The Role of Nonlinear Body Force in Electrostatic Propeller Driven by Atmospheric DC Corona Discharges

In this study, the body force generated by atmospheric positive and negative corona discharges were investigated using a wire-cylinder configuration experimentally and numerically. We provided new insight into the atmospheric electric thruster by introducing a nonlinear term in body force constituent the thrust of the system. It was observed that the direction of both body forces and electric winds is always from the wire to the cylinder irrespective of the applied voltage polarity. It was illustrated that the corresponding thrusts and the electric wind of the positive corona are larger than that of the negative corona discharge. We took into account the nonlinear mechanisms to explain the difference in thrust forces in positive and negative corona discharges. To elucidate the origin of the body force in corona discharges, we performed 2-D simulations via COMSOL Multiphysics and MATLAB software. The results of the numerical simulation showed that in addition to the linear body force (Coulomb force) a strong nonlinear body force is generated around the wire electrode that plays a crucial role in corona thrusters. To verify the direction and magnitude of the thrust, a simple theory was proposed based on variable mass systems and confirmed by published experimental works.

Degradation of glyphosate in water by the application of surface-corona-discharges

Glyphosate (GLP) is one of the most widely applied herbicide, which is found ubiquitously in the environment. The removal of glyphosate from waste water and soil is challenging and can be achieved with chemical or biological methods, which, nevertheless, suffer from different disadvantages. The application of a physical plasma for the removal of GLP in water was examined by the application of surface corona discharges in a wire-to-cylinder setup filled with argon. The plasma was ignited at the liquid surface without any additives. By applying a photometric method, GLP was detected after derivatisation with fluorenyl methoxycarbonyl chloride, whereas phosphate was determined with ammonium molybdate. A GLP degradation rate of 90.8% could be achieved within a treatment time of 30 minutes with an estimated energy efficiency of 0.32 g/kWh.

Corona discharge of a vibrated insulating box with granular medium

Corona discharges are luminous signs of strong local electric fields allowing a continuous discharge into the surrounding atmosphere. They commonly occur at the ends of conductors at high voltage. Here we report the observation of a faint glow surrounding an insulating cm-sized box filled with mm-sized basalt beads. At an ambient pressure in the mbar range two light bands occur as soon as and only if the box is vibrated and only if it is filled with a granular medium. In addition, a glow also occurs at the inside of the box. We measured periodic electric fields at the outside of the box with spatial peaks at the positions of the light bands. The period correlates to the vibration frequency. These observations imply strong alternating fields beyond atmospheric breakdown, which are generated inside and also emerge at the outside of the insulating box. The observations can be explained by tribocharging and periodic displacement of charges between grains and the inside walls of the box.