Particle-in-cell simulation of a radioactive probe in wind

A two-dimensional particle simulation model was developed to investigate wind effects on charge density measurements under HVDC lines, using a radioactive probe. The particle simulation technique was successful in macroscopically describing the motion of charged particles under the influence of wind, electric field, and diffusion. The simulation results were in good agreement with wind tunnel experiments. The simulation revealed that at higher wind speeds, the charged particles in the ionization region were convected away faster than at lower wind speeds. This reduced the recombination rate at the probe and thereby resulted in a more negative floating potential. At constant wind speed, the floating potential was less negative when the probe emitting surface was in the wake because wind velocity in the wake was much smaller (assumed zero in the simulation.)