<Sync_>
what's so bad about it, once it's gone it's gone
<Sync_>
use it while we can
<Sync_>
huh 10" conflat blanks are ... spendy
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<diginet>
because we lose a tonne of things like MRIs, particle accelerators, cryogenics in general, etc
<Sync_>
I guess there will be an effort to make better superconducting magnets that work at LN2 temperatures
<diginet>
it's not the critical temperature that is the issue, the superconductors which need LHe have a much higher critical field, and also have much better mechanical properties
<Sync_>
yes, but that is just an engineering problem ;)
<diginet>
the latter yes, but not the former
<diginet>
although, one potential option could be MgB2, which only needs LH2
<Sync_>
I guess if we really run out sensors will have improved
<Sync_>
we're currently also making a mass spec for breathing air
<Sync_>
to detect trace acetone
<diginet>
azonenberg: are you around?
<Sync_>
which appears in a few ppm just before you have a sugar shock or epileptic seizure
<diginet>
I was wondering, what is the DPI on photomasks generally? Because I wondering, would FLCDs work as a sort of digital photomask? They have ridiculously high pixel density
<Sync_>
but the vacuum system is the main problem
<Sync_>
good question diginet
<diginet>
if an FLCD could work as a photomask, that would be my number one choice, if not, then e-beam
<Sync_>
ebeam would be mine because that is pretty easy to make
<diginet>
sure, but vacuum
<diginet>
then again, the mask is just PMMA in a solvent, which is absurdly cheap/simple/safe
<Sync_>
vacuum is easy
<diginet>
is it though? you need a pretty hard vacuum for e beam
<Sync_>
yeah but getting in the 10^-7mbar range is not too bad
<Sync_>
which is acceptable for ebeam
<diginet>
well, you can cannibalize a rotary vane from an old fridge for the first stage, and an ion beam pump might be DIYable
<Sync_>
not really
<Sync_>
that will not be sufficient
<diginet>
I don't know enough about them, but I wonder if a turbomolecular pump could be made from a turbocharger for a car
<Sync_>
just get a two stage rotary and a turbo
<diginet>
turbos at least $5k
<diginet>
I don't call that DIYable, at all
<diginet>
and they're insanely fragile and tempermental
<Sync_>
then why do I have 7 rotaries and 2 turbos?
<Sync_>
somewhere there should also be a tsp and an ion pump
<diginet>
you do?
<Sync_>
yes
<diginet>
where did you get them?
<Sync_>
mostly ebay
<Sync_>
or fron work
<Sync_>
~from even
<diginet>
how much?
<Sync_>
my first rotary turbo set was 450€
<diginet>
hmm
<diginet>
still pricey though
<Sync_>
thinking about getting a cryo pump
<diginet>
cryo pumps could be DIYed I think
<diginet>
it's just a stirling engine in reverse
<Sync_>
yes
<Sync_>
but it is quite a challenge to get it working at 12K
<Sync_>
it is easier just to buy one
<Sync_>
nobody said it would be cheap but it is not really expensive
<diginet>
do rotaries have oil?
<Sync_>
yes
<Sync_>
they have to
<diginet>
are there any oil-less first stage pumps?
<Sync_>
yes membrane pumps
<Sync_>
why do you want to go oilless?
<Sync_>
the problem with membrane forepumps is low throughput and the turbo needs to be a modern hybrid one
<diginet>
because oil creates a lot of problems
<diginet>
what about sorption pumps? they seem rather simple
<Sync_>
yes but you need to have access to ln2
<Sync_>
oil isn't too much of a problem
<diginet>
LN2 isn't either
<Sync_>
yeah but you need a supply of it
<diginet>
LN2 is cheaper than water
<Sync_>
oil just sits in the pump
<diginet>
I'm building an air liquefaction machine
<diginet>
the problem is when it gets into the chamber, which is especially a problem for semiconductors
<Sync_>
yes for ultra modern devices and mass production it is an issue
<Sync_>
but not for a hobbyist or research
<Sync_>
two of our evap chambers are oil pumped and it is all good
<Sync_>
I'd have a scroll pump here just in case tho
<diginet>
yeah, those are cool
<Sync_>
again, you complain about vacuum being expensive and then complain about the cheapest way to get there by using oil sealed rotaries...
