The HiPIMS power supply used here was designed in home and suitable for a rather small size of magnetron. The power supply, referred to as the impulse unit, is basically a unipolar pulse power supply delivering high power pulses to the magnetron. The principle of the impulse unit based on the resistor-capacitor (RC) circuit in which the power is charged up to a bank capacitor and discharged down to the magnetron and an internal resistor. The essential parts in the impulse unit are shown in gure 5.4 including a dc charger, an energy storage capacitor, an insulator gated bipolar transistor (IGBT),an IGBT controller and a TTL pulse generator. The maximum charging voltage applied to the capacitor was 950V. This charging voltage was used to control an amount of the energy stored in the bank capacitor which in turn control the current and the power delivered to the magnetron. The stored energy in the capacitor was delivered to the magnetron when the IGBT was biased by a TTL pulse either from the built-in signal
generator or from the external triggering signal.