Hows this for a side business (Re-gassing lasers)

[k-shell]

For many years I have been into vacuum technologies. And over these years I have collected some rather useful tools. My most highly cherished possessions are my vacuum pumps. I have two UHV turbo pumps and a few two-stage oil lubricated rotary vane pumps.
My second most cherished are my vacuum gauges and precision gas flow control systems. I have a hot filament (ion gauge) for measuring ridiculously high vacuum levels from 10^-4 torr all the way down to 10^-10 torr. I have 3 convectron gauges for measuring atmosphere, down to 10^-4 torr. And I have two gas flow controllers that can precisely flow argon, n2, co2, helium, neon and all the other noble gasses down to a resolution of 1sccm.
My third most cherished items in vacuum tech are all kinds of fittings, flanges and adapters (a box full of over 75 pounds of random stainless fittings).

I would love to try to regas some lasers. As a hobby for now but if all works well I could do it as a business/service.

I have tons of knowledge when it comes to flowing gasses in a vacuum and corona discharging. I am currently an Excimer laser operator (which requires cycling the gas every few months, though these are high pressure lasers its still the same concept), more than that im a Vacuum systems engineering technician. I do setup optics every time I go to install a new system too.

I really want to stay away from HeNe lasers and I don’t want to try to connect to a glass tube that doesn’t have a service port. If you have an Argon, CO2 or ar/kr laser that needs a fill, I can try to give it a shot (no guarantee). And yes I will read Sam's laser FAQ for guidance!!!  

Does this sound like something anyone would be interested in????

by the way, even though i have access to rare gasses, i cant use them for personal use. so if you have something with Neon, Xenon, Fluorine or Krypton you would have to supply that. but i have tons of five nines pure Argon and Helium, and pretty pure Nitrogen. im sure CO2 isn't very expensive either.

 

[k-shell]

Re: So lets talk gas laser business

Heres a video that shows my Fisher Scientific rotary vane pump roughing down my Varian turbo v70 UHV pump. you can also see one of my convectron gauge tubes and the digital pressure readout along with a bunch of reducers, flexible bellows, valves and fitting.

http://s44.photobucket.com/player.s...bums/f9/laserskys/100_2156.flv&fs=1&os=1&ap=1

 

[digital_blue]

Re: Hows this for a side business (Re-gassing lase

OMG you have a freaking Turbo pump? I've been looking for a cheap/used one that will get me below 10[sup]-3[/sup] torr... Too bad most turbo pumps with controllers go for over 2K :'( ...

 

[k-shell]

Re: Hows this for a side business (Re-gassing lase

low threes can easily be achieved using a two stage rotary vane pump with very clean oil (I use Fisherbrand 19 or Welch DuoSeal). If i need a deep vacuum i will run my pumps till they are hot, drain them, flush them and fill them with fresh oil. i have managed to get my Welch 1402 and almost get my Fisher Scientific maxima C+ to break into the minus fours.

In this pic you can see that the gauge is almost bottomed out, the bottom of the gauge is 1^-3
Fisher Scientific Maxima C+ (at 2 militorr)

And this one the gauge is at 0 so its less than 10^-4
Welch 1402 (below 1 militorr)

And heres my collection of roughing pumps:

 

[diachi]

Re: Hows this for a side business (Re-gassing lase

CO[sub]2[/sub] Will be more difficult than Argon, as CO[sub]2[/sub] lasers use a mixture of gases, I believe its around 2% CO[sub]2[/sub] and the rest is nitrogen, or something like that anyway.

Good luck

-Adam

 

[daguin]

Re: Hows this for a side business (Re-gassing lase

CO[sub]2[/sub] Will be more difficult than Argon, as CO[sub]2[/sub] lasers use a mixture of gases, I believe its around 2% CO[sub]2[/sub] and the rest is nitrogen, or something like that anyway.

Good luck

-Adam

Most gas lasers have a "mixture" of gasses. Argon lasers also have a mixture of gasses. When the argon is depleted in a tube, the red glow is from helium.


Peace,
dave

 

[diachi]

Re: Hows this for a side business (Re-gassing lase

[quote author=Diachi link=1228285379/0#4 date=1228326782]CO[sub]2[/sub] Will be more difficult than Argon, as CO[sub]2[/sub] lasers use a mixture of gases, I believe its around 2% CO[sub]2[/sub] and the rest is nitrogen, or something like that anyway.

