The effect of gas on tribocharging of particles in a vibrated bed

The total charges acquired by soda-lime glass particles and polyethylene particles were measured in a vibrated bed under a nitrogen or argon environment. The charge magnitudes were lower in argon compared to nitrogen. Complementary Discrete Element Method simulations using the gaseous dielectric strength as a constraint largely reproduce the experimental observations. The electric field was found to reach the breakdown constraint during particle-wall contact. The particle charge levels in argon were found to strongly correlate with gas breakdown. A simplified analysis using Gauss's law revealed that the charge levels in glass particle experiments are limited by dielectric breakdown associated with particle surface area and the charge levels in polyethylene particle experiments are limited by dielectric breakdown associated with the surface area of the bounding wall.