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Re: Laser Triggered Spark Gap



> Original Poster: "Steve Young" <youngs-at-konnections-dot-com>
>  <snip>
> 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'm assuming you mean having a hole in each electrode for the beam to pass
through? or do you mean over the top of them?

> 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?

I'd love to see you try.  I have worked with lasers for 7 years... any red
light source such as a diode laser cannot and will not provide any ionization
what-so-ever, to anything.  Red is a subtractive wavelength, which means not
only will it not ionize air, but it reduces ionization in a medium by reducing
the ionization level of the particles it comes in contact with.  For example,
hold up a glow-in-the-dark toy to a light bulb so it glows real bright.  then
shine a diode or HeNe laser onto it focussing on one spot.  take the beam off
after a few seconds and you will see a dark spot where the beam was.

>  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?

red light WILL ionize air under certain conditions.  a ruby laser (3 kW+ per
pulse) leaves a nice glowing sheath of ionized air in its path.  this would be
greatly suitable for gap quenching, as the pulse is usually very quick.  you
can put together a ruby or excimer laser for $1500, if you know where to get
the parts.  Remember that home made ruby lasers are about as temperamental
as a
tesla coil, so you'd be dealing with more than you could handle having to
constantly tune yet another piece of equiptment.  A relatively cheap
alternative that might possibly work would be to get a GREEN doide pumped YAG
laser.  they are only around 350 bucks, and are about 30 times brighter than a
red diode laser. They are sold in the shape of a pen, and are really on the
break front of technology as far as lasers go.  (www.amazing1-dot-com has
them....if you'd want to buy from the self-famed Ianini) Green is a most
suitable color for ionizing air. red will not ionize air unless you go above
1000 watts, and your run-of-the-mill radio shack part number 1234 laser pen
will blow when pulsed at that power level.

> In summary, isn't it time to move toward triggered spark gaps for
> disruptive TCs?
>

maybe yes, but lasers may not be the way to go for most ameteurs.  its simply
too expensive.

--
Cabbott Sanders
Salem Oregon
Website: http://members.aol-dot-com/cabbotttt
Phone 503-390-8992
Cel   503-930-9173