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).
Proc. SPIE. 11042, XXII International Symposium on High Power Laser Systems and Applications
KEYWORDS: Mirrors, Atomic, molecular, and optical physics, Continuous wave operation, Lithium, Process control, Chemical elements, Energy conversion efficiency, Hydrogen fluoride lasers, Chemical lasers, Diffraction gratings
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.
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.
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 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.
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
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
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.
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.
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.