydrofluoric acid, hollow spherical silicon-shell arrays were produced. This technique is capable of fabricating structures with complete photonic band gaps, which is predicted by simulations with the plane wave method. The techniques developed in this study have the potential to flexibly engineer the positions of the PBGs by varying both the silica particle size and the silicon-shell thickness. Ellipsometry was used to investigate the specific photonic band gaps for both structures.

  8. Laser surface modification of electroplated, physically vapor deposited and plasma sprayed coatings

    SciTech Connect

    Dini, J.W.

    1996-05-01

    Lasers are used to modify surface characteristics in order to improve properties for a variety of industrial applications. Typical surface alterations include: transformation hardening, melting, cladding, alloying, coating, and smoothing. This paper is a critical review that covers surface alloying. It concentrates on coatings applied by electroplating, plasma spraying or physical vapor deposition and the resultant properties obtained after laser treatment. In many cases, significant improvement in properties such as corrosion resistance, wear resistance, creep strength, porosity, and structure was noted after coatings were exposed to a laser treatment. 112 refs., 12 figs., 4 tabs.

  9. A new mass spectrometer system for investigating laser-induced vaporization phenomena

    NASA Technical Reports Server (NTRS)

    Lincoln, K. A.

    1974-01-01

    A laser has been combined with a mass spectrometer in a new configuration developed for studies of high-temperature materials. A vacuum-lock, solid-sample inlet is mounted at one end of a cylindrical, high-vacuum chamber one meter in length with a nude ion-source, time-of-flight mass spectrometer at the opposite end. The samples are positioned along the axis of the chamber at distances up to one meter from the ion source, and their surfaces are vaporized by a pulsed laser beam entering via windows on one side of the chamber. The instrumentation along with its capabilities is described, and results from laser-induced vaporization of several graphites are presented.

  10. Perspectives of transurethral robotic laser resection of the prostate: vaporization and coagulation effects with the Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Ho, Gideon; Teo, Ming Y.; Kwoh, Chee K.; Ng, Wan S.; Cheng, Wai S.

    2000-05-01

    A longer operating time and steeper learning curve in mastering the techniques for transurethral laser resection of the prostate are the main problems faced by surgeons compared to standard transurethral resection of the prostate (TURP). However, these disadvantages can be solved with the introduction of a treatment modality designed and developed based on an integrated system of computer, robotics and laser technology. In vitro experiments were carried out to determine variables affecting the vaporization and coagulation lesions, in order to identify the parameters that could optimize this modality. Human cadaveric prostate and fresh chicken breast tissues were irradiated with different parameters using continuous wave Nd:YAG laser fiber in contact with the tissue. The effects of irrigant flowrate, fiber/tissue angle of inclination, number of passes, direction, speed and power of lase on the volume of tissue vaporized and coagulated, were assessed. A non-contact optical coordinate measuring machine was used to measure the depth and width of the vaporized and coagulated lesion. Results reveal that for each directional vaporization path (forward, clockwise and counter-clockwise), power and speed of lase are the most significant parameters influencing the volume of the vaporized and coagulated lesion. Optimized values of the power and speed of lase at 100 W and 1 - 3 mm/s respectively were obtained from the experiments when the tissues were irradiated in the forward, clockwise and counter-clockwise directions. It was concluded from our study to quantify tissue removal and damage, optimized values of irradiation power and speed could be obtained and implemented in the procedure of transurethral robotic laser resection of the prostate.

  11. Infectious papillomavirus in the vapor of warts treated with carbon dioxide laser or electrocoagulation: Detection and protection

    SciTech Connect

    Sawchuk, W.S.; Weber, P.J.; Lowy, D.R.; Dzubow, L.M.

    1989-07-01

    Papillomavirus DNA has been reported recently in the vapor (smoke plume) derived from warts treated with carbon dioxide laser; this raises concerns for operator safety. We therefore have studied a group of human and bovine warts to define further the potential risk of wart therapy and to test whether a surgical mask could reduce exposure. Half of each wart was treated with carbon dioxide laser and the other half with electrocoagulation. The vapor produced by each form of therapy was collected with a dry filter vacuum apparatus and analyzed for the presence of papillomavirus. Vapor from human plantar warts was analyzed for the presence of human papillomavirus DNA, because there is no infectivity assay for human papillomavirus. Of plantar warts treated, five of eight laser-derived vapors and four of seven electrocoagulation-derived vapors were positive for human papillomavirus DNA. Greater amounts of papillomavirus DNA were usually recovered in the laser vapor than in the electrocoagulation vapor from the same wart. Bioassay readily detected infectious bovine papillomavirus in the vapor from bovine warts treated with either modality; more virus was present in laser-derived material. A surgical mask was found capable of removing virtually all laser- or electrocoagulation-derived virus, strongly suggesting that such masks can protect operators from potential inhalation exposure to papillomavirus.

  12. Method of and apparatus for measuring vapor density

    DOEpatents

    Nelson, L.D.; Cerni, T.A.

    1989-10-17

    Apparatus and method are disclosed which determine the concentration of an individual component, such as water vapor, of a multi-component mixture, such as a gaseous mixture for cooling a nuclear reactor. A hygrometer apparatus includes an infrared source for producing a broadband infrared energy beam that includes a strong water vapor absorption band and a weak water vapor absorption region. The beam is chopped to select infrared pulses. A temporally first pulse has a wavelength in the weakly absorbing region, a temporally second pulse has a wavelength in the strong band and a temporally third pulse has a wavelength in the weakly absorbing region. A fourth reference pulse representing background radiation is interposed in such chopped pulses. An indium arsenide infrared sensor is responsive to the pulses for generating an output signal in proportion to an equation given in the patent where N1 is proportional to the transmission through the sample of the first signal, N4 is related to the background radiation, and [K2 (N2-N4) + K3 (N3-N4)] is the time-weighted average of the transmission through the sample of the second and third pulses applicable at the time of the second pulse, with the reference pulse N4 being subtracted in each case to render the ratio independent of variations in the background radiation. 11 figs.

  13. Method of and apparatus for measuring vapor density

    DOEpatents

    Nelson, Loren D.; Cerni, Todd A.

