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Re: Coronas (was Toroid Design Features)
From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Wednesday, November 19, 1997 2:14 PM
To: Tesla List
Subject: Coronas (was Toroid Design Features)
Gomez, all,
Speaking of coronas.....
> From: Gomez[SMTP:gomez-at-netherworld-dot-com]
> Reply To: gomez-at-netherworld-dot-com
> Sent: Tuesday, November 18, 1997 12:22 PM
> To: Tesla List
> Subject: Re: Toroid Design Features
<snip>
> I have found significant corona formation even on toroids made from the
> expanded metal ducting. I find that a smooth toroid gets you the more
> desirable single brush discharge, even at higher frequencies.
One of the coils I was evaluating for a job gave some neat effects
you don't normally see due to the lack of darkness (gaps and the
like) when fired single shot.I had a 9" sphere on top. There was no
discharge rod present. With the gap covered and in very dark
conditions, you could see a 3 foot diameter *ball* of wispy stremers
reaching out all round the top. I had previously only seen this type
of discharge from small table top coils. Not as spectacular as hot
arcs of course but fascinating nonetheless.
In his early lectures, Tesla speculated that each streamer was
attributable to a single cycle of oscillation. This demonstration
showed that that cannot possibly be true as the coil only rang at any
appreciable power level for a few tens of cycles at 150kHz or so. The
streamers would have numbered in the thousands easily. It appears
that the air ionizes on many fronts simultaneously.
I also set up my replica of one of Tesla's early coils (circa
1893) with two foot vertical wires coming from the terminals last
night and saw the same bands of streamers all the way up the wires
that had mystified and and amazed his audiences at his early lectures.
There is a great photo of one of Tesla's coils doing this in the
small book on his lectures to the NY Academy of Sciences. All a bit
of fun.
Malcolm