Directed Energy and the Optical Effects of Fluids
Speaker: Steven La Cava, Ansys Government Initiatives
Presentation
Abstract
Directed energy systems are complex involving multiple physics, including fluids, mechanics and optics. The optical fluid interaction between beam and flow field can cause the beam to exhibit numerous forms of optical aberration. Some are induced by the environment, such as scattering, absorption and refraction. Other aberrations are self-induced, such as thermal blooming, where the index of refraction of the fluid changes due to the heat generated from the beam. Additionally, thermal lensing effects of optical elements may occur. The index of refraction of optical elements changes due to the energy of the beam and the energy absorption of the optical elements. Structural deformation to the optics caused by thermal expansion and movement of mounting subsystems creates ridged body motion.
Some of these effects can be mitigated through cooling, however, cooling such systems is a complex endeavor. Accurately modeling both the cooling of the optics and any optical aberrations the flow field induces is critical to the successful design of a directed energy system. The on-target energy of a beam is typically assumed to have a cross section of a disk, however, with these optical aberrations from the flow field accounted for, the shape of the cross section is not always a disk. Refraction effects through fluids can place the final position off course, the target and source may not be in direct line of sight. Accounting for both the position and the cross section of the beam are important when modeling ablation of a target. Finally, all of these physical effects have an impact on the mission, dwell time, cycle rate, power consumption, etc. can be affected even by modest changes in conditions. This webinar seeks to illustrate the modeling of such systems and compare against known public results.
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