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IT WORKS :)))))))))))))))))))))))))))))

James Lerch
 

Greetings All,

Just came in from my first evaporation attempt and everything went perfect! :)

I shot some images of the filament wiring, some more glow discharge phenomenon,
and finally an image of the system evaporating Al :) Images available here:


Only complaint at the moment is it takes 90 minutes to evacuate the chamber!
Fortunately, this seems to make sense as the old small chamber took 10 minutes,
the new chamber is ~9 times the volume, so it takes 9 times as long to
evacuate..

On the upside I think my bottle neck is the little HVAC rough pump. Perhaps it
is time to upgrade to a real Rough pump :)

Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
Calvin Coolidge
 

Greetings James / All,

Congratulations, interesting enough I just coated my first telescope mirror, I was waiting to open the tank when I read your post. This?was my 3rd attempt on this 8" after a couple of dozen practice successes.?There are a few?pinholes and the coating is a bit thin around the edges but all in all it looks good considering I only used 1 tungsten.?

I think I deposited a bit of tungsten over the aluminum or the aluminum foil may not be pure aluminum. ?The coating is a?very slightly?gold color?I ran the glow discharge for 10 minutes after evaporating so I may have sputtered a bit of stainless steel.

?

Any info would be greatly appreciated.

?

Next step a rotating holder. I have been playing with an ion beam source with only a little success.

?

90 minutes isnt so bad try it with a 2 air cooled diff pump I need close to 2 hours for a 24 diameter X 12 high tank. When I find a cheap valve Ill set up the 6 diff pump.

?

Dumb question # 2 is there any advantage to backing the 6 diff pump with the 2. Is the ultimate pressure limited by the type of oil? ?Would I get significantly faster pump rate at very low pressure? If I get the ion beam source to work Ill need to suck the extra air out quicker.

?

Yea I know I dont need Ion beams but its all for fun.

Any thoughts on a home made E-Beam? It looks easy enough.

?

Later

Ron White

James Lerch wrote:

Greetings All,

Just came in from my first evaporation attempt and everything went perfect! :)

I shot some images of the filament wiring, some more glow discharge phenomenon,
and finally an image of the system evaporating Al :)? Images available here:


Only complaint at the moment is it takes 90 minutes to evacuate the chamber!
Fortunately, this seems to make sense as the old small chamber took 10 minutes,
the new chamber is ~9 times the volume, so it takes 9 times as long to
evacuate..

On the upside I think my bottle neck is the little HVAC rough pump.? Perhaps it
is time to upgrade to a real Rough pump :)

Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
?????????????????????????????????????????????????????????? Calvin Coolidge


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James Lerch
 

----- Original Message -----
From: "RON WHITE" <ron_white@...>



Greetings James / All,

Congratulations, interesting enough I just coated my first telescope mirror, I
was waiting to open the tank when I read your post.

Congratulations to you as well!

This was my 3rd attempt on this 8" after a couple of dozen practice successes.
There are a few pinholes and the coating is a bit thin around the edges but all
in all it looks good considering I only used 1 tungsten.

I currently suppose that pinholes are the result of static charged dust
particles on the optic. I know that contaminants left over from cleaning (like
my thumb print image the other day) only discolor the aluminum. Understanding
the pinhole phenomenon would be rather nice!

I think I deposited a bit of tungsten over the aluminum or the aluminum foil
may not be pure aluminum.

'Reynolds Wrap' aluminum foil is 98.5% pure aluminum, the remaining balance is
primarily Iron and Silicon. I've been using this stuff for the last two years
to coat optics and never had one come out 'gold' colored :)

The coating is a very slightly gold color I ran the glow discharge for 10
minutes after evaporating so I may have sputtered a bit of stainless steel.

I also run the glow discharge after coating, but only for a few minutes..
Perhaps switching to aluminum for the Glow Discharge electrodes might help..


Next step a rotating holder. I have been playing with an ion beam source with
only a little success.

What are you using for an Ion Beam Source?? :)


Dumb question # 2 is there any advantage to backing the 6" diff pump with the
2". Is the ultimate pressure limited by the type of oil? Would I get
significantly faster pump rate at very low pressure? If I get the ion beam
source to work I'll need to suck the extra air out quicker.

I don't think so... I believe we need to start thinking about flow rate instead
of ultimate pressure.. For instance my little HVAC roughing pump can get down
to a pretty low pressure on its own, but I noticed that while backing the
diffusion pump with the large chamber the fore line pressure was hovering around
500 milli-torr. If I could get the fore line pressure down, I could pump
faster. To get the fore line pressure down I need a higher Flow Rate pump, not
one that can get to a lower pressure (I think..)

