Also, not a physicist, but one would expect by using the coil to induce the angular momentum its easier to implement changes to the system overall. Firstly, a variable input capability on the coil means they can play with that without too much hardware modifications. Secondly, a physical coil swap, in the event the coil is the wrong length, as opposed to replacing the electrodes with a different spiral shape, in the event the initial shape didn’t produce the desired result. It would seem too costly to have to go through many electrode shapes vs. using a simple coil of copper to get the same effect. There’s probably a simple physical reason, but if its not that, its probably a logical choice that won out.