    1989-01-01

    Apparatus and method determine the concentration of an individual component, such as water vapor, of a multi-component mixture, such as a gaseous mixture for cooling a nuclear reactor. A hygrometer apparatus includes an infrared source for producing a broadband infrared energy beam that includes a strong water vapor absorption band and a weak water vapor absorption region. The beam is chopped to select infrared pulses. A temporally first pulse has a wavelength in the weakly absorbing region, a temporally second pulse has a wavelength in the strong band and a temporally third pulse has a wavlength in the weakly absorbing region. A fourth reference pulse representing background radiation is interposed in such chopped pulses. An indium arsenide infrared sensor is responsive to the pulses for generating an output signal in proportion to: ##EQU1## where N1 is proportional to the transmission through the sample of the first signal, N4 is related to the background radiation, and [K2 (N2-N4)+K3 (N3-N4)] is the time-weighted average of the transmission through the sample of the second and third pulses applicable at the time of the second pulse, with the reference pulse N4 being subtracted in each case to render the ratio independent of variations in the background radiation.

  14. Delay of explosive vaporization in pulsed laser-heated droplets.

    PubMed

    Park, B S; Biswas, A; Armstrong, R L; Pinnick, R G

    1990-02-15

    Measurements of time delays for explosion of pulsed CO(2) laser-heated droplets are presented. A simple model based on classical nucleation theory in superheated liquids, which neglects heat and mass transport, is used to interpret the data. The model shows good agreement with the experimental observations. PMID:19759758

  15. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, Charles R.; Hammond, Robert B.

    1981-01-01

    The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  16. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, C.R.; Hammond, R.B.

    The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  17. Spectral characteristics of a ternary-mixture of dyes in a dye laser pumped by copper vapor laser

    NASA Astrophysics Data System (ADS)

    Khare, R.; Shukla, P. K.; Shrivastava, V. K.; Nakhe, S. V.

    2014-02-01

    The spectral characteristics of a ternary-mixture, composed of Rhodamine 640, Rhodamine 6G and DCM in ethanol and excited by copper vapor laser, are reported. The concentration of each dye in the ternary-mixture was optimized to provide peak emission at 633 nm and absorb both wavelengths of copper vapor laser, i.e. 510.6 and 578.2 nm. A fluorescence range of 612-679 nm with a relatively broad peak at 631-634 nm was obtained when concentrations of Rhodamine 640, Rhodamine 6G and DCM in the ternary-mixture were 0.90 mM, 0.30 mM and 0.90 mM respectively. This ternary-mixture of dyes in ethanol, when used as a gain medium in a narrowband, tunable dye laser oscillator, transversely pumped by both wavelengths of a copper vapor laser, provided a spectral tuning range of 620-665 nm with an almost flat peak at 630-634 nm.

  18. Laser photoacoustic detection of the essential oil vapors of thyme, mint, and anise

    NASA Astrophysics Data System (ADS)

    El-Kahlout, A. M.; Al-Jourani, M. M.; Abu-Taha, M. I.; Laine, Derek C.

    1998-07-01

    Photoacoustic studies of the vapors of the essential oils of thyme, mint and anise have been made using a line-tunable waveguide CO2 laser in conjunction with a heat-pipe type of photoacoustic vapor sample cell operated over the temperature range 20 - 180 degree(s)C. Identifying spectral fingerprint features are found in the 9 - 10 micrometers spectral region for each of the three essential oils investigated. The principal features of the photoacoustic spectrum of each essential oil are associated with the dominant chemicals present i.e. thymol in thyme oil, menthol in mint and anethole in anise.

  19. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, Karl F.; Haynam, Christopher A.; Johnson, Michael A.; Worden, Earl F.

    1999-01-01

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

  20. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

    1999-08-31

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

  1. Method and apparatus for producing thermal vapor stream

    DOEpatents

    Cradeur, Robert R.; Sperry, John S.; Krajicek, Richard W.

    1979-01-01

    Method and apparatus for producing a thermal vapor stream for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, including a pressure vessel containing a high pressure combustion chamber for producing a heating gas for introduction into a heating gas injector. The heating gas injector is partly immersed in a steam generating section of the pressure vessel such that the heating gas is passed through the steam generating section to produce steam and combustion products which are directed between the pressure vessel and the combustion chamber for simultaneously cooling of the combustion chamber by further heating of the steam and combustion gases.

  2. Identification of vapor-phase chemical warfare agent simulants and rocket fuels using laser-induced breakdown spectroscopy

    SciTech Connect

    Stearns, Jaime A.; McElman, Sarah E.; Dodd, James A.

    2010-05-01

    Application of laser-induced breakdown spectroscopy (LIBS) to the identification of security threats is a growing area of research. This work presents LIBS spectra of vapor-phase chemical warfare agent simulants and typical rocket fuels. A large dataset of spectra was acquired using a variety of gas mixtures and background pressures and processed using partial least squares analysis. The five compounds studied were identified with a 99% success rate by the best method. The temporal behavior of the emission lines as a function of chamber pressure and gas mixture was also investigated, revealing some interesting trends that merit further study.

  3. Modeling of laser-analyte-substrate interaction in photo-thermal infrared imaging and laser trace vaporization

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Großer, Jakob; Kendziora, Christopher A.; Papantonakis, Michael R.; Nguyen, Viet; McGill, R. Andrew

    2011-05-01

    We are developing two techniques for non-contact detection of explosives and other substances with low vapor pressure. In one approach, quantum cascade lasers (QCLs) at eye-safe power levels heat trace residues on surfaces at stand-off distances and the photo-thermal signal is imaged with an infrared camera. When using wavelengths corresponding to vibrational resonances specific to the trace molecules, the traces can be selectively heated and become visible in the infrared. In a second approach, a QCL or other IR laser of higher power is used to enhance the vapor signature of the analyte, thus facilitating vapor-based (e.g. ion mobility spectrometry) techniques. Details and advances in these techniques will be reported elsewhere. In this paper, we study the laser heating of analytes on substrates using the simulation software COMSOL. A model is validated with experimental results for particles of well characterized shape and size. The heat transfer between particle and substrate is of special interest, but not necessarily the dominant contributor to heat loss. Both air- and substrate-mediated heating of neighboring interferent particles is generally negligible. The presence of neighboring explosives particles affects the thermal kinetics via air-mediated heat transfer.

