Magnetic levitation of a ball within a transparent tube

[artis]

Hi, after reading much interesting information on the subject I want to made a small project, the idea is to have a transparent plexiglass tube and a (diamagnetic?) material ball within the tube and to have permanent magnets outside the tube in such a way that I can suspend the ball so that it does not stick to the inner side of the tube as a ferromagnetic material ball would do in a similar situation.
The idea is to be able to move the tube back and forth or make a circle out of the tube and rotate it but the ball always maintains the same position where the external magnets are located.

I read that such levitation cannot be achieved by ordinary metals like steel balls from ball bearings because ferromagneetic materials tend to always move towards field maxima so one cannot achieve a stable position of such material but diamagnetic materials tend to move towards the field minimum.

Can you please give some advice on possible common easy to access diamagnetic materials and the arrangement of permanent magnets for such a setup to work?

thanks.

 

[sysprog]

A thin wafer of pyrolytic graphite or bismuth could exhibit the behavior you described. I imagine that making a hollow sphere of bismuth would be prohibitively difficult (bismuth is brittle and powders easily), but pyrolytic graphite can be grown onto a polypropylene sphere (like a table tennis ball). Perhaps a cube in a square tube would be simpler to make.

American Science and Surplus sells this graphite magnetic levitation demo apparatus for $12.00:

If you were to decide to make a more extreme device, you could use a graphite sphere or spheres in an evacuated ring tube, with sequenced electromagnets to drive the sphere(s) at various speeds around the ring.

 

[artis]

@sysprog thanks for stopping by, i see lots of videos on youtube about using bismuth and permanent magnets to have a simple levitation kit, as I understand it works both ways , either one has two larger pieces of bismuth and a magnet positioned between them or one has two magnets and a bismuth piece between the magnets doesn't matter right?

My idea sort of was what you mentioned, I see that bismuth powder is rather cheap I was thinking maybe I could buy that powder and coat it with some thin layer of plastic to form a sphere, maybe add some additional teflon spray just to make it have less friction and then try it out within a plexiglass tube , it should levitate a small distance from the walls,
One thing I'm not sure is would a simple B field perpendicular to the tube be enough to maintain the ball in position or would I need additional fields so that the ball doesn't want to push out ?

Now I am not sure whether a toroidal magnet would be required , also would the ball stay right inbetween the flux or maybe it would rather like to either be above or below the place where the flux cuts the tube? I am a bit unfamiliar of how exactly this works, the way I understand is that diamagnetic material expels B field lines similarly to a superconductor so the field loops around the material and in this regard such a material would tend to gravitate towards a place of weakest B field,