Physical Properties of Materials and Testing Methods

The use of materials in particle accelerator applications implies the consideration of physical properties in different environments than usual industrial applications. Cryogenic temperatures, high radiation, medium to high vacuum and high magnetic fields are requirements for which the behavior of materials has to be evaluated. In this lecture, Thermal, Electrical and Magnetic properties are briefly introduced, highlighting the mechanisms governing variation with temperature and magnetic field. Standards and testing methods for different properties are described, illustrated with practical examples. With regard to the characterization of thermal properties of a material, testing methods of heat capacity and thermal conductivity are described, with details of the main working principle and measurement examples. Determination of electrical resistivity and the residual resistivity ratio (RRR) are the main characteristics of electrical properties, together with specific characterization of superconducting materials. Testing magnetic properties deserve special attention; different methods are commonly employed to characterize non-magnetic and magnetic materials. In magnetic metals and ferrites non-linear behavior and hysteresis effects need to be considered in order to assess their suitability for applications or to model material performance.