DC discharge simulation with idle time

Topics: 5.2a, Plasma Module

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Vasily Kozhevnikov

Vasily Kozhevnikov

January 11, 2017 4:47am UTC

DC discharge simulation with idle time

Dear Friends,

Im simulating low-pressure 2D DC discharge with COMSOL Plasma module. The peculiarity of this simulation is in the anode voltage supply. Anode voltage waveform is represented by small duty cycle pulse train (rectangular + long pause each). The high voltage application time is much smaller than entire pulse period, but it is enough to ignite self-sustained discharge ~ 2 us at low pressure. After the ignition of self-sustained discharge voltage source switching off for the long time about ~ 100 us.
COMSOL successfully simulates the ignition, but after the switching the source off at about 20-30 us from the beginning of the simulation I receive "Repeated error test failures. May have reached a singularity" error for BDF and Generalized alpha time-dependent solvers both. Also I've tried to set Relative tolerance at specified value from 0.01 down to 1e-5.
I can't explain why is it so? There is no convection at that time point, only diffusion and surface reactions. Do you know how to avoid such disconvergencies? Please, share your opinions.

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Amine Mesbahi

Amine Mesbahi

January 11, 2017 8:38am UTC in response to Vasily Kozhevnikov

Re: DC discharge simulation with idle time

Hi,
In begining try to do your simulation in 1D if possible to see if the problem don't come from your chemical reaction.
In 2D plasma simulation the mesh must be very small (small than Debye lenth).
You can try also to use iterative solver.
Good luck

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