Re: Research on lasers + high voltage discharges

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman" <bert.hickman-at-aquila-dot-net> 

Tesla list wrote:

>Original poster: Teslamad-at-aol-dot-com
>Did anyone read that post that just went out about that new research on 
>using lasers to direct high voltage discharges? It looks like one of the 
>many dreams of tesla! HA HA "Death ray" If you haven't, you should check 
>out the power point presentation they have at their site. I sure hope the 
>person that sent the idea to the list is reading this because I lost the 
>E-mail including the links etc. Please send it again. PLEASE. It was real 
>intriguing! Imagine, being able to direct (assuming I understood the 
>research correctly) a high voltage discharge with a laser beam. Does 
>anyone know how this is even possible??? How can a laser which emits 
>photons (a mass less particle... emphasis) direct a flow of plasma? If 
>anyone does get a chance to see this again, take a look at the car test. 
>Its amazing! They shot the laser over the car, sent a discharge along the 
>beam, then cut the laser and naturally, the plasma found its way to the 
>hood of the car! Someone please respond to this, and please resubmit the 
>link if the original sender is reading this!
>Thanks again
>Regards,
>~Drew
>.

Hello Drew,

Sounds like science fiction, doesn't it. But as hard as it might be to 
believe, it is legitimate. It's been know for quite some time that UV light 
can knock free electrons from O2 and (at shorter wavelengths) N2 molecules. 
More recently, it was discovered that ultrashort, high-power UV laser 
pulses will also "self focus", forming filamentary plasma paths in the air 
instead of spreading out with distance. These paths consist of a plasma 
having a relatively high concentration of free electrons (~10^16/cm^3). 
And, free electrons, combined with a sufficient E-field to support electron 
avalanching, are key ingredients for spark propagation.

So... by using intense subpicosecond self focused UV laser pulses (with low 
average power, but still not trivial to do), the inventors create an 
invisible filamentary ionized "pathway" in the air. A chain of HV pulses 
can then provide the high E-field necessary to propagate a streamer (and 
leader) along this path. Unbelievable, but it apparently works... :^)

Some background:
"Filamentation of ultrashort pulse laser beams resulting
from their propagation over long distances in air", B. La Fontaine,a) F. 
Vidal, Z. Jiang, C. Y. Chien, D. Comtois, A. Desparois,
T. W. Johnston, J.-C. Kieffer, H. PeŽ pin, and H. P. Mercure, PHYSICS OF 
PLASMAS, May 1999 -- Volume 6, Issue 5, pp. 1615-1621

"High-voltage electrical discharges induced by an ultrashort-pulse UV laser 
system", Patrick Rambo, Jens Schwarz and Jean-Claude Diels, 2001 J. Opt. A: 
Pure Appl. Opt. 3 146-158

Best regards,

-- Bert --
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