Using Radiation from the Wakefield of a Hydromechanically Generated Toroidal Argon Plasma for Electron Parameter Diagnostics*

Toroidal plasmas generated through extreme hydrodynamic shear are a unique instance of atmospheric plasmas that are indefinitely stable without external sources of electric current or potential. The extreme shear created from an impinging water jet creates intense polarization (via triboelectrification) resulting in ionizing discharges into the ambient gas. In this work, optical emissions from this type of toroidal plasmoid in argon are used as the diagnostic medium to measure electron behavior in the plasma. Measurement of spectral lines of argon and continuum radiation emitted from the plasma allow a calculation of a spatial distribution of electron temperature. It is shown that the bremsstrahlung radiation from electron-neutral collisions is the dominant source of continuum radiation. Furthermore,  a radial blue-shift of bremsstrahlung radiation is measured, indicating electron acceleration through an electric field.