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Journal Articles Journal of Fluids Engineering Year : 2020

Effect of turbulence on the wavefront of an ultra high intensity laser beam


Ultra high intensity lasers face thermal management issues that limit their repetition rates. The key challenge is to efficiently evacuate the heat deposited in the amplifier by the optical pumping without impacting the output laser beam quality. The amplifier can have a multi-slab geometry where the laser beam crosses successive amplifying slabs and the cooling channels that separate them. The present work investigates numerically how a cryogenic cooling of the multi-slab amplifier by turbulent channel flows may affect the wavefront of the laser beam. To this end, Large Eddy Simulations representative of the amplifier cooling are performed using TrioCFD, a code developed by the CEA. First, validation simulations are carried out for heated channel flows, allowing comparisons to Direct Numerical Simulation results from the literature. Then Large Eddy Simulations of an open turbulent channel flow cooling two slabs are conducted using conjugated heat transfer between the solid and the fluid. The phase distortions, mean and fluctuations, induced by the inhomoge-neous and turbulent temperature field are computed directly from the LES. The Sutton model is widely used in aero-optic studies ; its validity and applicability to this problem is then examined. Finally, the effect of an increased optical heating of the slabs is investigated. It is the first time that TrioCFD is used to address the question of the impact of the cooling of laser amplifiers, and it has proven to be a valuable tool for this application.
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Dates and versions

hal-02572291 , version 1 (13-05-2020)
hal-02572291 , version 2 (30-11-2020)



Morgane Bellec, Alain Girard, Guillaume Balarac, Ulrich Bieder, François Millet, et al.. Effect of turbulence on the wavefront of an ultra high intensity laser beam. Journal of Fluids Engineering, 2020, ⟨10.1115/1.4049113⟩. ⟨hal-02572291v2⟩
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