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Re: Coil ideas for experiments

Hello,

    Much of the information posted from the quoted message below is
incorrect and based on a false relationship between joules and watts.

THIS IS CORRECT:

1 joule = 1 watt-second   -------- joule is a unit of energy
1 watt  = 1 joule/second  -------- watt is a unit of power (energy/time)

Regards,
Alfred Erpel



> Original Poster: "Mark Broker" <broker-at-uwplatt.edu>
>
> Comments below
>
> Tesla List wrote:
>
> > Original Poster: ANTarchimedes-at-aol-dot-com
> >
> > In a message dated 4/14/2000 12:58:24 PM US Mountain Standard Time,
> > tesla-at-pupman-dot-com writes:
> >
> > <<
> >  Actually, you'll need 10^12 W/cm^2.  I talked to one of the optics
profs
> > today.
> >  We worked out a nice plan:
> >
> >  Pulsed (CO2, I think) laser at 10mJ per pulse, 10ns Pulses, at 10
pulses per
> >  second.  Focus the beam down to a spot size of 10um, and you have your
> >  10^12W/cm^2.
> >
> >  The down side is that this is still a pretty huge laser requring some
> >  interesting optics to handle the high power.  Also remember that m ost
> lasers
> >  are less than 10% efficient:  put in 1kW, and you'll get at most 100W
laser
> >  (continuous).  I'm not certian how much power input would be needed for
this
> >  device, however.
> >
> >  The prof did say that one could use a prism, or accousto-optic
modulation to
> >  make figures that the arc could/would follow.  I must admit, it would
be
> > pretty
> >  sweet to see a TC spit out streamers that trace out a square, circle,
or my
> >  name  :-)
> >
> >  I still feel that using a laser this large in a non-laboratory
environment
> >  could
> >  have some serious safety problems.
> >   >>
> >
> > So with 10% efficiency, 10 mJ per pulse, and 10 pulses per second
(What's
> > with you and the number 10?), it should use about 36 watts (joules) and
hour
> > with the assumption that 10mJ is equal to 1/100th of a watt.  So then,
if
> > powered by an ordinary 120vac source, it should pull about 1/4 an amp.
> > That's not too much power.  The problem would be in acquiring the
equipment.
> > Outside of a lab, it shouldn't be too dangerous as long as it isn't
pointed
> > at any living things, man made or flammable objects, or reflective
surfaces.
> > In short, point it at a dark rock.  The only problem I see with this
idea
> > would be in preventing the laser from traveling towards the laser and
arcing
> > toward it's power source.  In this case, a system of prisms would be
> > desirable.  Perhaps I should speak with my optrician about his laser to
see
> > if a system of that type would work.
>
> First of all, a Joule is *NOT* a Watt.  A Watt is a unit of power, and a
> Joule is
> a unit of energy.  They are related: W = J*s  (s == second).  Also, 10mJ
is
> .01J
> (not to be mistaken for mircoJoule).  I like the number 10 because it's
easy to
> calculate with ([10^6]^2, not [2.5*10^6]^2).
>
> J = w/s => .01 = W/10^-8 =>  W = 10^6Watts per pulse.  Times 10 pulses per
> second
> = 10MW.  The laser then puts out 100MW.  That's a darn big laser!  Of
> course the
> avearge current draw isn't quite that high ;-)  I couldn't tell you what
it
> is, as
> I've had no experience with pulsed lasers.
>
> A high-power pulsed laser is very dangerous.  I've seen lasers this
> powerful blast
> heavy objects into the air (military and NASA was experimenting with
pulsed
> lasers
> as new launching mechanisms).  I doubt that a laser this large could be
> obtained
> by a "lay person" for less than one hundred thousand dollars (US),
although I
> never really asked about price (the 10mJ/10ns pulse told me that this idea
> isn't
> really for an ameture to be playing with).
>
> This thread is getting quite off topic....  (Sorry, Terry)*
>
> Mark
>
> <<<* - Please keep the laser triggered gap topic practical and about
firing
> spark gaps - Terry>>>
>
>