  4. Photodynamic therapy with gold vapor laser in the treatment of bladder cancer

    NASA Astrophysics Data System (ADS)

    Zhu, Qing; Zhang, Hui-Guo; Lu, Mei-er; Zhu, Bang-ji; Dai, Shen-guo; Jiang, Yu; Wu, Jia-Jun

    1993-03-01

    Vhe paper reports that 149 bladder tumors in 40 patients were treated by gold vapor laser photodynamic therapy in the period from June 1989 to August 1991. The light fiber output power of gold vapor laser is more than 2 W, that spread through a spherical diffuse light leading fiber. Focusing the irradiation on the tumor and the whole bladder the power density was 70.77 mw/cm2 to approximately 509.55 mw/cm2. After a follow-up of 4 to 24 months we found the following results: cured 28 cases (70%); good effect in 11 cases (27.5%); improved 1 case (2.5%); and regenerated 4 (10%).

  5. Upper Tropospheric and Lower Stratospheric Measurements of Water Vapor by the JPL Laser Hygrometer Mark 2

    NASA Astrophysics Data System (ADS)

    Troy, R. F.

    2015-12-01

    The concentration of water vapor in the upper troposphere and lower stratosphere has a significant impact on climate. Over the last sixteen years, the JPL Laser Hygrometers have collected a significant data record of atmospheric humidity from several platforms, including the NASA ER-2, WB-57, DC-8, and Global Hawk. Here, we describe the observed relation between atmospheric humidity and temperature in-cloud and out of cloud near the tropopause. The relation between cloud microphysical properties and humidity is also explored. We feature measurements of water vapor from a substantially improved instrument, JPL Laser Hygrometer Mark 2, made during the 2013 NASA SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) field mission.

  6. Kinetics of laser pulse vaporization of uranium dioxide by mass spectrometry

    SciTech Connect

    Tsai, C.

    1981-11-01

    Safety analyses of nuclear reactors require knowledge of the evaporation behavior of UO/sub 2/ at temperatures well above the melting point of 3140 K. In this study, rapid transient heating of a small spot on a UO/sub 2/ specimen was accomplished by a laser pulse, which generates a surface temperature excursion. This in turn vaporizes the target surface and the gas expands into vacuum. The surface temperature transient was monitored by a fast-response automatic optical pyrometer. The maximum surface temperatures investigated range from approx. 3700 K to approx. 4300 K. A computer program was developed to simulate the laser heating process and calculate the surface temperature evolution. The effect of the uncertainties of the high temperature material properties on the calculation was included in a sensitivity study for UO/sub 2/ vaporization. The measured surface temperatures were in satisfactory agreements.

  7. High-power copper vapor lasers and their application to precision drilling and cutting

    SciTech Connect

    Warner, B.E.; Weber, P.D.

    1993-07-27

    High-power copper vapor lasers (CVLs) have been under development at Lawrence Livermore National Laboratory (LLNL) for more than 15 years in support of the DOE`s Program in Laser Isotope Separation. The technology is now quite mature, having met many of its goals in system architecture, power, reliability, and maintainability. Over the past several years we have begun an effort to utilize this technology in other industrial applications, such as metals processing, and have found a number of unique processes. In this paper we describe briefly the general characteristics of the CVL, our recent progress in developing the laser as an industrial tool, and our progress in using the laser in precision drilling and cutting.

  8. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  9. Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry.

    PubMed

    Bednařík, Antonín; Tomalová, Iva; Kanický, Viktor; Preisler, Jan

    2014-10-17

    Here we present a novel coupling of thin-layer chromatography (TLC) to diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). DLTV is a new technique of aerosol generation which uses a diode laser to induce pyrolysis of a substrate. In this case the cellulose stationary phase on aluminum-backed TLC sheets overprinted with black ink to absorb laser light. The experimental arrangement relies on economic instrumentation: an 808-nm 1.2-W continuous-wave infrared diode laser attached to a syringe pump serving as the movable stage. Using a glass tubular cell, the entire length of a TLC separation channel is scanned. The 8-cm long lanes were scanned in ∼35 s. The TLC - DLTV ICP MS coupling is demonstrated on the separation of four cobalamins (hydroxo-; adenosyl-; cyano-; and methylcobalamin) with limits of detection ∼2 pg and repeatability ∼15% for each individual species. PMID:25193171

  10. Laser/Plasma/Chemical-Vapor Deposition Of Diamond

    NASA Technical Reports Server (NTRS)

    Hsu, George C.

    1989-01-01

    Proposed process for deposition of diamond films includes combination of plasma induced in hydrocarbon feed gas by microwave radiation and irradiation of plasma and substrate by lasers. Deposition of graphite suppressed. Reaction chamber irradiated at wavelength favoring polymerization of CH2 radical into powders filtered out of gas. CH3 radicals, having desired sp3 configuration, remains in gas to serve as precursors for deposition. Feed gas selected to favor formation of CH3 radicals; candidates include CH4, C2H4, C2H2, and C2H6. Plasma produced by applying sufficient power at frequency of 2.45 GHz and adjusting density of gas to obtain electron kinetic energies around 100 eV in low-pressure, low-temperature regime.

  11. Modification and simulation of the power supply of a metal vapor laser

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, D. N.; Trigub, M. V.; Torgaev, S. N.; Vasnev, N. A.; Evtushenko, T. G.

    2016-04-01

    The modification of a power supply circuit used for pumping metal vapor lasers is analyzed. The results of OrCAD simulation of the processes that occur in the power supply are presented. The effect of the capacitance ratio on the charging process of a storage capacitor is described. The mode which provides more time for the recovery of the thyratron is discussed. The results of the development of the small-size high pulse repetition frequency laser with up to 3 W average output power are presented.

  12. Synthesis of Cobalt Oxides Thin Films Fractal Structures by Laser Chemical Vapor Deposition

    PubMed Central

    Haniam, P.; Kunsombat, C.; Chiangga, S.; Songsasen, A.

    2014-01-01

    Thin films of cobalt oxides (CoO and Co3O4) fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures. PMID:24672354

  13. Synthesis of cobalt oxides thin films fractal structures by laser chemical vapor deposition.

    PubMed

    Haniam, P; Kunsombat, C; Chiangga, S; Songsasen, A

    2014-01-01

    Thin films of cobalt oxides (CoO and Co3O4) fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures. PMID:24672354

  14. Method of physical vapor deposition of metal oxides on semiconductors

    DOEpatents

    Norton, David P.

