I have a problem similar to what was discussed in this post and this post.
I try to create a Gas File for 0.75 mbar propane gas. It worked out for 1 mbar, but at this pressure, I get, at 56.5124 V/cm, the error: PROGRAM STOPPED TOO MANY PRIMARIES IPRIM=*******
The solution in the other posts was to change the field range. But I actually need the range from low fields (a few V/cm) to high fields (about 4 kV/cm) at this low pressure.
I also varied the ncoll in gas.GenerateGasTable(ncoll), but the error persisted.
Is there any option to prevent this from happening?
Is there an option to do a workaround when I only want to simulate ion drift trajectories with my ion mobility dataset?
This error is typically related to a too high Townsend coefficient, which can happen at very high E/N values. You cannot solve this by playing with the ncoll parameter, as this governs only the precision of the calculation.
Well, if you are only interested in the ion drift trajectories, and you do not need any electron-gas interaction at all, then you do not need a gasfile. Your component holds the values of the electric field in your detector and you can just simulate your ion trajectories using the ion mobility dataset.
Instead if you need a gasfile, but you do not need high precision, you could think of calculating your gasfile up to a lower field value and then use the extrapolation at higher fields. Maybe you can make a plot of your electron drift velocity or townsend coefficient (if you need these observables) and see which extrapolation (cst, lin, exp) is implemented by default an see if it is reasonable for you. You can have a look at an example here and try to make such a plot for your gasfile at 1mbar to understand the situation.
The electron-gas collisions depend on the reduced electric field value E/N, where N is the number density (atoms/cm3) and this depends on the pressure. So I am quite surprised that for 1mbar you would be able to calculate the gasfile for the full range (few V/cm to 4kV/cm), but for 25% less pressure you run into troubles already at 56V/cm.
Since it is just a matter of scaling, we should find a way to use a gasfile calculated at a certain pressure A and scale the swarm parameters to used at a pressure B. I am not sure whether this is already possible now, I let @hschindl comment, or I would invite you to have a look at the source code and try out (e.g. load your file at 1mbar and change the pressure afterwards and see if the swarm parameters are scaled accordingly).