Accounting for speckle scale beam-bending in classical ray tracing schemes for propagating realistic pulses in indirect drive ignition conditions

We propose a semi-analytical modeling of smoothed laser beams deviation induced by plasma flows. Based on a Gaussian description of speckles [1,2], the model includes spatial, temporal and polarization smoothing techniques, through fits issued from hydrodynamic simulations with a paraxial description of electromagnetic waves. This beam bending model is then included in a ray tracing algorithm, and carefully validated. When applied as a post-process to the propagation of the inner cone in a full-scale simulation of a NIF experiment, the beam bending along the path of the laser affects the refraction conditions inside the hohlraum and the energy deposition, and could explain the anomalous refraction measurements, the so-called glint observed in some NIF experiments [3]. We will finally discuss about possible inline implementation strategies.

[1] C. Ruyer, A. Debayle et. al., Phys. Plasmas 27, 102105 (2020)

[2] C. Ruyer, A. Debayle et. al., submitted to Phys. Plasmas

[3] D. Turnbull, P. Michel et. al. Phys. Rev. Lett. 114,125001 (2015)