Abstract: A stator has a plurality of core pieces being arranged in a ring shape around a rotation axis, and is configured such that a coupling part having a fitting structure is formed between the core pieces adjacent to each other in an arrangement of the ring shape, the coupling part allowing rotation about a pillar portion and restricting displacement in the axis direction by a snap-fit coupling that is formed with the pillar portion being provided on the yoke side of one of the core pieces and extending in a direction parallel to the axis and an open ring portion being provided on the yoke side of the other of the core pieces.

Abstract: The ammonia synthesis system of the present invention includes an ammonia synthesis reaction unit (10) that synthesizes ammonia from nitrogen and hydrogen; an ammonia cooler (20) that cools an ammonia-containing gas discharged from the ammonia synthesis reaction unit (10); a gas-liquid separator (30) that separates ammonia liquefied by the ammonia cooler (20) from a circulated gas; and an ammonia synthesizing gas supplying unit (40) that supplies nitrogen gas and hydrogen gas, the circulated gas being supplied to the ammonia synthesis reaction unit, the circulated gas supplied to the ammonia synthesis unit having an ammonia gas concentration of 3% by volume or more. The method for producing ammonia of the present invention includes reacting nitrogen and hydrogen using a circulated gas having an ammonia gas concentration of 3% by volume or more and using an ammonia synthesis catalyst under a condition of a reaction pressure of 10 MPa or less to produce ammonia.