Garfield++ message meaning

Garfield++
1

Hi,
I’m using Garfield++, Gmsh, and Elmer to perform gas amplification simulations of electrons.
I’m referring to the lem example.
The simulation can run to the end, but halfway through I will often get the following message:

MediumMagboltz::GetElectronCollisionRate:
    Rate at 42.2937 eV is not included in the current table.
    Increasing energy range to 44.4084 eV.
AvalancheMicroscopic::TransportElectron: Increasing null-collision rate by 5%.

What does this message mean and how does it affect the simulation?
I have attached the program I am using.
Appreciate your help.

avalanche.cc (9.8 KB)

2

Hi,
by default, MediumMagboltz creates a table of the electron-atom/molecule cross-sections from 0 to 40 eV. If an electron energy higher than that is encountered, this table is updated, with the upper limit of the table increased by 5%. To avoid this from happening, you could set the upper energy limit upfront, e. g. to 200 eV:

gas.SetMaxElectronEnergy(200.);

But otherwise the message is nothing to worry about…

3

Ok, I’ll try to use the code you taught me.
If no problem, I don’t care about the message.
Thank you very much.

4

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