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Thread: Co2 Laser Re-Gas discussion

  1. #31
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    Default done

    Quote Originally Posted by mixedgas View Post
    Ed, let me know when you have all this copy-pasted and have grabbed the links. There is one post here I'd like to redact.

    Steve

    all copyed, and triple saved, done!!!

    Ed.

  2. #32
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    Default sucsess on 80 and 130watt tube

    looks like the 40 watt tubes are not the best for refill, i have sucsessfully refilled a 90watt reci w2 tube to 115watt power and a 130watt reci w4 tube to 155watt



    Quote Originally Posted by sinfocomp View Post
    ive got all the equipment needed and partially sucsesfull at recharging and old 40 watt tube,
    but i only get about 50% power
    any thoughts?

  3. #33
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    Quote Originally Posted by sinfocomp View Post
    looks like the 40 watt tubes are not the best for refill, i have sucsessfully refilled a 90watt reci w2 tube to 115watt power and a 130watt reci w4 tube to 155watt
    Congratulation
    Can you tell us details?

  4. #34
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    Hello.
    I have some rf co2 laser sources uls/synrad/coherent that need regasing.
    What gas cylinders purity must get to refill them ? 99.999% pure is ok for He/N/Co2 ?
    I have also found premixed gas for co2.. get the premixed gas or separate cylinders ?
    Also a dual stage vacuum pump with vacuum about 10^-3 mbar is enough to make vacuum ?
    I have some swagelok high purity/vacuum/pressure valves.
    My needs is the rf laser to have enough power near the rated power
    i do not have requirement laser last forever if last 1 year is ok to me
    because i will use the tubes so if need refill i will repeat the process.
    Thanks.

  5. #35
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    RF tubes use a much different gas mix then premix.. The OP invested around 10,000$ in hardware to be able to do this. As have I for other types of lasers.
    ~
    I suggest you have a professional fill your RF lasers, as a bottle of the required purity of Xenon alone costs 700$ in most of the world. Which is roughly equal to the cost of a commercial refill. When you can have the lasers refilled with new optics for far less then the cost of the required turbopump station, gasses, and tooling, it is best that you use a commercial service.

    Do not believe it is just as simple as pumping down and filling the gas again and again, in most cases this is not true. Often the optics need replaced as well. The electrodes will need to be cleaned/reprocessed with a cleaning gas mix, The laser cavity may need baked to remove impurities etc... You need 1x10-7 or better vacuum and a dual stage will not get you there...
    ~
    Also each of your lasers will require a slightly different gas mix, buying a single tank to specification instead of mixing your own gasses will be VERY disappointing. RF tubes need trace gasses added to maintain power, and xenon is only the first of those.
    ~
    The older Synrads will need their RF amplifiers adjusted post fill, and it is not just as simple for adjusting for peak laser power. That alone adds at least another 500-1000$ worth of hardware. The RF amplifier in some of your lasers uses the laser cavity as a RF resonator, and will be unstable if not properly loaded during filling. So you must have the pressure in the right range before turning on, or the amplifier can/will die..
    ~
    RF uses a 3:1:1 + trace gas mix to start with. Usually with 0.5 to 5% Xenon trace depending on manufacturer, plus one or more additives from the list Ar, CO, H2O, O2, N2O, H2, to regenerate the CO/Co2 balance. Without the additives the laser power quickly goes flat. As in less then four weeks of production operation. Often they use isotopic gases to get better peak power.
    ~
    Send the laser out for refill. It is easer and cheaper... One GOOD refill can get you several years of 24/7 operation.
    ~
    This reaction disassociates the CO2 in a matter of hours in a RF laser without trace gases.
    e` + Co2 = Co2` + e`2 which becomes CO+O + e` in the laser.
    ~
    The simplest, slowest recombination uses a trace of water to provide H2 to drive this reaction forward: CO+H2O + e` = Co2 +H , which occurs faster in the presence of Xe and other traces. The Xe also depopulates the lower laser level and controls the plasma temperature of the gas. A RF tube gets filled with Co2, CO, the N2, a trace of H2O, and the He and Xe minimum. However too much H20 drives the reaction backwards. If the manufacturer has installed a catalyst in the tube, the mix gets even more complicated.
    ~
    Thus refilling a RF tube is known as a time consuming "Research Project".
    ~
    Steve
    Last edited by mixedgas; 02-14-2019 at 11:47.
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  6. #36
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    Thank you for your useful information..
    Iam in europe and here the refill costs 3keuros+vat from trotec/uls representatives...
    To buy a new coherent c30 chinese clone costs 2k from china(shipping included).
    I have bought 2keuro coherent clone and the quality is exactly the same as coherent.
    Iam running this clone continuously almost 2 years now and the performance is top none loss in output power.
    Chinese factory that produces coherent clones wants 250euros for refill the clone tubes that produces.
    The problem for china refill is customs and shipping costs not the quality.
    When i say premixed gas i don't mean premixed gas for continuous flow laser but premixed gas especially for rf synrad/coherent.
    I have opened 20years old tubes with many thousands operation hours and the optics are in top condition they not need replacing..
    To tune rf power supply is not prob to me..
    What tools i need to mix the gases and inject them into the tube?
    pfeiffer vacuum pumps are good for the vacuum needed rf tubes?
    I have lathe & milling machine & industrial oven & induction heater if these help..
    If in china can do refill for 250 euros and the result is good that means that is not so difficult as shown and the other companies do it at multiple prices have large profit..
    Heating the tube i do not think is a good idea because sealing orings can damaged and metal tube to bend from heating
    Here 2 photos of US factory that fills co2 tubes.. i do not see any special equipment..
    Click image for larger version. 

