Electrostatic wall

  1. wolram

    wolram 3,762
    Gold Member

    I came across this by accident.

    http://amasci.com/weird/unusual/e-wall.html.

    David Swenson of 3M Corporation describes an anomaly where workers encountered a strange "invisible wall" in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This "invisible wall" was strong enough to prevent humans from passing through. A person near this "wall" was unable to turn, and so had to walk backwards to retreat from it.
     
  2. jcsd
  3. Ivan Seeking

    Ivan Seeking 12,529
    Staff Emeritus
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    Gold Member

    At a glance this Bill Beaty [the source] seems to be a bit fringe but okay... not sure yet. Still the claim itself sounds total bogus to me.
     
  4. Nope, I come from Australia and our biggest telecommunications company Telstra (the old telecom) is running adds that suggest they have the tech to do such a thing and will be selling it within ten years. I know it sounds like complete garbage to suggest it's possible and I was equally surprised to see a credible company like Telstra advertising such a futuristic idea but they are and I don't know what they think they have but it shows a woman walking through a field that according to the add detects your person as you approach and allows you to pass through while stopping unwanted trespassers from entering. They also say that they will be providing this service in the future? Sounds like science fiction and as I said I was surprised they said or implied it would be possible but they did and I would like to here if anyone has got any info on the matter as I know a fair bit about QFT and this sounds like crap but surely Telstra aren't scientifically challenged. It scares me to think what tech realy big buisness may own and don't release to the likes of us until it's commercially viable.
     
  5. wolram

    wolram 3,762
    Gold Member

    It sure sounds (futuristic) i know nothing about Telstra, but i guess they have little to gain from crackpot claims.
     
  6. Hmm...it would seem to me that this is more a problem of plasma dynamics than it is of electrodynamics. Of course, if Telstra really is marketing something of this nature, I would think that long-term exposure is unhealthy, simply because the production of ionized air will create a ton of ozone along with it.
     
  7. Ivan Seeking

    Ivan Seeking 12,529
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  8. That is interesting, Ivan. And I did chuckle at this:

    "..Curiously, the plasma window functions in a way which very superficially resembles the force field in the Star Trek TV series. For example, there is an area on the Enterprise (the Shuttle Bay) from which shuttle crafts leave for flights into space. At the edge of that area there is a force field (with a bluish glow at its perimeter) which separates the atmosphere (air) on the Enterprise and the vacuum (space) outside. Similarly, in the plasma window, a plasma (which is an ionized gas confined by electric and magnetic fields) separates air from a vacuum by preventing the air from rushing into the vacuum. A variety of gases can be used to operate this window. When argon is used, the window color is blue, similar to that shown in Star Trek..."

    I was rather surprised when I saw the date, 1998. I thought this was something brand new. The original post about "the wall" is quite old too, 1995. Interesting.
     
  9. That Telstra ad is about network security.

    This description is for those who haven't seen the ad: The ad basically shows a woman walking along the footpath in a city. She then turns and walks through a glass panel (as if it didn't exist) into a building. Then other people try to enter through the same panel, but alas, they hit the glass and are not granted passage.

    It says something along the lines of "network security so advanced only you can pass through". Obviously the ad is meant metaphorically and not literally. I highly doubt a telecommunications company will ever even try to research a technology so abstract, let alone questionable in terms of the physics.
     
  10. I think all that's probably happening here is that, as the person approaches the highly charged sheet of plastic they become similarly charged. Like charges repell and they are prevented from approaching closer by simple electrostatic repulsion.
     
  11. Isnt it possible though?
     
  12. There is a huge static charge developed when plastic sheet is unrolled. It is usually a hazard for these companies. While this "wall" was active a guys static meter pegged at 200 KV from 50 ft from the spools. He estimated the voltage to be in the megavolt range.

    The wall was perpendicular to the moving sheet. There is a rough drawing of the arrangement somewhere on the net.

    The final prevailing theory was that the moving charged sheet induced a rotating region of highly charged air between the sheet and the concrete. Humidity effectivly cancelled the effect. Due to the action of static charge moving in this way it tends to center on the sheet, and in the air beneath the sheet. This was explained as the moving charges behaving like similar current flows in wires. The current flows are attracted together by their magnetic field.

    Crazy but true. The plant owner said he didn't know wether to, "fix it or sell tickets."
    They fixed it.
     
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