[Prev][Next][Index][Thread]

Re: HV + laser beams



Subject:     Re: HV + laser beams
      Date:  Wed, 21 May 1997 21:09:52 -0800
      From:  Greg Leyh <lod-at-pacbell-dot-net>
        To:  Tesla List <tesla-at-pupman-dot-com>
References:  1


Alfred A. Skrocki wrote:

> > Several hundred feet?  I am skeptical, as the laser needs to have an
> > intensity sufficient to ionize the air along the entire light path.
> > A 100kW pulsed laser can ionize the air if focussed to a point, but
> > tens of megawatts are required in order to ionize an appreciable
> > linear path to the point of conduction.  Even though a 10MW pulsed
> > laser is relatively available (large table top, <1M$), I doubt that
> > even 10MW pulsed could ionize more than a 10 foot path thru the air.
> 
> Hi Greg, what you have to realize about Nitrogen lasers is they
> operate in pulsed mode and even though their average power may be
> only a few watts the pulsed beam can approach the megawatt range.
> It's as if you charged a capacitor with 1 watt hour of power and
> discharged it in one millionth of a second, that would effectively
> be 36 billon watts but only for one millionth of a second. In the
> case on the UV laser even though the path is ionized in fractions of
> a second it takes much longer for the path to stop conducting so for
> all intents and purpose it may as well be a continous conducting path.


Please note that I was, in fact, talking about pulsed lasers in the 
previous missive.  
At work we have a YAG-pumped, Ti-Sapphire laser, that produces 15W
average
and 240kW peak pulsed.  It's a fun laser to play with -- if the beam is 
focussed using a short focal length lens, a pinpoint electric arc forms 
at the focal point, suspended in free space!

-