echisholm 5/2016

Have a relative (sort of) who works at a 3M plant. Shit still occasionally happens.

> You can't just say that and go away!! How are you not irresistibly

> interested in that?? I would've interrogated that relative so hard

It just came up in passing at Thanksgiving! I don't really know him that well; he's an in-law. He mentioned being able to throw small washers and bolts at the field and watching them get repelled. People got interested, and so someone came with a voltmeter, and after throwing a couple more, they checked for voltage, and there was a residual charge after they finally caught on on a plastic sheet to prevent immediate grounding. It also had a very slight magnetic field. It's apparently fairly common, but engineering hasn't come up with a solid explanation why.

ALSO: dc469 5/2016

I met this guy at an ESD meeting in austin once. He said the strength of the field maxed out his equipment at a distance so he couldn't get a maximum measurement.

After he published the paper he was contacted by NASA and all the three letter agencies asking for more info. He wanted to experiment around with it but no company had millions to throw into such a project (presumably, the government did). It had to be a pretty narrow window of temperature, pressure, humidity, etc. They kept the garage door open so that's where the insects and sparrows got sucked in (which obviously ruined the product).

He said it was actually known to the technicians for awhile before he experienced it and they just were kinda like "meh". Eventually they fixed the grounding issue on the machine and the problem never popped up again.

edit: found the ESD website. David Swenson apparently is still with them on their board of directors. http://centxesdassoc.homestead.com/

LINKS WIRED magazine 1/2018

ESD Journal

Askreddit 2017

Reddit TIL

Sticky Electrostatics, classroom physics demos

Another poly unwind setup (vid) Problems: coulomb forces would be expected to attract a person into the "chamber" formed by the PP film, and the attractive force should increase linearly across distance. There should be no "wall" in the center, a discrete wall is repulsive, also nonlinear.

If for some reason a person was repelled from the center of the chamber rather than being attracted, there still should be no "wall," since the repulsion force should exist over a large distance; it should act like a deep pillow which exerts more and more force as one moves deeper into it. Large fuzzy fields, this is how magnets and iron behave, and this is how e-fields and conductive objects should also behave.

A thought: unspooling of film typically generates a much higher net charge on the long piece of film than on the small surface of the spool. However, since charge is created in pairs, and net charge is conserved, the imbalances of charge must be equal and opposite. The charge on the entire length of moving film must be equal in magnitude to the charge on the spool. Yet the charge on the film is very large and is continuously increasing. The limited surface-charge on the spool required that opposite charge is being lost through some unseen path.

Very probably the spool is spewing out enormous quantities of ionized air with polarity opposite that of the charge on the moving plastic film.

Charged air would be created by discharge in the cleft between film and spool as the film was peeled from the spool. I wonder if film was being peeled from the top of the spool, so that any ionized air created in the cleft would be launched into the "tent-chamber" region? (If it was peeled from the bottom of the spool, the charged air would end up outside the "tent.") Or, if a corona discharge arises in the cleft between film and spool, perhaps the UV and e-fields of this corona can ionize the air on both sides of the exiting plastic film, and spray the charged air everywhere.

So, if the charged "tent" of film is negative in the above situation, and if a large quantity of positively charged air is being generated by the spool, then perhaps the "invisible wall" is caused by a cloud of suspended air ions held in position by e-fields. Perhaps it's a pressure gradient created by ionized air trapped under the tent by electrostatic attraction. Yet again this effect would be expected to create a diffuse zone of increasing force, not a "wall", but an "invisible pillow." Added note: concrete floors behave as conductors (resistors) in this situation. Where megavolts at microamps are involved, the division between insulators and conductors is at 10^6/10^-6 = 1000 gigaohms. Concrete resistivity is in the realm of megohms, so it behaves like a grounded metal sheet.

However, a volume of charged air is somewhat analogous to iron filings near a magnet. If a solid sheet of iron filings is held in place by a magnet, then a literal "wall" is created, and this wall will resist penetration by nonferrous objects. If in the above manufacturing plant, a sheet of highly charged air is for some reason being held in place by the fields created by the charged film, then a transparent "wall" made of charged air would come into being. It might produce pressures on surfaces, and resist penetration by human bodies.

My question is this: if the entire situation could be turned on its side, so the "invisible wall" became an "invisible floor", could a person *stand* on it? Have we discovered the long-sought "Zero-G waterbed?" :) - B.B. Reference: Article about the "Wall" in ESD Journal (IT'S BACK! 8/2000)

