High-strength conductors for supermagnets

With the introduction of powerful magnets such as the National Magnet Laboratory´s 225-kG device that recently went into continuous operation, it has become necessary to consider the structural problems that arise because of the high stresses¿and high temperatures¿involved in generating these high fields. Primarily, a magnet material must be provided that possesses strength as well as porosity. Various combinations of ETP copper, steel, beryllium-copper, and zirconium-copper have proved effective. Also, it is pointed out that stresses can be reduced by proper arrangement of the coils, and that there is an advantage to using high-strength materials in stress-limited magnets despite their increased resistivity.