In the PBII method, the ion density in the sheath could be obtained based on the modulator equivalent circuit. In the PBII method, the self-ignitting plasma used in the sterilization process was formed, and the plasma density and sheath length could be calculated from the obtained discharge current-high voltage voltage waveform. Using this method, some of the important parameters such as plasma density and sheath length could be obtained when designing the equipment in the future.