<Sync_>
it is much less a problem than one would think
<Sync_>
you can even inject nitrogen into the forepump line to keep it at an elevated pressure
<diginet>
sorry, I didn't mean to complain, :P
<Sync_>
what approach are you using for your liquifier?
<diginet>
hampson-linde cycle, with pre-cooling
<diginet>
it's not the most efficient, but it's not so bad
<Sync_>
ah lame
<diginet>
why do you say that?
<Sync_>
because that's the easy way
<diginet>
what would you propose using then? reverse-brayton?
<Sync_>
I bought a high pressure compressor for that but then changed my mind, an autocascading precooler is just easier
<Sync_>
but that project is on ice since I just can open the ln2 tap at work
<diginet>
hmm, is a cascade cooler more efficient?
<Sync_>
that really depends
<diginet>
but you say cascade is easier?
<Sync_>
we have a small ln2 generator in one lab because getting a ln2 line installed is too expensive and it uses a cascade
<Sync_>
well, you only have to get the gas mix right
<Sync_>
which is not too bad
<diginet>
I guess that makes sense considering there is no compressor (the compressor is definitely expensive)
<Sync_>
yes no dicking around with high pressure air too
<diginet>
indeed
<diginet>
one thing I've considered is starting it off with a membrane to at least eliminate some of the O2, I'd rather not have to deal with LOX
<Sync_>
lox is fun
<Sync_>
it is also blue :D
<diginet>
sure, but it's explosive and dangerous
<diginet>
but it is pretty, no denying that
<Sync_>
it is only supporting combustion very well so just keep it away from combustibles
<Sync_>
it is also quite magnetic
<Sync_>
which is also fun to demonstrate
<diginet>
yes! I've seen that before, well, diamagnetic technically
<Sync_>
yeah
<Sync_>
you can have very good fun burning things quite fast with lox
<diginet>
this is insane, but what I really want is some DIY Ar
<diginet>
that stuff is pricey (even though it shouldn't be)
<Sync_>
huh
<Sync_>
20l bottle refill is around 40€
<Sync_>
which is quite good
<diginet>
that's almost $70, not cheap IMO
<Sync_>
???
<Sync_>
you're getting a gas, known to be oil free, 4 9s or better in quality
<Sync_>
I mean really, that's cheaper than you could do it
<diginet>
I don't need 4N though
<Sync_>
what do you want to use it for?
<diginet>
glovebox
<diginet>
problem is purge and fill means I need several times the volume of the chamber for one session
<Sync_>
use a load lock
<Sync_>
a 50l bottle of n2 would probably be the easiest
<Sync_>
yeah 50l n2 is +-50€ per fill
<Sync_>
for a continious application that'd be quite a lot but then n2 concentrators are quite spendy
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<azonenberg>
diginet: For SEM coating you can sputter/evaporate almost anything
<azonenberg>
sputtered Au can be done with a less high vacuum and cheaper equipment
<azonenberg>
as with sputtered Pt
<azonenberg>
with deeper vacuum you can evaporate C but that doesnt work well on samples with complex topography
<nmz787>
diginet: what's an FLCD?
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<B0101>
azonenberg: do you test your wafer conductivity when you get them?
<azonenberg>
B0101: I have not done any semiconductor work per se
<azonenberg>
so i've never needed to
<azonenberg>
all of my fab to date has been purely mechanical
<azonenberg>
lithography testing, MEMS, etc
<B0101>
oh
<azonenberg>
That way i dont care about metal contamination ;)
<B0101>
hehehe
<B0101>
I may sound crazy, but do you think you can grow oxide layers using a normal oven?
<B0101>
I want to pump steam into a normal oven, but I think it will be a slower process than if I were to use a kiln at temperatures above 1000 deg C, am I right?
<azonenberg>
It's exponential
<azonenberg>
You will get oxide growth even at room temperature
<azonenberg>
But it wont be usefully fast below 600C or so
<azonenberg>
I would suggest you look into spin-on glass if you want to avoid thermal oxidation
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<diginet>
FLCD is ferrofluid liquid crystal display
<diginet>
so I've been working on an intersting-ish side project, basically, DIY e-paper
<azonenberg>
ooh
<azonenberg>
how far have you gotten?
