In April, Wang Qiuliang research group of Institute of electrical engineering, Chinese Academy of Sciences cooperated with Ningbo Jianxin Machinery Co., Ltd. to successfully develop the first 0.7T open superconducting magnet system for nuclear magnetic resonance imaging in China. The system is composed of two superconducting magnet systems with large separation gap and a complex shape yoke. A GM refrigerator is used to realize the zero volatilization of liquid helium in the system. It has an adaptive balance structure to overcome the huge electromagnetic force between the superconducting coil and the yoke. The superconducting magnet with the yoke forms a magnetic loop to effectively shield the divergence of the magnetic field (5 gauss line is less than 4 m). The system cost is reduced and the magnetic field is reduced The uniformity is improved.

The open MRI system has the characteristics of large openness, easy to realize the integration of interventional therapy and treatment, and can achieve the effect of real-time monitoring and reducing claustrophobia. At present, the open magnetic resonance imaging system is mainly permanent magnetic resonance imaging system, with the maximum central field intensity of 0.5T. The cost of the 0.7T open Superconducting Magnet MRI system is lower than that of the 0.35T Permanent Magnet MRI system. The liquid helium zero volatilization technology is adopted to greatly reduce the consumption of liquid helium. It has the advantages of simple and compact structure, high magnetic field strength and uniformity, good controllability, stable and reliable operation, continuous adjustable magnetic field, energy saving, economy, environmental protection, and outstanding cost performance.

The successfully developed 0.7T open NMR superconducting magnet system, gradient coil, RF coil and image processing software system will be industrialized by Ningbo Jianxin Machinery Co., Ltd., with an estimated output value of more than 1 billion yuan. The successful development of the system improves the ability and level of our country in the industrialization of superconducting magnet technology and high-performance medical MRI equipment, and has good economic and social benefits.

In 2010, the Chinese Academy of Sciences introduced the first Siemens 7T nuclear magnetic resonance system in China. With excellent quality and high-quality service, our products were successfully applied in the magnetic resonance supporting project of this system.