A few years ago, while visiting a profession vacuum fabrication shop, they used
a Roots Type blower between the diff pump and rough pump. The idea was the
roots blower would help boost the pressure seen by the rough pump. The higher
pressure at the rough pump increased its pumping flow rate.


Yea I know I don't need Ion beams but it's all for fun.
** Very Well Put ** :)


Any thoughts on a home made E-Beam? It looks easy enough.
Microwave magnetron and the steering coil off a TV picture tube? (BTW, I have no
idea what so ever if this would work!!!)


Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
Calvin Coolidge
Joe Keaser
 

¿ªÔÆÌåÓý

Ron,
You may have run out of aluminum during the deposition run, I have had that same problem. Are you using a shutter ?

----- Original Message -----
From: RON WHITE
Sent: Thursday, January 29, 2004 11:10 PM
Subject: Re: [VacuumX] IT WORKS :)))))))))))))))))))))))))))))

Greetings James / All,

Congratulations, interesting enough I just coated my first telescope mirror, I was waiting to open the tank when I read your post. This?was my 3rd attempt on this 8" after a couple of dozen practice successes.?There are a few?pinholes and the coating is a bit thin around the edges but all in all it looks good considering I only used 1 tungsten.?

I think I deposited a bit of tungsten over the aluminum or the aluminum foil may not be pure aluminum. ?The coating is a?very slightly?gold color?I ran the glow discharge for 10 minutes after evaporating so I may have sputtered a bit of stainless steel.

?

Any info would be greatly appreciated.

?

Next step a rotating holder. I have been playing with an ion beam source with only a little success.

?

90 minutes isn¡¯t so bad try it with a 2¡± air cooled diff pump I need close to 2 hours for a 24¡± diameter X 12¡± high tank. When I find a cheap valve I¡¯ll set up the 6¡± diff pump.

?

Dumb question # 2 is there any advantage to backing the 6¡± diff pump with the 2¡±. Is the ultimate pressure limited by the type of oil? ?Would I get significantly faster pump rate at very low pressure? If I get the ion beam source to work I¡¯ll need to suck the extra air out quicker.

?

Yea I know I don¡¯t need Ion beams but it¡¯s all for fun.

Any thoughts on a home made E-Beam? It looks easy enough.

?

Later

Ron White

James Lerch wrote:
Greetings All,

Just came in from my first evaporation attempt and everything went perfect! :)

I shot some images of the filament wiring, some more glow discharge phenomenon,
and finally an image of the system evaporating Al :)? Images available here:


Only complaint at the moment is it takes 90 minutes to evacuate the chamber!
Fortunately, this seems to make sense as the old small chamber took 10 minutes,
the new chamber is ~9 times the volume, so it takes 9 times as long to
evacuate..

On the upside I think my bottle neck is the little HVAC rough pump.? Perhaps it
is time to upgrade to a real Rough pump :)

Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
?????????????????????????????????????????????????????????? Calvin Coolidge


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    ?
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James Lerch wrote:

I also run the glow discharge after coating, but only for a few minutes..
Perhaps switching to aluminum for the Glow Discharge electrodes might help..

Thanks the pressure should have been to high for any kind of sputtering but I often see gold / yellow and purple coloring around the electrodes area when I let?the glow discharge ?run for a while never had it on the test glass before.


What are you using for an Ion Beam Source?? :)

Hollow anode fabricated from 1/2" pyrex tube and .010 hypo tube.? I have had short bursts of plasma but I can't control it?in such a small chamber (1/2" X 3")

?? To get the fore line pressure down I need a higher Flow Rate pump, not
one that can get to a lower pressure (I think..)

My little pump backs the 2" with no problem but I think I would have the same problem as you with the 6". Thats why I was thinking of doubling the diffs up to get?a higher for line pressure and?better pumping out of the rough pump.??

A few years ago, while visiting a profession vacuum fabrication shop, they used

I was looking at a walk in sized?E-Beam welder they had a 10 diff backed by a blower cycle time was less than 10 min.

Thanks

Ron White
 



Joe Keaser wrote:

Ron,
You may have run out of aluminum during the deposition run, I have had that same problem. Are you using a shutter ?
?
Joe,
?
the coverage was? better than what I thought it would be but it was thicker it the middle as i expected it would be. the final setup will have at least 3 tungsten sources and probably rotate. I don't us a shutter, how would that help / hurt?? I use 2 -.025 tungsten wires together this holds a lot more aluminum?and less problems with burn out. The aluminum spreads?along the double wires very nicely
Joe Keaser
 

¿ªÔÆÌåÓý

I am not sure how the telescope mirror is used, now that I think about it I assume you are coating first surface mirrors. The shutter might improve the coating by effectively?closing off the aluminum while you are still getting a good rate of evaporation. A second surface mirror would require a shutter so you could bring the aluminum to the deposition point and then open the shutter and flash coat the mirror. I have noticed on some of my coatings as I ramp down on power the mirror has a white smoky look to it, but when I use the shutter they come out great.

