Re: It works! Solid state driver (hf spark)

From: 	Harri Suomalainen[SMTP:haba-at-cc.hut.fi]
Sent: 	Wednesday, December 10, 1997 3:59 PM
To: 	Tesla List
Subject: 	Re: It works! Solid state driver (hf spark)

OK, someone did bring up the subject of spark phenomena. A few words might
be said about them.

Air (gases) act differently depending on type of the spark.
1) DC spark/pulse spark: air ionizes. As the pulse is longer and longer
even more air is ionized. The more current you pump in, the more
ionisation and the lower the spark voltage over the sparking object.
Object might be something like spark gap or fluorescent tube or whatever.
2) HF spark. HF spark is essentially *resistive*. However, it has no
stable point for very long feeding without some ballasting. That can be
seen eg. in fluorescent tubes or discharge lamps. When a few cycles
is the time of observing eg. sine wave fed tube acts purely resistive.
For stabilating the long-term operating point they need some sort of
ballasting though. If not the current would grow at finite rate to huge

Conclution: as cw-driven tube/solid state tesla does not have constant
energy feed the current will *not* rise to huge value. It will spark,
act like resistive load. Then it will stop sparking and store energy in
the coil (say for a few cycles) and during this time the charged particles
(ions) in the air will be reduced. Then it will spark again and so on.

This can be observed by scoping nicely. Feed a coil without any
ballasting. Watch the current wave form. It will not be disorted exept
every now and then. Most of the waveform is almost pure sine wave. (Coil
storing the energy -stage). At the time of spark you'll see a definate
change in the waveform. Unfortunately, due to the lack of a storage scope
I'm unable to tell you all what's the wave form appearing at irregular
interval rate.
See "Malin Tunic: Chemistry of structure - function references in cheese" for
further details!
Harri.Suomalainen-at-hut.fi - PGP key available by fingering haba-at-alpha.hut.fi