    2001-01-01

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  15. Vaporization of the Prostate with 150-W Thulium Laser: Complications with 6-Month Follow-Up

    PubMed Central

    García-Larrosa, Alejandro; Capdevila, Santiago; Laborda, Ainhoa

    2014-01-01

    Abstract Purpose: To analyze the efficacy and safety of vaporization of the prostate (VP) with the 150-W thulium:yttrium-aluminum-garnet (Tm:YAG) laser. Patients and Methods: In a prospective series of 55 patients with small- and medium-size prostates undergoing major outpatient surgery (MOS), the primary objectives were to analyze changes in maximum flow (Qmax) and International Prostate Symptom Score (IPSS) after 6 months. Immediate (<30 days) and late (>30 days) complications were subsequently recorded. Results: An increase in mean Qmax of 9.33 mL/s (95% confidence interval [CI] of the mean difference 6.73–11.93; P<0.001) was recorded, and mean IPSS was reduced by 16.88 points (95% CI 14.22–19.54; P<0.001). The immediate complications recorded were acute urinary retention (one patient), urinary tract infection without fever (two patients), and macroscopic hematuria (two patients). The only late complication observed was bladder neck sclerosis (one patient). Conclusion: After 6 months, VP with 150-W Tm:YAG presents promising results in the clinical improvement of patients with small- and medium-size prostates. Its complication rate is low and it offers excellent hemostasis. The data from our study provide the basis for the design of clinical trials to compare this technique with other procedures. PMID:24521152

  16. Method for the generation of variable density metal vapors which bypasses the liquidus phase

    DOEpatents

    Kunnmann, Walter; Larese, John Z.

    2001-01-01

    The present invention provides a method for producing a metal vapor that includes the steps of combining a metal and graphite in a vessel to form a mixture; heating the mixture to a first temperature in an argon gas atmosphere to form a metal carbide; maintaining the first temperature for a period of time; heating the metal carbide to a second temperature to form a metal vapor; withdrawing the metal vapor and the argon gas from the vessel; and separating the metal vapor from the argon gas. Metal vapors made using this method can be used to produce uniform powders of the metal oxide that have narrow size distribution and high purity.

  17. Effect of surrounding gases and water vapor on the induced electric current associated with a laser-induced plasma

    NASA Astrophysics Data System (ADS)

    Matsuta, Hideyuki

    2016-04-01

    The effect of surrounding gases and water vapor on the laser-induced electric current was investigated. Laser-induced plasma was generated on an aluminum alloy target. The laser-induced plasma was optically examined to estimate the excitation temperature and electron density in room air. There was a linear relationship between the maximum amplitude of the laser-induced current and the electron density. As the electron mean free path of the surrounding gas increased, the observed amplitude of the current increased. The amplitude of the induced current signal in dry air became maximum upon mixing with the optimum amount of water vapor. This enhancement of the induced current signal might be due to the large relative permittivity of water vapor. The laser-induced plasma as a whole seems to be a low-temperature plasma consisting of electrons, a large amount of cold surrounding gas, injected hot atoms, hot ions, and hot particles.

  18. Method and apparatus for detection of chemical vapors

    SciTech Connect

    Mahurin, Shannon Mark; Dai, Sheng; Caja, Josip

    2007-05-15

    The present invention is a gas detector and method for using the gas detector for detecting and identifying volatile organic and/or volatile inorganic substances present in unknown vapors in an environment. The gas detector comprises a sensing means and a detecting means for detecting electrical capacitance variance of the sensing means and for further identifying the volatile organic and volatile inorganic substances. The sensing means comprises at least one sensing unit and a sensing material allocated therein the sensing unit. The sensing material is an ionic liquid which is exposed to the environment and is capable of dissolving a quantity of said volatile substance upon exposure thereto. The sensing means constitutes an electrochemical capacitor and the detecting means is in electrical communication with the sensing means.

  19. Combustion chamber and thermal vapor stream producing apparatus and method

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.; Cradeur, Robert R.

    1978-01-01

    A new and improved method and apparatus for burning a hydrocarbon fuel for producing a high pressure thermal vapor stream comprising steam and combustion gases for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, wherein a high pressure combustion chamber having multiple refractory lined combustion zones of varying diameters is provided for burning a hydrocarbon fuel and pressurized air in predetermined ratios injected into the chamber for producing hot combustion gases essentially free of oxidizing components and solid carbonaceous particles. The combustion zones are formed by zones of increasing diameters up a final zone of decreasing diameter to provide expansion zones which cause turbulence through controlled thorough mixing of the air and fuel to facilitate complete combustion. The high pressure air and fuel is injected into the first of the multiple zones where ignition occurs with a portion of the air injected at or near the point of ignition to further provide turbulence and more complete combustion.

  20. Waterproof Silicone Coatings of Thermal Insulation and Vaporization Method

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E. (Inventor)

    1999-01-01

    Thermal insulation composed of porous ceramic material can be waterproofed by producing a thin silicone film on the surface of the insulation by exposing it to volatile silicone precursors at ambient conditions. When the silicone precursor reactants are multi-functional siloxanes or silanes containing alkenes or alkynes carbon groups higher molecular weight films can be produced. Catalyst are usually required for the silicone precursors to react at room temperature to form the films. The catalyst are particularly useful in the single component system e.g. dimethylethoxysilane (DNMS) to accelerate the reaction and decrease the time to waterproof and protect the insulation. In comparison to other methods, the chemical vapor technique assures better control over the quantity and location of the film being deposited on the ceramic insulation to improve the waterproof coating.

  1. Urethral stricture vaporization with the KTP laser provides evidence for a favorable impact of laser surgery on wound healing

    NASA Astrophysics Data System (ADS)

    Schmidlin, Franz R.; Venzi, Giordano; Jichlinski, Patrice; Oswald, Michael; Delacretaz, Guy P.; Gabbiani, Giulio; Leisinger, Hans-Juerg; Graber, Peter

    1997-12-01

    The objective of this study was to evaluate and compare the safety and efficacy of the KTP 532 laser to direct vision internal urethrotomy (DVIU) in the management of urethral strictures. A total of 32 patients were randomized prospectively in this study, 14 DVIU and 18 KTP 532 laser. Patients were evaluated postoperatively with flowmetry and in the case of recurrence with cystourethrography at 3, 12, 24 weeks. With the KTP 532 laser complete symptomatic and uredynamic success was achieved in 15 (83%) patients at 12 and 24 weeks. Success rate was lower in the DVIU group with 9 (64%) patients at 12 weeks and 8 (57%) patients at 24 weeks. Mean preoperative peak-flow was improved from 6 cc/s to 20 cc/s at 3, 12 and 24 weeks with the KTP laser. With DVIU mean preoperative peak-flow was improved from 5.5 cc/s to 20 cc/s at 3 weeks followed by a steady decrease to 13 cc/s at 12 weeks and to 12 cc/s 24 weeks. No complication was observed in either group of patients. Our results confirm that stricture vaporization with the KTP 532 laser is a safe and efficient procedure. The better results after laser surgery make it also a valuable alternative in the endoscopic treatment of urethral strictures. These findings suggest a favorable influence of laser surgery on wound healing with less wound contraction and scarring. The lack of contraction of laser wounds might be related to the absence and the lack of organization of myofibroblasts in laser induced lesions.