Good luck

-Adam

Most gas lasers have a "mixture" of gasses. Argon lasers also have a mixture of gasses. When the argon is depleted in a tube, the red glow is from helium.


Peace,
dave[/quote]


Oh right :-/ my bad, Why is the helium still left then ?

-Adam

 

[pullbangdead]

Re: Hows this for a side business (Re-gassing lase

Nice collection, I would love to have some at-home vacuum systems.  Alas, I just get to play with them at work and such.  

I'm sure you know this, k-shell, but for others who want to do what digital_blue is talking about with getting into low millitorr and below with just a mechanical pump, one thing to remember:  At those pressures, you're no longer in laminar flow, you're in molecular flow.  This means that you are back-streaming gas from pump to chamber as well as gas flowing from chamber to pump, and with some pumps, this means you are back streaming oil vapors from pump to your chamber.  so, if you're getting to those pressures with a mechanical, make sure the pump is one that will not allow backstreaming into your chamber, or your clean chamber will not be very clean anymore. Any new, good pump I think won't do that, but there are old pumps out there, and they're cheaper.

One system I worked on a couple of years ago was an astmospheric-pressure dielectric barrier discharge that just had a mechanical pump, and when not running we would leave the pump running and a needle valve open such that it maintained about 200mTorr, just to keep the chamber clean.

I'm sure you've seen all kinds, but some of the things I've worked with:

The same lab with the AP-DBD had a couple of turbo-pumped sputter systems, a couple of cryo-pumped sputter systems, and about 3 diffusion-pumped ion-beam deposition system (1 single beam, one dual beam).  

In my internship last summer, the tool I mainly worked with had 14 chambers: the 2 loadlocks each had ~6 inch diameter turbopumps, and the 2 buffer/transfer chambers and 10 process chambers each had a ~12-16 inch (I really don't remember) turbo pump with a single high-T cryo stage on top of it (They suggested the single-stage of the cryo might help with getting water vapor out of the chamber, I'm not sure though and these guys weren't the vacuum techs who had designed the system).  All those turbos were backed by 4 VERY large mechanical pumps that were housed in the basement/subfab about 2 stories below the tool.  The process chambers were routinely in the 10^-9 range, and they were pretty big chambers.

I was in the room with the tool when someone in the basement accidently hit the emergency-off (EMO) button for the tool one day.  Ideally, the EMO should cut off everything EXCEPT for the mechanical pumps, but when the system was installed, apparently the mechanical pumps were on the EMO circuit as well.  So they cut off, and with the turbos still spinning at almost full speed, gas began to backstream into the tubes behind the turbos.  Not sure if you've ever heard that noise of atmosphere hitting turbo blades, but it had to have been one of the scariest noises I've ever heard, as all 14 turbos started screaming from the air coming in from the backside.  I could have sworn the vanes/blades were just going to shred inside the housings at any second.  Luckily, they slowed down quickly enough and nothing was permanently damaged.  I think if the tubes from the turbos to the mechanical pumps to outside had been any shorter, there may have been some REAL damage.

 

[pullbangdead]

Re: So lets talk gas laser business

Heres a video that shows my Fisher Scientific rotary vane pump roughing down my Varian turbo v70 UHV pump. you can also see one of my convectron gauge tubes and the digital pressure readout along with a bunch of reducers, flexible bellows, valves and fitting.

http://s44.photobucket.com/player.s...bums/f9/laserskys/100_2156.flv&fs=1&os=1&ap=1

That is an extremely cute little turbo pump; I would love to have on of those at home, count me very jealous. there are just so many cool things you can do.  

I also must say, I had to LOL at the 3 sequential KF flanges to get from the pump to the convectron gauge, very cool.  Also, what were you doing with the rough line at the end fo the video, I couldn't make it out and no sound at the moment, so I'm not sure if you said in the video.

 

[digital_blue]

Re: Hows this for a side business (Re-gassing lase

I'm a little noobish when it comes to vacuum systems, but does a turbo pump require a roughing pump?

I'm looking for a pump that goes down to 10[sup]-3[/sup] Torr and lower(lowest I need is probably 10[sup]-7[/sup] torrs). I considered using a diffusion pump but they apparently have a tendency to contaminate the chamber.

