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Re: Spark Propagation



Subject:   Re: Spark Propagation
  Date:    Fri, 2 May 1997 21:56:09 +0500
  From:    "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
    To:    Tesla List <tesla-at-pupman-dot-com>


On Thu, 24 Apr 1997 23:21:02 -0400 (EDT) Rscopper-at-aol-dot-com
wrote;

> I think the back EMF induced by the tesla coil into the laser power
> supply would smoke it.

Not if it's hooked up properly, thusly;

                      screen
                        |                       ______
    -----------------   |                      |      |
     U.V. Laser light-->|------------------>>>>|Target|
    -----------------   |                      |______|
                       _|                         |
                     (                            |
                     (                            |
     Tesla Coil ---> (                          -----
                     (                           ---
               ( ( ( | ) ) )                      - 
                   -----
                    ---
                     -   
 
The U.V. laser beam would ionize the air thus rendering it more 
conductive and in passing through the screen connected to the Tesla 
coil would conduct the Tesla coil R.F. to the target and the 
conductive path would be completed through ground.

> So....I took my HeNe tube (3mW) out from the supply and taped just the
> tube to a cardboard tube and when it got within about 2 feet from the 
> top of the tesla coil it started to light intermittently.  I could see
> sparking around the outer foil on the HeNe tube, so I quit this experiment.

First mistake is using a HeNe laser it emits visible red, green and a 
small amount of infrared light. To ionize the air you need short wave 
Ultra Violet light which aside from chemical dye lasers is only 
produced by CO2 lasers. I have successfully driven HeNe lasers with 
Tesla coils but it must be a low powerer Tesla coil The vacume testes 
or old Violet ray Tesla coils that generate around 30 to 50KV work 
fine, I've used them to drive HeNe up to 100mw with no problem what 
so ever.

> I didn't see any sparks in any way follow the path of the laser light.

Again this is becaused you used a HeNe laser instead of a CO2 laser. 
There were plans for a CO2 laser in the back issues of Scientific 
American some where between 1955 and 1970, it used CO2 and a little 
Nitrogen and it was powered by a neon sign transformer and it could 
burn a hole through the old Gillet steel razor blades. In fact I 
remember that everyone who built it and tried to improve it's output 
rated the output in terms of how many Gillets it could burn through.
I think that whats their name Unlimited sells reprints of the article
(poor quality reprints!)

> I don't think the electric field from the tesla coil is stable enough to
> get the laser to fire smoothly.

It is if you match the output of the Tesla coil to the laser in 
question. The flyback transformer circuits being used for plasma 
globes will do an admirable job of running your 3mw HeNe.

                               Sincerely

                                \\\|///
                              \\  ~ ~  //
                               (  -at- -at-  )
                        -----o00o-(_)-o00o-----
                           Alfred A. Skrocki
                   alfred.skrocki-at-cybernetworking-dot-com
                             .ooo0   0ooo.
                        -----(   )---(   )-----
                              \ (     ) /
                               \_)   (_/