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Has anyone seen this before?

Discussion in 'Lighting' started by Amelia M. Samples, Nov 23, 2003.

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  1. Apologies if this shows up as a duplicate, but Google seems to have "eaten"
    my first post...
    I'm a collector of lightbulbs, and use one of my "plasma globes" to
    check the discharge lamps I get to see if their arc tubes are still
    gas intact. I recently acquired a few newer HPS lamps, they glowed as
    normal when I applied the current from the globe, but when I removed
    the power (turned the globe off) - the arc tube KEPT GLOWING...I know
    that they keep glowing reddish orange normally when they cycle at EOL,
    but I have never seen this phenomenon before. When I had the lamp
    connected to the output (direct coupled - output wire of flyback
    directly connected to bulb base) the lamp glowed the usual Ar/Xe
    spectrum, with the Na color at the electrodes like I have seen so many
    times before...but when I turned the globe off, the arc tube was
    luminescent - only the discharge streamer and Na color had gone, and
    the intensity was reduced. I have pictures at my site...
    www.clubsilicon.com/naglowpowered.jpg
    www.clubsilicon.com/naglowunpowered.jpg
    Does anyone know what's going on here? I've never heard of luminescent
    aluminum oxide before...then lamp in question is a Sylvania Lumalux 200W
    that appears unused. I went thru a small pile of lamps, my SLI lamps showed
    no trace of this effect (as well as showing Ne color in the starting
    discharge), a couple of used GE 1000W lamps showed a bit of glow, but not
    nearly as much as the Lumalux.
     
  2. I have seen this before sometimes. Some HPS arc tubes do phosphoresce
    after operation at low current and low temperature (room temperature). I
    think it's a couple older (but in new condition) 1 KW GE "Lucalox" lamps
    that did this for me. I somewhat remember my arc tube afterglow being
    reddish.
    Mercury vapor lamp arc tubes often have some dim afterglow after being
    operated at low current at room temperature.

    - Don Klipstein ()
     
  3. nanotech1

    nanotech1 Guest

    i have seen this phenomena on a hand held battery operated tugsten halogen
    spot light ( the 1,000,000 c.p. type )
    if you turn it off after a 3 or more min of operation you will see a faith
    blue glow of the quarts envelope that dims away in about 30 sec to one min
    ( it suprized me when i notice it the first time i saw it )

    the way i analysed it is the halogen or any other gas get charge with excess
    electrons and when it is turn off the electrons
    discharge to the surrunding envelope witch may have a little fluorescent
    propriety that gives the glowing

    please correct me if i am wrong
     
  4. It is a HF output, but what perplexed me was the glow after I turned the
    power off - I love demoing the distance glow for friends..."look - it lights
    up when I hold it...;)" - I've just never noticed that blue glow after the
    RF field was removed. It is almost a Cerenkov
    (http://nova.nuc.umr.edu/~ans/cerenkov.html) - color...maybe I can save this
    pic and scare my friends with the "atomic light bulb" (it contains atoms, so
    technically, it's true;))
    thanks...
    A
     
  5. Amelia, I posted a very similar question a couple years ago related to an
    automotive MH burner exhibiting a very similar blue afterglow. Got several
    good answers. Thread is here: http://tinyurl.com/wcwp

    DS
     
  6. I remember doing that with my 1KW GE "Lucalox" and saw a single line
    somewhere in the red. Makes me think some trace of something in the arc
    tube material, definitely not anything glowing in the gas. Maybe
    strontium, maybe europium, maybe who knows what??? I no longer remember
    whether it is near 610 nm (orangish) or further out in the red.

    Some Philips UV-absorbing doped quartz (or possibly hard glass) bulbs
    fluoresce/phosphoresce whitish slightly greenish blue, and that has a
    broad continuous spectrum.

    - Don Klipstein ()
     
  7. thanks....I'll try to get hold of the spectroscope and some 'dark' time in
    the lab...
    A
     
  8. I am familiar with that one, and I thought the lamp needed to be warmed
    up enough to get some sodium vapor in order to do that.
    If it was sodium, then it was the only sodium line being produced.
    I did not see any 515 nm at the time, and both that and the 616 nm ones
    are S to 3P transitions.

    The lamp was cold and getting low current, and the radiation from the
    discharge looked like just xenon radiation.

    - Don Klipstein ()
     
  9. I went thru another stash of lamps and was able to reproduce the effect in a
    couple of other new Lumalux lamps, but no other manufacturer's lamps will do
    it. I also noticed a glow in the glass envelope. After the long weekend
    (everything's closed) - I'll try to get in the lab...thanks to the group for
    the help...
    me

     
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