This device (in its current form) is an entertaining low velocity magnetic accelerator.
Introduction:
The PMA was an entertaining side effect of my (temporarily) defunct railgun-EM weapon project. I began to wonder about magnetic flux lines, and began messing around with magnets, setting up many experiments, and getting several unexpected outcomes, which I may enumerate at a later time. This project proper began when I placed a steel ball bearing slightly off center on a disc-shaped refrigerator magnet, and it jumped away from my forceps, accelerating to the outer edge (pole) of the magnet. It occurred to me that this principle could be used to launch an object, if the object were dragged across the face of the magnet, but could be prevented from sticking. Essentially this is the same principle involved in a single stage coilgun. But how could the projectile achieve this behavior on a permanent magnet?
Experiments/findings:
In my efforts to force the ball-bearing to escape the force of the poles, I attempted cutting a notch in a frame around the magnet, hoping the ball would be slung over the edge. No such luck. Next I tried a simple ramp arrangement, which failed as well. Then it occurred to me that I was going about this all wrong, what I needed to do was set up a sort of Newton�s Cradle arrangement, to transfer kinetic energy from the ball-bearing to a non-ferromagnetic projectile.
The device:
I obtained two small bar magnets (oddly enough the �poles� were the long sides, not the ends) and placed them side to side at one end of a cardboard frame, like poles lined up and adhering to one another. I placed a ball- bearing at one end of this arrangement, where the north poles connected, and nudged it up with a toothpick. It jumped to the across the magnets, and jerked backwards, vibrating about halfway between the ends of the magnets. I placed a plastic bead about 3/4th the distance from one end to the other, in front of a small cardboard �ramp�, and reset and released the ball-bearing again. It sprung forward and knocked into the bead, sending it flying.
Why does it do that?
A magnet releases �virtual� (massless) photons at it�s poles. These photons make arcs around the magnet, exiting one pole and entering the other. These are known as magnetic flux lines. The ball-bearing is dragged along the inner (closest to the magnet) lines of flux, and comes to rest at their return point near the center of the magnet�s pole, where the flux is most intense. I made a suspension of steel filings in a glass of vegetable oil, and it made the flux lines quite easy to see. There are many more than what are shown in my diagram, but for simplicity�s sake I opted to leave them out.
What next?
I plan on constructing a larger version of my prototype. This will be a pair of giant neodymium iron boron magnets held together, with a track composed of two long non-conducting rails connected to the top. The real question is whether or not an accelerator of this type would work on a larger scale.
Interesting facts:
This accelerator shares characteristics with many other devices, for instance: The ball-bearing is pulled beyond the center of the magnet, as in a coilgun; the accelerator uses two parallel magnets, as in a railgun, and the motion of the non-conducting projectile is directed by the action of a magnetic �armature� (ball-bearing) as in an arc-driven railgun; The ball-bearing is accelerated by permanent magnets, as in a Gauss Gun.
Another thing to note is that the PMA behaves similarly to a coilgun, without requiring input of electricity.
If you choose to construct one of these devices, good luck, and have fun!
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