Re: 3m plant case of invisible wall

A fascinating question Ryuaska, and thanks for bringing it to MadSci.
I think this is an example of a charged sheath vortex, something that 
happens in tornadoes. In this case the high speed of the polyester base 
creates very large static voltage differences – in the same way the moving 
belt does in a Van Der Graaf generator. Because of the scale and the 
geometry of the situation a spinning vortex of air is created, which also 
becomes very highly charged, and is stable because of the conditions of 
its creation being held constant. I would guess the “wall” is experienced 
because of opposing forces – charge and static forces on one hand and air 
pressure differences and the effect of gravity on the body on the other. 
Insects and birds are not held in place but sucked upwards onto the moving 
web.  
It is clearly reproducible, because the people in the plant concerned were 
able to demonstrate the effect on more than one occasion. Their failed 
attempts to reproduce it point to the mechanism as high humidity destroys 
the effect, because charge will dissipate more easily in moist air.
There are many links available through the web address in your question – 
with many speculative attempts to explain things, and diagrams showing the 
situation. Take a look at this one, which shows how tornadoes can cause 
similar effects:
 http://uk.geocities.com/tornad
odrive/ 
It was referenced on this page:
  http://www.esdjou
rnal.com/articles/final/final.htm 
which goes into some of 
the physics concerned. As for the phenomenon being created to order for 
military or other purposes in the field – this seems unlikely – because so 
much depends on atmospheric conditions, and I doubt if “wall” is the 
correct description – it is probably not planar at all. To stop something 
like a train would need energy generated equal to the energy of the train, 
so again – not practical.
Thanks again for the question – it points to a really interesting and 
perhaps not well known or understood phenomenon.