----- Original Message -----
From: RON WHITE
Sent: Friday, January 30, 2004 10:25 PM
Subject: Re: [VacuumX] IT WORKS :)))))))))))))))))))))))))))))



Joe Keaser <keaser.home@...> wrote:
Ron,
You may have run out of aluminum during the deposition run, I have had that same problem. Are you using a shutter ?
?
Joe,
?
the coverage was? better than what I thought it would be but it was thicker it the middle as i expected it would be. the final setup will have at least 3 tungsten sources and probably rotate. I don't us a shutter, how would that help / hurt?? I use 2 -.025 tungsten wires together this holds a lot more aluminum?and less problems with burn out. The aluminum spreads?along the double wires very nicely

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arcstarter
 

James,
Thanks for the great pictures of your awesome coating chamber!

Are you implying that the first item coated was that monster mirror?

Can you tell us what size diffusion pump you are using to pump that
tank down?

It is hard to tell how thick your removable lid (onto which you
attach the optic) is. Looks about 1/2 inch thick. I was surprised
you didn't need to weld on reinforcing ribs etc (but I have had no
experience designing square sided tanks).

Is that a regular old Home Despot (sic) air purge valve (with thered
handle) on the side of your tank? Do you find them to be leakproof
against 1e-6 Torr?

Also I have a question about your neon sign plasma cleaning
process. I see what appear to be two 'antenna' lugs (complete with
pose-able wire rabbit ears) inside your tank. I presume that these
connect directly to the two 'hot' posts on the neon sign
transformer? I also assume the tank is grounded, as is the case of
the neon sign xfmr?

Last - I see some sort of white deposit on your buss bars. Any clue
what this is?

Now - one of my associates from the semiconductor industry informs
me that I have a very low chance of producing any quality aluminum or
chromium coatings without using a cold trap on top of my diffusion
pump. I commented that my DP oil (KJL's Diffoil 20) has a base vapor
pressure ~10x lower than my target pressure. He responsed that this
doesn't matter, and in his experience the cold trap is mandatory. I
mention this as a possible course of some of your pinhole problems
(although I have no firsthand experience, yet).

Thanks!
-Bill

--- In VacuumX@..., "James Lerch" <jlerch1@t...> wrote:
Greetings All,

Just came in from my first evaporation attempt and everything went
perfect! :)

I shot some images of the filament wiring, some more glow discharge
phenomenon,
and finally an image of the system evaporating Al :) Images
available here:
arcstarter
 

--- In VacuumX@..., RON WHITE <ron_white@s...> wrote:

Greetings James / All,
This group is becoming downright energetic!

Next step a rotating holder. I have been playing with an ion beam
source with only a little success.

OK you have my attention!

Dumb question # 2 is there any advantage to backing the 6" diff
pump with the 2".

I suppose you'd have to have the full 3-dimensional (mass flow, inlet
pressure, foreline pressure) performance data on both pumps to answer
this one. I suspect the diffusion pump closest to the roughing pump
will be overpressured at it's inlet and would probably spew all it's
oil into the 2nd DP's foreline...

I think that if you ran them in parallel (and assuming adequate rough
pumping ability) you could pull the tank down more quickly at the
lower pressures.

Is the ultimate pressure limited by the type of oil?
Ultimate is limited by the pressure vs temp (and adsorbed gas load of
the DP oil) of the oil exposed to the pump inlet, and by the system
leak rate, including virtual leaks such as gas trapped under bolts,
organic contamination, gasses dissolved into your vacuum greases and
o-rings etc...

I note that most of the larger diffusion pumps contain a 'cold cap' -
a cooled plate above the top jet. Purpose is apparently to deflect
hot oil molecules from shooting out the top of the pump.

So, has anyone else noticed that a diffusion pump is rather similar
to a heat pipe? Both use a single fluid under high vacuum, plus
phase change for their operation.

Would I get
significantly faster pump rate at very low pressure? If I get the
ion beam source to work I'll need to suck the extra air out quicker.
Hmm what can you tell us about this?? It was my impression that the
guys doing much ion work (reactive etching, sputtering etc) operate
at much higher pressures (20 micron etc) than the pressures required
for thermal evaporation. Seems reasonable since all those ions doing
the work will certainly measure as a pressure. Therefore I would
think that the DP isn't going to be used in this realm.