  2. Effect of laser power on orientation and microstructure of Ba2TiO4 film prepared by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Guo, Dongyun; Goto, Takashi; Wang, Chuanbin; Shen, Qiang; Zhang, Lianmeng

    2012-08-01

    Ba2TiO4 films were prepared on Pt/Ti/SiO2/Si substrates by laser chemical vapor deposition method. The effect of laser power (PL) on orientation and microstructure was investigated. With increasing PL from 52 to 93 W, the deposition temperature (Tdep) increased from 845 to 946 K. With increasing Tdep from 845 to 927 K, the preferred orientation of Ba2TiO4 films changed from (0 9 1) to (1 0 3), the surface morphologies changed from faceted to rectangular, and the columnar cross-section became thicker. The films prepared at high Tdep (931-946 K) had the porous cross-section consisted of powder-like grains. Ba2TiO4 film prepared at 881 K had high deposition rate (Rdep) of 51.4 μm h-1, which was advantageous to industrial production.

  3. Relationship between 578-nm (copper vapor) laser beam geometry and heat distribution within biological tissues

    NASA Astrophysics Data System (ADS)

    Ilyasov, Ildar K.; Prikhodko, Constantin V.; Nevorotin, Alexey J.

    1995-01-01

    Monte Carlo (MC) simulation model and the thermoindicative tissue phantom were applied for evaluation of a depth of tissue necrosis (DTN) as a result of quasi-cw copper vapor laser (578 nm) irradiation. It has been shown that incident light focusing angle is essential for DTN. In particular, there was a significant rise in DTN parallel to elevation of this angle up to +20 degree(s)C and +5 degree(s)C for both the MC simulation and tissue phantom models, respectively, with no further increase in the necrosis depth above these angles. It is to be noted that the relationship between focusing angles and DTN values was apparently stronger for the real target compared to the MC-derived hypothetical one. To what extent these date are applicable for medical practice can be evaluated in animal models which would simulate laser-assisted therapy for PWS or related dermatologic lesions with converged 578 nm laser beams.

  4. Subnatural linewidth in room-temperature Rb vapor using a control laser

    NASA Astrophysics Data System (ADS)

    Rapol, Umakant D.; Wasan, Ajay; Natarajan, Vasant

    2003-05-01

    We demonstrate two ways of obtaining subnatural linewidth for probe absorption through room-temperature Rb vapor. Both techniques use a control laser that drives the transition from a different ground state. The coherent drive splits the excited state into two dressed states (Autler-Townes doublet), which have asymmetric linewidths when the control laser is detuned from resonance. In the first technique, the laser has a large detuning of 1.18 GHz to reduce the linewidth to 5.1 MHz from the Doppler width of 560 MHz. In the second technique, we use a counterpropagating pump beam to eliminate the first-order Doppler effect. The unperturbed probe linewidth is about 13 MHz, which is reduced below 3 MHz (0.5Γ) at a detuning of 11.5 MHz.

  5. New multiplexed all solid state pulser for high power wide aperture kinetically enhanced copper vapor laser.

    PubMed

    Ghodke, D V; Muralikrishnan, K; Singh, Bijendra

    2013-11-01

    A novel multiplexed scheme is demonstrated to combine two or more pulsed solid state pulsers of moderate capabilities. Pulse power supply comprising of two solid state pulsers of ~6 kW rating each in multiplexed mode with common magnetic pulse compression stage was demonstrated and optimized for operating with a wide aperture kinetically enhanced copper vapor laser. Using this new configuration, the multiplexed pulsed power supply was capable of operating efficiently at net repetition-rate of ~13 kHz, 12 kW (wall plug average power), 18-20 kV discharge voltage and pulse rise-time of ~80 ns. The laser under multiplexed configuration delivered un-interrupted output power of about ~80 W with scope of further increase in laser output power in excess of 100 W. PMID:24289383

  6. Soft-Bake Purification of SWCNTs Produced by Pulsed Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Yowell, Leonard; Nikolaev, Pavel; Gorelik, Olga; Allada, Rama Kumar; Sosa, Edward; Arepalli, Sivaram

    2013-01-01

    The "soft-bake" method is a simple and reliable initial purification step first proposed by researchers at Rice University for single-walled carbon nanotubes (SWCNT) produced by high-pressure carbon mon oxide disproportionation (HiPco). Soft-baking consists of annealing as-produced (raw) SWCNT, at low temperatures in humid air, in order to degrade the heavy graphitic shells that surround metal particle impurities. Once these shells are cracked open by the expansion and slow oxidation of the metal particles, the metal impurities can be digested through treatment with hydrochloric acid. The soft-baking of SWCNT produced by pulsed-laser vaporization (PLV) is not straightforward, because the larger average SWCNT diameters (.1.4 nm) and heavier graphitic shells surrounding metal particles call for increased temperatures during soft-bake. A part of the technology development focused on optimizing the temperature so that effective cracking of the graphitic shells is balanced with maintaining a reasonable yield, which was a critical aspect of this study. Once the ideal temperature was determined, a number of samples of raw SWCNT were purified using the soft-bake method. An important benefit to this process is the reduced time and effort required for soft-bake versus the standard purification route for SWCNT. The total time spent purifying samples by soft-bake is one week per batch, which equates to a factor of three reduction in the time required for purification as compared to the standard acid purification method. Reduction of the number of steps also appears to be an important factor in improving reproducibility of yield and purity of SWCNT, as small deviations are likely to get amplified over the course of a complicated multi-step purification process.

  7. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.

