An experimental study of combustion-driven HBr chemical laser based on D<sub>2</sub>/NF<sub>3</sub> 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 P<sub>1</sub>(5) , P<sub>1</sub>(6) , and P<sub>3</sub>(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.
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.
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.
The visible and near infrared spectra of cavity chemiluminescence of a combustion driven HF laser fueled by NF<sub>3 </sub>were collected and analyzed. The spectral line at 529 nm for the green chemiluminescence was attributed to electronic excited NF molecules in b<sup>1</sup>∑ state, i.e. NF(b). The diffuse bands from 570 nm to 700 nm were attributed to the N<sub>2</sub>(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 a<sup>1</sup> 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 NF<sub>2</sub> 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 NF<sub>3</sub> might be harmful to the HF(v<=2) population.
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 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.
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 NF<sub>3</sub> 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.