What sort of mass flows or sccms etc are you planning on using? Do
you have a mess flow controller? I presume you will be using argon
due to it's cheapness and availability?

BTW my local welding supplier can get the higher purity gasses
(99.999 etc) for not much more $$$ than standard.

Yea I know I don't need Ion beams but it's all for fun.
Same here!

I correspond with a fellow who experiments with DIY high vacuum
gauges rolled from scratch. His latest sensor is essentially an
ionization gauge which uses the radioactive element out of a smoke
detector! From what I gather the source ionizes the inlet gas, which
then produces a measurable current across two suitably biased
plates. I will try to get him hooked into this list.

Any thoughts on a home made E-Beam? It looks easy enough.
The early ones used a ring as the cathode, with a central rod of the
material being evaporated as the anode. I would like to know more
about this but so far all references have been so far from
practicality as to not list anything useful for the home experimentor
(details such as volts, amps, pressures, materials etc).

The fusor site did contain a bit in information on the use of CRT
electron guns for this purpose.

-Bill
James Lerch
 

----- Original Message -----
From: "arcstarter" <arcstarter@...>


James,
Thanks for the great pictures of your awesome coating chamber!

Are you implying that the first item coated was that monster mirror?
Bill,

Yup, I did one test run with the tank empty using only 6 of the 18 filaments.
That worked so Ron drug his 22 over and in it went :)

Can you tell us what size diffusion pump you are using to pump that
tank down?
The Diff pump is roughly 5" ID x 18 inches long. However I don't believe my
bottle neck is the diff pump. As I monitor the fore line pressure, its still
hangs out around 1/2 torr with both of the rough pumps pulling on it. I imagine
a third rough pump would (or one BIG rough pump) reduce pump down time even
more. I'm currently using two HVAC service pumps as rough pumps. As-Is I'm
pretty tickled with a 25 minute cycle time, but a larger chamber would need
larger rough pumps.

It is hard to tell how thick your removable lid (onto which you
attach the optic) is. Looks about 1/2 inch thick. I was surprised
you didn't need to weld on reinforcing ribs etc (but I have had no
experience designing square sided tanks).
Yup, tank walls are all 1/2 thick hot rolled mild steel. Both the door and the
back wall flex about a 1/16" concave as the vacuum pulls it down.

Is that a regular old Home Despot (sic) air purge valve (with thered
handle) on the side of your tank? Do you find them to be leakproof
against 1e-6 Torr?
Yup!! The o-rings on my electrical pass thru's are also from the plumbing
department :)

Also I have a question about your neon sign plasma cleaning
process. I see what appear to be two 'antenna' lugs (complete with
pose-able wire rabbit ears) inside your tank. I presume that these
connect directly to the two 'hot' posts on the neon sign
transformer?
Yup!

I also assume the tank is grounded, as is the case of
the neon sign xfmr?
Yes and No. The tanks is grounded, but I added a switch to toggle grounding of
the transformer case. Toggle the transformer case does make a change in the
plasma. With case grounded the plasma turns a more Purple-ish color, with
transformer un-grounded (just don't touch the transformer!) the plasma turns a
very deep white-blue. No Idea why it does this, nor which is a better method as
both methods seem to work and neither causes any problems..

Last - I see some sort of white deposit on your buss bars. Any clue
what this is?
Not certain, my old chamber would do it as well. I'm guessing its from handling
the buss bars while loading the tungsten and aluminum.

BTW I should not that for the first time I actually got to re-use my tungsten
filaments for more than one burn! The center 6 filaments now have three burns
on them and seem perfectly happy! I can only suppose that my old chamber, or
buss bars, were contracting expanding as the pressure or temperature changed....

Now - one of my associates from the semiconductor industry informs
me that I have a very low chance of producing any quality aluminum or
chromium coatings without using a cold trap on top of my diffusion
pump. I commented that my DP oil (KJL's Diffoil 20) has a base vapor
pressure ~10x lower than my target pressure. He responsed that this
doesn't matter, and in his experience the cold trap is mandatory. I
mention this as a possible course of some of your pinhole problems
(although I have no firsthand experience, yet).
Well, I did do a few coatings in my old chamber with out running the cold trap,
and I use CHEAP diffusion pump oil ($55/gal). One thing I did notice, but can't
statistically agree with yet, is so far pin hole formation has been nearly
eliminated in the new chamber.. I still think dust is the major contributor of
pin holes, but I might be wrong...


