An experimental study of combustion-driven HBr chemical laser based on D2/NF3 combustion was carried out. The exotherm of the reaction system was analyzed, and the thermal blockage issue of supersonic flow was solved by adjusting the buffer coefficient ω. By optimizing the laser operating conditions, a maximum HBr laser output of 141W was obtained, with the primary laser lines being HBr P1(5) , P1(6) , and P3(6).
KEYWORDS: Hydrogen fluoride lasers, Chemical lasers, Continuous wave operation, Mirrors, Chemical elements, Diffraction gratings, Process control, Lithium, Atomic, molecular, and optical physics, Energy conversion efficiency
The optical and temporal characteristics of a cw hydrogen fluoride chemical laser with spectral lines is investigated. The distributions of populations on the energy levels of transition line are altered by the cascade effect. The output power of the target line is improved due to this process. Also the laser operational parameters is optimized, in order to demonstrate single line oscillation and laser output enhancement.
In order to determine the concentrations of trace amount metastable species in chemical lasers, an off-axis cavity enhanced absorption spectrometer for the detection of weak absorption gases has been built with a noise equivalent absorption sensitivity of 1.6x10-8 cm-1. The absorption spectrum of trace amount gaseous ammonia and water vapor was obtained with a spectral resolution of about 78 MHz. A multiple-line absorption spectroscopic method to determine the temperature of gaseous ammonia has been developed by use of multiple lines of ammonia molecule absorption spectrum.
KEYWORDS: Molecules, Chemiluminescence, Molecular energy transfer, Optical resonators, Hydrogen fluoride lasers, Chemical lasers, Hydrogen, Visible radiation, Near infrared, Chemical species
The visible and near infrared spectra of cavity chemiluminescence of a combustion driven HF laser fueled by NF3 were collected and analyzed. The spectral line at 529 nm for the green chemiluminescence was attributed to electronic excited NF molecules in b1∑ state, i.e. NF(b). The diffuse bands from 570 nm to 700 nm were attributed to the N2(B-A) emission. The spectral lines from 850 nm to 1000 nm were attributed to the HF Δυ = 3 emission bands. At the end of every experiment, the spectral line at 874 nm would be observed, which was attributed to the electronic excited NF molecules in a1 Δ state, i.e. NF(a). The NF(a-X) emission was found experimentally to be always avoiding the HFΔυ = 3 emission bands. It was also found experimentally that the NF(b-X) emission always accompanied the HF Δυ = 3 emission bands and their emission intensities had the same trends as a function of experimental time. Whereas the NF(a) molecules was produced in the optical cavity directly by the reaction of H atoms with NF2 molecules in the incomplete combustion effluents, the NF(b) molecules were suggested to be produced mainly by the near resonant energy transfer from vibrational excited HF(v<=2) molecules to NF(a) molecules. In other words, the vibrational excited state HF(v<=2) molecules can be efficiently deactivated by the NF(a) molecules by near resonant V-E energy transfer process. Therefore we concluded that incomplete dissociation of NF3 might be harmful to the HF(v<=2) population.
An optical cavity temperature test method has been established for the HF chemical laser. This method assumes that in HF optical cavity the rotational distribution of vibrationally excited HF molecules meets the statistical thermodynamic distribution, the first overtones (v = 3-1 and 2-0) spontaneous emission spectral intensity distribution is obtained by using OMA V, the optical cavity temperature is calculated by linear fitting the rotational thermal equilibrium distribution formula for each HF vibrationally excited state. This method is simple, reliable, and repeatable. This method can be used to test the optical cavity temperature not only without lasing, but also with lasing.
KEYWORDS: Chemical lasers, Photonic integrated circuits, Pulsed laser operation, Control systems, Logic, Oxygen, Interfaces, Data acquisition, Laser development, Chlorine gas
A user-friendly data acquisition and control system (DACS) for a pulsed chemical oxygen -iodine laser (PCOIL) has been developed. It is implemented by an industrial control computer,a PLC, and a distributed input/output (I/O) module, as well as the valve and transmitter. The system is capable of handling 200 analogue/digital channels for performing various operations such as on-line acquisition, display, safety measures and control of various valves. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a PCOIL. The DACS system has been programmed using software programmable logic controller (PLC). Using this DACS, more than 200 runs were given performed successfully.
