From: Michael M. Butler (butler@comp-lib.org)
Date: Sun Jul 30 2000 - 00:41:20 MDT
I think Mr. Lorrey misspoke. What's "evaporating" in laser cooling is
photons, mostly. One could make a swamp cooler using a laser, and
something very like that can be done profitably in the case of laser
enrichment of U and Pu, but I don't believe it is what microKelvin
researchers mean when they talk about laser cooling.
I believe that the description below is pretty close to right, apart
from the use of the word "orientated" (ish!).
See
http://homepages.strath.ac.uk/~acp96102/Research/Laser_cooling/How/How.htm
for more details on the theory.
Quoting from there: "At a very basic level 3 intersecting orthogonal
pairs of counter-propagating laser beams of equal intensity and
frequency, tuned slightly below the chosen atomic transition, are
transmitted into the center of a vapour cell. The absorption of the
photons from this transition slow down the atoms by imparting momentum
against the direction of motion of the atom; the emission is orientated
in a random direction. Over many cycles the velocity and thus the
temperature of these atoms falls to a fraction above absolute zero. "
Everitt Mickey wrote:
>
> >AND?????? What are you thinking (assuming that IS what is going on)? ;)
> >
>
> In my own humble fashion...yes.
>
> >Lasers cool by evaporating a part of a substance, the evaporation
> >causing the heat of the substance to drop.
> >
>
> Bummer.....I didn't realize that.
>
> So laser cooling is just a high tech swamp cooler huh?
>
> I was dreaming of a laser beam to space offloading excess Btu's into the
> void....
>
> Rats....
>
> -----Original Message-----
> From: Michael S. Lorrey <retroman@turbont.net>
> To: extropians@extropy.org <extropians@extropy.org>
> Date: Sunday, July 30, 2000 12:30 AM
> Subject: Re: Laser Cooling
>
> >Everitt Mickey wrote:
> >>
> >> I've heard the term "laser cooling" used....in fact I think that is how a
> >> "Bose Condescant" is generated.
> >>
> >> That being the case then it appears that somehow lasers are used as a
> heat
> >> pipe.....
> >>
> >> I've also heard of OTEC's....(Ocean Thermal something or
> another)....where
> >> electrical energy is supposed to be generated via tempeture differential
> of
> >> surface vs deep sea.
> >>
> >> Not that I'm thinking that lasers would be much use in that regard...but
> it
> >> got me to thinking........
> >>
> >> Four Degrees Kelvin.
> >>
> >> Laser Cooling.....
> >>
> >> ????????????
> >
> >AND?????? What are you thinking (assuming that IS what is going on)? ;)
> >
> >Lasers cool by evaporating a part of a substance, the evaporation
> >causing the heat of the substance to drop.
> >
> >OTEC: Ocean Thermal Energy Conversion systems are electricity generators
> >and water purifiers that use either closed or open Carnot cycle heat
> >engines to transfer heat from surface water to cold water that is pumped
> >up from the depths. Hawaii has a few installations, and there are others
> >on islands around the world where sources of water and energy are useful
> >when neither is in abundant supply locally from more conventional
> >sources.
> >
> >A Carnot engine is a rather interesting device, to be sure, and a quick
> >read on them is recommended.
> >
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