 

[pullbangdead]

Re: Hows this for a side business (Re-gassing lase

Yes.  You pretty much need a rough pump with any high-vacuum pump, and you need it for roughing the chamber and for backing the high-vacuum pump.

A high-vacuum pump like a turbo can't pump from vacuum directly to atmospheric pressure behind it, it needs a lower pressure behind it to function properly.  So you have your chamber at high vacuum (10^-4, or lower, down to 10^-9 or 10^-10 with a turbo possibly) with the turbo pump, and connected behind the turbo pump is the mechanical pump, which gives an intermediate step in pressure between high-vacuum and atmosphere.  Between the mechanical pump and the turbo pump, the pressure will be something like a few millitorr probably (not sure exactly, never had a a pressure gauge on that side of the lines before).

So yes, you need the mechanical pump for both roughing the chamber and backing up the vacuum pump.  

And yes, diffusion pumps can be very dirty.  Also with them, you will need a good chiller to keep cold water cooling on it all the time that it's running.  If you lose cooling water, that's when they're at their dirtiest.  Lose that cooling, and you FILL the chamber will oil vapors and spend a few days cleaning it out.

10^-7 is not trivial to get to.  A turbo I think would be the easiest, and you do need the rough pump (like I said before).  I'm sure you've looked at a lot of the equipment you would need, as well as the safety aspects of it.  Depending how clean you'll need it, you'll need stainless parts/connections/fittings and all, the 2 pumps, pressure gauges to know what's going on, maybe nitrogen purge, maybe a means for baking out the chamber (water vapor/excess water in the chamber is notorious for causing a floor in available pressure in the 10^-5 range, you can sometimes wait forever without ever getting below the -5s if you can't bake the water and other crap off the walls). Especially if it's something where you'll have to be opening the chamber often, it can be a pain getting and staying at low pressures consistently every time, especially if you end up with a pump a little too small because it was cheaper.

 

[digital_blue]

Re: Hows this for a side business (Re-gassing lase

For my application, a bit of water and such isn't really a concern, the chamber needs to be moderately clean. I just can't have a diffusion pump fouling up my chamber every now and then... Does anyone know where I can get a custom chamber made for a reasonable price?

The design is quite simple:

- 2 six inch hemispheres with non-rotating conflat flanges (The two hemispheres will be bolted together to form a "sphere-like" chamber)
- Three 2.75" Conflat half nipples(One will be used as a viewport, Another will be a high voltage feedthrough)
- 1.33" Conflat Half Nipple
- Swagelock fitting

Any ideas of the cost involved?

 

[k-shell]

Re: Hows this for a side business (Re-gassing lase

What’s your application?

And when you're talking custom chamber you are talking big money!

Your best bet is to find some old research chamber that someone is selling.

But the easiest way I can think to make a DIY chamber is to get a spool with two CF's on each end. Then you can cut some holes ware you need them and braze the half nipples in. I’m sure someone with moderate mechanical knowledge could make a good enough seal by brazing if they only need to meet the -7s.

pullbangdead:

Sounds like you have been in vacuum for a while. As with anyone who has been in the field for long enough you do experience some idiot who dumps a pump. Personally I have seen quite a bit of pump damage in my life! I have heard someone open a vent valve on a turbo at speed, and due to some glitch in software on a -9s system from AJA I personally witnessed a VAT valve open to a large CTI Cryo while the system was opened for loading (That was actually very beautiful and destructive at the same time!!!).

I used to work for Rietschle Thomas/Welch as a mechanic and technical service rep. I have seen rotary vane pumps that have ingested water, Lobe pumps that threw bearings, and even a regenerative blower that sucked up a chicken. But with all that being said, I know how to take care of pumps, what sighs to listen for, and I have never dumped a pump myself.

The company I work for now is a leader in Pulsed Laser Deposition, but we do Sputtering, pulsed electron deposition, ion milling, Rheed growth monitoring.
Our mechanical engineer is brilliant at designing our systems. We do noting standard and still ship almost one tool per month. The most recent tool we shipped was Osram Sylvania, Dublin City University, Turkey, Spain and getting ready to ship for New York.

At the end of my video I was closing the valve after I shut down the turbo to show how long it would stay under 1 militorr without any backing (but i ran out of video), besides, it helps spin down the pump! As long as the pump stays under a few militorr, nothings gonna happen…