Passive Shimming by Eliminating Spherical Harmonics Coefficients of all Magnetic Field Components Generated by Correction Iron Pieces

• Published in: IEEE transactions on magnetics Vol. 50; no. 2; pp. 605 - 608
• Main Authors: Noguchi, So, SeokBeom Kim, Hahn, Seungyong, Iwasa, Yukikazu
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01-02-2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Harmonic analysis; Iron; Magnetic moment; Magnetic moments; Magnetic resonance imaging; Magnetism; Materials science; MRI; Nuclear magnetic resonance; nuclear magnetic resonance (NMR); Optimization; Other topics in materials science; passive shimming; Physics; spherical harmonics expansion; Superconducting magnets; MRI; Magnetic resonance; nuclear magnetic resonance (NMR); Magnetic field effects; Magnetic moments; passive shimming; Nuclear magnetic resonance; Magnetic fields; Expansion; spherical harmonics expansion; Magnetic properties; Magnetic moment
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2013.2276736

When a magnet generating highly homogeneous magnetic field is designed, a shimming is required. The shimming is usually performed so that the magnetic field only in the axis direction is compensated by iron pieces and/or coils. The compensation is commonly achieved by eliminating the coefficients of the spherical harmonics expansion of the magnetic field generated by the main magnet. Some papers showed the coefficients of the spherical harmonics expansion in only the z-direction for passive shimming. However, recently some magnets generate a magnetic field tilted from the z-axis, such as a magic-angle-spinning nuclear magnetic resonance/MRI. It is, therefore, necessary to eliminate the coefficients of the spherical harmonics expansion in the x- and y-direction.