Study of the electric field in a diffuse nanosecond positive ionization wave generated in a pin-to-plane geometry in atmospheric pressure air
Résumé
The dynamics of a nanosecond positive ionization front generated in a pin-to-plane geometry in
atmospheric pressure air is simulated using a 2D axisymmetric drift-diffusion fluid model. For a
16 mm gap and a sharp pin electrode, the plateau of the applied voltage is varied between 40
and 60 kV and the rise time is varied between 0.5 and 1.5 ns or a DC voltage is applied. The
discharge ignition time and the voltage at ignition are shown to depend mostly on the voltage
rise time. The connection time, i.e. the time for the ionization wave to ignite, propagate and
connect to the plane is shown to strongly depend on both the values of the voltage plateau and
rise time. For all cases, the discharge has a conical shape with a maximal radius of about 8 mm
as it connects to the grounded plane. The average propagation velocity of the ionization front is
found to vary in the range 3.1 to 8.5 mm ns−1. These values are in rather good agreement with
experiments. Temporal evolutions of the electric field are recorded on the symmetry axis at
different positions in the gap. At each location, an increase and decrease of the electric field is
observed as the ionization front, propagating from the pin to the plane, passes the studied point,
in accordance with experimental observations. Finally, for a voltage plateau of 55 kV and a rise
time of 0.5 ns, a temporal sampling of 100 ps is shown to be sufficient to capture the dynamics
of the electric field during the ionization front propagation when it passes close to the middle of
the gap. Conversely, a temporal sampling of 10 ps is required when the ionization wave is close
to both electrodes, or during the fast redistribution of the electric field after the connection of the
ionization front at the cathode.
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Bourdon+et+al_2020_J._Phys._D__Appl._Phys._10.1088_1361-6463_abbc3a.pdf (900.82 Ko)
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