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Re: [VacuumX] Re: Baffle design

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  • Andrew Aurigema
    Attila, This may be old to everybody else but could you explain the IBAD you have. Is it for aluminization or SiO overcoating or both ??? I understand
    Message 1 of 15 , Nov 27, 2012
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      Attila,

      This may be old to everybody else but could you explain the IBAD you have.  Is it for aluminization or SiO overcoating or both ???  I understand tungsten coil evaporation process very well but not the others.  How you power that sort of process is what I really want to know. 

      Thanks in advance.

      Drew in sunny Florida

      --------------------------------------------------------------------

      On Tue, Nov 27, 2012 at 1:46 PM, Attila <schneyolo@...> wrote:
       

      Hi Alex,

      I can explain only my experience. Actually I don't use those baffles.
      Because I do IBAD coating for mirrors. During this process my ion gun needs gas flow to work properly. To maintain a working pressure I need as much pumping speed as possible. Those baffles, at least what I own, reducing the pumping speed to 50-60% of the original. This is not acceptable for me.

      So if you need a clean low vacuum you should use those baffles. If you need to maintain a working pressure(tipically 1-5x10-4 Torr), you need high pumping speed instead.

      Br.

      Attila

      --- In VacuumX@yahoogroups.com, "grossmann200" <email@...> wrote:
      >
      > Based on the pictures uploaded by David and Attila (thank you both!), it is pretty obvious, that the baffle has quite some complexity. Most likely, a baffle maybe not so easy to build on your own.
      >
      > So, there is the question:
      > - In which (coating-) situation do you really need a baffle?
      > Or to ask the way around: when would I not need such a baffle?
      >
      > Cheers
      > Alexander
      >


    • Attila
      Andrew, Well, the Ion Beam Assisted Depositon means, there is an assisting ion source in the chamber which helps to change the physical and mechanical
      Message 2 of 15 , Nov 28, 2012
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        Andrew,

        Well, the Ion Beam Assisted Depositon means, there is an assisting ion source in the chamber which helps to change the physical and mechanical properities of the protective oxide layer.

        That means, the ion gun only used during the overcoating.
        Beacuse I make high reflective aluminium coating, called enhanched multilayer aluminium coating. Over the Sio2 layer, there is a Tio2 layer too.

        And because of Tio2, I use electron beam gun to evaporate the materials.
        The ebeam gun is very good controllable, especially the evaporation rate is important. And I can evaporate everything which in the periodic table exist, some materials at very high rate.

        So during the aluminium evaporation, I don't use the ion source. I evaporate at 10nm/sec, at the lowest pressure possible.
        After this, the ion assisting gun is turned on, and during the Sio2 and Tio2 process it hammers the atoms to the mirror surface. This way the oxide layer will have higher refractive index, totally dense(no absorption), less stress and no collumar structure.
        And because of the layer thickness is precisly controlled and measured, I can make constructive intrference layer, which tunes up the reflectivity to 97%.

        The IBAD process is a surface "phenomenon", that is why it works at relative high pressure(1-5x10-4 Torr), even though the mean free path is smaller at this pressure, than the source to substrate distance.

        Hope this helps.

        Best Regards
        Attila
        www.ebeamguns.com


        --- In VacuumX@yahoogroups.com, Andrew Aurigema <eosraptor@...> wrote:
        >
        > Attila,
        >
        > This may be old to everybody else but could you explain the IBAD you have.
        > Is it for aluminization or SiO overcoating or both ??? I understand
        > tungsten coil evaporation process very well but not the others. How you
        > power that sort of process is what I really want to know.
        >
        > Thanks in advance.
        >
        > Drew in sunny Florida
        >
        > --------------------------------------------------------------------
        >
        > On Tue, Nov 27, 2012 at 1:46 PM, Attila <schneyolo@...> wrote:
        >
        > > **
        > >
        > >
        > > Hi Alex,
        > >
        > > I can explain only my experience. Actually I don't use those baffles.
        > > Because I do IBAD coating for mirrors. During this process my ion gun
        > > needs gas flow to work properly. To maintain a working pressure I need as
        > > much pumping speed as possible. Those baffles, at least what I own,
        > > reducing the pumping speed to 50-60% of the original. This is not
        > > acceptable for me.
        > >
        > > So if you need a clean low vacuum you should use those baffles. If you
        > > need to maintain a working pressure(tipically 1-5x10-4 Torr), you need high
        > > pumping speed instead.
        > >
        > > Br.
        > >
        > > Attila
        > >
        > > --- In VacuumX@yahoogroups.com, "grossmann200" <email@> wrote:
        > > >
        > > > Based on the pictures uploaded by David and Attila (thank you both!), it
        > > is pretty obvious, that the baffle has quite some complexity. Most likely,
        > > a baffle maybe not so easy to build on your own.
        > > >
        > > > So, there is the question:
        > > > - In which (coating-) situation do you really need a baffle?
        > > > Or to ask the way around: when would I not need such a baffle?
        > > >
        > > > Cheers
        > > > Alexander
        > > >
        > >
        > >
        > >
        >
      • Gomez Addams
        If your pumps are very clean, you may not need a trap. If you are using mechanical pumps which are sealed by oil, you will need a trap. clean (no
        Message 3 of 15 , Nov 30, 2012
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          If your pumps are very clean, you may not need a trap.
          If you are using mechanical pumps which are sealed by oil,
          you will need a trap.

          "clean" (no back-streaming) pumping techs include:

          • turbopumps backed by a diaphragm, scroll, or dry screw roughing pump

          • sorption pumps

          My apologies if you stated you have existing pumps and I missed it.

          On Nov 27, 2012, at 11:46 AM, Attila wrote:

          > Hi Alex,
          >
          > I can explain only my experience. Actually I don't use those baffles.
          > Because I do IBAD coating for mirrors. During this process my ion
          > gun needs gas flow to work properly. To maintain a working pressure
          > I need as much pumping speed as possible. Those baffles, at least
          > what I own, reducing the pumping speed to 50-60% of the original.
          > This is not acceptable for me.
          >
          > So if you need a clean low vacuum you should use those baffles. If
          > you need to maintain a working pressure(tipically 1-5x10-4 Torr),
          > you need high pumping speed instead.
          >
          > Br.
          >
          > Attila
          >
          > --- In VacuumX@yahoogroups.com, "grossmann200" <email@...> wrote:
          >>
          >> Based on the pictures uploaded by David and Attila (thank you
          >> both!), it is pretty obvious, that the baffle has quite some
          >> complexity. Most likely, a baffle maybe not so easy to build on
          >> your own.
          >>
          >> So, there is the question:
          >> - In which (coating-) situation do you really need a baffle?
          >> Or to ask the way around: when would I not need such a baffle?
          >>
          >> Cheers
          >> Alexander
          >>
          >
          >
          >
          >
          > ------------------------------------
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          >
          >
          >
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