First and second sets of magnet assemblies and magnetic assemblies are alternately arranged in a circumferential direction in a first portion along an axial direction, and the first and second sets are alternately arranged in the circumferential direction in a second portion along the axial direction. When viewed in the axial direction, the first set of the first portion and the second set of the second portion overlap with each other, and the second set of the first portion and the first set of the second portion overlap with each other.