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Re: big plasma ball
HI Paul,
I'm guessing that DC Cox and other professional HV firms
would know more about this than I do but having repaired a 3'
diameter ball, I learnt a few things that may be of interest to you:
> Original Poster: "Paul Mathus" <pmathus-at-learningco-dot-com>
>
> Folks,
>
> I've been thinking about designs for a BIG plasma ball, maybe 8'-9' in
> diameter. I was thinking of making a geodesic sphere from pvc or
> steel pipe, and cauking on clear plastic sheeting, or perhaps screwing
> on clear plexi plates and sealing with weather stripping. It would be
> a bit leaky, but I imagine you could hold gas long enough for a show.
I think strength would be a major factor as the internal gas pressure
has to be very low. Anything other than a spherical shape might be
a challenge for a ball that size.
> You would then fill with argon or your gas of choice, pumping in more
> as needed to replace loss while you astounded the masses. This is a
> possible Burning Man installation I've been tossing around for my 6"
> coil.
>
> I was wondering what the best geometry for placing a coil in this
> contraption would be. If the primary was inside you would risk
> primary strikes from the increased spark length, no?
Yes.
If the primary
> was outside, the sphere would interfere with coupling, wouldn't it?
No.
> Also, does anybody have any guesses/experience on the spark length and
> other effects you get from running a coil in an gas mixture? Would it
> look similar to the typical gift store plasma ball?
The insulation which works at normal atmospheric pressure would
be *gone*. However, the voltages at which these things work is
nowhere near typical TC voltages. What I found was needed for the
ball I fixed (it ran CW from an inverter) was a lot of power. The
shunt capacitance it presented to the power supply was very high.
You would have to take this into account when considering the use
of a TC. In fact, you'd really need to know the range of values under
different streamer conditions before you even started designing a
TC to run it.
Regards,
Malcolm