Levitation using microwave-induced plasmas

[nextwave]

Hi all,

I came across this interesting paper the other night:

http://www.odu.edu/~spopovic/index_files/pub/LevitationPaper.pdf

An experiment was conducted involving the levitation of a Syrofoam object above a plasma created by a microwave horn.

The following explanation given for the levitation effect seemed vague (purposely?) to me.

"The thermal effect of the surface plasma brings about a localized increase in the pressure and results in a vertical flow of air, thus levitating the object"

I would think a local DECREASE in air pressure would first happen as the hot (less dense) plasma expands which would result in an updraft of air as cooler (denser) air rushes in from the sides due to the pressure gradient. However, in the photos the plasma appears nothing like the vertical shape of a candle flame as one would expect (are the changes happening too quickly to be seen before the next pulse ?).

I don't know anything much about plasma physics or aerodynamics,but how much more complicated is the situation compared to a bonfire?

Anyway, what about practical applications ? How about building a microwave plasma version the Sun-powered Electro-Suspension car from Disney's Magic Highway USA that just travels on horizontal surfaces ? :)

See @ 7.05 mark:
http://www.youtube.com/watch?v=F6pUMlPBMQA&feature=related

 

[harralk]

I didn't read through the entire paper but it looks similar to a method of flying a reflective disc with a high powered laser. The laser heats up the air directly under the disc, causing it to expand, thus pushing against the disc.

If I understand what I'm seeing it's just taking advantage of a phenomenon which occurs when plasma is confined by thermal/fluid boundaries. I would think a laser would be more efficient than a plasma generator.