TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here:

Linear Induction Slides

Discussion in 'Cars and Transportation' started by Jeff, May 16, 2008.

  1. Jeff

    Jeff Member

    Dec 19, 2007
    Somewhere, Pennsylvania
    #1 Jeff, May 16, 2008
    Last edited by a moderator: Mar 13, 2016
  2. TEG

    TEG TMC Moderator

    Aug 20, 2006
    Silicon Valley
    Cool! (I guess that qualifies as electric transportation)
  3. doug

    doug Administrator / Head Moderator

    Nov 28, 2006
    Stanford, California
    Yeah, that's pretty neat. I suppose you shouldn't ride if you have a pacemaker, though. Also might be a small issue if you have a metal plate in your leg.

    I remember when they first started putting linear induction motors (LIM) on roller coasters. Always thought that was a great idea. This is a nice extension of that.

    Someone in the vid mentions that an aluminum (Al) plate is in the base of the raft. Al is a non magnetic material, however the magnetic field of the LIM induces currents in the Al. Those currents produce their own magnetic field which then interacts with the field from the LIM. This is how the LIM is able to apply a force onto the raft even though the raft itself is not magnetic.

    I used to do a little science demo for kids based on that principle. I had an Al disk which was supported from below such that it was able to spin freely about its axis. Then I had a bar magnet with a piece of string tied round the middle. First I'd prove that the Al disk was non magnetic by showing that there was no attraction between it and the magnet. Then I'd suspend the magnet above the disk with the string, and then flick the magnet so that it would start spinning. Eventually the Al disk would spin as well. Amazing how the kids and especially their parents would look the demonstration as if it were magic.

    In the lab I have an 8 Tesla superconducting magnet with optical windows. When I ramp up the field for the first time during an experiment, I have Al cover plates that I leave on the windows just in case there's a loose tool or bolt that might want to launch towards the magnet and break a window (which can be catastrophic). Once the field is up and everything looks safe, I have to remove those Al plates by hand. It's always a creepy feeling since the plates basically don't seem to want to move. The faster I try to move them the more force there is holding them back as if I'm pulling them through invisible molasses. This is essentially the same as dynamic braking.
  4. vfx

    vfx Well-Known Member

    Aug 18, 2006
    CA CA

Share This Page