DC discharge simulation with idle time
Posted 10-Jan-2017 11:47 pm EST Plasma Physics Version 5.2a 5 Replies
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.