    1994-01-01

    Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

  8. Tissue ablation after 120W greenlight laser vaporization and bipolar plasma vaporization of the prostate: a comparison using transrectal three-dimensional ultrasound volumetry

    NASA Astrophysics Data System (ADS)

    Kranzbühler, Benedikt; Gross, Oliver; Fankhauser, Christian D.; Hefermehl, Lukas J.; Poyet, Cédric; Largo, Remo; Müntener, Michael; Seifert, Hans-Helge; Zimmermann, Matthias; Sulser, Tullio; Müller, Alexander; Hermanns, Thomas

    2012-02-01

    Introduction and objectives: Greenlight laser vaporization (LV) of the prostate is characterized by simultaneous vaporization and coagulation of prostatic tissue resulting in tissue ablation together with excellent hemostasis during the procedure. It has been reported that bipolar plasma vaporization (BPV) of the prostate might be an alternative for LV. So far, it has not been shown that BPV is as effective as LV in terms of tissue ablation or hemostasis. We performed transrectal three-dimensional ultrasound investigations to compare the efficiency of tissue ablation between LV and BPV. Methods: Between 11.2009 and 5.2011, 50 patients underwent pure BPV in our institution. These patients were matched with regard to the pre-operative prostate volume to 50 LV patients from our existing 3D-volumetry-database. Transrectal 3D ultrasound and planimetric volumetry of the prostate were performed pre-operatively, after catheter removal, 6 weeks and 6 months. Results: Median pre-operative prostate volume was not significantly different between the two groups (45.3ml vs. 45.4ml; p=1.0). After catheter removal, median absolute volume reduction (BPV 12.4ml, LV 6.55ml) as well as relative volume reduction (27.8% vs. 16.4%) were significantly higher in the BPV group (p<0.001). After six weeks (42.9% vs. 33.3%) and six months (47.2% vs. 39.7%), relative volume reduction remained significantly higher in the BPV group (p<0.001). Absolute volume reduction was non-significantly higher in the BPV group after six weeks (18.4ml, 13.8ml; p=0.051) and six months (20.8ml, 18ml; p=0.3). Clinical outcome parameters improved significantly in both groups without relevant differences between the groups. Conclusions: Both vaporization techniques result in efficient tissue ablation with initial prostatic swelling. BPV seems to be superior due to a higher relative volume reduction. This difference had no clinical impact after a follow-up of 6M.

  9. Elucidating the Structure of Sugars: MW Spectroscopy Combined with Ultrafast UV Laser Vaporization

    NASA Astrophysics Data System (ADS)

    Cocinero, Emilio J.; Ecija, Patricia; Basterretxea, Francisco J.; Fernandez, Jose A.; Castano, Fernando; Lesarri, Alberto; Grabow, Jens-Uwe; Cimas, Alvaro

    2013-06-01

    Carbohydrates are one of the most versatile biochemicalbuilding blocks, widely acting in energetic, structural or recognition processes. Even the small monosaccharides display unique structural and conformational freedom and may coexist in many open-chain or cyclic forms. We recently initiated the investigation of a series of monosaccharides using a combination of ultrafast laser vaporization and microwave spectroscopy in supersonic jet expansions. We present several structural studies on carbohydrates of aldoses and ketoses of five and six carbon sugars vaporized by UV ultrafast laser vaporization and stabilized in a jet expansion. The experimental evidence confirms that sugars exhibits a α-/β-pyranose conformation (6-membered ring), sharply contrasting with the furanose form (5-membered ring) found in the nature (as component of RNA, sucrose). In addition, thanks to the use of enriched samples, we have experimentally determined the substitution and effective structures. Finally, the structure of several monosaccharides was compared and common structural patterns of their conformational landscape will be showed. E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño Angew. Chem. Int. Ed. 51, 3119-3124, 2012. E. J. Cocinero, A. Lesarri, P. écija, Á. Cimas, B. G. Davis, F. J. Basterretxea, J. A. Fernández and F. Castaño J. Am. Chem. Soc. 135, 2845-2852, 2013.

  10. Vapor Corrosion Cell and Method of Using Same

    NASA Technical Reports Server (NTRS)

    Davis, Dennis D. (Inventor)

    2001-01-01

    The present invention provides a vapor corrosion cell for a real-time and quantitative measurement of corrosion of conductive materials in atmospheres containing chemically reactive gases and water vapor. Two prototypes are provided. Also provided are various applications of this apparatus in industry.

  11. Physics of zinc vaporization and plasma absorption during CO{sub 2} laser welding

    SciTech Connect

    Dasgupta, A. K.; Mazumder, J.; Li, P.

    2007-09-01

    A number of mathematical models have been developed earlier for single-material laser welding processes considering one-, two-, and three-dimensional heat and mass transfers. However, modeling of laser welding of materials with multiple compositions has been a difficult problem. This paper addresses a specific case of this problem where CO{sub 2} laser welding of zinc-coated steel, commonly used in automobile body manufacturing, is mathematically modeled. The physics of a low boiling point material, zinc, is combined with a single-material (steel) welding model, considering multiple physical phenomena such as keyhole formation, capillary and thermocapillary forces, recoil and vapor pressures, etc. The physics of laser beam-plasma interaction is modeled to understand the effect on the quality of laser processing. Also, an adaptive meshing scheme is incorporated in the model for improving the overall computational efficiency. The model, whose results are found to be in close agreement with the experimental observations, can be easily extended for studying zinc-coated steel welding using other high power, continuous wave lasers such as Nd:YAG and Yb:YAG.

  12. Theoretical studies of Resonance Enhanced Stimulated Raman Scattering (RESRS) of frequency-doubled Alexandrite laser wavelength in cesium vapor

    NASA Technical Reports Server (NTRS)

    Lawandy, Nabil M.

    1987-01-01

    The solutions for the imaginary susceptibility of the Raman field transition with arbitrary relaxation rates and field strengths are examined for three different sets of relaxation rates. These rates correspond to: (1) Far Infrared (FIR) Raman lasers in the diabatic collision regime without consideration of coupled population decay in a closed system, (2) Raman FIR lasers in the diabatic collision regime with coupled population conserving decay, and (3) IR Raman gain in cesium vapor. The model is further expanded to include Doppler broadening and used to predict the peak gain as a function of detuning for a frequency doubled Alexandrite laser-pumped cesium vapor gain cell.

  13. Reduction of degradation in vapor phase transported InP/InGaAsP mushroom stripe lasers

    SciTech Connect

    Jung, H.; Burkhardt, E.G.; Pfister, W.

    1988-10-03

    The rapid degradation rate generally observed in InP/InGaAsP mushroom stripe lasers can be considerably decreased by regrowing the open sidewalls of the active stripe with low-doped InP in a second epitaxial step using the hydride vapor phase transport technique. This technique does not change the fundamental laser parameters like light-current and current-voltage characteristics. Because of this drastic reduction in degradation, the vapor phase epitaxy regrown InP/InGaAsP mushroom laser seems to be an interesting candidate for application in optical communication.