An effective single line continuous wave HF chemical laser operation has been demonstrated using a Littrow-mounted diffractive grating cavity experimentally. Selection of spectral lines of the laser was investigated when the grating used as a reflector and an output mirror respectively. The feedback factor of the cavity is demonstrated important parameter of line selection. Output power of single line from grating cavity is obviously stronger than the same line within the full spectrum of the laser that operated without line selection.
A fluorescence image detection system that can visualize the COIL hot mixing
flow field by taking images of the fluorescence of active I2 with a high speed camera
was set up. Based on the captured flow field image, O2(a1Δ)/I2 mixing quality was
evaluated quantitively by an exclusive image processing program. With this method,
the hot supersonic mixing flow field in COIL which uses parallel stream supersonic
mixing nozzles with a set of trip tabs was investigated. Meanwhile the effectiveness
of the trip tabs was demonstrated.
KEYWORDS: iodine lasers, Combustion, Chemical species, Chlorine, Iodine, Chemical oxygen iodine lasers, Signal detection, Chemical lasers, Semiconductor lasers, Molecules
A supersonic all gas-phase iodine laser driven by NF3/D2/DCl/CF3I combustion has been
experimentally studied. the gain signals of I(2P3/2,F=4)← I(2P1/2,F=3) at 1315.246nm and
I(2P3/2,F=3)← I(2P1/2,F=3) at 1315.222nm were observed with an intensity of 3x10-5cm-1
and 1x10-5cm-1
respectively. The small signal gain of I(2P3/2,F=4)← I(2P1/2,F=3) at different
location relative to HN3 injector along the flow direction also was obtained. The
experimental results indicate that the AGIL driven by NF3/D2/DCl/CF3I combustion is
feasible.
A novel concept of the chemical production of atomic iodine aimed for application in chemical oxygen-iodine laser was
proposed. The method is based on nitrogen trichloride spraying auto-decomposition to generate chlorine atoms which
subsequently react with iodine donors. Preliminary experimental and computational studies for the reaction system were
explored. The experimental results show efficient generations of excited atomic iodine and computational results reveal
that a large degree of atomic iodine can be generated via the reaction system including nitrogen trichloride combustion
effluents and iodine donors.
Production of hydrogen azide was studied using NaN3 and oleic acid as reactant. The HN3 yield no less than 70% in all experiments and the highest yield of 92.6% were obtained. The results show that HN3 preparation using oleic acid is feasible and better than those using strong inorganic acid or stearic acid as to safety and efficiency. An online measurement of HN3 was suggested by means of mass spectrometer with capillary sampling.
DC discharge characteristics of NF3/He have investigated experimentally at many kinds of experimental conditions, for example, different electrodes material, a few of distance between the two electrodes, flow rates of the gas NF3 or He, a series of series-wound resistances and give the steady and optimum discharge parameters finally. Fluorine atom yield from the DC discharge of NF3/He have studied experimentally and the relationship of fluorine atom yield and the load power is shown for the first time.
By means of radio frequency(RF) capacitively coupled discharge, pure CF3I and the mixture of CF3I and various inert gases were used to produce iodine atom for a chemical oxygen-iodine laser. The dependences of atomic iodine concentration on gas pressure and gas flow rate were studied. In the case of RF frequency of 13.56MHz, output power of 500W, gas pressure of 3.5Torr, pure CF3I without any carrier gas ,and CF3I flow rate of 1.2SLM, atomic iodine concentration of 4.0×1014 cm-3 was achieved. The concentration of atomic iodine was of the order of 0.4×1014cm-3 at p=15Torr in the case of the mixture of CF3I and some inert gases, which was lower by one order of magnitude than that of pure CF3I. A kinetics modeling was carried out and demonstrated that CF3 played dominant role in the loss mechanism of atomic iodine.
