Re: Q's ? Q's ? Q's ?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

> About operating a coil in a high vacuum
>
> > If the voltage is high enough it will become a vacuum emitter I
> > expect. In fact, it might well gain a net charge through emission
> > rectification (can lose electrons but not much else).
> >
> How high does the voltage need to be to let it become a vacuum emitter ???
> Is it possible to do the same with a VTTC ?

Actually.. you'll start to get some emission at a few hundred volts.  More
of an issue in a vacuum will be X-rays... around 20-30 kV you start to get
significant xray emission in a vacuum. (you DO need a target, by the way)


>
> > > 2. Is it possible to operate a coil on a higher frequency than it was
> > > designed for. I mean Mhz instead of Khz or maybe even Giga!hertz?
> > > Would it just burn up more quickly or do nothing because of
> > > hysterislus (how do I translate that right?). Is is posible to make a
> > > coil for that specific purpose?
> >
> > Short answer - no. It won't behave as you'd expect at any frequency
> > other than its natural 1/4 wave frequency. At higher harmonics, it
> > will develop voltage antinodes along its length. It would present
> > complex impedances whose identities would vary according to frequency
> > to the drive source.
>
> Is it possible to design and Build a Coil specifically for the Mhz or Ghz
> band ?
> It doesn't need to spark, it just needs to build a high potential.

Yes.. although at higher frequencies, you don't use lumped circuits like a
TC, but, instead, go to a transmission line approach.  The transmission line
would be of reasonable size (2.5 meters long at 30 MHz, for instance).  In
fact, this scheme is used in radars to protect the receiver when the
transmitter is on.  Put a 1/4 wave stub with a easily ionized gas across a
gap at the end.  If significant power is coming down the line, the voltage
on the stub rises, "turning on the ionization", shorting the stub, and
limiting the voltage

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