[FLASH-USERS] [EXT] Re: laser setup in cylindrical geometry

Thu Sep 10 21:55:45 EDT 2020

Hi Eddie:

Thank you for your reply.     At here i only use one beam coming at 45 degree, but in the end i will use maybe four beams from different angle to implode a part of this spherical shell. So i need to keep these beams symmetric to their incident axis.    

2D cartesian geometry is not accuurate in this simulation, and 3D simulation spend too much time, so I need use 2D cylindrical set up to do this. 

Thank you for your suggestion!

-Ke Fang

-----原始邮件-----
发件人:"Eddie Hansen" <ehansen at pas.rochester.edu>
发送时间:2020-09-10 19:02:33 (星期四)
收件人: "方可" <kfang at iphy.ac.cn>
抄送: "Shu Zhang" <shz133 at eng.ucsd.edu>, flash-users <flash-users at flash.uchicago.edu>
主题: Re: [EXT] Re: [FLASH-USERS] laser setup in cylindrical geometry

Not sure what else you have going on in your simulation, but why not rotate your frame of reference? The 1 beam coming in at 45 degrees is still just 1 beam pointed towards the center of a sphere. You could have it come from 0 deg (the equator), and then it will look symmetric.

On Thu, Sep 10, 2020, 2:55 AM 方可 <kfang at iphy.ac.cn> wrote:

Hi Shu:

Thank you for your explanation, this make sense and now i understand why at the pole end the intensity is always stronger. I will try some other methods like 3D simulation. 

Best regards,

-Ke Fang

-----原始邮件-----
发件人:"Shu Zhang" <shz133 at eng.ucsd.edu>
发送时间:2020-09-10 12:34:17 (星期四)
收件人: "方可" <kfang at iphy.ac.cn>
抄送: "flash-users at flash.uchicago.edu" <flash-users at flash.uchicago.edu>
主题: Re: [FLASH-USERS] laser setup in cylindrical geometry

Hi Ke, 

After 3D-in-2D projection, the simulation is working like you have a ring of lasers injected at 45 deg. So at the pole, you have higher overlapped intensity, but at the equator, the averaged intensity is lower. This is real when multiple large spot beams are injected at 45 deg. 

-Shu

On Sep 9, 2020, at 8:32 PM, 方可 <kfang at iphy.ac.cn> wrote:

Shu:

Thank you very much for your answer, but i think there is still some problem.  What i mean is when i inject the laser with 45 deg, truly the intensity and energy is not uniform, but i think it should be symmetrically to the 45 degree injection axis.  

When i use the cartesian geometry without 3Din2D laser setup, the results is symmetrical, but I need run this in cylindrical geometry. I added 2 screenshot of these results of pressure distribution in the mail attachment.

Thank you for your help! 

-Ke Fang

-----原始邮件-----
发件人:"Shu Zhang" <shuzhang at princeton.edu>
发送时间:2020-09-10 10:56:45 (星期四)
收件人: "方可" <kfang at iphy.ac.cn>
抄送: "flash-users at flash.uchicago.edu" <flash-users at flash.uchicago.edu>
主题: Re: [FLASH-USERS] laser setup in cylindrical geometry

Hi Ke,

Your settings are correct. The 3D in 2D laser ray tracing is calculating the laser ray deflection and the energy deposition in 3D and then project the energy deposition on the 2D RZ coordinates. Thus, when the laser is injected in 45 deg, naturally the projected energy deposition is not really uniform. It would look like uniform if you have a planar target normal to the Z(Y) axis. 

-Shu

On Sep 9, 2020, at 7:42 PM, 方可 <kfang at iphy.ac.cn> wrote:

Hi, everyone:

My simulation is using one laser beam irradiate on a spherical shell, and this laser beam have a 45 degree angle to x-axis. I used the cylindrical geometry, and from the output hdf5 files, I found that the intensity of laser is not symmetrically on the surface of the shell. But when i used the cartesian geometry with same 45 degree incident laser, the intensity on the shell is uniform and symmetrically.

I guess here are some problems when i'm seting up the laser beam. My laser setup in the .par file is as follows:

useEnergyDeposition = .true.
ed_maxRayCount      = 20000
ed_gradOrder        = 2

# Activate 3D-in-2D ray trace:
ed_laser3Din2D           = .true.
ed_laser3Din2DwedgeAngle = 0.1

### LASER IO OPTIONS ###
ed_useLaserIO                  = .true.
ed_laserIOMaxNumberOfPositions = 10000
ed_laserIOMaxNumberOfRays      = 128

### SETUP LASER PULSES ###
ed_numberOfPulses = 1

# Define Pulse 1:
ed_numberOfSections_1 = 4

ed_time_1_1  = 0.0
ed_time_1_2  = 0.01e-09
ed_time_1_3  = 0.50e-09
ed_time_1_4  = 0.51e-09

ed_power_1_1 = 0.0
ed_power_1_2 = 1.52e+012
ed_power_1_3 = 1.52e+012
ed_power_1_4 = 0.0

### SETUP LASER BEAM ###
ed_numberOfBeams = 1

# Setup Gaussian Beam:

ed_lensX_1                    =  10.0
ed_lensZ_1                    =  10.0
ed_lensY_1                    =  0.0
ed_lensSemiAxisMajor_1        =  3.0e-01

ed_targetX_1                  =  212.0e-04
ed_targetZ_1                  =  212.0e-04
ed_targetY_1                  =  0.0

ed_targetSemiAxisMajor_1      =  225.0e-04
ed_targetSemiAxisMinor_1      =  225.0e-04

ed_pulseNumber_1              =  1
ed_wavelength_1               =  0.351
ed_crossSectionFunctionType_1 = "gaussian2D"
ed_gaussianExponent_1         =  4.0
ed_gaussianRadiusMajor_1      =  212e-04
ed_gaussianRadiusMinor_1      =  212e-04
ed_numberOfRays_1             =  4096
ed_gridType_1                 = "radial2D"
ed_gridnRadialTics_1          =  64
ed_semiAxisMajorTorsionAngle_1=  0.0
ed_semiAxisMajorTorsionAxis_1 = "x"

And in mesh parameters:
geometry = "cylindrical" 

And, this shell is a hollow spherical shell with outer radius 300 microns and inner radius 150 microns.

So, what should i do to let the intensity of the laser on the shell to be symmetrically to the 45 degree incident axis? 

Thank you for your attention and help !

Best regards,

Ke Fang

phd student
Chinese Academy of Sciences

<45degree_cartesian.PNG><45degree_cylindrical.PNG>

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