Control of particle charge by atmospheric pressure plasma jet (APPJ): A review

Atmospheric pressure plasma jets (APPJs) have more advantages regarding flexibility of operation than low pressure plasmas. Because the ions and/or electrons in the APPJ can be arbitrarily extracted to a gas-phase space by changing the DC bias voltage and efficiently deposited onto particle surfaces in an external electric field, this operating technique can be applied towards controlling particle charge. Several methods to control the particle charge using an APPJ system have already been reported. This article summarizes the specifications and operations of these systems, their mechanisms of charge transfer, and methods for particle charging, based on previously reported work. The methods are categorized into three groups, i.e., direct charging of particles, direct charging of a powder bed, and indirect charging of particles, and the corresponding experimental setups, procedures, results, and discussions are presented.