Magnetically levitating graphite can be moved with laser
(phys.org)
(Phys.org)—Magnetic levitation has been demonstrated for a variety of objects, from trains to frogs, but so far no one has developed a practical maglev-based actuator that converts some external source of energy into motion. Now in a new study, researchers for the first time have used a laser to control the motion of a magnetically levitating graphite disk. By changing the disk's temperature, the laser can change the disk's levitation height and move it in a controlled direction, which has the potential to be scaled up and used as a light-driven human transportation system. Laser light or sunlight can also cause the levitating disk to rotate at over 200 rpm, which could lead to a new type of light energy conversion system.
I can imagine in a controlled environment, like a factory setting or shipping center (think of Amazon's massive fulfillment centers) a maglev sled using a laser light to guide it would require virtually no energy for movement on it's rounds.
The experiment also demonstrated the disk would spin just using sunlight - could we one day see massive disks hovering over a field of magnets using sunlight to cause it to spin, would it generate enough torque to drive machinery?
Demonstrations of a diamagnetic graphite disk being moved in a linear direction and rotated by a laser, and rotated by sunlight. A large enough graphite disk could potentially be used as a new type of light-driven human transportation system. Video credit: Masayuki Kobayashi and Jiro Abe
Rotation also occurs when the set-up is exposed to sunlight. By converting solar energy into rotational energy, the disk can reach a rotational speed of more than 200 rpm, which could make it useful for applications such as optically driven turbines.
Of course a 'Crookes radiometer' can spin just using sunlight, but there's no useful torque to be gained from this device for driving machinery. (There are multiple theories over the cause of this effect, more than a hundred years after it's first demonstration.)
I think this experiment shows a great deal of potential, but also how little we still grasp magnetism.
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