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Hi All

I am trying to take the 2D axisymmetric DC Discharge example in the COMSOL Plasma Module and convert it to a conventional 2D model. This is to gain experience with 2D DC discharges as I will be developing another DC Discharge simulation where an axisymmetric geometry cannot be used. I have taken the axisymmetric example and copied it exactly into a 2D model in COMSOL (obviously except for the geometry which is instead the full discharge tube as opposed to the half discharge tube given in the example). All the other parameters are identical. When I try and run this simulation I obtain this error message:

Nonlinear solver did not converge.
Maximum number of Newton iterations reached.
Time : 0
Last time step is not converged.
- Feature: Time-Dependent Solver 1 (sol1/t1)

I have tried altering the initial conditions of the model and instead receive this error instead:

Repeated error test failures. May have reached a singularity.
Time : 1.220345147543987e-016
Last time step is not converged.
- Feature: Time-Dependent Solver 1 (sol1/t1)

I have tried experimenting with different meshes and different times for the time dependent study, but this hasn't helped. Maybe I am missing a boundary condition that is required in the 2D model that isn't needed in the axisymmetric one? Any help would be greatly appreciated!

Kind Regards
William