How to set the focal position of laser propagation in plasma

[ouyangchen666]

Dear teacher I would like to ask how to set the focal position in the EPCOH laser block. Here are my own settings, but I am not sure if the laser will focus at position x_m after emission, achieving the value of Intensity in l constant block.

begin:constant
  las_lambda       = 0.8 * micron
  las_omega        = 2.0 * pi * c / las_lambda
  laser_period     = las_lambda/c
  x_m              = 2*micron
  laser_k          = 2*pi/las_lambda 
  w0               = 10.0 * micron   # spot size 2.5 *micron
  rayleigh_length  = pi*w0^2/las_lambda
  wz               = w0*sqrt(1+(x_m/rayleigh_length)^2)
  radius_curv      = x_m*(1.0+(rayleigh_length/x_m)^2)
  a0= 9.446  #对应300TW
  Intensity        = (1.37*10^18)*a0^2/((las_lambda^2)*10^12)   #8.56e20[W/cm^2]
  las_t_fwhm       = *femto     #32 * femto    # 12 periods
  r=sqrt(y^2+z^2)
end:constant

begin:laser
   boundary          = x_min
   intensity_w_cm2   = Intensity*(w0/wz)^2
   lambda            = las_lambda 
   pol_angle         = 0.0
   phase             = 0.0
   t_profile         = sin(0.5*pi*time/las_t_fwhm)
   t_start           = 0.0
   t_end             = 2*las_t_fwhm
   profile           = gauss(r,0.0, w0)
end:laser

[Status-Mirror]

Hi @ouyangchen666,

Have you tried running our Gaussian focus beam demo? This provides an example input deck with a user-defined focal spot position.

Cheers, Stuart

[ouyangchen666]

thanks for you advance，I'm now more convinced about setting the focus of the laser this way.