Take Care,
James Lerch
(My telescope construction,testing, and coating site)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "
Calvin Coolidge
arcstarter
 

James, (group)
I'd like to ask a question about this post of yours from a few
months (Jan 30) ago:

--- In VacuumX@..., "James Lerch" <jlerch1@t...> wrote:
----- Original Message -----
From: "RON WHITE" <ron_white@s...>

<snip>
I believe we need to start thinking about flow rate instead
of ultimate pressure.. For instance my little HVAC roughing pump
can get down
to a pretty low pressure on its own, but I noticed that while
backing the
diffusion pump with the large chamber the fore line pressure was
hovering around
500 milli-torr. If I could get the fore line pressure down, I
could pump
faster. To get the fore line pressure down I need a higher Flow
Rate pump, not
one that can get to a lower pressure (I think..)
James,
When I first had my evaporator running - I didn't have the ion tube
controller working. So I just ran the pumps until the DP foreline
pressure equalized out. In my case I could pull it down to about 20
microns or so, steady state, in about an hr or so.

Once I had the ion tube working- seems that this is a system pressure
of 1.4e-4 torr at the lowest. At the pressure I can evap copper,
gold, silver into some really nice looking films. However, shooting
aluminum or chromium at this pressure makes nothing more than a huge
mess (pressure is too high, too much O2 etc probably).

My question is whether you have an ion tube on your system or not.
I'd like to know what pressure you have found works with aluminum.

I fear my poor little DP is max'd out. Despite my evaluating fluid
charge (20-100 ml), heat input (200-600 watts), and cooling water
temp ('cold' to 'hot') I can't get the system pressure under 1.4e-4
Torr. I've even let a tungsten filament burn brightly for 1 hr to
heat the innards in an attempt to drive off water and adsorbed
materials etc (no change in pressure). With the main vac valve
closed, the min pressure is 4e-5 Torr (a bit better). This seems to
be somewhat higher than most pumps are rated - and I am definitely
disappointed in it's performance.

I just ordered a new ion tube, and will fab an adapter to permit
mounting the ion tube DIRECTLY onto the inlet of the DP. This should
reveal the last word in ultimate pressure of this little pump.

Thanks!
-Bill
James Lerch
 

----- Original Message -----
From: "arcstarter" <arcstarter@...>


James, (group)
I'd like to ask a question about this post of yours from a few
months (Jan 30) ago:

My question is whether you have an ion tube on your system or not.
I'd like to know what pressure you have found works with aluminum.
Not on the current 24" box chamber, but I did on my old 12" chamber. Al
evaporation occurred at 2e-5 torr with no problems. (assuming my Penning gauge
is still calibrated properly)

I fear my poor little DP is max'd out. Despite my evaluating fluid
charge (20-100 ml), heat input (200-600 watts), and cooling water
temp ('cold' to 'hot') I can't get the system pressure under 1.4e-4
Torr. I've even let a tungsten filament burn brightly for 1 hr to
heat the innards in an attempt to drive off water and adsorbed
materials etc (no change in pressure). With the main vac valve
closed, the min pressure is 4e-5 Torr (a bit better). This seems to
be somewhat higher than most pumps are rated - and I am definitely
disappointed in it's performance.
With the main vac valve closed, you're only evacuating a very small chamber,
yes? If so I'd would expect ANY diff pump to reach a fairly decent vacuum. I'm
still thinking you've got a leak somewhere.

Your story from the "dropped Diff Pump" incident, you spoke of a rubber coupling
to connect your DP to the Valve adapter. Is this coupling still exposed when
the main vac valve is closed? Perhaps this coupling isn't sealing properly, or
the material is permeable at the low pressures (say 4e-5 torr range???)

In any event, I have a difficult time believing your Diff Pump is "broke /
bad"... There just isn't much to go wrong asides from heaters not working or
the jet stack being improperly assembly.

Any Chance you could find a 3 inch O-Ring to go between the DP pump and the
valve adapter? Perhaps having an O-ring between the pump and adapter, inside
your 'vacuum rated' hose might help. (Going on the assumption the hose is
permeable, with the idea being the hose will keep the O-ring held in place until
the pressure drops in the pump body. As the pressure drops, atmospheric
pressure will squeeze the pump and adapter together, compressing the Hose and
allowing the O-Ring to form a seal..) Long shot, but cheap to implement if you
can find an O-ring and make it work...

One other thought / question... Your main vac valve (the one where you think
the handle shaft seal might be leaking.) When the valve is closed, is the shaft
seal on the chamber or Diff Pump side? If its on the Diff pump side, can you
flip the valve over?

James

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