One way to make the pulse compression switching process occur automatically was
devised by Melville in the 1940s [1]. The inductors in the magnetic pulse compression
circuit (Figure 13.7) have saturating soft magnetic cores, typically of NiFe ferrite or
amorphous metal. These give the inductors a magnetic switching characteristic. While
the core is unsaturated (μ0μr ), the inductor presents a high impedance to current flow.
When the core is driven into saturation, the inductor presents a low impedance (μ0),
and current is able to flow according to the value of Lsat . The transition between
unsaturated and saturated states can occur in 10–100 ns timescales, which means that
the inductor exhibits a quite rapid magnetic switching characteristic.