Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>
Tesla list wrote:
Original poster: "Denicolai, Marco" <Marco.Denicolai@xxxxxxxxxxx>
Hello Jim, all,
Based on my readings there are 3 different situations for breakdown:
- small gaps (some cm), Efield required 30 kV/cm, breakdown with
avalanche (Townsend).
- medium gaps (< 1 m), Efield required 5 kV/m, breakdown with
stable streamers and final jump.
- large gaps (> 1 m), Efield required only 1 kV/m, breakdown with
leader-streamer phases and final jump.
These phenomena are very well documented, although usually with
different names and in not such a clear manner. So, for a 2 m
breakdown you need a 30 kV/m on the toroid surface, then at least
some 5 kV/m within 1 m from it and the rest of the travel will
succeed if 1 kV/m can be ensured.
This is interesting. In looking at sparks between two balls, there is
evidently a distance where sparks cease to occur, even with corona at
the spheres still occurring. A certain minimum required electric field
in the space between the terminals is evidently required.
But values as 5 kV/m seem too low, at least for relatively short sparks.
For example, I have an electrostatic machine that can produce sparks
with up to 16.5 cm between 2.4 cm spheres. I can simulate this in the
Inca program, that predicts a breakdown voltage of 66.5 kV. Charging
the balls to +/- 33.25 kV, the electric field exactly between the balls
has a minimum of 96 kV/m. So, for sparks in this range, apparently
something as 100 kV/m is required.
But this is of a single spark. RF sparks, that grow progressively,
may need less.