  14. Spectral and temporal features of the pumping of rhodamine 6G by radiation from a copper vapor laser

    SciTech Connect

    Soldatov, A.N.; Sukhanov, V.B.

    1983-01-01

    An experimental investigation was made of the influence of the relative delay time tau and of the intensity ratio R/sub 21/ of the spectral components emitted by a copper vapor laser on the energy and spectral characteristics of lasing in rhodamine 6G. For certain values of tau and P/sub 21/, lasing in the dye was disrupted. A clamping effect was discovered between the rhodamine 6G laser emission spectrum and the yellow line of the copper vapor laser. The results obtained were used to determine the parameters of an interference filter for suppressing the yellow line from the copper vapor laser, and this made it possible to raise the efficiency of conversion of the pump radiation into lasing in the dye.

  15. A single surgeon's experience with contact laser vaporization of the prostate

    NASA Astrophysics Data System (ADS)

    Mueller, Edward J.

    1995-05-01

    Herein, I report on my first 50 contact laser prostatectomies performed with the SLT Nd:YAG laser. The obstructed prostatic urethra is opened via contact laser vaporization of the obstructing adenoma. The average pre-op AUA symptom score was 22.9 (range 14 - 30). The average 3 month post-op AUA symptom score was 2.1 (range 0 -8). Eighteen of the patients had the foley catheter removed approximately 4 - 6 hours post-op and were discharged the same day. Thirty patients had the foley catheter removed the morning following surgery and were discharged. And two patients had the foley catheter removed the morning following surgery, but remained in the hospital for medical reasons unrelated to the TURP. Thus, 48 (96%) of the patients were discharged within 24 hours of admission. No patient had to be readmitted to the hospital for any reason. All patients were allowed to return to full activity within 24 hours of discharge. The average hospital cost for the 48 patients discharged within 24 hours was DOL4,694. This compares to the average hospital cost of an electrocautery TURP of DOL6-8000. In summary, contact laser TURP using the SLT Nd:YAG laser relived the symptoms of an obstructing prostate comparable to electrocautery TURP. However, these results were achieved with a much shorter hospitalization, a quicker return to full activity and at a lower cost.

  16. An investigation into the output characteristics of a discharge-heated copper vapor laser

    NASA Astrophysics Data System (ADS)

    Wang, Tieh C.; Yang, Ching Y.

    1989-11-01

    The laser output characteristics of a discharge-heated copper vapor laser (CVL) were investigated at a charging voltage of 14.5 kV, laser tube temperature of 1450 C, pulse repetition rate (PRR) range from 0.5 to 9.5 kHz, and buffer gas pressures of 20 and 75 Torr. Changing buffer gas pressure from 20 to 75 Torr causes no significant variation of the rates of relaxation of metastable atoms. Increase of the current rise of pumping pulse with increasing PRR is the predominant factor for improving the laser behavior when PRR is greater than 3.5 kHz with buffer gas pressure of 20 Torr and when PRR is less than 4.5 kHz with buffer gas pressure of 75 Torr. For short pulse applications, the CVL is preferably operated at high PRR and low buffer gas regime. For the 25-W CVL used here, the prepulse electron density should be higher than 10 to the 13th/cu cm for efficient laser operation. The output power of this CVL can be increased to much higher than 30 W if the thermal insulation is optimized and the PRR is increased.

  17. Review of Various Air Sampling Methods for Solvent Vapors.

    ERIC Educational Resources Information Center

    Maykoski, R. T.

    Vapors of trichloroethylene, toluene, methyl ethyl ketone, and butyl cellosolve in air were collected using Scotchpac and Tedlar bags, glass prescription bottles, and charcoal adsorption tubes. Efficiencies of collection are reported. (Author/RH)

  18. Optimization of the alexandrite laser tuning elements for a water vapor lidar

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Higdon, Noah S.; Browell, Edward V.

    1990-01-01

    An overview of some of the developments completed on an alexandrite laser for making water vapor DIAL measurements is presented in this paper. A computer control for active stabilization of the two intracavity etalons has been implemented and recently tested in an aircraft environment. Long-term frequency drift (i.e., 2 hours) of less than 0.7 pm has been observed in the laboratory. An alignment technique to get the optimum free spectral range ratio for the two etalons is also developed.

  19. Schottky diodes and ohmic contacts formed by thermally assisted photolytic laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Braichotte, D.; van den Bergh, H.

    Thermally assisted photolytic laser chemical vapor deposition (LCVD) of platinum on n-doped gallium arsenide, a two-phase hybrid scheme for the production of Schottky diodes, is discussed. The low temperature photolytic deposits of the initial slow phase contain a nonnegligible fraction of organic ligand material and tend to be amorphous. In the second phase, light absorption of the photolytically deposited metal causes a temperature rise which facilitates the removal of ligand material from the deposit, and which is sufficient for fast pyrolytic LCVD. Measurements of the influence of light intensity, in addition to metalorganic and inert gas pressure, on the deposition rates in both phases are obtained.

  20. Prediction of water vapor transport rates across polyvinylchloride packaging systems using a novel radiotracer method

    SciTech Connect

    Wood, R.W.; Mulski, M.J.; Kuu, W.Y. )

    1990-09-01

    A radiotracer method is used to study the transport properties of water vapor in polyvinylchloride (PVC), a plastic commonly used in the packaging of parenteral solutions. Water vapor transport across a PVC film appears to be Fickian in nature. Using the steady-state solution of Fick's second law and the permeability coefficient of water vapor across the PVC film obtained using the described method, the predicted water vapor transport rate (WVTR) for a parenteral solution packaged in PVC is in reasonable agreement with actual WVTR as determined by weight loss under precisely controlled conditions.

  1. KTP laser selective vaporization of the prostate in the management of urinary retention due to BPH

    NASA Astrophysics Data System (ADS)

    Kleeman, M. W.; Nseyo, Unyime O.

    2003-06-01

    High-powered photoselective vaporization of the prostate (PVP) is a relatively new addition in the armamentarium against bladder outlet obstruction due to BPH. With BPH, the prostate undergoes stromal and epithelial hyperplasia, particularly in the transitional zone, mediated by dihydrotestosterone (DHT). This periurethral enlargement can compress the prostatic urethra leading to bladder outlet obstruction and eventually urinary retention. Treatment of uncomplicated symptomatic BPH has evolved from the standard transurethral resection of the prostate (TURP) to multiple medical therapies and the putative minimally invasive surgical procedures. These include microwave ablation, needle ablation, balloon dilation, stents, as well as fluid based thermo-therapy, ultrasound therapy and cryotherapy. Different forms of lasers have been applied to treat BPH with variable short and long term benefits of urinary symptoms. However, the controversy remains about each laser regarding its technical applicability and efficacy.

