CMC for Amorphous Magnetic Cores in a 100 kHz-1 MHz Frequency Range

The CMC (control magnetization curves) of amorphous cores, in both toroidal and ring shapes, were measured at frequencies up to 1 MHz. The high-frequency measurements were facilitated by use of a FET dc chopper. The characteristics at 1 MHz, compared with those at lower frequencies, are characterized by a smaller maximum flux density, probably due to core heating, and a narrower region of proportionality. For all samples, H
_r
was found to obey H
_r
∝ f
^0.9
~f
^1.1
, where f is the magnetizing frequency.