Re: 1pF+220k....

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

Terry & other streamer modelers,

It is interesting to determine the dynamic load capacitance presented by
streamers/leaders.  What I haven't seen discussed here is the possible
increase in topload (toroid) capacitance due to the effective toroid size
being larger due to the layer of ionized air surrounding it.  I am thinking
the larger ionized air area would in effect be a larger capacitor plate
relative to the ground.  Of course the "surface area" of the ionized air
layer would increase with increasing toroid voltage, and the ionized air
capacitor "plate" probably behaves differently than a metal "plate" (toroid
surface)..  Isn't the effective toroid size/capacitance vs secondary voltage
another parameter to include in load modeling?

--Steve Y.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, July 02, 2005 5:06 PM
Subject: Re: 1pF+220k....


> Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
>
> At 02:59 PM 7/2/2005, Tesla list wrote:
> >Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> >
> >Hi All,
> >
> >I now think our long time streamer load estimation of 1pF/foot + 220k
ohms
> >(series) for a streamer load we use in models should have the "1pF/foot"
> >part replaced by:
> >
> >The capacitance in pF is:
> >
> >C = 0.0666667 x L        from 0 to 30 inchs
> >
> >C = 0.15 x L - 0.25     from 30 to ? inches
> >
> >L is in inches.
> >
> >It really does not change many things much, but there is a lot of hard
> >evidence to support that this is a "better" estimation that agrees with
HV
> >leader folks, models, and testing...
>
>
> Hmmm..  While this empirically might work "better", I'm wondering what the
> physical basis is.
>
> Longer sparks will, in general, be created by a higher power source, which
> will have a larger Topload C, which will have higher currents, which will
> make a larger diamter spark channel, but I doubt that channel diameter has
> enough effect on C.
>
> More "furry offshoots" on longer streamers?
>
>
> Here's an experimental idea that might prove useful:
>
> 1) Take a given coil, and figure out a way to measure the C of the
streamer
> (change in fres?) at sea level.
>
> 2) Take the same coil, run it in a low pressure environment (i.e. at
> 10000-15000 ft MSL (Drive to the top of Pike's Peak, or some high mountain
> resort), where the breakdown voltage is lower, and hence, with the same
> power input it should make longer sparks.  measure the C of the streamers.
>
>
>
>
>
> >Cheers,
> >
> >         Terry
>
>
>
>
>