Modelling of a room temperature plasma source

Hi all,

I am trying to model a room temp. plasma torch that uses a pulsed DC voltage to generate argon plasma. The goal is to model the electron number density of the plasma for different applied voltages and flow rates. I am using a 2-D axisymmetric model in the time domain (not sure if this is correct), I am using the plas module with laminar flow as well.

I have used an analytic to act as the pulsed voltage, it has a frequency of 10kHz and a duty cycle of 0.1.

Currently my model is not working, I believe this is due to poor setup of boundary conditions or incorrect time step. I have not been able to find any example models that are particularly applicable to my case, does anyone have any recommendations on:
- Time step
- Most suitable plasma module
- Study type (stationary, time, frequency)

Model parameters:
- Voltage, 10 kV
- Flow rate, 0.29 m/s

The model is attached below, I'd be happy to answer any questions.

Thanks,
Ben Brooks