in-vacuum lighting for UHV system?

[P.C. Snijders]

Hi,

I am looking to illuminate the interior of my UHV system from the inside.

 

This is purely to be able to see what I do: there are (808 nm) laser shields on the viewports that block a lot of visible spectrum light going in and out. So with a light on the outside shining in, I already loose a lot of photons going in, and the light coming out is pretty weak.

I can't find in-vacuum lights anywhere online.

 

So:

-does anyone know whether in-vacuum lighting exists?

-if not, does anyone have experience with what brand (halogen?) light bulbs may be suitable to mount on an electrical feedthrough inside a 1E-11 mbar UHV system?

 

Thanks!

Paul

[David Wieliczka]

Paul:

    Simply use a thin wire of tungsten and place it across a set of feed throughs.  A little current through the tungsten will heat it and create the light you need.  You will have to degas the filament prior to your experiments but this is a simple solution.

Regards

Dave

--
You received this message because you are subscribed to the Google Groups "Surface Science" group.
To unsubscribe from this group and stop receiving emails from it, send an email to surfacescienc...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Lipton-Duffin, Josh]

Hi Paul,

about 10 years ago when I was in grad school we wired a couple of high power bulbs from a slide projector inside our chamber. We ran them in parallel, the goal being to use the IR heating to add a little zest to our bakeouts. They throw off a fantastic amount of light when run at full power, but for illumination purposes I think they could work well at half-power with minimal outgassing. As I recall they were all ceramic/glass construction, we saw no strange peaks on our RGA and our semiconductor samples remained clean.

I believe that any glass/metal/ceramic halogen bulb will likely do the trick. I think we also tried a long one from a torch light: they didn’t work as well for bakeout, but would do the job of illumination just fine.

Best,
-josh

Josh Lipton-Duffin
Research Associate/Associé de Recherche
Université du Québec, INRS-ÉMT
1650 Boul. Lionel Boulet
Varennes, QC CANADA J3X 1S2
Tel: +1 514 228 6910
Fax: +1 450 929 8102

[Navrotski, Gary]

Hi Paul,

 

Dr. Lipton-Duffin is correct.  I have used lamps inside my UHV and XHV chambers for 20 years.

 

From any hardware store, purchase a simple quartz halogen lamp. It has metal leads sealed to the quartz that you connect directly to a feed through or that you extend from the feed through with kapton (or ceramic) coated wire.  The quartz is quite thick to contain the pressurized halogen.  Do not handle the quartz without gloves and clean it appropriately before installation. The vacuum only sees clean quartz and the clean Mo leads. There is no W contamination (or C outgassing) that you could have if you used David Wieliczka’s nude filament suggestion.    

 

I’ve attached a photo of the G8 form-factor lamp that I like best.  I use the General Electric brand because it is handy.  Brand doesn’t matter, just make sure it is a quartz lamp.

(If your mail is text only, see http://www.lampsplus.com/products/35-watt-120-volt-bi-pin-halogen-g8-light-bulb__34982.html for the photo).

 

I’ve used varieties from 120V AC down to 12V DC with no problems. (Pick the bulb to match whatever power supply you have available.)  I have never broken one even at the highest power ratings.   If you over power them, the filament burns out and you just have a dead quartz bulb in vacuum.

 

I hope this helps.

 

Best,

Gary

 

 

════════════════════════════════

Gary Navrotski, P.E., Ph.D.           navr...@anl.gov

Advanced Photon Source              Office:  437-E002

Argonne National Laboratory        calendar link

9700 South Cass Avenue               Ph:    (630)252-7576

Argonne, IL 60439-4801               Fax: (630)252-9350

════════════════════════════════

[P.C. Snijders]

All, thanks for the responses.

 

As a summary:

 

The suggestions offered to me were:

 

-a tungsten filament (e.g. from a heat lamp bulb from the store) mounted on thicker Cu wire feedthrough. Outgassing and W deposition from the filament may be an issue.

If oxidation is a possibility (such as in an oxide MBE system), filament burn-out may occur.

 

-Overhead projector high power halogen bulbs - can be used for increased bake-out efficiency as well. RGA did not show contamination. Semiconductor samples remained clean. Quartz shell is thick enough to not crack under overpressure (i.e. halogen pressure inside the bulb and vacuum outside).

Specifically, G8 formfactor bi-pin 35 W halogen bulbs (such as this one:

 http://www.lampsplus.com/products/35-watt-120-volt-bi-pin-halogen-g8-light-bulb__34982.html, or a 35 W 12 V from the same site) should work.

Note to clean off the ink (power and voltage) from the bulb if present.

(and as always: no touching with finger grease).

Leads of these bulbs used to be Mo - which would be a problem for systems with ozone (as MoO3 has a high vapor pressure, possibly polluting samples with Mo).

 

 

Thanks to Scott Schmucker, David Wieliczka, Josh Lipton-Duffin, and Gary Navrotski for suggestions!

 

Paul