Development and Optical Emission Spectroscopy Characterization of a 13.56 MHz RF Plasma Source

This paper presents the development of a radio-frequency (RF) plasma source capable of operating on molecular gases and its initial physical testing and characterization via optical emission spectroscopy (OES). The plasma source has a cylindrical geometry and is powered by a 13.56 MHz radio frequency (RF) power supply. The source is designed to serve as a testbed for molecular plasma investigations in support of electric propulsion applications. The source’s thermal limits, pressure capabilities, and coupling efficiency were first evaluated. Then, broadband (time-averaged) survey spectra were obtained for species identification and to study specific non-equilibrium plasma temperatures. A rovibrational fit was performed using the Specair non-equilibrium code for spectra collected during operation on nitrogen and specific rotational and vibrational temperatures are reported.