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21 Feb 2024
@davidrblackman:matrix.orgdoubleagentdavebut not if dr is reduced12:07:11
@davidrblackman:matrix.orgdoubleagentdaveWhat was the intended behaviour of timestep_over_CFL in AM geometry?12:07:35
@davidrblackman:matrix.orgdoubleagentdave If it's not 1/sqrt(dx2 +dr2) maybe the guide on the website needs to be adjusted. 12:09:15
@davidrblackman:matrix.orgdoubleagentdavejust so it's not used in the AM geometry12:10:00
@davidrblackman:matrix.orgdoubleagentdaveAnyway, I can use it properly now I know that I was setting up dt wrongly using that input.12:12:21
@davidrblackman:matrix.orgdoubleagentdaveI'll try something like 0.9/(1/dx +1/dr)12:15:12
@z10f:matrix.orgz10f Hello, in the benchmark benchmarks/tst3d_04_laser_wake.py you will find a laser initialised in a 3D simulation through python functions and the laser block. Since the laser is propagating from x=0, you need to specify the profiles for By and Bz in the coordinates y,z of that plane. You need to adapt this procedure to your case, by changing the laser with the one you wish to use. However you will need to specify the laser only as function of r (it's a cylindrical grid), taking into account the axes defined as here https://smileipic.github.io/Smilei/Understand/azimuthal_modes_decomposition.html#conventions-for-the-namelist and specifying the laser profile through space_time_profile_AM described here https://smileipic.github.io/Smilei/Use/namelist.html#lasers 12:15:23
@z10f:matrix.orgz10fThe CFL condition hard coded in that message is not exact, since there is no exact expression for a CFL in this geometry (which depends also on the number of modes)12:16:30
@z10f:matrix.orgz10fso I don't recommend to specify a dt through the CFL12:16:45
@z10f:matrix.orgz10f use directly timestep 12:16:50
@z10f:matrix.orgz10for it will be difficult to tune it and understand what is happening12:17:04
@davidrblackman:matrix.orgdoubleagentdaveThanks12:19:44
@z10f:matrix.orgz10fyou're welcome, let us know if the problem persists12:20:12
@beck-llr:matrix.orgbeck-llr Sanjeev Kumar: i had not realized your j0 was a function of r. I thought it was only (x,t). In that case you ll have to follow to general procedure indeed. 12:32:54
@sanjeev273:matrix.orgSanjeev Kumar
In reply to @beck-llr:matrix.org
Sanjeev Kumar: i had not realized your j0 was a function of r. I thought it was only (x,t). In that case you ll have to follow to general procedure indeed.
thanks
12:54:28
@abigailjames:matrix.orgabigailjamesHi again. Could someone advise on applying a linear chirp to a laser pulse. So far I've found that I need to use the Laser() rather than the gaussian2d() but can shape the beam using the temporal and spatial profiles. However the chirp is also a temporal profile. Ideally I want to have a gaussian beam with a chirp of a specified amount. I thought I could maybe use the trapezoidal temporal profile and set the slope1 to be the duration of the laser pulse and then the plateau and slope2 to zero but it's not really working. I've achieved it in other code by applying a conditional statement to the laser wavelength and I've worked out how much the omega value needs to shift by but it's not clear how I can control the amount of shift over the duration of the pulse. And advice or direction is appreciated!17:27:24
@yb12bine:matrix.tu-darmstadt.de@yb12bine:matrix.tu-darmstadt.de removed their display name Carolin Elisabeth Goll (TUDa).17:51:03
@z10f:matrix.orgz10fHello, there a chirp argument implemented in some Laser Profiles https://smileipic.github.io/Smilei/Use/namelist.html#chirp_profile , but not everyone uses this definition18:57:21
@z10f:matrix.orgz10f an alternative way is to use a strategy similar to benchmarks/tst3d_04_laser_wake.py. The laser is injected from xmin in that namelist, so since it is a 3D simulation you need to specify the Bz(y,z,t) and By(y,z,t) at the border x=0 through python function, so you have virtually full control of the laser profile 18:59:00
@z10f:matrix.orgz10fMaxwell's equations will take care of the other components while the laser is injected and propagated18:59:19
@z10f:matrix.orgz10f note that in that in that namelist you specify a time profile as time_envelope = tgaussian(center=2**0.5*laser_fwhm, fwhm=laser_fwhm) 18:59:47
@z10f:matrix.orgz10fbut it's not mandatory18:59:51
@z10f:matrix.orgz10fyou can use any 1D function for the temporal profile, knowing that 0 is the start of the simulation19:00:13
@z10f:matrix.orgz10f the final result is return a0 * w * math.exp( -invWaist2*r2 ) * time_envelope( omegat/omega ) * math.sin( omegat ), so you can add your phase yielding the desired chirp 19:01:16
@z10f:matrix.orgz10fplaying with the delay of this phase you can control the chirp along the laser pulse19:01:37
@z10f:matrix.orgz10fsince you specify the y,z,t profiles you can virtually add even spatio-temporal couplings19:02:05
@z10f:matrix.orgz10f * you can use any 1D function of t for the temporal profile, knowing that t=0 is the start of the simulation19:04:56
22 Feb 2024
@kcharbo:matrix.orgKcharboHello smilei team, I was wondering for the AMCylindrical particle boundary conditions, does removal mean that any particles that cross the r=0 axis are removed? Or are they only removed at r=R where R is the radius of the cylinder?00:09:16
@beck-llr:matrix.orgbeck-llrHi. There is no particle boundary at r=0 since particle live in a 3d geometry. Particle BC are applied only when they cross Rmax.06:35:23
@kcharbo:matrix.orgKcharboOkay got it, thanks!!08:32:25

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