Physicists: lifters - how do they work?

I don’t know whether any of you have come across these things called lifters before. They’re basically a triangular balsa wood frame with a pair of wires (one sometimes replaced by foil) running around the frame. One wire is then attached to a large power supply (normally a computer monitor or another supply capable of outputting large voltages) and turned on. The result being that the lifter levitates.

Pictures can be seen here http://www.mara.org.uk/Antigravity.htm (forgive the tin foil hattery of that website. There are more reliable sources but they seem to have crap pictures).

Searching for how they work gives two possible explanations. Either they work by causing ions to jump from the top wire to the bottom one causing a movement of air and lifting the craft, or they exploit the Befield Brown effect, where there’s a tendency to move from a negative charge to a positive one.

Firstly, are these things definitely real? Secondly, how exactly do they work? The Befield Brown explanation sounds like the craft is lifting itself off the ground! Thirdly, how useful could they be, is the upward thrust that they produce related to the voltage across their wires? What’s the largest one that’s been built? Can any lift themselves and their powersupply, yet?

Thanks.

This page explains how they work pretty well:

http://www.blazelabs.com/l-vacuum.asp

In short, it’s an ion wind effect. They generate no thrust in a vacuum. And they’re not terribly useful; the lift generated can barely support the lifter, let alone the power supply.