More Observations

Xrays had a distinct shadow, caused probably by the electron impact region of the magnet. At higher negative bias, the shadow moved down, indicating either a broadening of the electron spot or a motion of the spot poleward.
Spinning the magnet slowly (few rpms) caused shadow pattern to move with magnet motion.
Spinning the magnet quickly (500 rpm) caused a slow (~1s) random fluctuation in X-ray shadow, as if electrons were changing energy randomly.

Xrays had a distinct shadow, caused probably by the electron impact region of the magnet. At higher negative bias, the shadow moved down, indicating either a broadening of the electron spot or a motion of the spot poleward.