<diginet>
pretty far actually
<diginet>
it is surprisingly simple
<diginet>
it uses electrochromism instead of electrophoresis
<diginet>
prussian blue pigment sandwich between ZnO:Al coated glass (patterned of course)
<azonenberg>
I guess the low resolution but cheap option
<diginet>
or PEDOT
<azonenberg>
would be thermochromism :P
<diginet>
heh
<azonenberg>
nice little grid of heating elements
<azonenberg>
backing a thermochromic dye on a plate
<azonenberg>
refresh rates on the order of 0.5 Hz
<azonenberg>
massive power consumption
<azonenberg>
resolution of 0.5cm or so
<diginet>
well prussian blue is insanely cheap, and PEDOT and/or ZnO:Al are as well
<azonenberg>
Sounds interesting
<azonenberg>
Why ZnO/Al instead of ITO?
<diginet>
because ITO is stupidly pricy
<diginet>
and I prefer to use sustainable materials
<azonenberg>
Hmm, how about like sputtered Au or something
<azonenberg>
a few nm of it cant be that expensive
<diginet>
wouldn't work, too thin
<diginet>
thus too high resistivity
<azonenberg>
As in, to be thick enough to have good resistivity it'd be opaque?
<diginet>
yeah
<azonenberg>
Hmm
<diginet>
AZO is already in use though, it's much more common in the solar cell industry
<azonenberg>
I see
<diginet>
the only problem is that it needs a moisture barrier because it is more susceptible to atmospheric water vapour than ITO
<azonenberg>
Yeah, i was just reading that
<diginet>
seriously though, ITO is a thorn in the side of the display industry
<azonenberg>
How about just spin-on glass?
<diginet>
yeah, or acrylic or whatever
<azonenberg>
Well i was thinking
<azonenberg>
ZnO/Al film
<azonenberg>
pattern it
<azonenberg>
coat the whole surface with a transparent insulator of some sort, say SOG or reactive sputtered SiO2
<azonenberg>
Then etch windows in the glass where you want "bond pads"
<azonenberg>
and put down, say, a thick aluminum or copper layer
<diginet>
I think what is often used is PEDOT, which is of course also conductive, and protects it (where you need contact with the electrolyte)
<diginet>
PEDOT:PSS is interesting, very easy to make, the problem is it only has about 1/10 the conductivity as ITO
<diginet>
that being said, electrochromics are bistable, so maybe it doesn't matter
<diginet>
you know what's cool though? prussian blue is the same pigment used in blueprints/cyanotypes, so this would be literally, "e-blueprints"
<azonenberg>
lol
<diginet>
e-ink is amusing, because it's /way/ over-engineered
<diginet>
there have been much simpler options around for a long time
<diginet>
the best part is that the bistability means no need for active matrix
<azonenberg>
ooh
<diginet>
what I don't understand is, considering how simple this stuff is, why it isn't in use
<azonenberg>
well the wiki article suggests that AZO is difficult to etch
<azonenberg>
You might want to consider a lift-off process
<azonenberg>
Not that those have great resolution either
<azonenberg>
How is it normally deposited - sputtering?
<diginet>
no, not AZO, i mean electrochromics
<azonenberg>
And is that reactive sputtering of an Al/Zn target in Ar+O2?
<azonenberg>
oh
<diginet>
even using ITO
<diginet>
I mean, electrochromics are absurdly simple
<diginet>
azonenberg: my preference is sol-gel, which has been demonstrated
<azonenberg>
"Recent advancements in modified porous nano-crystalline films have enabled the creation of electrochromic display. The single substrate display structure consists of several stacked porous layers printed on top of each other on a substrate modified with a transparent conductor (such as ITO or PEDOT:PSS)."
<azonenberg>
Looks like it's an ongoing research problem
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<Sync_>
hmm yeah
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<B0101>
Anyone here knows about optics?
<Sync_>
just ask
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<B0101>
I want to know how to set up a proper system in which take a photomask and shrink the pattern down for exposure