wwp@yahoogroups.com:
Re: Caption Help
Dan Ruettimann 2007-Apr-03 13:51:00
Gerardo,
Your English is great. I just made a few changes.
Dan
Vacuum Chamber??Atmosphere is the general name for a
layer of gases that ?surround a celestial body of
sufficient mass. The gases are ?attracted by the
gravity of the body, and are retained for a ?longer
duration if gravity is high and the
atmosphere's?temperature is low. But? it is possible
remove it for a ?while??... Not exactly but we have
something close.
Here you are in a vacuum chamber which essentially
takes out all gases inside. The internal pressure
could be less than 100.000.000 times the ?outside
pressure (1/100.000.000) .??This chamber is used to
restore the aluminium coating from the ?main mirrors
at the National Observatory in Venezuela. Due to the
dust, ?humidity and oxidation reflectivity of the
mirrors is lost and approximately ?once every two
years the aluminium coating is removed and a new one
is applied. ??The chamber is two meters in diameter
and several vacuum pumps?spend around two hours
removing all the inside air. Three tungsten ?bars are
used to burn out a small amount of pure aluminium and
due to the low pressure inside the chamber, the
aluminium is deposited over ?the glass in a very thin
and regular layer. During the process the?round plate
is spinning to help get a more homogeneous
reflective?layer.??The round plate and the triangle
plate at the ceiling also are used as electrodes. A
big current is applied over them creating a magnetic
field that attracts small particles from down to
upside electrode cleaning the glasses. This process,
called efluvium, is easily seen from the outside
windows as a very nice blue light path.??After several
hours of work the "new" mirrors are removed from the
chamber and put replaced inside the telescopes.??This
picture reflects the state a few seconds before
burning the ?aluminium. There are nine small mirrors
ready to get new ?reflective layers. Can you see all
them? (answer is here in ?this picture)
--- gerardoant <#removed#> wrote:
> Hola todos.
>
> I found a nice place to take my pano for this
> challenger theme that
> Don, Landis et all pic for us. But this time it is a
> very technical
> stuff that I would like to explain in easy words to
> everyone. As
> usual: could some one of you help me with my poor
> English and correct
> my caption? (final caption will have some links to
> pictures for easy
> understanding)
>
> Please answer directly to me to keep wwp list clean.
>
> Thanks in advance, Gerardo
>
>
>
> Here is the pano if you like to see:
>
>
http://www.merida360.com/wwp/atmosfera/atmosfera.html
>
>
> Vacuum Chamber
>
> Atmosphere is the general name for a layer of gases
> that
> surround a celestial body of sufficient mass. The
> gases are
> attracted by the gravity of the body, and are
> retained for a
> longer duration if gravity is high and the
> atmosphere's
> temperature is low. But? it is possible take it out
> for a
> while??... not exactly but we have something near:
> here you are
> inside a vacuum chamber which essentially take out
> all gases it has
> inside. The inside pressure could be less than
> 100.000.000 times the
> outside pressure (1/100.000.000).
>
> This chamber is use to restore back the aluminium
> coating from the
> main mirrors at the National Observatory in
> Venezuela. Due the dust,
> humidity and oxidation the mirrors reflectivity is
> lost and almost
> once every two years the aluminium coating is
> removed and applied a
> new one.
>
> The chamber has two meters diameter and several
> vacuum pumps
> spent around two hours to take out all the inside
> air. Three tungsten
> bars are used to burn out an small amount of pure
> aluminium and due
> the small pressure inside the chamber the aluminium
> is deposited over
> the glass in a very tiny and regular layer. During
> the process the
> round plate is spinning to help get a more
> homogeneous reflective
> layer.
>
> The round plate and the triangle plate at the
> ceiling are use also
> as electrodes. A big current is applied over them
> creating a
> magnetic field that attract small particles from
> down to upside
> electrode cleaning the glasses. This process, call
> efluvium, is
> easily watch from the outside windows as a very nice
> blue light path.
>
> After several hours of work the "new" mirrors are
> take out from
> the chamber and put back again inside the
> telescopes.
>
> This picture reflect the status few seconds before
> burn the
> aluminium, there are nine small mirrors ready to get
> a new
> reflective layer. Can you see all them? (answer is
> here in
> this picture)
>
>
>
>
>
>
>
>
>
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