[FLASH-USERS] laser deposition not homogeneous

[Garcia Rubio, Fernando]

Hi Antoine,

I have some experience regarding this issue. As far as I know, FLASH does not count with energy deposition smoothing techniques, so this problem is somewhat unavoidable regardless of how many rays you use.

What has been useful to me is to simultaneously increase the temperature of the “vacuum species” (~10 eV) and smooth the edge of the slab using a Tanh profile for density. This would crudely recreate a coronal region where thermal diffusion would smooth the hot spots created by the laser energy deposition.

The only precaution you have to take is that the initial pressure is much smaller than the ablation pressure generated by the laser so that this trick does not affect the dynamics of your problem.

Hope this helps! Let me know otherwise.

Fernando

------------------------------------------
Fernando García Rubio, PhD
Assistant Scientist
Laboratory for Laser Energetics
585-957-1743
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El 9 nov 2022, a las 9:09, Antoine Gintrand <antoine.gintrand at gmail.com<mailto:antoine.gintrand at gmail.com>> escribió:

Dear flash users,

I have a question regarding the laser deposition a the laser slab simulation.
I am using a laser to shoot a solid target using the 3to2D ray tracing in cylindrical
symmetry, but the deposition is very heterogeneous and is not physical (see the 3 figures attached
with 4200, 8400, and 100 000 rays where the laser comes from the top).

I tried to increase the number of rays from 4200 to 100 000, but the problem remains.
Do you have by any chance a suggestion to fix this issue and make the spatial deposition smooth
around the critical density?

I am also giving the flash.par attached

Thank you so much for the help,

All the best,

Antoine Gintrand
<depo_4200rays.png><depo_8400rays.png><flash.par><depo_1e5rays_IonCond.png>_______________________________________________
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