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Growing large arcs
At 02:48 AM 11/26/98 -0700, you wrote:
>Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
>> Original Poster: Scott Stephens <Scott2-at-mediaone-dot-net>
>> Lets say a large transformer is connected to a large bridge rectifier and
>> filter cap, and generates a large ionizing voltage, for the purpose of
>> generating (what else?) a large spark. Lets assume the initiating electrode
>> is positive, for minimum required energy.
>>
>> My purpose is, to understand why no one has put a thyratron bridge
rectifier
>> on the output of their TC, to generate enormous sparks. Or have they?
>
>Well, a few significant reasons come to mind - cost, availability, and
>tube voltage withstand capability. While moderate voltage thyratrons (15
>kV) are readily available at comparatively low cost even at Hamfests,
>higher voltage/high power ones are very scarce.
Since I found a working 'fridge compressor/vacuum pump, the idea of building
my own hollow cathode 100KV thyratron doesn't seem so far out. Sure it might
age/burn quickly, but maybe my circuit could adapt itself to that.
The idea of using the hollow cathode discharge e-beam for triggering is also
possible. Nuf sed, don't want to re-kindle the laser spark gap thread.
>AC-couple the base the resonator in a 2-coil system to ground using a
>comparatively high-valued HV capacitor charged to a high positive DC
>potential. This would permit the top of the secondary to have a high
>superimposed DC voltage in addition to the normal high RF voltage.
..
>the base capacitance would provide an additional reserve of energy to aid
in formation >and extension of streamers once formed.
I would like to grow a long, thin, cool low power arc, rather than create a
plasma blast explosion. I wonder if they tried putting a very large inductor
in series with the capacitor, to gradualy let the energy expand the 'crack'
or arc channel in the air.
>I also seem to remember that Bill's system created
>a massive EMP pulse during a ground strike that was also quite
>destructive to nearby electronics... :^)
Yea, a high-current discharge through the BIG loop created by the secondary
and its arc would tend to make a nasty EMP. Another reason for slow
application of energy, less radiation loss & field effects. As in rocket
science, slow initial acceleration has energy advantages.
So how slow can you grow an arc channel? What is the minimum ion velocity?