Magnetic field homogenizing method and apparatus, and magnetic field generating apparatus
View Patent ↗For the purpose of efficiently homogenizing a magnetic field, when homogenizing a strength distribution of a magnetic field generated in a space between a pair of facing pole surfaces, a continuous magnetization distribution for homogenizing the strength distribution of the magnetic field is determined with respect to planes on which magnetic elements are to be disposed for homogenizing the strength distribution of the magnetic field; and magnetic elements are disposed based on the magnetization distribution. The magnetic distribution is determined as a polynomial of an orthogonal function. The polynomial is determined by an optimization method. The optimization method is a method of least squares.
1. A magnetic field homogenizing method for homogenizing a strength distribution of a magnetic field generated in a space between a pair of facing pole surfaces, comprising the steps of:
determining a continuous magnetization distribution with respect to planes including one of a plurality of said pole surfaces and a plurality of plates attached to said pole surfaces on which magnetic elements including shim magnets are to be disposed for homogenizing the strength distribution of said magnetic field; and
disposing said magnetic elements on said planes based on said magnetization distribution, wherein said determining the magnetization distribution includes optimizing the magnetization distribution before said disposing said magnetic elements on said planes.
2. The magnetic field homogenizing method of claim 1 , wherein said magnetization distribution is determined as a polynomial of an orthogonal function.
3. The magnetic field homogenizing method of claim 2 , wherein said polynomial is determined by an optimization method.
4. The magnetic field homogenizing method of claim 3 , wherein said optimization method is a method of least squares.
5. The magnetic field homogenizing method of claim 1 , wherein said disposition of said magnetic elements is achieved based on said magnetization distribution that is discretized.
6. The magnetic field homogenizing method of claim 1 , wherein said planes are said pole surfaces.
7. A magnetic field homogenizing apparatus for homogenizing a strength distribution of a magnetic field generated in a space between a pair of facing pole surfaces, comprising:
a calculating device configured to determine a continuous magnetization distribution with respect to planes on which magnetic elements are to be disposed for homogenizing the strength distribution of said magnetic field, wherein said planes include one of a plurality of said pole surfaces and a plurality of plates attached to said pole surfaces; and
a disposing device configured to dispose said magnetic elements on said planes based on said magnetization distribution, wherein said magnetic elements include shim plates, and said calculating device determines the magnetization distribution by optimizing the magnetization distribution before said disposing device disposes said magnetic elements.
8. The magnetic field homogenizing apparatus of claim 7 , wherein said calculating device determines said magnetization distribution as a polynomial of an orthogonal function.
9. The magnetic field homogenizing apparatus of claim 8 , wherein said calculating device determines said polynomial by an optimization method.
10. The magnetic field homogenizing apparatus of claim 9 , wherein said optimization method is a method of least squares.
11. The magnetic field homogenizing apparatus of claim 7 , wherein said disposing method disposes said magnetic elements based on said magnetization distribution that is discretized.
12. The magnetic field homogenizing apparatus of claim 7 , wherein said planes are said pole surfaces.
13. A magnetic field apparatus comprising:
a pair of facing pole surfaces, wherein a space is formed between said facing pole surfaces;
planes on which magnetic elements are to be disposed, wherein said planes include one of a plurality of said pole surfaces and a plurality of plates attached to said pole surfaces, said magnetic elements disposed on said planes based on a continuous magnetization distribution over said planes determined to homogenize a strength distribution of the magnetic field in said space, and said magnetic elements include shim magnets;
a first device; and
a second device, wherein said first device configured to determine the magnetization distribution by optimizing the magnetization distribution before said second device disposes said magnetic elements on said planes.
14. The magnetic field apparatus of claim 13 , wherein said magnetization distribution is determined as a polynomial of an orthogonal function.
15. The magnetic field apparatus of claim 14 , wherein said polynomial is determined by an optimization method.
16. The magnetic field apparatus of claim 15 , wherein said optimization method is a method of least squares.
17. The magnetic field apparatus of claim 13 , wherein said magnetic elements are disposed based on said magnetization distribution that is discretized.
18. The magnetic field apparatus of claim 13 , wherein said planes are said pole surfaces.
19. The magnetic field homogenizing method of claim 1 , wherein said optimizing the continuous magnetization distribution comprises reducing a difference between said magnetic field and a homogeneous magnetic field.