Having just conducted a experiment in which I levitated a small neodymium magnet above a liquid nitrogen cooled YCBO superconductor, I was wondering if anyone knew of any factors that affect the height at which the magnet levitates at (e.g does magnet strength affect it?), and whether this applies inversely (i.e does a stronger magnet allow a superconductor to levitate higher above it?). In addition, I was wondering whether anyone could think up an inexpensive (under £100, ($~170)) way to keep liquid nitrogen above the superconductor, which is 1" in diameter, in order that it remains at its critical temperature. I had thought of a half ping-pong ball and have yet to try that out - however, there is little insulation provided by that, so it would only work for a short while.
Sorry for the long post...
Any ideas would be very welcome.