Optimizaion between pulsed power supply and Dielectric Barrier Discharge plasma reactor for sterization

Abstract

Dielectric Barrier Discharge (DBD) reactor is frequently used in sterilization with atmospheric pressure plasma in pulsed corona or glow discharge mode. The suggested mechanisms responsible for sterilization include oxygen excited states, ozone, high temperature, UV, and run away electron bombardment. Although which is the key mechanism is yet to be identified due to variations in reactor design and experiment condition, it is generally believed a higher plasma density would facilitate the sterilization process, while a lower ion temperature less en the surface damage, but the these two imply contradictory output characteristics from the pulsed power supply. Higher pulse voltage or repetition frequency not necessarily creates better sterilization effect. A compact, energy efficient power supply is desired in many portable applications, but often energy is wasted as a reflection due to impedance mismatch between transmission line and the impedance of DBD, or dissipated in the dielectric layer of DBD. This work analyzes the energy efficiency of a pulsed power supply to a DBD reactor by introducing equivalent circuit models in different stages: initiation, pulsed corona, glow discharge, and try to link the performance of the pulsed power supply to the mechanisms responsible for sterilization. One conclusion is high pulse voltage with fast rise time is vital to run away electron generation, but not necessary for excited oxygen generation. Enough repetition rates for needed plasma can save considerable energy, and a DBD reactor with low dielectric layer thickness and low dielectric constant will render the highest electric field across the gap and thus most energy efficiency.