I am trying to simulate argon ion beam extraction for a single aperture 2 gridded system using the 103 plasma surface emitter in OPERA-SCALA.

I wish to calculate the number of particles that fall on the acceleration grid after each run and the number of particles which are completely extracted just to check how efficient is the extraction for a particular number density and extraction voltage.

In short I want to plot a perveance curve by varying extraction voltage and number density simultaneously.

Can anyone suggest how can one find the number of particles at particular length in OPERA?

Thanks in advance!