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Re: Low voltage sparkgaps for ignition coil driver...
Tesla List wrote:
> Original Poster: Jim Lux <jimlux-at-jpl.nasa.gov>
>
> Tesla List wrote:
> >
> > Original Poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
> >
> > Tesla List wrote:
> >
> > > The dielectric strength of air is 20k(!!)V per mm not 20v/mil.
> >
> > 30 kV/cm, or 3 kV/mm, or 76 kV/inch, or 76 V/mil, is a better figure.
> > But I read somewhere that less voltage than about 240 V (or
> > something in this range) cannot cause air breakdown, no matter
> > what is the distance. (Does someone know more about this?)
>
> This is true.. If you look at the Paschen curve, it has a minimum at
> some combination of density and distance. If you reduce the distance
> even further, the breakdown voltage actually goes up.
>
> It has to do with the mean free path of the ions in the gap. If the gap
> gets very small, a cascade of ionization can't develop. The worst
> pressure, from a breakdown standpoint, is around .01 Atmosphere,
> equivalent to about 30 km altitude (100 kFt). This is a real problem in
> designing high power radio equipment (like radars) to operate in the
> upper atmosphere.
Does this mean that the current goes up at small distances where the
breakdown voltage increases? Is the electron transfer bypassing the small
number of Air molecules in the gap?
What is the association to AC frequency? Is it reasonable to assume that
breakdown
voltage decreases at all distances with increasing frequency? What is the
principle?
Does it relate to molecular electron orbital polarizability? If so, this
would predict a quantum drop in discharge voltage at the resonance frequency
of the highest occupied and lowest unoccupied MO.