Mailing List picongpu-users@hzdr.de Message #58
From: Khikhlukha Danila <Danila.Khikhlukha@eli-beams.eu>
Subject: laserGaussianBeam initialization
Date: Mon, 2 May 2016 11:06:19 +0000
To: picongpu-users@hzdr.de <picongpu-users@hzdr.de>
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Hi all,                                                                                                                
                                                                                                                       
I have a couple of short questions regarding the Gaussian beam initialization.                                         
                                                                                                                       
1. As far as I understood from the code comments (simulation_defines/param/laserConfig.param)                            
the initialization for laser pulse is done based on the sigma of the intensity envelope. However in the code           
(src/picongpu/include/fields/laserProfiles/laserGaussianBeam.hpp) it looks like PULSE_LENGTH is the sigma of electrical field envelope.
I also wasn't able to find any conversion (namely sqrt(2))                                                             
                                                                                                                       
2. So at the moment I'm assuming that the initialization of the Gaussian beam is done based on the sigma of an electrical field envelope.
So if we consider k = 2*sqrt(2*log(2))=2.3548 as a coefficient between FWHM and sigma of the Gaussian curve            
then the coefficient between sigma of an electrical field and FWHM of the intensity becomes sqrt(2)/k = 0.6006.        
However, in comments for laserGaussianBeam it is stated the number 1./1.17741 = 0.8493 and I'm not sure what is it.       
                                                                                                                       
Can you please double check if comments are up-to-date? Otherwise I got something wrong in the description.          
                                                                                                                       
Thank you,                                                                                                  
Danila.
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