A Design Method of Magnetic Resonance Halbach Type Shim Coil

Abstract

The invention discloses a design method of a magnetic resonance Halbach type shim coil, which divides the cylindrical surface of the coil into grids; selects target points on the target spherical surface; establishes the grid node current density flow function and the grid node current density Finite difference relationship; set the magnetic field strength of the target point; establish the equations between the current density flow function of the grid node and the axis direction component of the magnetic field strength of the target point; construct the combined constraint function of power consumption and local uniform distribution, obtain the constraint matrix, and use Tikhonov The regularization method solves the specific value of the current density flow function of the grid node; according to the equipotential line of the distribution of the current density flow function of the grid node on the corresponding coil cylindrical surface, the equipotential line is arranged to obtain the winding of the shim coil model. The invention can effectively eliminate the inhomogeneous magnetic field components of each order of the main magnetic field introduced by the Halbach type magnet system due to manufacturing errors, and further improve the uniformity of the main magnetic field of the Halbach type magnet system.

Description

technical field [0001] The invention relates to the technical field of nuclear magnetic resonance shim coils, in particular to a design method of a magnetic resonance Halbach type shim coil. Background technique [0002] Halbach type (also known as Halbach, Halbach, etc.) magnet is a new type of magnet design proposed by American physicist K.Halbach in the 1980s. The Halbach type magnet is composed of multiple magnetic blocks with different magnetization directions according to certain rules, and can use less magnetic materials to generate a more uniform unilateral magnetic field, such as figure 1 shown. Compared with conventional magnet designs, Halbach-type magnets have the advantages of smaller volume and less material consumption when the effective space and field strength of the magnets are comparable. MRI) and electron paramagnetic resonance (EPR) and other magnetic resonance instruments have great application prospects. However, Halbach-type magnets also have the p...

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Problems solved by technology

[0003] In order to solve the problem of the inhomogeneity of the main magnetic field of the Halbach-type magnet system, the patent of the present invention proposes a design method of the magnetic resonance Halbach-type shim coil. Inhomogeneous magnetic field components to improve the uniformity of the main magnetic field (such as figure 1 shown)

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