Sprengel pump flashes

Discussion in 'Physics' started by KL7AJ, Sep 26, 2016.

  1. KL7AJ

    Thread Starter AAC Fanatic!

    Nov 4, 2008
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    I was recently reading about the mercury Sprengel pump, which, until the arrival of the diffusion pump, created the highest vacuum possible. Several references to the Sprengel pump mention the periodic flashes of light in the high vacuum vessel, during the pumping process....but no explanations are ever given for this. Does anyone have any information on this?

    Eric
     
  2. GopherT

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    Nov 23, 2012
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    I would guess that glass holds electric charge very well and the Mercury falling through the glass tube can act like a silk cloth rubbing the glass and creating a static charge on the surface of the glass. The Mercury does conduct and can dissipate charge but, in the case of this vacuum pump, the beads of mercury are separated by the residual gas pulled from the bulb and, therefore, cannot form a continuous connection and, I would assume, the flash occurs either as 1) a bead of mercury passes by a specific point where charge was deposited on the glass from a previous bead, or, 2) as the bead comes in contact with the resivoir at the bottom. I would guess option 1 is more likely.
     
  3. KL7AJ

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    That sounds reasonable, though the only way to test it is to build one and see. I don't think the wifeypoo would appreciate me playing with a few quarts of mercury on her kitchen counter though. *-^
     
  4. GopherT

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    Nov 23, 2012
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    Yeah, You are in North Pole, AK. Getting sent to the dog house would be hella cold. Let's see if some guy in Russia posted a YouTube video of it.
     
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