Permanent magnet device for magnetic resonance analysis

Abstract

The invention discloses a permanent magnet device for magnetic resonance analysis. The permanent magnet device comprises a yoke, magnet pole plates, guide iron and shimming coil plates; one pair of symmetrical magnet pole plates are fixed to the yoke; the yoke encloses a closed magnet loop, and the magnet pole plates are located in the magnet loop; the shimming coil plates are fixed on the magnet pole plates through the guide iron; heating resistors are fixed onto the yoke; the heating resistors are connected with a constant temperature control power source; and the magnet pole plates are provided with temperature sensors; the permanent magnet device further comprises a PID constant temperature control system for regulating the current of the heating resistors to control the uniformity of a magnetic field; the temperature sensors are connected with the PID constant temperature control system; the shimming coil plates, a shimming power source group and an automatic shimming adjustment system are connected with the PID constant temperature control system; and the PID constant temperature control system adjusts the operating current of the heating resistors according to the compensation current of the shimming coil plates. With the permanent magnet device for magnetic resonance analysis provided by the invention adopted, the problem of deterioration of the stability of the magnetic field caused by magnet temperature variation which is further caused by heat emission increase of coils can be solved.

Description

technical field

[0001] The invention relates to a permanent magnet device for magnetic resonance analysis. Background technique

[0002] Magnet is a key component in all NMR systems, even called the heart; its main technical indicators include uniformity, stability, and uniform area range; currently, superconducting magnets and permanent magnets are mainly used as NMR magnets. Superconducting magnets are expensive, and there are certain differences in the uniformity and stability of permanent magnets. Therefore, permanent magnets need to be shimmed. There are several methods for shimming. The first is the magnet design, and the second is the control of the magnet process (including the uniformity of the magnet particles, the uniformity of the magnetization angle, the uniformity of the sintering temperature of the magnet, smoothness of the surface of the magnetic steel), mechanical shimming (mainly to adjust the parallelism and concentricity of the magnetic steel), passive s...

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