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    Here is an rf laser with valve for user refilling
    Click image for larger version. 

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    Last edited by javanam; 02-15-2019 at 00:57.

  7. #37
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    And you think there are not vacuum sensitive chemical layers in some of these tubes that aid in catalysis and regeneration? They get put together in clean rooms and glove boxes for a reason.
    ~
    Yes, there were a few RF co2s made with valves. Then the goal was to eliminate the valve by changing the materials in the tube to catalyze the gas so the valve was not needed, but that is mixture dependent. . And not to make to so users cannot repump, but to get the lifetime up. Gas lifetime on the valve tubes I've seen was less then 3000 hours.
    ~
    In nearby Columbus, Ohio there is a small company that refurbs these lasers and has for a long time. . Photovac… Not as much cheap as China, but far cheaper then 2000 Euro. You will get your unit back, without the risks of China. 800$ a tube or so... Maybe less.
    ~
    Teflon can take a minimal bakeout….
    ~
    Let me put it this way, there are a few items missing on that vacuum station picture that an experienced user would desire. Residual mass analyzer, digital manometer, tube oven, heat tapes, sealing tooling, Spectrum Analyzer to check the amplifiers, external RF power supply for the tube etc... Lets not forget the high purity gas regulators that wont "run away" when exposed to a vacuum, and micrometer leak valves.
    ~
    You want to do low cost "Chop and pump", and that will come back to burn you. You will have to adjust the gas ratios and fill pressure to each manufacturer's mixture.
    ~
    The "Valve Actuator" tool for getting into some of these lasers is 1600$ US. The tool to seal off the fill stems is 3200$ You'll find that a good rebuild requires new optics, too. If I'm your customer, I'm not going to like it when you tell me I am beholden to you once you mount a valve on my laser and seal it with just vacuum epoxy. How are you going to clean, anodize, and passivate the tube walls if you TIG on a fill stem?
    ~
    The liquid nitrogen Dewar means he is using a cryopump. Which means about 40 liters of LN2 a day.
    ~
    There is your partial shopping list, good luck... Yeah, I know, you have CNC and can make everything, so you have a lot of work ahead of to clone that valve actuator.
    ~
    And to do this properly, you'll find the 2000 E charge is to cover another used laser for parts if you mess up a customer's laser.
    ~
    Setting alone with a tube for 24-48 hours to process it costs how much of your production time as a shop owner? Do you have a spare laser to keep the shop running while you do this? Is it worth three to six months of spare time to R&D this?
    ~
    Flowing gas CO2 is not difficult, a hobbyist can build one in a few days. Sealed gas systems are designed by teams of engineers and Phd for a reason. If it were easy , the market would be flooded by Chinese Synrad clones. But the Chinese stick to DC Excited glass tubes for a reason.
    ~
    I've got four Synrads on my desk at home, and I'm not just spouting off as a senior technician from academia. I'll spend a week and a half of my pay to send the laser out, before I order the Xenon for my Vacuum station, before I spend a couple of evenings on my ancient manual mill making the tooling. Unless you can grind 4 cm Diameter Tungsten Carbide to shape within .01 mm, you will buy the sealing tool for copper stems. 4000 Euros on Ebay parts sound worth it for a try?
    ~
    Do it for fun if you love technology... Weld your own cryopump.. Make your own lasers run first... Try it.
    ~
    Edit, the main thing that changes is the amount of Helium and the trace gasses. If things are going well, the whole inside of the laser is coated as a catalyst and will have something to remove hydrogen. Peter Laakmann is probably spinning in his grave...


    ~
    Steve
    Last edited by mixedgas; 02-15-2019 at 10:22.
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  8. #38
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    Check your PMs.. Warning, this mixture stuff is complex...

    Steve
    Last edited by mixedgas; 02-15-2019 at 07:59.
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  9. #39
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    I know in US there are reasonely priced options for refilling like photovac but no in europe. If i send one tube to US for refill with shipping costs/insurance & customs will cost more than to get new coherent/iradion clone from china that i have tested and is the same quality as original. The shipping costs/customs to china are far less than US and in china refill costs 250euro. To me 250eur+shipping+customs for china refill is expensive.. US refill cost is prohibitive due to shipping&customs cost. I want to refill my own tubes so a quick drop in power is not problem because i will repeat the process. Yes sealed rf tubes are high technology but for example davi from china cloned 100% coherent & iradion. The quality is same as coherent i have checked that. The reason why davi cloned coherent & iradion and not synrad is because they have more compact models than synrad higher watt at low volume.. How in china do refill rf tube only for for 250?(the refill lasts it is not low quality / shipping-customs cost is the prob ) So i want to refill my tubes with low cost if tube does not last long is not prob to me because i will refill again and again. In europe many factories closing so you can get scientific machines-equipment at 1/200 of original price so i want to know what tools need for refill to buy them if i find from closing factories at very low price.

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