  2. Gas-dynamic acceleration of laser-ablation plumes: Hyperthermal particle energies under thermal vaporization

    SciTech Connect

    Morozov, A. A.; Evtushenko, A. B.; Bulgakov, A. V.

    2015-02-02

    The expansion of a plume produced by low-fluence laser ablation of graphite in vacuum is investigated experimentally and by direct Monte Carlo simulations in an attempt to explain hyperthermal particle energies for thermally vaporized materials. We demonstrate that the translation energy of neutral particles, ∼2 times higher than classical expectations, is due to two effects, hydrodynamic plume acceleration into the forward direction and kinetic selection of fast particles in the on-axis region. Both effects depend on the collision number within the plume and on the particles internal degrees of freedom. The simulations allow ablation properties to be evaluated, such as ablation rate and surface temperature, based on time-of-flight measurements. Available experimental data on kinetic energies of various laser-produced particles are well described by the presented model.

  3. Gas-dynamic acceleration of laser-ablation plumes: Hyperthermal particle energies under thermal vaporization

    NASA Astrophysics Data System (ADS)

    Morozov, A. A.; Evtushenko, A. B.; Bulgakov, A. V.

    2015-02-01

    The expansion of a plume produced by low-fluence laser ablation of graphite in vacuum is investigated experimentally and by direct Monte Carlo simulations in an attempt to explain hyperthermal particle energies for thermally vaporized materials. We demonstrate that the translation energy of neutral particles, ˜2 times higher than classical expectations, is due to two effects, hydrodynamic plume acceleration into the forward direction and kinetic selection of fast particles in the on-axis region. Both effects depend on the collision number within the plume and on the particles internal degrees of freedom. The simulations allow ablation properties to be evaluated, such as ablation rate and surface temperature, based on time-of-flight measurements. Available experimental data on kinetic energies of various laser-produced particles are well described by the presented model.

  4. Acoustic monitoring of carbon film formation by laser-induced chemical vapor deposition

    SciTech Connect

    Iida, Y.; Yeung, E.S. )

    1993-04-01

    Acoustic signals generated by the deposition of carbon thin films were monitored in situ by a microphone. Photolysis of benzene or adamantane vapor in the presence of helium buffer gas of 5 to 100 Torr by an ArF excimer laser formed several kinds of carbon films (e.g., polymeric, amorphous, and graphitic films), depending on the optical configuration, the ambient pressure, the laser fluence, and the reagent pressure. Analysis of the acoustic signal offers some insight into the mechanism of the deposition processes, which include the graphitization of the deposited films and the role of energetic particles, such as vibrationally excited benzene, in the deposition of amorphous hydrogenated carbon film. Also, the acoustic signal clearly showed the presence of surface-related processes in the course of film deposition. 26 refs., 6 figs., 1 tab.

  5. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, M.W.; Biblarz, O.

    1991-10-15

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process. 2 figures.

  6. Modeling of Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Fay, Catharine C.

    2012-01-01

    Flow in a pressurized, vapor condensation (PVC) boron nitride nanotube (BNNT) production rig is modeled. A laser provides a thermal energy source to the tip of a boron ber bundle in a high pressure nitrogen chamber causing a plume of boron-rich gas to rise. The buoyancy driven flow is modeled as a mixture of thermally perfect gases (B, B2, N, N2, BN) in either thermochemical equilibrium or chemical nonequilibrium assuming steady-state melt and vaporization from a 1 mm radius spot at the axis of an axisymmetric chamber. The simulation is intended to define the macroscopic thermochemical environment from which boron-rich species, including nanotubes, condense out of the plume. Simulations indicate a high temperature environment (T > 4400K) for elevated pressures within 1 mm of the surface sufficient to dissociate molecular nitrogen and form BN at the base of the plume. Modifications to Program LAURA, a finite-volume based solver for hypersonic flows including coupled radiation and ablation, are described to enable this simulation. Simulations indicate that high pressure synthesis conditions enable formation of BN vapor in the plume that may serve to enhance formation of exceptionally long nanotubes in the PVC process.

  7. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  8. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, Edward S.; Chen, Guoying

    1990-05-01

    A method and means for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived.

  9. Study of water molecule decomposition in plasma by diode laser spectroscopy and optical actinometry methods

    NASA Astrophysics Data System (ADS)

    Bernatskiy, A. V.; Lagunov, V. V.; Ochkin, V. N.; Tskhai, S. N.

    2016-07-01

    The methods of diode laser radiation absorption at vibrational–rotational molecule transitions and optical actinometry with measurements of its electron emission spectra are used independently to study water molecule dissociation in glow discharge plasma in a mixture of water vapor and inert gases at reduced pressure. The methods yield close results. The dissociation reaches 98%.

  10. The melanosome: threshold temperature for explosive vaporization and internal absorption coefficient during pulsed laser irradiation.

    PubMed

    Jacques, S L; McAuliffe, D J

    1991-06-01

    The explosive vaporization of melanosomes in situ in skin during pulsed laser irradiation (pulse duration less than 1 microsecond) is observed as a visible whitening of the superficial epidermal layer due to stratum corneum disruption. In this study, the ruby laser (694 nm) was used to determine the threshold radiant exposure, H0 (J/cm2), required to elicit whitening for in vitro black (Negroid) human skin samples which were pre-equilibrated at an initial temperature, Ti, of 0, 20, or 50 degrees C. A plot of H0 vs Ti yields a straight line whose x-intercept indicates the threshold temperature of explosive vaporization to be 112 +/- 7 degrees C (SD, N = 3). The slope, delta H0/delta Ti, specifies the internal absorption coefficient, mua, within the melanosome: mua = -rho C/(slope(1 + 7.1 Rd)), where rho C is the product of density and specific heat, and Rd is the total diffuse reflectance from the skin. A summary of the absorption spectrum (mua) for the melanosome interior (351-1064 nm) is presented based on H0 data from this study and the literature. The in vivo absorption spectrum (380-820 nm) for human epidermal melanin was measured by an optical fiber spectrophotometer and is compared with the melanosome spectrum. PMID:1886936