[FLASH-USERS] Convergence of RadTrans in LaserSlab

[Kirill Lezhnin]

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Dear FLASH users,

I am trying to simulate a laser-solid tin target interaction scenario starting from LaserSlab and modifying only a few parameters (using 2D cartesian geometry, using solid tin slab and He chamber filling, modifying laser parameters, etc, please see flash.par and log file for details).

Throughout the first few nanoseconds, the evolution looks as expected (electron density normalized to critical density, laser power deposition [erg/s/cm^3], electron/ion/radiation temperatures [eV], fluid speed along x [km/s]):

[tin_180.png]

However, later on, at around ~7 ns into the simulation, I start to observe weird behavior in Trad -unexpected rapid growth of Trad around the laser spot & target-chamber interface, with irregular spatial structures, which persists even when the laser is turned off (at 10.1 ns); it eventually leads to strong target front heating after the laser pulse is gone, which seems unphysical to me. Here is what I observe at 8.2 ns and later on at 32 ns:

[tin_280.png][tin_500.png]


I suspect that such unphysical target evaporation may be caused by the failure of RadTrans module to converge - I think I also confirm it by turning off RadTrans in flash.par before the “failure” and running further without radiation transport/opacities, without any notable problems with target evaporation. At the same time, I haven’t seen any warning/error messages related to radiation transport in log file.

I’d really appreciate suggestions about how to make RadTrans module converge, or any other suggestions about what could cause such a problem. Thanks!

Sincerely yours,
Kirill Lezhnin

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tin2D.log
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flash.par
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