Comment by sharpshadow

“The fastest rotation achievable by standard motors is of the order of 10 kHz and a record of 667 kHz is reported for a millimetre-sized magnetically levitated sphere.”

From the spinning metal cylinder you can extract EM energy. It’s like a flywheel. The trick is how do you bring up the spin in the first place. The indication here is I guess that you can amplify the spin with EM waves.

“…depending on its rotation speed Ω compared to the field oscillation frequency ω, it can either absorb or amplify.”