Electric field measurements in atmospheric pressure plasmas

Low temperature plasmas at atmospheric pressure offers possibilities that were not accessible to plasma-based technologies for a long time, such as usage on materials sensitive to high temperatures, (bio)materials that are not resistant to vacuuming or even fully drying, (bio)targets that are sensitive to significant current transfer. In addition to the simplicity with which the plasma sources can be built and the ease with which they can be operated, lot temperature plasmas have become very popular in the recent years. A great number of scientific publications has followed this rise in interest for atmospheric pressure plasmas, covering different geometries of mostly dielectric barrier discharges (DBDs), used with or without gas flow and a wide range of excitation frequencies from Hz to MHz. Most commonly reports address the discharge dynamics, densities of heavy species, at times gas temperature measurements, imaging of flow fields and rarely electron densities and electric field but very few on electric field measurements.

This paper will give an overview of the recent work in the electric field measurements in atmospheric pressure plasma jets that operate in the ’bullet mode’. A Helium jet with flow rates up to 2 SLM, in a low-power mode (up to 1 W dissipated in the discharge). The jet is run in the bullet mode where one plasma bullet is emitted per voltage period. The results fill focus on the comparison between the jets driven by 30 kHz sine voltage and jets driven by short high voltage pulses. Two measurement methods have been used that allow for comparison between the electric field in the gas phase and on the treated targets, which vary from dielectrics to liquids.