| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnet apparatus capable of raising the uniformity of the static magnetic field by suppressing leakage magnetic fields.SOLUTION: A magnet apparatus comprises: a pair of opposingly arranged, nearly disk-like magnetic poles 4U; and a yoke 3 which is C-shaped or U-shaped in side view, and both ends of the C shape or U shape of which are positioned close to the magnetic poles 4U. The yoke 3 has a yoke side opposing part 15U which is positioned close to and opposed to the magnetic pole 4U. The yoke side opposing part 15U has: a center band area 15b including a part of a vertical symmetric plane α of the yoke 3; and both sideband areas 15c positioned at both sides of the central band area 15b, apart from the vertical symmetric plane α. The center band area 15b (W3b) is higher than both sideband areas 15c (W3c) at a height W3 from a yoke side opposing surface 15a which is close to and opposed to the magnetic pole 4U of the yoke side opposing part 15U. The height W3 from the yoke side opposing surface 15a of the yoke side opposing part 15U decreases broadly monotonously as it is separated from the vertical symmetric plane α and the maximum and minimum values are different. |
