2. Generating magnetic fields

2.1 Magnetic field sources

The characterization of technical magnetic materials requires the ability to generate and control the field over an amplitude range covering several orders of magnitude. If soft materials are to be tested, we can exploit the fields generated by suitably shaped coils, through which direct or alternating currents flow. For the characterization of hard materials, which require fields in excess of 10 ⁴ -10 ⁵ A/m, the use of conventional air coils is only conceivable in pulsed regime, due to obvious heat dissipation problems. To produce strong continuous or slowly varying fields, electromagnets (up to around 2 · 10 ⁶ A/m) or...