**2. References**

[1] Takizawa T and Murakami M Eds. (2005) Critical Current in Superconductors. Tokyo: Fuzambo International.

[2] Matsushita T (2007) Flux Pinning in Superconductors. Berlin, Heidelberg New York: Springer.

78 Superconductors – Materials, Properties and Applications

**Author details** 

*TUMSAT-OLCR, Tokyo, Japan* 

*CRISMAT/LUSAC-UNICAEN, Caen, France* 

Motohiro Miki, Brice Felder and Beizhan Li.

Fuzambo International.

Mitsuru Izumi

Jacques Noudem

**2. References** 

**Acknowledgement** 

the growth window and processing large bulk superconductors.

realized by the present new method. It was demonstrated that the texture growth can be transferred from a high-*T*p pellet to a low-*T*p pellet, which may be promising for extending

The single domain of Y123 bulks with multiple holes has been processed and characterized. SEM investigations have shown that the holes' presence does not hinder the domain growth. The perforated samples exhibit a single domain character evidenced by a single dome trappedfield distribution and neutron diffraction studies. This new structure has great potential for many applications, with improved performances in place of Y123 hole free bulks, since it should be easier to maintain at liquid nitrogen temperature and/or to improve thermal conductivity during application, avoiding the appearance of hot spot. It is clear that the Y123 bulks with an artificial pattern of holes are useful for evacuating porosity from the bulk and assisting the uptake the oxygen. The ability of the Y123 material with multiple holes to trap a high field has been demonstrated. Using high pressure oxygenation, the trapped field increases up to 0.8 T at 77 K for the thin wall pellet, corresponding to 50% more than the bulk material without holes. Using pulse magnetization, the trapped fields increases by up to 60% for the drilled pellet with respect to the plain one. Superconducting bulks with an artificial array of holes can be filled with metal alloys or high strength resins to improve their thermal properties without any important decrease of the hardness [50], so as to overcome the built-in stresses in levitation and quasi-permanent magnet applications. The thin wall bulks superconducting on extruded shapes for portative permanent magnets are under development for the introduction at the large scale of this innovative approach of "material by design".

The present work was supported by KAKENHI (21360425), Grant-in-Aid for Scientific Research (B) and the "Conseil Régional de Basse Normandie, France". This work was partly performed using the facilities of the Materials Design and Characterization Laboratory, Institute for Solid State Physics, University of Tokyo. The authors would like to thank Caixuan Xu, Yan Xu, Xu Kun, Keita Tsuzuki, Difan Zhou, Shogo Hara, Yufeng Zhang,

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**Chapter 5** 

© 2012 Wang et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Wang et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In this chapter, basic magnet principles, methods of generating a magnetic field, magnetic field applications and numerical methods for the magnet structure design are briefly introduced and reviewed. In addition, the main numerical optimal technology is

**Superconducting Magnet** 

**Technology and Applications** 

Qiuliang Wang, Zhipeng Ni and Chunyan Cui

Additional information is available at the end of the chapter

The development of superconducting magnet science and technology is dependent on higher magnetic field strength and better field quality. The high magnetic field is an exciting cutting-edge technology full of challenges and also essential for many significant discoveries in science and technology, so it is an eternal scientific goal for scientists and engineers. Combined with power-electronic devices and related software, the entire magnet system can be built into various scientific instruments and equipment, which can be found widely applied in scientific research and industry. Magnet technology plays a more and more important role in the progress of science and technology. The ultra-high magnetic field helps us understand the world much better and it is of great significance for the research into the origins of life and disease prevention. Electromagnetic field computation and optimization of natural complex magnet structures pose many challenging problems. The design of modern magnets no longer relies on simple analytical calculations because of the complex structure and harsh requirements. High-level numerical analysis technology has been widely studied and applied in the large-scale magnet system to decide the electromagnetic structure parameters. Since different problems have different properties, such as geometrical features, the field of application, function and material properties, there is no single method to handle all possible cases. Numerical analysis of the electromagnetic field distribution with respect to space and time can be done by solving the Maxwell's equations numerically under predefined initial and boundary conditions combined with all kinds of

http://dx.doi.org/10.5772/48465

mathematic optimal technologies.

introduced.

**1. Introduction** 

