That poses another question. A thin conductor does not have much
capacitance. The model calculations for a real arc indicate about
10 to 20 pF/m.
That is much more than a 0.2mm wire would have. Possibly a thin
conductor like that would be a perfect breakout point for sideways
arcs or create corona around the main arc, adding capacitance.
Antonio Carlos M. de Queiroz wrote:
Thin conductors have really this range of capacitance. The inductance
of a thin wire is approximately 1 uH/m. Adding distributed
capacitance, a transmission line is formed. With L being the
inductance per meter and C the >capacitance per meter, the speed of a
signal
travelling through the line is 1/sqrt(LC). As this speed must be
smaller than the speed of
light c, c^2<1/(LC), C<1/(Lc^2) = 1/(1e-6 x 9e16) =11.1 pF/m.
If I apply the equations for a wire of 0.2 mm diameter 1 m
above a conducting plane from
http://en.wikipedia.org/wiki/Capacitance
I get 5.6 pF/m. For 11.1 pF/m I would need wire diameter of 2.7 cm.
The arc model discussed here doesn't work well with 5.6 pF/m. At a low
capacitance like that the arcs become impossibly long if I adjust the
series resistances, so that the arc consumes 20 kW at 70kV peak
voltage.