Re: Triggered spark gaps for coils

["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>


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, March 18, 2001 11:24 AM
Subject: SV: Triggered spark gaps for coils


> Original poster: "Jan Ohlsson by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<jan.ohlsson-at-mbox319.swipnet.se>
>
> If I remember correctly there are no chokes to ballast the current to the
> xenon tubes in photographic flash equipment. The resistance of the
> conducting gas in the flash tube does all the limiting of the current, if
I
> have understood the circuits correctly. That would make them unsuitable
for
> a tesla gap, where you want the lowest resistance possible while the gap
is
> conducting.

Some very large flash set ups (tens of kJoule, as for lighthouses or laser
pumps) use series chokes to limit the current (to prevent the tube inner
wall from ablating!).

>
> The bigger xenon tubes for photographic studio work use about 1-4
> kilojoules at the most. The tubes are quite expensive in the bigger sizes,
> several hundred dollars is not an uncommon prize for a replacement tube
for
> a large studio unit.  The voltage is around 400-500 volts and the flash
> duration is about 1-4 ms. The flash repetition rate is at the most 0.5 - 2
> Hz. For high flash energy and high repetition rates the tubes are fan
> cooled. The trigger electrode is often external in the form of a thin wire
> on the outside of the quartz glass. The trigger pulse is from a small
pulse
> transformer that is fed from a capacitor.

You can get really big tubes for industrial applications.. Tube voltages
well up into the 10 kV range, water cooled, etc.

As Jan points out.. pretty expensive...
You're paying for a lot of things that aren't really needed for for TC use.
If you've got the infrastructure to cool a high power flashtube, you've got
the infrastructure to build a decent triggered blast gap.