The effect of NCl(a1Δ) self-annihilation on the production of NCl(a1Δ) and energy extraction of NCl(a1Δ)-I laser was simulated by means of a simplified continuous flow F-P resonator model. The results show that NCl(a1Δ) self-quenching is an important influence on NCl(a1Δ) production and energy extraction of NCl(a1Δ)-I laser and is the most important channel for transport losses of NCl(a1Δ). The efficiency of NCl(a1Δ) production with NCl(a1Δ) self-annihilation is much less than that without NCl(a1Δ) self-annihilation. The optimal location for cavity resonator, the profile of power density along the flow direction and the total power are dramatically dependent on the order of magnitude of the rate constant of NCl(a1Δ) self-quenching reaction. The results show that it is necessary to do more works on the measurement of the rate constant of NCl(a1Δ) self-annihilation reaction and its dependency on temperature in order to accurately analyze, design and value AGIL(All-gas Phase Iodine Laser).
By means of a microwave generator chlorine diluted by helium was dissociated to chlorine atoms that subsequently reacted with hydrogen azide to produce the excited states of NCl(a1Δ). Meanwhile, molecular iodine with carrier gas of helium reacted with atomic chloride to produce atomic iodine which then was pumped to excited state of I(2P1/2) by an energy transfer reaction from NCl(a1Δ). In this paper, the changes of NCl(a1Δ) and NCl(b1Σ) emission intensity is presented upon admitting I2/He into the stream of Cl/Cl2/He/HN3/NCl(a1Δ)/NCl(b1Σ). Moreover, the production of excited state of atomic iodine I(2P1/2) dependent on flow rates of gases was also investigated. The optimum parameters for I(2P1/2) production are given.
By means of Microwave generator chlorine diluted by helium is dissociated to chlorine atoms that subsequently react with hydrogen azide to produce excited states of NCl(a1(Delta) ) and NCl(b1(Sigma) ). In this paper, the intensity of NCl(a1(Delta) ) and NCl(b1(Sigma) ) emission dependent on the flow rates of different gases is studied. Moreover, the production of NCl(a1(Delta) ) and NCl(b1(Sigma) ) along the reaction tube is also investigated. By using a simple titration method, we obtain the dissociation efficiency of molecular chlorine up to 100 percent at the flow rates of chlorine no more than 1 mmol/s. We also achieve the quenching rate of NCl(a1(Delta) ) by Cl2 is about 4 X 10-13 cm3/sec molec with excess flow rates of chlorine. Finally, the optimum parameters for NCl(a1(Delta) ) and NCl(b1(Sigma) ) production are summarized.
Using a doubled Nd: YAG laser as a spontaneous vibrational Raman scattering source, and a single intensified CCD array at the exit of an imaging monochromator, the Raman scattering system is used to directly measure the concentrations of the O2(a1(Delta) ) and the O2((Chi) 3(Sigma) ) in the chemical oxygen-iodine laser singlet oxygen generator in real time. We present the results from the tests that conducted on a 0.1-mol singlet oxygen-iodine generator. With the current reported uncertainty of the Raman cross-section, the error in the yield measurement is calculated to be less than 8 percent.
A calibrated piston source of light, which simulates a cylindrical-volume source, has bene used to measure the absolute concentration of O2(a1(Delta) ). It is proved that this Piston Source Method is one of the simplest and most convenient ways to measure the O2(a1(Delta) ) concentration in a singlet oxygen generator, especially in real time measurements.
Hyperfine gain spectrum of a chemical oxygen-iodine laser (COIL) is investigated experimentally. Six hyperfine lines are obtained in a COIL gain medium as well as an iodine absorption cell. Meanwhile, gain profiles and cavity temperatures are calculated.
KEYWORDS: Resonators, Mirrors, Chemical oxygen iodine lasers, Near field, Chemical lasers, Laser resonators, Off axis mirrors, Near field optics, Reflection, Oxygen
The experimental results on unstable ring resonator with 90 degree beam rotation for kilowatts class Chemical Oxygen Iodine Lasers (COIL) are reported. The distribution of near field phase and far field intensity were measured. The beam quality of 1.6 plus or minus 0.2 were achieved while COIL average output power was about 5 kw, and most of these results were compared with that using a conventional unstable resonator.
KEYWORDS: Chemical oxygen iodine lasers, Oxygen, Chemical lasers, Continuous wave operation, Iodine, Laser beam diagnostics, Beam splitters, Signal detection, Chemical species
A dedicated continuous wave chemical oxygen iodine mini- laser is constructed and used to probe the 2D distribution of small-signal gains in a supersonic continuous wave chemical oxygen iodine laser. The uneven lateral gain distribution may possibly be explained by boundary layer effects.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.