Yesterday my hubby took me to his place of work to show me the ‘toys’ he works on/with. Let me share!
First was the MRI machine. Have you really gotten to examine one of these? With your clothes on (not a paper gown), and standing outside the hole (or bore), these things are pretty amazing. Also amazing is what they do to aluminum.
You probably know that MRI machines work with magnets, so magnetic metals are strictly forbidden around these machines. We left things–my purse, his ID badge and wallet–in the outer room, then walked in to the MRI room. The machine hummed, and the room was cool (deep-freezing keeps the magnet functioning; a power-outtage means there’ll be a ridiculous expense to re-start). Still, nothing weird. This was a machine just like those you’d see in a hospital, with a table/bed/shelf-y slider going into a doughnut-shaped body-length space.
After a moment’s observation, he pulled out a wire attached to an aluminum box. Aluminum isn’t magnetic, so it can be in the room without fear of damaging the MRI. The wire, however, is magnetic under that layer of insulation. The wire, once he stepped close enough, pulled to the side of the machine and snuggled against the outside. But if he waggled the wire near the hole, or bore, it went wild, pulling and snaking, trying to leap into the bore. The magnetic field sucked at it, and flinging the end of the box about made the wire leap and jump like a fish in a current, or like your hand outside a car’s window while you drive on the highway. It’s amazing to watch magnetic currents suddenly become visible.
Next came the aluminum box without a wire. It was hollow, like a gutter’s downspout, and about five inches long. Not heavy, not amazing in any way. He had me wave the box in my hand over by the door to the room. Duh, nothing happened except that I waved a box. Then we walked over to the opening of the bore. Next to the whole, he had me wave the box again. It slowed, as if I was trying to move it under water and the water was pressing back. In front of the bore, moving the aluminum box became even harder, as if something opposed my motions. I saw hubby try it, and it looked so fake. Without trying it myself, I’d only believe what it looked like: a badly-done acting job of a special effect.
He explained this repulsive force is caused by eddy currents generated by the magnetic fields. It was simple to see how the force grew and flowed by how hard the aluminum box fought pushing, how it slide along the field’s ‘line of flow.’
Then he took me to the research machine. This machine is over 2 times stronger than the ones found in hospitals now. The back of this machine, where the magnet is, was huge. It was wrapped in layers of shielding. Still, a door blocked this area, so people didn’t walk behind the machine and into the magnetic field there willy-nilly. The magnet, hubby told me, was so strong that if you walked too fast behind the bore, your eyes would see stars. I was not even tempted to try.
What I did discover, though, was that there was some metal in my shoes, probably nails joining my sole to the body of the shoe. I had to shuffle my feet slowly and low to the ground so that the magnetic forces didn’t pull my feet up from under me. It felt very odd, that sensation of something trying to lift your feet from below. It’s not the way gravity works, after all. Also, whenever I’d shift my body, the magnetic forces worked on the tiny bits of metal in my, um, well–in the straps of my undergarment. The straps leapt and flopped, feeling very much like flopping fish, or like grasshoppers taking flight from my skin and landing again–all under my sweater. That was very unnerving! (I’m glad it wasn’t an underwire. *shudders*)
The Eddy currents here were awesome. I could barely move a half-pound of aluminum. When the box was set on edge, so that it stood like a diamond instead of square, it stayed there, perfectly balanced against the force of gravity that wanted it to fall flat. And feeling the strength of the fields and direction of their currents was simplicity itself. It was as if there was a track that the box moved along when it went parallel to a field, and like pushing sideways against that track if I tried to shove completely against the current.
As we were leaving, we stopped in the lab for a moment while hubby dropped off the aluminum boxes. A co-worker was welding something, and we chatted for a moment. then hubby pointed some things out along the wall. And then came the whammy. “Oh,” he said. “There’s the 3-D printer.”
“You have a 3-D printer?” I managed to squeak. “That is awesome!”
He and his co-worker looked at one another, then at me. I could see what they were thinking: show her cutting edge magnetics research, and it’s cool, but a 3-D printer makes her sparkle.
It wasn’t working at the moment, but I got to see some things it’d made. It apparently is a smaller machine, since the one assembly I saw had been created in pieces and then put together manually afterwards. And it had taken some five weeks to create this thing, which was about 2.5 feet long by a foot or so wide. Still, I was amazed, and, absorbed by all the things this printer could do, I bubbled all the way home. And it wasn’t just the woozy-headedness left over from exposure to high magnetics, either.
Isn’t science amazing?