Abstract
AbstractThe chemical oxygen–iodine laser (COIL) is the shortest-wavelength high-power chemical laser that has been demonstrated. The characteristics, such as good atmospheric propagation, short wavelength and excellent transmission through optical fibers, make the COIL a good candidate for high-power laser application. To model the complete COIL lasing interaction, a three-dimensional formulation of the fluid dynamics, species continuity and radiation transport equations is necessary. The computational effort to calculate the flow field over the entire nozzle bank with a grid fine enough to resolve the injection holes is so large as to preclude doing the calculation. The approach to modeling chemical lasers then has been to reduce the complexity of the model to correspond to the available computational capability, adding details as computing power increased. The modeling of lasing in the COIL medium is proposed, which is coupling with the effects induced by transverse injection of secondary gases, non-equilibrium chemical reactions, nozzle tail flow and boundary layer. The coupled steady solutions of the fluid dynamics and optics in a COIL complex three-dimensional cavity flow field are obtained following the proposal. The modeling results show that these effects have some influence on the lasing properties. A feasible methodology and a theoretical tool are offered to predict the beam quality for large-scale COIL devices.
Highlights
The chemical oxygen–iodine laser (COIL) has been an important research and technology since the first successful demonstration in 1977[1]
The COIL is unique among chemical lasers because it is the only chemical laser to utilize electronic transitions rather than vibrational transitions[2]
The effects induced by transverse injection of secondary gases, non-equilibrium chemical reactions, nozzle tail flow and boundary layer are coupled to the inflow boundary conditions for the resonator flow calculations, and to the resonator flow calculations
Summary
The chemical oxygen–iodine laser (COIL) has been an important research and technology since the first successful demonstration in 1977[1]. Wu et al.[11,12] studied the flow and optical fields of a supersonic COIL by coupling the three-dimensional Navier– Stokes equations and the paraxial wave equation together within the whole laser cavity. The results[11,12] do not show any mixing and nozzle tail flow effect imprints on the flow or optical fields as seen in[8,9]; perhaps the grid is not fine enough to resolve them These studies have shown reasonable comparisons with measured gain, power and dissociation data[7,8,9,10,11,12], they have provided incomplete insight into some of the fluid dynamic effects within COIL flow fields
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