Handbook of Magnetic Measurements

Testing of Magnetic Materials 307

In the pulse technique, the large error can appear due

to eddy currents and magnetic viscosity. Figure 5.107

presents the result of testing of neodymium magnet for

two different pulses. The static value of

J

H

c

was about

1200 kA/m while for pulse 40 ms pulse the result was

1385 kA/m. This difference can be much larger for very

short pulses and for pulses shorter than 1 ms this error

can be even 40% (Grössinger et al. 1993). Fortunately,

the methods for effective correction of this error were

developed (Jewell et al. 1992, Golovanov et al. 2000).

The commonly used method known as f/2f method

con