Re: Streamer Voltage

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi David,

At 12:08 AM 5/7/2003 -0500, you wrote:
>Hi All,
>
>This has been bugging me for a while. Is the streamer voltage measured by 
>the combination of topload geometry plus streamer length, or just by 
>streamer length?

Streamer length is more a function of power as shown in John Freau's 
streamer length formula:

L = 1.8 x SQRT(input power)

Since streamers grow on stands of already established hot ionized 
air,  Relatively low voltages can reach out a considerable distance.

>With my 4" coils, the 6" sphere had a breakdown voltage of 571KV by 
>Sd=((MV/7.5)*2)*100.  Sd=sphere dia in cm.  MV= voltage in megavolts.

The radius of a 6 inch diameter sphere is 3 inches or 0.0762 meter.  For 
3MV/m, that gives a voltage of ~229kV to break out.

>It's 18" streamer would come to 502.92KV at 1.1KV/mm.  If the two add 
>together it would make the total voltage 1MV+.  If it were just streamer 
>length the 502KV would not even produce corona on the sphere.


A pretty good guess for maximum top voltage is:

Vt = 0.7 x SQRT( Cp / Cs) * Vfire


>Or could it be that, the voltage peaks enough to produce corona, and then 
>drops, as the streamer is formed.

Yes. It is very likely that a high initial voltage gets loaded down by the 
increasing size of the streamer.

Cheers,

         Terry
>
>David E Weiss