Results 1 to 7 of 7

Thread: Coherent Innova 400 Purelight info requests ....

  1. #1
    Join Date
    Jan 2013
    Posts
    3

    Default Coherent Innova 400 Purelight info requests ....

    Hi all,

    A while ago I acquired two Innova 400's for a real bargain for hobby and educational use.
    I know that these are not the typical in your basement things as these are more then power (3-phase 70 Amps/phase @ 480V) and cooling 22.7 liters/minute hungry.

    As I don't have a 125amp circuit breaker in my home this could be a no-go an first sight. However in the manual (major thx to the coherent guys who where so friendly to mail me a copy) I found that minimum tube current in current regulation mode on all Innova 400 models is 10A, while tube voltage is approx 505 ~ 538 V (depending on model).

    My idea (if this is possible - I happily read your comments) is to design a switching power supply which does around 15A at desired tube voltage, which is much more likely to fit my home's circuit breaker then the electrical power required to have these things lasing at full power. It won't run at full power but it's only hobbying and experimenting.

    Both systems are Innova 400 Purelights (mixed argon/krypton), one is an 400/15 and the other is an 400/25.

    Does someone has the tubespecs for these (voltage drop, etc) and the filament/magnet voltage ? so I can a) run them in pulsed mode (with heated filament) and/or b) try to think of a power supply design ....

    Regards,

  2. #2
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,468

    Default

    An I400 at 15A of STABLE plasma might get you all of 10 milliwatts of 488 with the existing optics. The OC has too high a transmission to run at low powers. Even if you changed that, you might see lasing but no productive power generation. Maybe 25 milliwatts. It would be a heck of a lot of work for nothing. As well as a nightmare to align with no gain.

    Tube pressure is very high for pulsed mode be say 300 milliTorr for the CW regime vs tens of microns for true pulsed mode ion. You'd need a long pulse of 10-20 milliseconds duration to approximate CW operation and even establish a stable plasma. What you also missing is the need of a high current to form the "cathode spot" which allows for emission of stable plasma. The PSU really does not limit the current for a few milliseconds after starting.

    BTW, Repeated starting pulses without stable plasma do cathode damage very quickly. Its just not the right kind of cathode.

    There is no hope of pulling the plasma pressure down to enhance "pulse" mode on a Innova bore. The stacked disks do not support low pressure. I and One other guy have cracked tubes trying, in order to run Xenon mixes. That was only 50 mTorr below standard pressure.

    This means you'd need a pulse forming network for your long pulse and to power the magnet. The magnet needs rectified line at say 4-6 Amps by itself.

    You probably have a 3.25 volt, 150 to 200 watt AC Cathode.

    Sorry, but what you want to try is just not worth the effort.

    Short version: Rent a Generator and be happy. Otherwise scrap them or sell/trade them to Laser Innovations etc.

    I know we have a line about doing this for air-cooled tubes in the FAQ. That does work, as a big stack of Electrolytics give you a few milliseconds of lasing at 6 amps or so on a 95 to 106 volt tube. But the large tube is a whole different ballgame.

    Your tube is a 50 Amp tube. Which means spec power is probably obtained at 40-45 amps when new.

    Steve
    Last edited by mixedgas; 01-06-2015 at 05:29.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  3. #3
    Join Date
    Jun 2007
    Location
    Phoenix AZ
    Posts
    347

    Default

    " 15 characters"
    Last edited by Laser Wizardry; 11-13-2015 at 12:29.

  4. #4
    Join Date
    Jan 2013
    Posts
    3

    Default

    Thx for your replies guys !

    There goes the idea about running them in CW mode or with a lower power supply ....
    Condition of the tubes is unknown ....
    @Laser wizardry (or steve) can you give hints/a procedure on determing the condition of the tube with respect to the cathode voltage on warming up ?
    (In fact I'm a total laser noob, it's just a fascination from childhood that I have for all sorts of plasma tubes and the possibilities with them)
    My guess it's wise to check the cathode voltage first before I will look for a (rental) genset ?

    BTW I'm located in the west of Belgium (around Ghent), maybe there are people over here from aprox the same location ...

  5. #5
    Join Date
    Jul 2006
    Location
    Belgium
    Posts
    293

    Default

    Quote Originally Posted by spacer76 View Post

    BTW I'm located in the west of Belgium (around Ghent), maybe there are people over here from aprox the same location ...
    Cool, so am I (East of Ghent).
    Trying to create a good diode mount....

  6. #6
    Join Date
    Jul 2005
    Location
    Tampa Florida
    Posts
    502

    Default

    Try to sell them and buy a laser you can run! The I 400's are power pigs and nobody runs them at home.
    Phil Bergeron( AKA 142laser)

  7. #7
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,468

    Default

    Those are Coherents, so there is less prestart adjustments then most of what you see in the FAQ. They usually have 2 or 3 fixed taps on the cathode transformer. They are probably already set for 50 hz, so they should just run if you have the right external three phase transformer. European versions of US Equipment often need a external transformer. Once your sure the AC power is correct, Hook them up, supply the massive amount of cooling water, check for leaks and loose Brewster covers, and hit start.

    The manual is very clear with the pre-start check list. There is not much to do. However there are a few things NOT to do. Coherent should send you a PDF of the operator's manual.

    Tube condition on these is determined with a volt meter. If you give Coherent service the head and psu serial numbers via email, they should give you the tube voltage and reference current for each tube. That sheet will have the cathode switch settings (IF ANY) for a given tube. You have a fill system on those tubes, so its easy to add gas and bring the tube voltage up to spec as needed. Don't fill till you've ran the tube for an half an hour. Large ions sometimes have "cobwebs" when they have not ran for a while. Cathode voltages and currents on Coherents are specified as a fairly board range, not a specific number.

    An "Amp Clamp" type clamp on voltmeter will tell you something with a normal cathode transformer. The test is ran when the plasma is just started. However, I'm not sure if European 400s have the constant voltage cathode transformer, that can complicate things for doing a "Cathode Delta" measurement. Look and see if there is a large capacitor in a metal can attached to the cathode transformer and get back to me.

    Make sure the metal Brewster stem covers are not touching anything electrical. Watch for leaks, in fact test for leaks in the heads before hooking up power. You can do that at home without a generator. If you have a "high field" magnet switch, do not activate it when the tube is running. Then make sure the intracavity Iris is wide open to enhance lasing.

    I don't have a 400 manual any more, and I'm hesitant to do things from memory. I've worked on too many similar Coherents, and some parts of the memory are a blur.

    AGAIN, Coherent Service should be helpful. As big as these are, it would help if you had an experienced Ion Laser person around. My only caution is not to maximize the tube current much beyond the reference current in the data sheet. Be prepared to clean the Brewster windows and align the mirrors if needed.

    Over some time, I can help you with procedures. Just not this week. Skype is also a possibility.

    You might just be the new hero on Laserfreak.de. Which would be a source of local help. Just watch out for the "wanta-be" types who have no external mirror experience. They like to ramp up the power, a bit too much. Something about Laserfreak translates to "Add More Amps" when it comes to plasma current. A few of their guys are VERY good.

    OK, I found your online pics. You have the newer style digital remote with the LCD. Life just got easier. It will tell you most of what you need to know from the LCD. You may also have Power Track which aids in maintaining alignment.



    Steve
    Last edited by mixedgas; 01-07-2015 at 12:50.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •