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RE: Laser Triggered Spark Gap



A diode laser is unlikely to trigger a gap.  The cheapest thing I know of
that would do the job is a nitrogen laser, which emits very short, powerful
pulses of UV light.  UV would cause ionization and photoemission where red
light would not.  See Bert Pool's homegrown N2 laser at
http://www.ticnet-dot-com/bertpool/n2laser.htm or maybe we can get Bert to shine
his laser on his gap !

Alternatively, UV is produced in a hot electrical spark, like from an
ignition coil.  Light from a small spark gap triggering a big spark gap is a
viable design, we used it in the 1980's to trigger CO2 TEA lasers.

Will

> ----------
> From: 	Tesla List[SMTP:tesla-at-pupman-dot-com]
> Sent: 	Tuesday, November 03, 1998 00:49
> To: 	tesla-at-pupman-dot-com
> Subject: 	Laser Triggered Spark Gap
> 
> Original Poster: "Steve Young" <youngs-at-konnections-dot-com> 
> 
> To fellow sparkers,
> 
> This list has a lot of discussion about spark gap performance, quenching,
> etc., which certainly is valuable and needed.  For static gaps,
> discussions
> seem to indicate quenching is improved for wider gaps.  But a point is
> reached where the gap is too wide for spark initiation.  Thus the need for
> a means to "help" a wider gap initiate a spark.
> 
> Occasionally the use of triggered spark gaps is mentioned, but the thread
> soon dies.  I would think this is an area for experimentation which could
> yield a LOT of benefits.  For one thing, the bps could be under our
> precise
> control simply by varying the trigger frequency.  If one chose to lock the
> trigger frequency to the AC line frequency and adjust the phase
> relationship, one would in effect be able to duplicate the performance of
> a
> RSG without having to mess with high RPM balanced rotors, etc.  Having the
> gap fire when WE want it to instead of when it can no longer resist firing
> itself would make for much better control and scope pictures for some of
> the other testing Terry and others are doing. 
> 
> The various triggering mechanisms have been touched on in this list.
> These
> can range from pulse generator driven ignition coils to lasers.  My
> experiments with SCR driven crummy ignition coils indicates they are good
> for break rates up to at least 800 bps.  I don't know how the good GM
> ignition coils perform at higher break rates - anyone have some
> experience?
>  
> 
> Lasers would have the advantage of being able to simultaneously trigger a
> bunch of aligned series gaps by aiming the beam through all the gaps.  I
> suspect some Marx generators are fired that way.  But where can the
> cash-strapped experimenter find a suitable laser which can sufficiently
> ionize the air to initiate spark breakdown?  The only potential cheap
> sources I am aware of would be to use a $15 laser pointer in a pulse mode.
> 
> Would this work?  Specifically, can the laser diodes handle microsecond
> pulses of a much higher energy without self destructing?  If so, could
> they
> produce enough pulse energy to trigger spark gaps?  If so, what would the
> pulse width and peak power need to be?  Does anyone know what the laser
> diodes used for tattoo removal, etc. cost and where to get them?
> 
> In summary, isn't it time to move toward triggered spark gaps for
> disruptive TCs?
> 
> Thanks in advance for your comments.
> 
> --Steve 
> 
>