[Prev][Next][Index][Thread]
Re: Spark Gap Losses And Thoughts...
>
>
>
> I also suspect that if one doubles the current through a spark gap, the
> resistance is half of what it was.
Basically true.... The voltage drop at a given current is a combination of
a constant (determined by the gap material and the gas) and the series
resistance of the plasma. The plasma grows bigger in diameter as the
current gets higher, so it's resistance gets less. Rule of thumb is that
the voltage drop per unit length goes as the square root of current, so the
R = sqrt(I)/I or, roughly 1/sqrt(I). The power dissipation is then Sqrt(i)
* I or I^1.5
Its basically a power balance between the heating of the gas by the current
and the power lost through the surface of the "arc tube". There is a very
sharp difference over a small temperature change in resistance of a plasma,
so the edge of the arc is pretty well defined.
Power lost is proportional to diameter (== surface area). Power dissipated
is a bit tricky because the resistance is inversely proportional to the
cross sectional area so the power dissipated is proportional to I/r^2