Re: Safety FAQ-discharge classification

To: tesla-at-pupman-dot-com
Subject: Re: Safety FAQ-discharge classification
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
Date: Wed, 21 Aug 1996 10:09:23 +1200

Hi all,
          Robert, thankyou for the accolade about the classification 
scheme. I think in the end most of the credit goes to you however.

    Re the phenomenon here....
<snip>
> A phenomenon which I have yet to hear anyone talk about, and which
> is especially evident in the streamer discharge to a grounded
> target in small tabletop systems is where a portion of the thin
> streamer seems to be twice as bright as the rest (majority) of the
> streamer.  This effect is often near dead center in the length of
> the streamer, but sometimes is much closer to the target end. 
> I've got video showing this effect near the target with my MTC
> unit with 10-12 foot scale arcs.  My observations so far conclude
> that this brightened area is actually an overlap area where the
> streamer is split into two streamers, following a nearly identical
> path shape, but separate and parallel to each other over this
> brightening distance.  Have you or anyone else seen this effect 
> and figured out a reasonable explanation?

Yep! I have observed this a lot (come to think of it). In single shot 
expts. it occurs when a discharge rod is just close enough to attract 
a single spark rather than a band of whiskers, AND k is not all that 
high. I've noticed when k is around 0.2 or so, I just get a solid 
channel. I haven't managed to come up with a definite explanation.
Current in the spark should be identical from one end to the other
which makes the thing rather surprising. I'll definitely have another 
look at it this weekend (I know I say that a lot but I've just got 
to the stage where a major side-issue has been dealt with - I'm back
into coiling time).
     Lastly, I too have noticed streamers issuing from targets when
the discharge gets close enough (higher V/metre perhaps). 

Malcolm