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Fw: instrumenting for leader growth
I would suggest that the conventional gap in the primary be replaced with
something that has very good repeatability on an external trigger. Probably
a triggered gap would work nicely.
The other thing that would probably be handy is a CCD camera with "open
flash" capability, that you can add a fast electrooptic shutter (Kerr or
Faraday) to. You can use conventional film cameras, but getting the timing
and exposure right will consume a lot of film. If a reasonable CCD camera
could be synchronized so that during the 1/60 or 1/100 second it's shutter
is open we can trigger the coil and EO shutter, we stand a chance. Sadly,
most of the consumer CCD cameras don't have deterministic "shutter button
press" to "exposure start" delays, if they even have some sort of external
interface to trigger the exposure. We might be able to work it backwards,
using the external flash "X" sync from the camera (which some DO have), or
even an optical pickup on the built in strobe.
Oddly, I happen to have some Maxwell triggered gaps and some circuitry to
drive them, and could lash up the rest... I've also always wanted to build a
Kerr Cell shutter (a'la Kim Vandiver in Amateur Scientist), so maybe this is
a good excuse.
-----Original Message-----
From: tesla-request-at-pupman-dot-com <tesla-request-at-pupman-dot-com>
Date: Friday, November 05, 1999 10:32 AM
>Hi Jeff, Antonio & List,
>
>Jeff, I must disagree, though concede there is activity below the "ability
>to see" threshold.
>
>I do believe we will see something such as is observed in natural lightning
>strikes:
>
> 1.) Faint leader(s) with stepped branch offshoots (probing for a return
>path)
>
> 2.) followed by a bright high current channel power event
> (through that path established by the leader that encountered
> a significant return path connection)
> which then drains all available energy from the cloud (or top TC
>terminal)
> to include the stored energy remaining in any substantial arc
>branches
> (note: I believe branches may tend to have some built in isolation as a
>function
> of their higher XL from independent high frequency (~2 to ~50MHz) self
>oscillation)
>
> What a feeling to observe an offshoot leader lose brightness just as
>the main channel
> ignites through the leader established path with a full charge in
the
>gas tank !
> Likely to need ~10's nS resolution/discrimination ability
> requiring a great deal of ingenuity to capture
> (Nothing is impossible !)
> The Single Shot mode is a good place to start,
> subsequently (after bugs worked out) applied to increasing
bang
>rates
> to observe discharge growth as a function of increasing break
>rate.
>
>(make a wish) instrumenting my DC TC: .1uF 7kVdc 2.5J vacuum switch gap,
>Lpri-spiral-1/4cu=6.7uH Lsec-#24awg6.3x19"=28mH k=.2 Ctorus+dist=25pF
>
>I would be most pleased to instrument simultaneously a capture in the
Single
>Shot mode:
>(single shot mode control allows good synchronization of event monitors)
>
> Vfield-Ctop-proximity, Vfield-arc-proximity, Vgap
> Ipri=cap, Isec, Iarc,
> still photo (integral) of the >1uS arc event (to compare with electrical
>signature)
> video of the arc event with fastest practical frame rate (search
>frame-frame for revelation)
>
>