[FLASH-USERS] "Vacuum" on both sides of target for LaserSlab?

[Arthur Hirsch-Passicos]

Hi David,

It will be the same pseudovacuum (i.e. low density Helium) if you define 
it as chamber material. And you should, the LaserSlab is not made for 
pure vacuum as it is not handled by the EOS of your case.

Best,
Arthur

-- 
Dr. Arthur Hirsch-Passicos
Post-doctoral Researcher

Laser Particle Acceleration Division
Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf e.V.

On 18/06/2025 00:03, David Montgomery wrote:
> Hi Xu,
>
> Thank you for the quick response.
>
> Will that extra space be truly vacuum, or will it be the same as the 
> low density Helium “chamber” species?
>
> David
> Sent from my iPhone
>
>> On Jun 17, 2025, at 3:57 PM, Xu Zhao <xu.zhao at york.ac.uk> wrote:
>>
>> 
>> Hi David,
>>
>> If you want to add some space behind the target (see attached) 
>> compared to the Laserslab default,
>>
>> I think just increasing ymax (the box length if you run in 2d) in the 
>> .par will work.
>>
>> Usually the _Simulation_initBlock.F90_ defines the "blocks (cells)" 
>> in the simulations.
>>
>> For example line 100 - line 129 in the _Simulation_initBlock.F90 
>> _define which part is the "target" species and the other is "Cham".
>>
>> You do not need to modify other files as they define the variables 
>> (like "sim_targetHeight") and material files ("like eos file").
>>
>> Hope this helps,
>> Xu
>>
>>
>> On Tue, 17 Jun 2025 at 22:17, David Montgomery <dsmont80 at gmail.com> 
>> wrote:
>>
>>     Hi All,
>>
>>     Another FLASH-newbie question. I’ve successfully run the
>>     LaserSlab example, and made some small modifications in my own
>>     *.par file.
>>
>>     If I want to add a “chamber gas” region (low density Helium) to
>>     the rear side of the target (surface NOT irradiated by the
>>     laser), in addition to the front side of the target, which files
>>     do I need to modify besides just the *.par file?
>>
>>     Do I have to modify one or more of the local *.F90 files?
>>
>>     Or can I use the same “species” (Cham) on both the rear and front
>>     side of the “target” species?
>>
>>     Any advice would be very helpful.
>>
>>     Thanks,
>>     David Montgomery
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>>
>>
>> -- 
>> Xu Zhao
>> PDRA
>> York Plasma Institute
>> School of Physics, Engineering and Technology
>> University of York
>> York YO10 5DQ, UK
>> <WX20250617-224328 at 2x.png>
>
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