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Opportunity at Air Force Research Laboratory (AFRL)

Advanced Gas Lasers and High-Performance Computing Simulation of Multiphysics

Location

Directed Energy Directorate, RD/Physical Sciences

RO# Location
13.10.02.B6932 Kirtland Air Force Base, NM 871175776

Advisers

Name E-mail Phone
Madden, Timothy J. timothy.madden.4@us.af.mil 505.846.9076

Description

This research is oriented toward investigation of the physical processes that underlie gas lasers: laser physics, optics, physical chemistry, spectroscopy, and fluid dynamics. Gas lasers use various mechanisms for generating a population inversion within the gas: chemical reactions, electric discharges, rapid gas dynamic expansion, and optically pumping. During generation of the population inversion, chemical kinetic processes may support or erode the inversion, having a significant impact on laser performance in conjunction with spontaneous and stimulated emission of photons. Broadening processes are associated with the lineshape of the lasing transmission, and measurement of intermediate species populations, determination of gas temperature, and visualization of the flow structure providing critical roles. With the population inversion in place, lasing action occurs as the optical physics interact with the laser gain generated in the gas media, dictating power extraction from the gas. Stable and unstable resonator configurations are used to control the lasing process and novel resonator configurations are of interest. As all of these processes occur within a gas; fluid dynamics play a critical role with flow stability, unsteadiness, and transition in subsonic through supersonic flows from very low to high Reynolds numbers being significant. Both experimental and theoretical research opportunities exist within the organization in all of the above areas.

Current fundamental experiment activities focus in the area of optically pumped alkali lasers, including the diode pumped variant commonly referred to as DPALs. These laser systems are resonantly pumped and have achieved high optical conversion efficiencies. Early work in the field of DPAL has focused primarily on small scale laser demonstrators. Scaling these systems to higher powers will require the guidance of detailed modeling; however, much of the fundamental information needed to achieve higher fidelity results is still unknown. Therefore  opportunities are available to conduct experiments to determine values for a multitude of parameters including fluorescence quenching rates, collisional broadening rates, and pooling rates for species of interest to DPALs, There are also opportunities to study other aspects of DPALs including the design and development of small scale demonstrators with surrogate sources that can lead to insight into operational limitations including aspects such as intensity scaling. Finally since there is also current interest into determining the atmospheric propagation characteristics of DPALs, research in this area is also being pursued.

Within the theoretical discipline, a significant activity is the modeling of complex physical processes utilizing high-performance computing on very large, parallel processing architectures. The employed models seek to capture as fully as possible the time-dependent physics underlying gas lasers, including pumping mechanisms, absorption and emission of radiation, 3-D radiation transport and optical field simulation, kinetics, fluid dynamics, and laser physics. Fundamental research is performed on the coupling between these physical processes and the resulting responses to the interactions. Research opportunities in the various associated disciplines are also available including applied mathematics, computational science, and computer science.

 

Keywords:
Gas lasers; Diode pumped alkali lasers; Spectroscopy; Chemical kinetics; Two phase reacting flows; Planar laser induced fluorescence; Chemically reacting flows; Computational fluid dynamics; Multiphysics simulation; Multiscale simulation; Unsteady fluid dynamics; Chemical oxygen-iodine lasers; High-performance computing; Applied mathematics;

Eligibility

Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral and Senior applicants
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