Re: very long sparks

Hi everybody,

(big snip)

 there IS ample evidence of the
> phenomenon of long-spark
> propagation under low average electric fields
> (compared to the often
> quoted 30 kV/cm breakdown for air at STP).
> While it is indeed hard to believe that a 5 MV
> impulse could generate a
> 100 meter spark,
Not hard to me.Here is simple explanation for
this.After about 4 MV DC voltage range pulse applied
stepping leader mechanism effects start almost
completely to overtake process of further spark
progression.(This is the most important thing that
allow lightning process too).How far the sparh will go
depends mostly on the capability of energy supply
source .What is observed is that spark jumps 10-20 m
,wait for 10s of microseconds for potential rise along
its end,and go on in steps that way.


there is ample precident that very
> long sparks can
> propagate under relatively low average applied
> fields - this includes
> lightning! While the 5 MV discharge had an "average"
> field of only 500
> volts/cm, it turns out that lightning strikes occur
> with an observed
> average field stress that may be as low as 100
> volts/cm when observed at
> ground level ("Lightning" by Uman). 
> Sometimes truth IS stranger than fiction...

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